研究者詳細 - 大野　哲靖

Tungsten fuzz growth at low temperatures (<900 K) on a surface with nanocones 査読有り国際誌

Shi Q., Kajita S., Ohno N.

Nuclear Materials and Energy 39 巻頁： 101668 2024年5月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Materials and Energy

The tungsten (W) fuzzy structure was widely observed in linear plasma devices under the fusion-relevant condition. This type of structure can be used in many application fields benefiting from its larger surface area and high optical absorbance. However, W fuzz can be barely formed when the sample temperature is lower than 900 K. This study decreased the threshold to ∼800 K using W co-deposition on a Si nanocones substrate. It suggests that the conventional threshold temperature is only necessary for He bubble rupture to create a rough surface that induces the uneven trapping of the adatom diffusion.

DOI： 10.1016/j.nme.2024.101668

Surface modification of ZrC dispersion-strengthened W under low energy He plasma irradiation 査読有り国際共著

Li L., Liu Z., Chen Z., Yin C., Mao S., Wu X., Ohno N., Ye M.

Nuclear Fusion 64 巻 ( 5 ) 頁： 56008 2024年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

ZrC dispersion-strengthened W exhibits high strength/ductility, low ductile-to-brittle transition temperature, and excellent thermal shock resistance, making it a promising candidate plasma-facing material for future fusion devices. In this study, surface modification of 0.5 wt.% ZrC dispersion-strengthened W (WZrC) under low energy and high fluence He plasma irradiation at high temperature was presented. Under the energy of 90 eV and fluence ranging from 6 × 1024 He·m−2-2 × 1026 He·m−2 He irradiation at 920 °C, a typical fuzz nanostructure appeared on the W matrix of WZrC. The thickness of fuzz layer is proportional to the square root of He irradiation fluence. The fuzz showed comparable thickness and structural features to pure W, indicating limited effects of the particle’s addition on resistance to high fluence He irradiation at high temperatures. Under continuous He injection, the fuzz would grow extending onto the particle area, making the particle obscured. Besides, the erosion behavior of particles under He plasma irradiation has been investigated, which is thought to be dominated by a sputtering process. Under the He influence of 6 × 1024 He·m−2, only nanopores were observed in the surface region. With fluence increasing to 5 × 1025 He·m−2, the surface became relatively uneven with larger holes. W aggregated in spots and distributed on the surface of the particle, which might be the result of subthreshold sputtering and deposition. When fluence further increased to 2 × 1026 He·m−2, the particles were eroded completely and covered by the extended fuzz, forming cavities. In addition, distinctive layered nanotendrils were observed above the cavities, which were characterized to consist of inner W-riched skeletons and outer Zr-riched layers. It indicates that the layered nanotendrils should be the result of fuzz extension combined with particle sputtering/deposition.

DOI： 10.1088/1741-4326/ad2f4c

Nanopatterning of Si surfaces by normal incident He plasma irradiation 査読有り

Liu Z., Li L., Gao Z., Chen Z., Yin C., Mao S., Kajita S., Ohno N., Ye M.

Applied Physics Letters 124 巻 ( 10 ) 2024年3月

出版者・発行元：Applied Physics Letters

This study reports on the formation of self-organized silicon (Si) nanostructures by 75 eV helium (He) plasma irradiation at normal incidence without the presence of impurities. In contrast to the featureless surface after normal incidence argon (Ar) ion beam irradiation without the co-deposition of impurities, the Si surface exhibits the development of faceted nanostructures under 75 eV He plasma irradiation. The faceted structures are interspersed with valleys that extend in two orthogonal directions, imparting a mountain-like morphology to the surface. Our investigation verifies that the He bubbles align themselves along the direction perpendicular to the surface underneath these valleys. Furthermore, the presence of He bubbles induces distortion in the surface layer and leads to the formation of an amorphous Si layer. The underlying mechanism driving this surface evolution could be attributed to the instability induced by the presence of He bubbles.

DOI： 10.1063/5.0186756

Cone array formation on Si surfaces by low-energy He plasma irradiation with magnetron sputtering pre-deposited Ta 査読有り国際共著

Liu Z., Li L., Gao Z., Chen Z., Yin C., Mao S., Kajita S., Ohno N., Ye M.

Journal of Applied Physics 135 巻 ( 9 ) 頁： 93302 2024年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Applied Physics

Low-energy ion beam irradiation, combined with the introduction of impurities, presents a promising approach for nanopatterning silicon (Si) surfaces. In this research, we investigate the surface evolution of Si (100) surfaces irradiated by 75 eV helium (He) plasma, in the presence of tantalum (Ta), traditionally regarded as an impurity incapable of initiating pattern formation, as evidenced in prior studies. The Ta impurities are pre-deposited onto the Si surfaces using the magnetron sputtering method, which offers a more controlled and quantifiable approach compared with the conventional co-deposition route. After irradiation at 800 K, dense cone arrays are produced on the Si surface. The growth of the cones is explored for fluence spanning (1-10) × 1025 m−2. The cross-sectional scanning electron microscope images indicate that the cone lengths and base width are well characterized by t1/2 dependence. The kinetics of the cone growth follow Fick’s law, characterized by an effective diffusive mechanism with the coefficients of diffusion: D = 6.49 ± 0.83 × 10−16 m−2 s−1. Transmission electron microscope observations reveal that the cone has distinct inner and outer parts with different microstructures and a clear interface. The growth mechanism of these cones is elucidated as a composite process involving preferential sputtering, the destabilizing influence of He bubbles, and the migration of adatoms.

DOI： 10.1063/5.0187265

Plasma-Driven Sciences: Exploring Complex Interactions at Plasma Boundaries 査読有り国際誌

Ishikawa K., Koga K., Ohno N.

Plasma 7 巻 ( 1 ) 頁： 160 - 177 2024年3月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plasma

Plasma-driven science is defined as the artificial control of physical plasma-driven phenomena based on complex interactions between nonequilibrium open systems. Recently, peculiar phenomena related to physical plasma have been discovered in plasma boundary regions, either naturally or artificially. Because laboratory plasma can be produced under nominal conditions around atmospheric pressure and room temperature, phenomena related to the interaction of plasma with liquid solutions and living organisms at the plasma boundaries are emerging. Currently, the relationships between these complex interactions should be solved using science-based data-driven approaches; these approaches require a reliable and comprehensive database of dynamic changes in the chemical networks of elementary reactions. Consequently, the elucidation of the mechanisms governing plasma-driven phenomena and the discovery of the latent actions behind these plasma-driven phenomena will be realized through plasma-driven science.

DOI： 10.3390/plasma7010011

Thermal Conductivity Measurement of Fuzzy W Using a Thermoreflectance Method 査読有り

Kajita S., Yagi T., Ohno N.

IEEE Transactions on Plasma Science Early Access 巻頁： 1 - 6 2024年1月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE Transactions on Plasma Science

Fuzzy nanostructured tungsten (W) is formed by helium (He) plasma irradiation. In fusion devices, the thermophysical properties are important to consider the response to pulsed heat load from the plasma. In this work, the thermal conductivity of the W fuzz is measured using a pulsed light heating thermoreflectance method. A detailed model was developed to explain the entire temporal evolution of the thermoreflectance signal. It was found that the thermal conductivity of the nanostructured layer was deduced to be in the range of 0.18%–0.21% of the pure (ideal) W and lower than the previously reported highly porous metallic materials. In addition to the porosity, the specific nonuniform nanofiber structure is likely to contribute to the low effective thermal conductivity.

DOI： 10.1109/TPS.2023.3348465

Thermal response of nano-tendril bundles to steady heat load 査読有り国際共著

Xue Q., Tanaka H., Zhang R., Kajita S., Hori K., Shi Q., Kuwabara T., Ohno N.

Japanese Journal of Applied Physics 62 巻 ( SN ) 2023年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Nano-tendril bundles (NTBs) are nanostructures formed on the surface of tungsten under helium plasma irradiation with impurities. Upon annealing, NTBs of different sizes exhibit distinct morphological changes. This study aims to elucidate the underlying reasons for the different morphological changes observed in NTBs through the analysis of their thermal responses. A simulation approach was employed to investigate the temperature distribution of NTBs with different heights, aspect ratios, and porosities during annealing experiments. The simulation results revealed varying degrees of impact of height, aspect ratio, and porosity on the temperature distribution of NTBs during annealing. This finding contributes to a better understanding of the thermal properties and reactions of NTBs.

DOI： 10.35848/1347-4065/ace6ac

Transition from MAR to EIR of deuterium plasma detachment in NAGDIS-II 査読有り国際共著

Shi J., Kaizawa H., Tanaka H., Kajita S., Ohno N., Ding H.

Physica Scripta 98 巻 ( 11 ) 頁： 115605 2023年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physica Scripta

Volumetric plasma recombination in a detached deuterium (D) plasma was experimentally studied in the linear plasma device NAGDIS-II. The radial distributions of the electron temperature (Te) and the electron density (ne) were measured by upstream and downstream laser Thomson scattering (LTS) systems and D-atom excited states of the Balmer series (n = 3-7) were measured by optical emission spectroscopy (OES). The results indicated that the electron static pressure, particle flux and heat flux present a two-step reduction with an increasing neutral pressure, suggesting that molecule activated recombination (MAR) and electron-ion recombination (EIR) were activated, respectively. The difference in the distributions of the atomic state population densities was observed to be a feature of the transition from the MAR-dominant phase to the EIR-dominant phase. The transition between the two phases had a distinct boundary at Te ∼0.7 eV, which was considered a transition point between the phases. The ratios of the atomic state population densities showed different features in the two phases, and are expected to be useful in characterizing the phase and degree of plasma detachment.

DOI： 10.1088/1402-4896/acfeb4

Application of machine learning for optical emission spectroscopy data in NAGDIS-II 査読有り

Kajita S., Sakakibara T., Kaizawa H., Natsume H., Tanaka H., Fujii K., Ohno N.

Fusion Engineering and Design 196 巻頁： 114012 2023年9月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Engineering and Design

In this study, we applied machine learning to optical emission spectroscopy (OES) data and device parameters from the linear plasma device NAGDIS-II to explore the potential application of machine learning for predicting electron density, ne, and temperature, Te. The covered ranges of ne and Te, which were measured by an electrostatic probe, are 3.6 × 1017–2.4×1019 m−3 and 0.3–7.1eV, respectively. A three hidden layer neural network (NN) is introduced to model the relationship between ne/Te and the combination of line intensities, radial position, and device parameters. It is shown that the errors in ne and Te become 18.0 and 18.8%, respectively, which were almost the same level for the electrostatic probe, using all available data. Lasso regression and greedy algorithm are used to select the necessary line emissions. It is shown that four or five line intensities are sufficient to obtain almost the same quality as the one with all the other lines.

DOI： 10.1016/j.fusengdes.2023.114012

Fabrication of tungsten-based optical diffuser using fiberform nanostructure via efficient plasma route 査読有り国際共著

Feng S., Natsume H., Kajita S., Li E., Yasuhara R., Tokitani M., Tanaka H., Ohno N.

Optics Express 31 巻 ( 16 ) 頁： 25438 - 25445 2023年7月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Optics Express

Optical diffusion is an essential process used to manage photons in a wide range of photoelectric systems. This work proposes an approach to fabricate novel optical diffusers by a plasma-processing technique, using fiberform nanostructures formed by helium plasma irradiation and subsequent annealing. After an annealing procedure in the air for oxidation, the optical properties and the light-diffusing abilities of these nanostructured thin films were studied. In addition to the morphology analysis and total transmittance measurement, the diffusion efficiency of the optical diffusers was analyzed using a transmitted scatter distribution function (TDF). It was revealed that the diffusion efficiency of a device with an irradiation time of 30 minutes could reach 97%. The results demonstrate the potential of these nanostructured optical diffusers for various photoelectric applications.

DOI： 10.1364/OE.493993

Field emission properties of nano-tendril bundles formed via helium plasma exposure with various additional impurity gases 査読有り国際共著

Zhang R., Kajita S., Hwangbo D., Tanaka H., Feng S., Ohno N.

Materials Research Express 10 巻 ( 5 ) 頁： 054002 2023年5月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Materials Research Express

Nano-tendril bundles (NTBs) were formed on tungsten via helium (He) plasma exposure with various additional impurity gases, such as neon (Ne), nitrogen (N2), and argon (Ar). The sizes of the NTBs showed different distributions with different additional impurity gases. The field emission property of the NTBs formed with various additional impurity gases was measured. The field-emission property was significantly affected by the morphology of the NTBs, especially the tips of the fibers. In the Ne- and Ar-seeded cases, the NTBs were formed with sharp tips, and the onset electric field for field emission was ∼1 kV mm−1 for all the NTB samples. The Ne-seeded samples showed the most rapid increase in the emission current. In the N2-seeded case, two types of NTBs were formed. The NTBs were formed with sharp tips when the ratio of N2 impurity gas was 2.1%. With an increase in the ratio to 3.0% or higher, the fibers of the NTBs became thicker and the tips became rounder. In the Fowler-Nordheim (F-N) plot analysis, the field enhancement factors were approximately 6000-7000 without significant differences, for all NTBs with sharp tips. NTBs with round tips showed totally different field emission property, as the emission current was only several μA, which is one-tenth of that for the other samples. This suggests that the local morphology of NTBs, especially the geometrical shape of the tips, and not the general size of NTBs, is the main factor in determining the field emission property of NTBs.

DOI： 10.1088/2053-1591/acd1d4

Growth origin of large-scale fiberform nanostructures in He-W co-deposition environment 査読有り

Hori K, Kajita S, Zhang R, Tanaka H, Ohno N

Scientific reports 13 巻 ( 1 ) 頁： 5450 2023年4月

Rapid growth of nanostructure on tungsten thin film by exposure to helium plasma 査読有り

Feng S., Kajita S., Tokitani M., Nagata D., Ohno N.

Plasma Science and Technology 25 巻 ( 4 ) 頁： 042001 2023年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plasma Science and Technology

A fiberform nanostructure was synthesized by exposing high-density helium plasma to a 100 nm thick tungsten thin film in the linear plasma device NAGDIS-II. After helium plasma exposure, the cross-section of samples was observed by a scanning electron microscope, transmission electron microscope, and focused ion beam scanning electron microscope. It is shown that the thickness of the nanostructured layer increases significantly for only a short irradiation time. The optical absorptivity remains high, even though it is exposed to helium plasma for a short time. The usage of the thin film can shorten the processing time for nanostructure growth, which will be beneficial for commercial production.

DOI： 10.1088/2058-6272/ac9f2d

Erratum: Morphologies of co-depositing W layer formed during He plasma irradiation (International Atomic Energy Agency (2018) 58 (106002) DOI: 10.1088/1741-4326/aad24e) 査読有り

Kajita S., Kawaguchi S., Yoshida N., Ohno N., Tanaka H.

Nuclear Fusion 63 巻 ( 4 ) 2023年4月

Correlation of the Orthogonal Basis of the Core Plasma Distribution to the Divertor Footprint Distribution in LHD

Tanaka H., Masuzaki S., Kawamura G., Hayashi Y., Kobayashi M., Suzuki Y., Mukai K., Kajita S., Ohno N.

Plasma and Fusion Research 18 巻 ( 0 ) 頁： 2402021 - 2402021 2023年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

We have applied the multivariable analysis technique called the proper orthogonal decomposition (POD) to both the divertor particle flux distribution and the electron pressure distribution in the core region of LHD. The cross-correlation analysis indicates that 3rd, 4th, and 5th POD modes of the electron pressure distribution are highly correlated with the divertor footprint index which is a measure of where the peak position of the particle flux distribution is located on the inner divertor plate. Both the 3rd and 4th modes seem to correspond to the shift of the electron pressure peak position from the magnetic-axis radius. In contrast, 5th mode has a strong influence on the peripheral gradient of the electron pressure distribution. Their relationships with the divertor footprint could be explained by the finite β and the Pfirsch-Schlüter current effects.

DOI： 10.1585/pfr.18.2402021

Study of the intermittent plasma structure around the divertor simulation experimental module in GAMMA 10/PDX 査読有り

Tanaka H., Ezumi N., Sugiyama T., Gamo H., Shigematsu N., Yoshikawa M., Kohagura J., Hirata M., Togo S., Ohno N., Sakamoto M.

Physics of Plasmas 30 巻 ( 3 ) 頁： 32501 2023年3月

掲載種別：研究論文（学術雑誌）出版者・発行元：Physics of Plasmas

We have investigated the generation region of intermittent plasma structures, which could be due to the blob-like cross field transport around the divertor simulation experimental module (D-module) in the tandem mirror device GAMMA 10/PDX. A positive skewness of the ion saturation current was clearly seen when the electrode of the movable probe was located at the radial edge and just in front of the entrance limiter of the D-module. Fourier analysis and conditional averaging clarified that positive spikes intermittently appeared in the same region. This is the first indication that the phenomenon producing the high-density isolated plasma structures occurred in the upstream of the D-module. A negative skewness was also found, and large amplitude fluctuation was detected between regions showing positive and negative skewness. Furthermore, this and light emission fluctuations become stronger during the transient state from attached to detached state on the V-shaped target.

DOI： 10.1063/5.0129886

Structural Correlation of Random Lasing Performance in Plasma-Induced Surface-Modified Gallium Nitride 査読有り

Shi Q., Fujiwara H., Kajita S., Yasuhara R., Tanaka H., Ohno N., Uehara H.

ACS Applied Optical Materials 1 巻 ( 1 ) 頁： 412 - 420 2023年1月

出版者・発行元：ACS Applied Optical Materials

The surface of GaN has been modified by a simple method that irradiates the substrate with Ar plasma and impurity codeposition, which is termed CoDE (Co-Deposition Etching). Unique structures were formed by the assistance of a small amount of Mo deposition without degradation of the crystal structure. The size of protrusions on the structure is influenced by the amount of deposited Mo particles. The mechanism for the structure formation is discussed based on transmission electron microscopy (TEM) observations and energy dispersive X-ray spectroscopy (EDS) measurements. Based on the GaN surface roughness, we have demonstrated random laser action in the UV region under photoexcitation. The lowest threshold (0.06 J/cm2) for random lasing was observed where the size of the structure is larger than 0.05 μm2, which was formed under conditions with the least amount of deposition. The correlation between the submicro/nanosize structures generated by plasma irradiation and lasing was evaluated in detail. The critical parameter to optimize the random lasing was determined to be the size of structures that can be modified by the Mo deposition rate. The results confirmed that the emission properties can be controlled by the processing conditions. This random laser fabrication technique is expected to be widely applicable to various direct-bandgap compound semiconductors.

DOI： 10.1021/acsaom.2c00085

Motion analysis of arc spots on tungsten fuzz by means of self-avoiding random walk model 査読有り

Hwangbo D., Nishijima D., Kajita S., Ohno N.

Japanese Journal of Applied Physics 62 巻 ( SA ) 頁： SA1007 2023年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Arc spot motions on nanostructrued “fuzz” tungsten surfaces are investigated on the basis of a two-dimensional Monte Carlo random walk simulation. To compare with previous experimental results, the effects of self-avoiding, bifurcation and extinction of arc spots, as well as the fuzz thickness dependence, are included in the simulation. Under a given temporal arc current profile which is set as close as possible to the experiment, the results derived from the simulation reveal that the motion and the number of arc spots depend significantly on the fuzz thickness.

DOI： 10.35848/1347-4065/ac79fe

Field emission current from protrusion structures formed by helium plasma with various impurity gases 査読有り

Zhang R., Kajita S., Tanaka H., Hwangbo D., Ohno N.

Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV 2023-June 巻頁： 529 - 532 2023年

出版者・発行元：Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV

Rod-like protrusion structures were formed on tungsten by helium plasma exposure with various impurity gases seeded as nitrogen (N2) and argon (Ar). Surface morphology observations and field emission current measurements were done for two samples. Cross-section observation shows that the inside of the protrusions was solid but not porous like conventional fuzz. Therefore, a new formation mechanism which is different from fuzz can be considered. The field emission current from N2-seeded case was slightly higher than that from fuzz, but much lower than that from NTBs, while the field emission current from Ar-seeded case was similar to that from NTBs. The difference in field emission current could be due to the different morphology of the tips between two samples.

DOI： 10.23919/ISDEIV55268.2023.10200357

Thermal conductivity measurement of fuzzy W using a thermoreflectance method 査読有り

Kajita S., Yagi T., Ohno N.

Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV 2023-June 巻頁： 526 - 528 2023年

出版者・発行元：Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV

Thermophysical properties of the fuzzy nanostructured tungsten (W) layer formed by helium plasma irradiation (a) are measured using a pulsed light heating thermoreflectance method. A three layered model has been developed to explain the temporal evolution of the themoreflectance signal. The thermal conductivity of the nanostructured layer was deduced to be in the range of 0.14-0.26% of the pure (ideal) W.

DOI： 10.23919/ISDEIV55268.2023.10200254

Use of machine learning for a helium line intensity ratio method in Magnum-PSI 査読有り国際共著

Kajita S., Iwai S., Tanaka H., Nishijima D., Fujii K., van der Meiden H., Ohno N.

Nuclear Materials and Energy 33 巻頁： 101281 2022年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Materials and Energy

Optical emission spectroscopy (OES) of helium (He) line intensities has been used to measure the electron density, ne, and temperature, Te, in various plasma devices. In this study, a neural network with five hidden layers is introduced to model the relation between the OES data and ne/Te from laser Thomson scattering in the linear plasma device Magnum-PSI and compared to multiple regression analysis. It is shown that the neural network reduces the residual errors of prediction values (ne and Te) less than half those of the multiple regression analysis in the ranges of 2 × 1018<ne<8×1020 m−3 and 0.1<Te<4eV. We checked two different data splitting methods for training and validation data, i.e., with and without considering the unit of discharge. A comparison of the splitting methods suggests that the residual error will decrease to ∼10% even for a new discharge data when accumulating a sufficient data set.

DOI： 10.1016/j.nme.2022.101281

Plasma induced surface nanostructure on semiconductors for the application of random laser 査読有り

Shi Q., Fujiwara H., Osaka R., Kajita S., Yasuhara R., Ohno N., Uehara H.

2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2022 - Proceedings 2022年

POWER TRANSMISSION FACTOR FOR TUNGSTEN TARGET W/WO FIBER-FORM NANOSTRUCTURE IN H PLASMAS WITH HOT ELECTRON COMPONENT USING COMPACT PLASMA DEVICE AIT-PID 査読有り国際誌

Takamura, S; Miyamoto, T; Ohno, N

FUSION SCIENCE AND TECHNOLOGY 63 巻 ( 1T ) 頁： 225 - 228 2013年5月

Simulation of dynamics of carbon dust particles in the JT-60U tokamak 査読有り国際共著国際誌

Tanaka, Y; Smirnov, RD; Pigarov, AY; Takenaga, H; Asakura, N; Uesugi, Y; Ohno, N

JOURNAL OF NUCLEAR MATERIALS 415 巻 ( 1 ) 頁： S1106 - S1110 2011年8月

Dusty sheaths in plasmas with two-temperature electrons 査読有り国際誌

Asano, K; Chutov, YI; Kravchenko, OY; Ohno, N; Pshenychnyj, AF; Smirnov, RD; Takamura, S

DUSTY PLASMAS IN THE NEW MILLENNIUM 649 巻頁： 277 - 280 2002年

Generation of high heat flux plasma in divertor plasma simulator by ion cyclotron wave heating 査読有り国際誌

Watanabe, S; Ohsawa, S; Takagi, M; Ohno, N; Uesugi, Y; Takamura, S

ICPP 96 CONTRIBUTED PAPERS - PROCEEDINGS OF THE 1996 INTERNATIONAL CONFERENCE ON PLASMA PHYSICS, VOLS 1 AND 2 頁： 1050 - 1053 1997年

Generation of high heat flux plasmas by rf heating in divertor plasma simulator NAGDIS-II 査読有り国際誌

Watanabe, S; Ohsawa, S; Takagi, M; Ohno, N; Uesugi, Y; Takamura, S

RADIO FREQUENCY POWER IN PLASMAS ( 403 ) 頁： 483 - 486 1997年

STUDIES ON SHEATH FORMATION IN DIVERTOR PLASMAS BY COMPUTER-SIMULATION USING PARTICLES 査読有り国際誌

OHNO, N; MASUZAKI, S; KONNO, H; TAKAMURA, S

CONTRIBUTIONS TO PLASMA PHYSICS 32 巻 ( 3-4 ) 頁： 249 - 254 1992年

イオンビーム・プラズマ系におけるサブハーモニクスの励起機構の研究査読有り

大野哲靖, 粕谷俊郎, 田中雅慶, 小森彰夫, 河合良信

九州大学大学院総合理工学報告 9 巻 ( 1 ) 頁： 23 - 27 1987年7月

Formation of micro-pillars on W by He plasma irradiation with N<inf>2</inf>/Ar impurities 査読有り国際誌

Zhang R., Kajita S., Hwangbo D., Tanaka H., Yamamoto Y., Ohno N.

Materialia 39 巻 2025年3月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Materialia

Tungsten samples were exposed to helium plasma with additional nitrogen and argon impurity gases. As a result, microscale pillar-like structures formed on the tungsten surface under similar conditions where nanotendril bundles can be formed. This study summarizes the condition under which those pillar-like structures form. The surface morphology and height profile were observed, and the field emission properties of the W sample with the pillar-like structure were analyzed. The possible formation mechanism of these structures was discussed.

DOI： 10.1016/j.mtla.2025.102341

TALIF measurements of atomic deuterium in toroidal divertor simulator NAGDIS-T 査読有り国際誌

Kajita S., Hiraiwa K., Tanaka H., Iwai R., Aramaki M., Yasuhara R., Ohno N.

Nuclear Materials and Energy 42 巻 2025年3月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Materials and Energy

The behavior of neutral deuterium (D) atoms is important for understanding the physics in the divertor region of nuclear fusion reactors. It is necessary to introduce an active measurement when considering the application to detached plasmas, where recombination processes dominate the processes determining the population distribution. In this work, we have developed a two-photon absorption laser-induced fluorescence (TALIF) system in the toroidal divertor simulator NAGDIS-T to measure D atomic density. The absolute D atomic density was obtained by calibrating the signal with the krypton TALIF signal. The gas pressure and power dependence of the D atomic density is shown. The D atomic density was in the range of 1.6 × 1018–1.4 × 1019 m−3, and the temperature was estimated to be <0.4 eV. The behavior of the D atoms is discussed in terms of the production process.

DOI： 10.1016/j.nme.2025.101898

DISCOVER: New integrated code to simulate helium detached plasma in a linear device 査読有り国際誌

Natsume H., Masuda S., Tanaka H., Migita R., Mano R., Sugiura K., Sawada K., Hoshino K., Hayashi Y., Ohno N.

Physics of Plasmas 32 巻 ( 2 ) 2025年2月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics of Plasmas

A detached plasma integrated simulation code with various elastic/inelastic reactions (DISCOVER) was developed for better understanding of detached helium plasma experiments. DISCOVER, which includes a neutral transport code, fluid code, and collisional radiative code, considers elastic and inelastic collisions between recycling neutrals and bulk particles, as well as the transport of metastable atoms [He( 21S) and He( 23S)]. The code was used for simulating helium plasma in the linear plasma device NAGDIS-II. The transition from attached to detached plasma was demonstrated in the simulation by increasing the upstream electron density through an increase in the gas supply from the plasma source while maintaining a fixed downstream gas injection rate. In addition, similar transition was also observed by introducing neutral particles from downstream, while maintaining a fixed upstream electron density. In the detached plasma, the density of He( 23S) near the end target was approximately seven times higher than that in the attached plasma. Furthermore, it was evident that the transport of He( 23S) enhanced the electron energy rate coefficient and influenced the spatial distribution of the detached plasma.

DOI： 10.1063/5.0243036

Dynamic response of recombining detached plasma to electron beam injection 査読有り国際誌

Tanaka H., Kajita S., Kaizawa H., Ohno N.

Physics of Plasmas 32 巻 ( 2 ) 2025年2月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics of Plasmas

Dynamic response of recombining detached helium plasma to high-energy electrons was investigated in the linear plasma device NAGDIS-II by introducing an electron beam source. A square wave bias was applied to the tungsten electrode to generate a pulsed electron beam with controlled beam energy. At high beam energy condition, a large increase in the target ion flux and different-shape time evolutions between emissions from low- and high-excited states were observed. From the analysis using a collisional radiative code applicable to two electron temperature components, qualitative changes were explained by contributions due to the excitation process from the ground state by the electron beam and the volume recombination process due to the parameter change of bulk plasma.

DOI： 10.1063/5.0242483

Thermal evolution of helium bubbles in tungsten by GISAXS and TDS 査読有り国際誌 Open Access

Teo S.H.B., Thompson M.A.T., Kirby N., Hughes D.R., Hammoud N., Khan A., Tanaka H., Ohno N., Mummery P., Harmer S.L., Corr C.S.

Journal of Nuclear Materials 604 巻 2025年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Materials

Grazing-incidence small-angle x-ray scattering (GISAXS) and thermal desorption spectroscopy (TDS) were used to study the thermal evolution of helium (He) bubbles in tungsten (W). W samples were exposed to a low ion energy (∼20 eV, sheath accelerated) He plasma at two sample temperatures: 573 K (low-temperature) and 1050 K (high-temperature). They were then annealed to temperatures of 773 K, 873 K and 998 K. GISAXS analysis showed an increase in the median bubble radius of the high-temperature samples from 6.42 Å to 12.87 Å as a result of annealing to 998 K. No changes in the bubble radii distributions were observed for the low-temperature samples and the median radius remained at ∼4 Å even after annealing. TDS showed that the desorption behaviour of He in W has a dependence on the sample temperature during plasma irradiation. The higher-temperature sample experienced a maximum desorption rate that is an order of magnitude larger than the low-temperature sample. The desorption profile of the high-temperature sample spanned a wider temperature range, 500 K - 1500 K, than the low-temperature sample, 500 K - 750 K. The formation and thermal evolution of He bubbles in W have a clear dependence on sample temperature during plasma exposure. The differences in annealing behaviour observed in this work agree with prior in-situ TEM annealing experiments and help explain macroscopic plasma-material interaction effects such as recrystallisation suppression.

DOI： 10.1016/j.jnucmat.2024.155524

Open Access

Evaluation of local erosion and deposition on the W-monoblock of JA-DEMO divertor 査読有り国際誌

Oya M., Hoshino K., Asakura N., Sakamoto Y., Ohno N., Hanada K.

Nuclear Materials and Energy 41 巻 2024年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Materials and Energy

We developed and performed a 3D Monte-Carlo simulation on local erosion and deposition in outer divertor target of JA-DEMO. The local erosion and deposition were evaluated considering the divertor plasma parameters and the roof shape of W-monoblocks. First, for local erosion simulation, the trajectories of D ions and impurity (He and Ar) ions were traced before irradiating the monoblock surface. The physical sputtering was calculated by these ions irradiation, considering their charge states, incident-energies and -angles. The highest sputtering flux was produced by multiply-charged Ar ions (Ar3+–Ar5+). The sputtering flux strongly depended on the poloidal positions along the divertor target. Although almost no erosion (sputtering) was obtained in low-temperature zone (∼1 eV), the erosion occurred in mid- (∼10 eV) and high-temperature (>10 eV) zone. Second, for local deposition simulation, the trajectories of W atoms emitted from the monoblock surface were traced. After transport (including ionization and recombination) in the plasma, W atoms and ions were deposited on the monoblock surface. The deposition occurred even on the area where plasmas did not irradiate (shadow). This was due to perpendicular diffusion to magnetic field lines, gyro-orbit effects for W ions and straight-line motion for neutral W atoms. The poloidal distribution of the deposition fluxes was similar to that of the sputtering fluxes. In low-temperature zone, no deposition flux occurred due to very low sputtering flux. The deposition flux in mid-temperature zone increased significantly and that in high-temperature zone remained high.

DOI： 10.1016/j.nme.2024.101793

Recent progress of JT-60SA project toward plasma operation 査読有り国際共著国際誌

Shirai H., Takahashi K., Di Pietro E., Abate D., Abdel Maksoud W., Abe H., Aiba N., Abe T., Akimitsu M., Ayllon-Guerola J., Arai T., Artaud J.F., Asakura N., Ashikawa N., Balbinot L., Barabaschi P., Baulaigue O., Belonohy E., Belpane A., Bin W., Bombarda F., Bolzonella T., Bonne F., Bonotto M., Botija J., Buermans J., Cabrera-Pérez S., Cardella A., Carralero D., Carraro L., Cavalier J., Cavinato M., Chernyshova M., Chiba S., Clement-Lorenzo S., Cocilovo V., Coda S., Coelho R., Coffey I., Collin B., Corato V., Cucchiaro A., Czarski T., Dairaku M., Davis S., Day C., Dela Luna E., De Tommasi G., Decool P., Di Pace L., Dibon M., Disset G., D’Lsa F., Ejiri A., Endo Y., Ezumi N., Falchetto G., Fassina A., Fejoz P., Ferro A., Fietz W., Figini L., Fornal T., Frello G., Fujita T., Fukuda T., Fukui K., Fukumoto M., Funaba H., Furukawa M., Futatani S., Gabellieri L., Gaio E., Galazka K., Garcia J., Garcia-Dominguez J., Garcia-Lopez J., Garcia-Munoz M., Garzotti L., Gasparini F., Gharafi S., Giacomelli L., Ginoulhiac G., Giruzzi G., Giudicotti L., Gonzalez-Martin J., Guillén-González R., Hajnal N., Hall S., Hamada K., Hanada K., Hanada M., Hasegawa K., Hatakeyama S., Hauer V., Hayashi N., Hayashi T., Heller R., Hidalgo-Salaverri J., Higashijima S.

Nuclear Fusion 64 巻 ( 11 ) 2024年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

Superconducting (SC) tokamak JT-60SA plays an essential role in fusion research and development by supporting and complementing the ITER project, providing directions to the DEMO design activity and fostering next generation scientists and engineers. Since the short circuit incident at the terminal joints of equilibrium field coil #1 during the integrated commissioning (IC) in March 2021, both EU and JA implementing agencies (IAs) have examined how to ensure safe operation of JT-60SA by mitigating the risk of possible discharge occurrence inside the cryostat. Based on the experience of the global Paschen tests, the IAs have established a strategy of risk mitigation measures, which is a combination of (i) reinforcement of insulation, (ii) avoiding unnecessary voltage application to the coil systems and (iii) immediate de-energization of the coils when deteriorated vacuum conditions are detected. Thanks to the considerable efforts of the Integrated Project Team members, the IC restarted in May 2023. After confirmation of the SC state of the coil systems (TF, EF and CS), the coil energization test and the plasma operation phase 1 (OP-1) started. The first plasma was successfully achieved on 23 October 2023 with a limited value of voltage and current applied to the coils. The plasma configuration control was also confirmed with low plasma current and low auxiliary heating power conditions. Based on the IO-F4E-QST collaboration, activities of JT-60SA have been shared with the IO and provided an important lesson for ITER assembly and commissioning, and will provide an outstanding contribution to fusion research at large. After OP-1, maintenance & enhancement phase 1 (M/E-1) starts from January 2024, in which in-vessel components are installed, and heating and diagnostic systems are extensively upgraded to allow a high power heating experiment planned in OP-2. In order to make the best use of JT-60SA, a newly organized JT-60SA experiment team will refine the research plan for the future high heating power operation phase.

DOI： 10.1088/1741-4326/ad34e4

Machine learning aided line intensity ratio method for helium-hydrogen mixed recombining plasmas 査読有り国際共著国際誌

Kajita S., Nishijima D., Fujii K., Tanaka H., Vernimmen J., van der Meiden H., Classen I., Ohno N.

Plasma Physics and Controlled Fusion 66 巻 ( 10 ) 頁： 105005 2024年8月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plasma Physics and Controlled Fusion

The helium line intensity ratio (LIR) with the help of a collisional radiative (CR) model has long been used to measure the electron density, n e , and temperature, T e , and its potential and limitations for fusion applications have been discussed. However, it has been reported that the CR model approach leads to deviations in helium-hydrogen mixed plasmas and/or recombining plasmas. In this study, a machine learning (ML) aided LIR method is used to measure n e and T e from spectroscopic data of helium-hydrogen mixed recombining plasmas in the divertor simulator Magnum-PSI. To analyze mixed plasmas, which have more complex spectral shapes, the spectroscopy data were used directly for training instead of separating the intensities of each line. It is shown that the ML approach can provide a robust and simpler analysis method to deduce n e and T e from the visible emissions in helium-hydrogen mixed plasmas.

DOI： 10.1088/1361-6587/ad6a81

Germanium nanostructures by helium plasma irradiation 査読有り国際誌

Kajita S., Shi Q., Tabata K., Kuwabara T., Tanaka H., Ohno N.

Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers 63 巻 ( 7 ) 頁： 07SP07 2024年7月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers

The effects of helium plasma irradiation, which has been widely studied on metals, on germanium have been experimentally investigated. The irradiation temperature ranges from 430 to 720 K, and the incident ion energy ranges from 30 to 100 eV. From the scanning electron microscope (SEM) observation, it was found that various morphological changes including pits, nanocones, nanopillars, and roughened surfaces occur. The spatial scale of the morphological change was analyzed by applying fast Fourier transform to SEM micrographs. Thermal desorption spectroscopy analysis suggests that He atoms implanted on Ge play major roles in forming roughened surfaces at a surface temperature higher than 500 K.

DOI： 10.35848/1347-4065/ad5afe

Hydrogen isotope effects on recombination dominant plasmas in NAGDIS-II 査読有り国際共著国際誌

Shi J., Kaizawa H., Uematsu Y., Tanaka H., Kajita S., Ohno N., Sawada K., Ding H.

Plasma Physics and Controlled Fusion 66 巻 ( 8 ) 頁： 085006(11 pp) 2024年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plasma Physics and Controlled Fusion

The detachment processes of the hydrogen (H) and deuterium (D) plasmas are comparatively investigated in the linear plasma device NAGDIS-II. The laser Thomson scattering measurements demonstrate that the recombination rate of the H plasma is greater than that of the D plasma as the neutral pressure increases in the molecular activated recombination (MAR) dominant detachment phase. As the recombination process by MAR is strongly dependent on the vibrational and rotationally excited states of the molecule, the rovibrational quantum state populations of the H and D molecules are measured using the Fulcher-α band spectroscopy. The results indicate that the vibrational temperature in the electronic ground state is considerably higher than the rotational temperature during detachment. The reaction rate coefficients for MARs due to charge exchange chains (CX-MAR) and dissociative attachment chains (DA-MAR) are calculated by the collision-radiation model under the measured temperature conditions. It can be observed that the CX-MAR is larger than the DA-MAR for both H and D, and that the CX-MAR of H is larger than the CX-MAR of D at electron temperatures T e above 1 eV. In consideration of the experimentally observed vibrational and rotational excitation temperatures, the reaction rate coefficients of CX-MAR and DA-MAR are increasing in the low T e region. These calculations are in accordance with the experimental results, which indicate that recombination processes due to MAR are more predominant in the H plasma compared to the D plasma. Furthermore, a transition from MAR to electron-ion recombination processes is observed in the D plasma at T e below 0.5 eV.

DOI： 10.1088/1361-6587/ad59c4

Lithography-Free Nanofabrication on Various Semiconductors by the Codeposition Etching Technique 査読有り国際誌

Shi Q., Kajita S., Ohno N., Tanaka H., Yasuhara R., Fujiwara H., Uehara H.

Langmuir 40 巻 ( 24 ) 頁： 12437 - 12442 2024年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Langmuir

Nano-/microstructures can be formed with the aid of small amounts of impurities during deposition with noble gas plasma irradiation, which is referred to as codeposition etching. This can be a new method for lithography-free semiconductor nanofabrication. Here, the codeposition etching method was employed with argon plasma and molybdenum (Mo) impurities on various semiconductors. Structures can be formed only on substrates that have a lower sputtering yield than the seed impurity. The density, area, and height of structures are related to both the impurity deposition rate and the substrate material. Moreover, two mechanisms of impurity nucleation are proposed according to time dependence results for the formation of the structures.

DOI： 10.1021/acs.langmuir.4c00686

PubMed

First results of multi-fluid modeling of detached hydrogen plasmas in a linear plasma device using fluid code LINDA-NU 査読有り国際誌

Sugiura K., Ido T., Tanaka H., Natsume H., Masuda S., Hoshino K., Sawada K., Ohno N.

Contributions to Plasma Physics 2024;e202300150 巻 2024年6月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Contributions to Plasma Physics

In order to simulate hydrogen (H) plasma in the linear plasma device NAGDIS-II, we have modified the fluid code LINDA-NU to allow the simultaneous calculation of multiple ion species consisting of hydrogen atomic ions ((Formula presented.)) and molecular ions ((Formula presented.)). In this simulation, H and (Formula presented.) neutrals are assumed to be uniformly distributed in space in order to obtain initial qualitative results. The fraction of (Formula presented.) ions increases as the (Formula presented.) molecular density increases, and the recombination process between (Formula presented.) and electrons is observed to reduce the particle flux to the target plate. With an increase in H density, the electron density increases due to the decrease in ion flow velocity due to the change exchange process, and the electron temperature decreases to less than 1 eV, leading to the detached plasma formation attributed to the electron-ion recombination process.

DOI： 10.1002/ctpp.202300150

Four-dimensional conditional averaging tomography of rotating plasma ejection from cylindrical detached plasma 査読有り国際誌

Tanaka H., Kajita S., Natsume H., Ohno N.

Scientific Reports 14 巻 ( 1 ) 頁： 9329 2024年4月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Scientific Reports

Detached plasma formation is a way to reduce the heat load on the wall in magnetic fusion devices. This study proposes a novel analysis technique consisting of the conditional averaging, sliding window, and tomography to reveal the spatiotemporal behavior of the rotating radial ejection event of detached plasma, which further contributes to local heat load reduction. The used equipment is a high-speed camera and an electrostatic probe located at the periphery of the linear plasma device NAGDIS-II. By applying this method, four-dimensional (4D) behavior of the emission structure along time (1D) and space perpendicular and parallel to the magnetic field (3D) was clarified; a rotating distorted structure appears as a precursor, which is then scraped and transported radially and axially. The proposed method is widely applicable to short-term rigid-body rotating structures, especially in linear plasmas.

DOI： 10.1038/s41598-024-59182-5

PubMed

Study of the intermittent plasma structure around the divertor simulation experimental module in GAMMA 10/PDX 招待有り査読有り

H.Tanaka, N.Ezumi, T.Sugiyama, H.Gamo, N.Shigematsu, M.Yoshikawa, J.Kohagura, M.Hirata, S.Togo N.Ohno, M.Sakamoto

Physics of Plasmas 30 巻 ( 3 ) 頁： 10.1063/5.0129886 2023年3月

Increased Photoelectrochemical Performance of Vanadium Oxide Thin Film by Helium Plasma Treatment with Auxiliary Molybdenum Deposition 査読有り国際共著

Kajita Shin, Eda Tomoki, Feng Shuangyuan, Tanaka Hirohiko, Bieberle-Hutter Anja, Ohno Noriyasu

ADVANCED ENERGY AND SUSTAINABILITY RESEARCH 4 巻頁： 2200141 2023年1月

Structural correlation of random lasing performance in plasma-induced surface-modified galium nitride 査読有り

Q.Shi, H.Fujiwara, S.Kajita, R.Yasuhara H.Tanaka, N.Ohno,H.Uehara

ACS Applied Optical Materials 1 巻頁： 412 - 420 2022年12月

Corrigendum to “Photoelectrochemical properties of plasma-induced nanostructured tungsten oxide” [Appl. Surf. Sci. 580 (2022) 151979] (Applied Surface Science (2022) 580, (S0169433221030166), (10.1016/j.apsusc.2021.151979)) 招待有り査読有り

S.Feng, S.Kajita, M.Higashi, A.Bieberle-Hutter, T.Yoshida, N.Ohno

Applied Surface Science 599 巻頁： 153668 2022年10月

Reduction of pulsed particle load with dynamic pressure induced by transient recycled neutral flux 査読有り国際共著国際誌

Hayashi Y., Tanaka H., Ohno N., Kajita S., Morgan T., van der Meiden H., Scholten J., Vernimmen J., Natsume H., Sawada K., Masuda S.

Plasma Physics and Controlled Fusion 64 巻 ( 10 ) 頁： 105013 2022年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plasma Physics and Controlled Fusion

From pulsed plasma experiments focusing on neutral pressure dependence, the impacts of a transition from a low to a high recycling target on the particle load were investigated and discussed in the linear plasma device, Magnum-PSI. Time traces of the target ion flux were mitigated in high neutral pressure cases because of a plasma-neutral interaction. On the other hand, in low neutral-pressure cases, the target ion flux indicated partial suppression in the last part of the pulse. The Langmuir probe, located 200 mm upstream from the target plate, did not exhibit such a suppression. Pulse suppression can be expected from the localized interaction between recycled neutral flux and pulsed plasma in front of the target. The mean-free paths of recycled neutral particles regarding the charge exchange with pulse ions and elastic scattering with background neutral particles were compared. Modeling using a fluid code coupled with a neutral transport code was performed, and it was concluded that dynamic pressure induced by the transient recycled neutral flux caused sufficient momentum loss to stagnate the pulsed plasma toward the target plate.

DOI： 10.1088/1361-6587/ac8acb

Bidirectional reflectance distribution function of recrystallized tungsten mono-block exposed to cyclic heat loading 査読有り国際誌

Natsume H., Nojiri K., Kajita S., Fukuda M., Ushiki T., Tanaka H., Sugie T., Kitazawa S.i., Kikuchi T., Yokozuka T., Ohno N., Ezato K., Hatae T.

Nuclear Materials and Energy 33 巻頁： 101243 2022年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Materials and Energy

The bidirectional reflectance distribution function (BRDF) of recrystallized tungsten mono-blocks exposed to cyclic heat loading for ITER divertor outer vertical target was measured using a goniophotometer at a wavelength of 473 nm. Laser microscope observations revealed that the surface roughness of the mono-block increased by an order of magnitude after cyclic heat loads of approximately 20 MWm−2. Furthermore, the overall values of BRDF decreased with an increase in cyclic heat loading. A comparison between the modeled and measured BRDFs showed that an additional Lambertian component is necessary to a specular function (microfacet model or Gaussian function) to fit the measured BRDFs when the surface of the mono-blocks becomes rough.

DOI： 10.1016/j.nme.2022.101243

Fuzz Growth Process under He-W Co-Deposition Conditions 査読有り国際共著国際誌

Shen W., Kajita S., Tanaka H., Shi Q., Ohno N.

Plasma and Fusion Research 17 巻 ( 0 ) 頁： 1302094 - 1302094 2022年8月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

Helium (He)-Tungsten (W) co-deposition experiments were conducted in the linear plasma device Co-NAGDIS at a temperature of 1223K to observe the characteristics of fuzz growth on theWsurface with auxiliary W deposition. The dependence on the deposition rate of W was investigated and a clear difference in fuzz thickness was found between He-only and co-deposition experiments. In addition, the fuzz structures on a single sample exhibited a spatially nonuniform distribution, which was probably caused by the nonuniformity in the deposition rate.

DOI： 10.1585/pfr.17.1302094

Measurement of the Bidirectional Reflectance Distribution Function of Tungsten Surface Sputtered in Argon Plasma 査読有り

H.Natsume, K.Nojiri, S.Kajita, T.Ushiki, T.Sugie, S.Kitazawa, T.Kikuchi, T.Yokozuka, H.Tanaka, N.Ohno, T.Hatae

Plasma and Fusion Research:Regular Articles 17 巻頁： 2405041 2022年5月

Isotope Effect for Plasma Detachment in Helium and Hydrogen/Deuterium Mixture Plasmas 査読有り国際誌

Guo X., Tanaka H., Kajita S., Ohno N., Hattori S., Sawada K.

Plasma and Fusion Research 17 巻 ( 0 ) 頁： 2402027 - 2402027 2022年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

To investigate the isotope effect on the plasma detachment in helium (He) and hydrogen (H)/deuterium (D) mixture plasmas, we performed H2, D2 or He gas puffing into He plasma in the linear plasma device NAGDIS-II. Axial distributions of electron density (ne) and electron temperature (Te) were obtained using a movable Langmuir probe. Additionally, optical emission spectroscopy (OES) was applied to measure axial distributions of Balmer lines and He I lines. When the neutral gas pressure was high (ΔPn = 7~10 mTorr), ne distribution in He-D2 mixture plasma was similar to that in pure He plasma, showing a sharp decrease at the downstream region where Te < 1 eV. In contrast, in He-H2 mixture plasma, a decrease in ne was confirmed from upstream region where Te > 1 eV. The upstream Hα/Hγ in He-H2 plasma was significantly larger than the Dα/Dγ in He-D2 plasma at the same Te. This result indicated that molecular activated recombination (MAR) processes significantly occurred in He-H2 plasma, while electron-ion recombination (EIR) processes were dominant in He-D2 and pure He plasmas.

DOI： 10.1585/pfr.17.2402027

Study of optical emission spectroscopy in dual frequency synchronized pulsed capacitively coupled discharges with DC bias at low-pressure in Ar/O2/C4F8 plasma etching 査読有り国際共著

B.B,Sahu, K.Nakane, K.Ishikawa, M.Sekine, T.Tsutsumi, T.Gohira, Y.Ohya, N.Ohno, M.Hori

Physical Chemistry Chemical Physics 24 巻頁： 13883 - 13896 2022年5月

Changes in morphology and field emission property of nano-tendril bundles after high temperature annealing 査読有り国際共著国際誌

Zhang R., Kajita S., Hwangbo D., Sinelnikov D., Tanaka H., Ohno N.

Nuclear Materials and Energy 31 巻頁： 101178 2022年4月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Materials and Energy

Nano-tendril bundles (NTBs) are known to be formed on tungsten by helium plasma exposure with additional neon impurity gas. In this study, the annealing experiments were conducted at the sample temperature of 1473 – 1673 K to investigate the changes of morphology and field emission property of NTBs. With NTBs formed on a W surface, the surface did not fully recover to a smoothed surface and the NTBs remained the fiber-form structures after the annealing at 1673 K for one hour. In addition, the onset electric field for field emission increased, while the emission current from NTBs significantly decreased after the annealing. When the samples were biased at −250 V during helium plasma exposure, arc ignition was confirmed on W surface with NTBs, whereas no arc ignition appeared on W with annealed NTBs.

DOI： 10.1016/j.nme.2022.101178

An approach to implement a heat flux limit in a model for fusion relevant plasmas 査読有り国際共著

M.Z.Tokar, M.Kobayashi, N.Ohno

Physics of Plasmas 29 巻頁： 32502 2022年3月

Completion of JT-60SA construction and contribution to ITER 査読有り国際共著国際誌

Kamada Y., Di Pietro E., Hanada M., Barabaschi P., Ide S., Davis S., Yoshida M., Giruzzi G., Sozzi C., Abdel Maksoud W., Abe H., Aiba N., Akiyama T., Ayllon-Guerola J., Arai T., Artaud J.F., Asakura N., Ashikawa N., Balbinot L., Bando T., Baulaigue O., Belonohy E., Bin W., Bombarda F., Bolzonella T., Bonne F., Bonotto M., Botija J., Cabrera-Pérez S., Cardella A., Carraro L., Cavalier J., Chernyshova M., Chiba S., Clement-Lorenzo S., Cocilovo V., Coda S., Coelho R., Coffey I., Collin B., Corato V., Cucchiaro A., Czarski T., Dairaku M., Davis S., Day C., de la Luna E., De Tommasi G., Decool P., Di Pace L., Di Pietro E., Dibon M., Disset G., Ejiri A., Endo Y., Ezumi N., Falchetto G., Fassina A., Fejoz P., Ferro A., Fietz W., Figini L., Fornal T., Frello G., Fujita T., Fukuda T., Fukui K., Fukumoto M., Furukawa M., Futatani S., Gabellieri L., Gaio E., Galazka K., Garcia J., Garcia-Dominguez J., Garcia-Lopez J., Garcia-Munoz M., Garzotti L., Gasparini F., Gharafi S., Giacomelli L., Ginoulhiac G., Giruzzi G., Giudicotti L., Guillén González R., Hajnal N., Hall S., Hamada K., Hanada K., Hanada M., Hasegawa K., Hatae T., Hatakeyama S., Hauer V., Hayashi N., Hayashi T., Heller R., Higashijima S., Hinata J.

Nuclear Fusion 62 巻 ( 4 ) 頁： 42002 2022年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

Construction of the JT-60SA tokamak was completed on schedule in March 2020. Manufacture and assembly of all the main tokamak components satisfied technical requirements, including dimensional accuracy and functional performances. Development of the plasma heating systems and diagnostics have also progressed, including the demonstration of the favourable electron cyclotron range of frequency (ECRF) transmission at multiple frequencies and the achievement of long sustainment of a high-energy intense negative ion beam. Development of all the tokamak operation control systems has been completed, together with an improved plasma equilibrium control scheme suitable for superconducting tokamaks including ITER. For preparation of the tokamak operation, plasma discharge scenarios have been established using this advanced equilibrium controller. Individual commissioning of the cryogenic system and the power supply system confirmed that these systems satisfy design requirements including operational schemes contributing directly to ITER, such as active control of heat load fluctuation of the cryoplant, which is essential for dynamic operation in superconducting tokamaks. The integrated commissioning (IC) is started by vacuum pumping of the vacuum vessel and cryostat, and then moved to cool-down of the tokamak and coil excitation tests. Transition to the super-conducting state was confirmed for all the TF, EF and CS coils. The TF coil current successfully reached 25.7 kA, which is the nominal operating current of the TF coil. For this nominal toroidal field of 2.25 T, ECRF was applied and an ECRF plasma was created. The IC was, however, suspended by an incident of over current of one of the superconducting equilibrium field coil and He leakage caused by insufficient voltage holding capability at a terminal joint of the coil. The unique importance of JT-60SA for H-mode and high-β steady-state plasma research has been confirmed using advanced integrated modellings. These experiences of assembly, IC and plasma operation of JT-60SA contribute to ITER risk mitigation and efficient implementation of ITER operation.

DOI： 10.1088/1741-4326/ac10e7

Nitrogen Atom Density Measurements in NAGDIS-T Using Vacuum Ultraviolet Absorption Spectroscopy 査読有り

Nishio Ryosuke, Kajita Shin, Tanaka Hirohiko, Asaoka Koji, Tsutsumi Takayoshi, Hori Masaru, Ohno Noriyasu

PLASMA AND FUSION RESEARCH 17 巻 ( 0 ) 頁： 1201004 - 1201004 2022年1月

Plasma induced surface nanostructure on semiconductors for the application of random laser 査読有り

Shi Q., Fujiwara H., Osaka R., Kajita S., Yasuhara R., Ohno N., Uehara H.

Optics InfoBase Conference Papers 2022年

Photoelectrochemical properties of plasma-induced nanostructured tungsten oxide 査読有り国際共著国際誌

Feng S., Kajita S., Higashi M., Bieberle-Hütter A., Yoshida T., Ohno N.

Applied Surface Science 580 巻頁： 151979(7 pp) 2021年12月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Surface Science

Helium (He)-induced nanostructured tungsten sheets were synthesized by He plasma irradiation under different plasma exposure durations. After calcination, nanostructured tungsten oxide samples were used as photoelectrodes to test photoelectrochemical (PEC) performance. The results showed that nanostructured WO3 photoanodes have higher PEC performance compared to the sample without nanostructures. The 15 min irradiated sample had the highest photocurrent density of 3.5 mA/cm2 under the thermodynamic potential of water oxidation (1.23 V vs. RHE). It was found that the oxide layer thickness and exposed crystal facet have a significant impact on PEC performance. The plasma synthesis technique has proved to be an effective method for preparing nanostructured WO3 photoelectrodes.

DOI： 10.1016/j.apsusc.2021.151979

Growth of Mo Large-Scale Fiberform Nanostructures 査読有り

Kajita Shin, Okuyama Tatsuki, Tanaka Hirohiko, Ohno Noriyasu

PLASMA AND FUSION RESEARCH 16 巻 ( 0 ) 頁： 1206105 - 1206105 2021年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

We performed helium (He) plasma irradiation to molybdenum (Mo) substrate with auxiliary Mo deposition. Different from W cases, large-scale fiberform nanostructure (LFN) growth did not occur easily. The experiments suggested that the experimental condition of Mo LFN growth has a much narrower conditional window than that of fuzz growth or another hidden control factor exists for LFN growth.

DOI： 10.1585/pfr.16.1206105

Penetration of deuterium into neutron-irradiated tungsten under plasma exposure 査読有り

Yajima M., Hatano Y., Alimov V.K., Toyama T., Kuwabara T., Schwarz-Selinger T., Oya Y., Spitsyn A.V., Ohno N.

Physica Scripta 96 巻 ( 12 ) 頁： 124042 2021年10月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physica Scripta

Hydrogen isotope trapping at lattice defects in neutron-irradiated tungsten (W), a leading candidate as plasma facing material, is an important problem determining tritium (T) inventory in a vacuum vessel of a future fusion reactor. In this study, W samples were irradiated with neutrons in the Belgium Reactor 2 at 563 K to 0.06 or 0.016 displacement per atom (dpa). After characterizing defects by positron lifetime measurements, deuterium (D) penetration under exposure to D plasma was examined at 563-773 K. Positron lifetime showed the presence of dislocations, monovacancies and relatively large vacancy clusters. These defects trapped D atoms with different values of binding energy. Dependence of D retention on plasma exposure temperature and damage level indicated that the concentrations of weak traps with smaller binding energy increased more significantly with damage level than those of strong traps.

DOI： 10.1088/1402-4896/ac2c20

その他リンク： https://iopscience.iop.org/article/10.1088/1402-4896/ac2c20/pdf

The dependence of Mo ratio on the formation of uniform black silicon by helium plasma irradiation 査読有り国際共著

Shi Quan, Kajita Shin, Feng Shuangyuan, Ohno Noriyasu

JOURNAL OF PHYSICS D-APPLIED PHYSICS 54 巻 ( 40 ) 頁： 405202 2021年10月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physics D: Applied Physics

Reducing the optical reflection of silicon (Si) material is a crucial issue on the surface of solar cells and other photonic applications. Fabrication of nanocone structures on the Si surface (black Si) by plasma (helium or argon) irradiation is a novel technique in recent decades with advantages, such as simple, economical, and harmless to the Si substrate. However, the uniformity and controllability of the surface remain problematic. In this study, uniform black silicon was obtained by low energy (<50 eV) helium ion irradiation with auxiliary Mo co-deposition. The characteristics of the nanocone show a clear relation with the Mo ratio. Deposited Mo was found to accumulate on the cone body, especially on the tip, and it worked as a nano mask to induce the formation of the nanocone and protect it from sputtering. The surface with high and large diameter nanocones possesses low reflectances of roughly 2%. The study of the relation between Mo ratio, characteristics of the nanostructure, and the reflectance of the surface raises a potential method of surface tailoring.

DOI： 10.1088/1361-6463/ac1190

Enhanced photocatalytic ethylene decomposition with anatase-rutile mixed nanostructures formed by He plasma treatment 査読有り

Kajita S., Miyaguchi K., Tanaka H., Yasunaga E., Yoshida T., Ohno N.

Journal of Photochemistry and Photobiology A: Chemistry 418 巻頁： 113420(8 pp) 2021年9月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Photochemistry and Photobiology A: Chemistry

In order to realize high-performance titanium dioxide (TiO2) photocatalysts for ethylene decomposition, titanium (Ti) thin film samples with fiberform nanostructures were prepared by helium (He) plasma treatment. Then, the oxidation condition for ethylene decomposition were optimized in terms of the oxidation temperature and duration. It is shown that He plasma irradiation with Ti deposition followed by oxidation in the air formed anatase-rich TiO2. The rutile anatase transition temperature increased to higher than 1000 K on the He treated samples and the best photocatalytic performance is twice higher than that on TiO2 sample formed in a magnetron sputtering device. Helium plasma treatment induces vacancies, He clusters, and He bubbles together with formation of nanostructures. The results suggested that those morphology changes lead to the formation of stable anatase structure, which is likely the key factor for the enhancement of photocatalytic activity. Based on the obtained ethylene decomposition rate, we will discuss the necessary light source and amount of photocatalysts to keep vegetables fresh in a long-distance transport cargo.

DOI： 10.1016/j.jphotochem.2021.113420

Thermal treatment of W large-scale fiberform nanostructures 査読有り

Kajita Shin, Okuyama Tatsuki, Tanaka Hirohiko, Kuwabara Tatsuya, Ohno Noriyasu, Yoshida Naoaki

PHYSICA SCRIPTA 96 巻 ( 9 ) 2021年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physica Scripta

Recent experiments have revealed that accelerated tungsten (W) nanostructure growth occurs during the exposure to helium (He) plasmas with an additional W deposition, and mm-thick large-scale fiberform nanostructures (LFNs) are formed when certain condition is satisfied. In order to reveal whether accelerated growth occurs in fusion device, it is important to understand the annealing process in addition to the growth process. In this study, we will perform thermal treatment of W LFNs. Detailed observation reveals that the LFNs shrink at a faster rate than that of conventional fuzz, though it takes longer time to fully be reintegrated to the surface because the thickness is orders of magnitude greater.

DOI： 10.1088/1402-4896/ac0866

Enhancement of Arc Ignition on Tungsten in Helium Plasmas with Impurity Gases 査読有り国際共著

ZHANG Rongshi, KAJITA Shin, HWANGBO Dogyun, TANAKA Hirohiko, OHNO Noriyasu

Plasma and Fusion Research 16 巻 ( 0 ) 頁： 24045069(5 pp) - 2405069 2021年5月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

Arcing was ignited on deformed tungsten (W) surfaces, where W fuzz and/or nano-tendril bundles (NTBs) were grown, by steady state helium (He) plasma exposures with impurity gas seeding. At the same sample potential of −250 V, the presence of NTBs enhanced the frequency of arc ignition, whereas no arc ignition appeared on typical fuzz surfaces without NTBs. After a series of arc ignitions on a sample surface with NTBs, the aspect ratio of NTBs decreased, indicating that protruded NTBs with larger aspect ratio tend to trigger arcing easily.

DOI： 10.1585/pfr.16.2405069

Influence of Nitrogen Ratio on Plasma Detachment during Combined Seeding with Hydrogen on Divertor Simulation Experiment of GAMMA 10/PDX 査読有り

Modeling of the impurity-induced silicon nanocone growth by low energy helium plasma irradiation 査読有り国際共著

Q Shi, S Kajita, S Dai, S Feng, N Ohno

Plasma Science and Technology 23 巻 ( 4 ) 頁： 45503 2021年4月

GAMO Hiroki, HWANGBO Dogyun, SAKAMOTO Mizuki, PERILLO Renato, KUWABARA Tatsuya, TANAKA Hirohiko, OHNO Noriyasu, SAWADA Keiji, TONEGAWA Akira, MASUZAKI Suguru, EZUMI Naomichi, SUGIYAMA Tsukasa, NOJIRI Kunpei, KONDO Ayane, HIRATA Mafumi, KOHAGURA Junko, YOSHIKAWA Masayuki, NAKASHIMA Yousuke

Plasma and Fusion Research 16 巻 ( 0 ) 頁： 2402041 - 2402041 2021年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

Influences of nitrogen ratio on plasma detachment and molecular activated recombination (MAR) processes during combined seeding with hydrogen have been investigated utilizing end-loss plasma in the GAMMA 10/PDX tandem mirror. Additional gases were injected under the condition that hydrogen partial pressure was fixed and nitrogen partial pressure was changed from 0% - 10% compared to that of hydrogen. Electron density and ion flux further decrease with increasing nitrogen ratio. In addition, it is suggested that the hydrogen-MAR process that begins with dissociative attachment is suppressed during combined seeding of nitrogen and hydrogen. Observed emission spectrum of NH radicals suggests that the density of NH increases as nitrogen ratio increases and nitrogen-induced MAR efficiently contributes to the reduction of particle flux.

DOI： 10.1585/pfr.16.2402041

Computer Tomography on Divertor Impurity Monitor for ITER with Minimizing Errors in a Logarithmic Scale 招待有り査読有り国際共著

NATSUME Hiroki, OGAWA Hiroaki, KITAZAWA Sin-iti, KAJITA Shin, NEVEROV Vladislav S., KHUSNUTDINOV Radmir I., VESHCHEV Evgeny, DE BOCK Maarten, POLEVOI Alexei R., TANAKA Hirohiko, OHNO Noriyasu

Plasma and Fusion Research 16 巻 ( 0 ) 頁： 2405019 - 2405019 2021年3月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

The computer tomography for divertor impurity monitor, which measures plasma emissions in the divertor region, for ITER has been conducted using a ray-tracing technique. We have attempted four different solution methods for the inversion problem and compared the results. The solution methods which minimize errors in logarithmic scale had better performance than the methods which minimize errors in linear scale. This is likely due to the fact that the values in the emission profile vary in a wide range of orders of magnitude. The accuracy of the reconstruction has been investigated by changing discharge conditions and the number of field-of-views used. The deterioration in accuracy was most noticeable when the emission profile was reconstructed using only two field-of-views. In addition, the accuracy deteriorated, making the estimation more challenging, under discharge conditions with low emission intensity because of the wider range of emission intensity under such conditions.

DOI： 10.1585/pfr.16.2405019

Particle-in-cell-Monte Carlo collision simulation and experimental measurement of Ar plasma in a fast atom beam source for surface-activated bonding 査読有り国際誌

R.Morisaki, T.Yamazaki, C.Oka, J.Sakurai, T.Hirai, T.Takahashi, H.Tsuji, N.Ohno, S.Hata

Japanese Journal of Applied Physics 60 巻 ( SC ) 頁： SCCB01 2021年3月

Doppler and Stark Broadenings of He II Emission in NAGDIS-PG 招待有り査読有り

KAJITA Shin, NAKAMORI Takaya, TANAKA Hirohiko, KIKUCHI Yusuke, OHNO Noriyasu

Plasma and Fusion Research 16 巻 ( 0 ) 頁： 1202013 - 1202013 2021年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

Time evolutions of the emission from helium (He) ion at 468.6 nm were observed in the magnetized co-axial plasma gun device NAGDIS-PG, and the broadening of the spectrum was analyzed in terms of Doppler and Stark broadenings to deduce the ion temperature and the electron density. A significant broadening of the He II spectrum was identified around a dip in the discharge current, suggesting that increases in the temperature and density occurred.

DOI： 10.1585/pfr.16.1202013

Thin film and noble metal loading effects on the photocatalytic reactivity of helium-plasma-induced nanostructured tungsten oxides 査読有り

Fabrication of nanostructured Ti thin film with Ti deposition in He plasmas 査読有り

Miyaguchi Kazuya, Kajita Shin, Tanaka Hirohiko, Ohno Noriyasu

JAPANESE JOURNAL OF APPLIED PHYSICS 60 巻 ( 3 ) 頁： 038004(4 pp) 2021年2月

Accelerated/reduced growth of tungsten fuzz by deposition of metals 査読有り国際共著

S. Kajita, T. Morgan, H. Tanaka, Y. Hayashi, N. Yoshida, D. Nagata, J. Vernimmen, S. Feng, R. Zhang, N. Ohno

Journal of Nuclear Materials 548 巻頁： 152844 2021年1月

Tungsten Large-Scale Fiberform Nanostructures Retained under High Temperature Conditions 査読有り

T.Okuyama, S.Kajita, N.Yoshida, H.Tanaka, T.Kuwabara, N.Ohno

PLASMA AND FUSION RESEARCH 16 巻頁： 1206001 2021年1月

Experimental observations and modelling of radiation asymmetries during N<inf>2</inf> seeding in LHD 査読有り国際共著

B.J. Peterson, G.Kawamura, P.L. van de Giessen, K.Mukai, H.Tanaka, R.Sano, S.N. Pandya, S.Y. Dai, S. Masuzaki, T. Akiyama, M. Kobayashi, M. Goto, G. Motojima, R. Sakamoto, N. Ohno, T. Morisaki, J. Miyazawa, the LHD Experiment Group

Nuclear Materials and Energy 26 巻頁： 100848 2020年12月

Experimental observations and modelling of radiation asymmetries during Ne and N2 seeding in LHD 招待有り査読有り国際共著

B.J. Peterson, G. Kawamura, P.L. van de Giessen, K. Mukai, S. Borling, H. Tanaka, R. Sano, S. N. Pandya, S. Y. Dai, S. Masuzaki, T. Akiyama, M. Kobayashi, M. Goto, G. Motojima, R. Sakamoto, N. Ohno, T. Morisaki, J. Miyazawa and the LHD Experiment Group

Nuclear Materials and Energy 26 巻頁： 100848 2020年12月

Unipolar arc plasmas on nanostructured tungsten surfaces under perpendicular magnetic field 査読有り国際共著

D.Hwangbo, D.Nishijima, S.Kajita, R.Doerner, N.Ohno

PLASMA SOURCES SCIENCE & TECHNOLOGY 29 巻 ( 12 ) 頁： 125015 2020年12月

Dynamics of Hydrogen Isotope Absorption and Emission of Neutron-Irradiated Tungsten 査読有り国際共著

T.Toyama, M.Yajima, N.Ohno, T.Kuwabara, V.Kh.Alimov, Y.Hatano

PLASMA AND FUSION RESEARCH 15 巻頁： 150581(7 pp) 2020年11月

Plasma Potential Measurement in Detached Plasmas by Emissive Probe Considering Space-Charge-Limited Effect 査読有り

S.Hattori, H.Tanka, S.Kajita, N.Ohno

PLASMA AND FUSION RESEARCH 15 巻頁： 1301082(4 pp) 2020年11月

Size distribution of nano-tendril bundles with various additional impurity gases 査読有り

R. Zhang, D. Hwangbo, S. Kajita, H. Tanaka, N. Ohno

NUCLEAR MATERIALS AND ENERGY 25 巻頁： 100843 2020年11月

Tungsten fuzz: Deposition effects and influence to fusion devices 査読有り

S Kajita, N Yoshida, N Ohno

NUCLEAR MATERIALS AND ENERGY 25 巻頁： 100828 2020年11月

Cross-field transport in detached helium plasmas in Magnum-PSI 査読有り国際共著

H.Tanaka, Y.Hayashi, S.Kajita, H.J. van der Meiden, M.Yoshikawa, J.W.M.Vernimmen, J.Scholten, I.Classen, T.W.Morgan, N.Ohno

PLASMA PHYSICS AND CONTROLLED FUSION 62 巻 ( 11 ) 頁： 115021 (14pp) 2020年10月

Nano-tendril bundles behavior under plasma-relevant electric fields 査読有り

V.V.Kulagin, D.N.Sinelnikov, D.G.Bulgadaryan, N.E.Efimov, V.A.Kurnaev, D.Hwangbo, N.Ohno, S.Kajita

VACUUM 183 巻頁： 109799 2020年10月

Evaluation of axial decay length of plasma pressure in detached plasma 査読有り

H.Tanaka, N.Ohno, S.Kajita, H.Takano, S.Hattori, Y.Imaeda

NUCLEAR MATERIALS AND ENERGY 25 巻頁： 100812(5 pp) 2020年10月

Detached helium plasma simulation by a one-dimensional fluid code with detailed collisional-radiative model 査読有り

H.Tanaka, I.Saeki, N.Ohno, S.Kajita, T.Ido, H. Natsume, A.Hatayama, K.Hoshino, K.Sawada, M.Goto

PHYSICS OF PLASMAS 27 巻 ( 10 ) 頁： 102505 2020年10月

Dust Formation from Arc Spots on Nanostructured Tungsten Surface 査読有り国際共著

M.Yajima, S.Kajita, N.Ohno, S.Masuzaki, N.Yoshida, D.U.B.Assems, T.W.Morgan, K.Bystrovc, H, van der Meiden

PLASMA AND FUSION RESEARCH 15 巻頁： 1205061(3 pp) 2020年8月

Atomic nitrogen density measurements by actinometry method in the toroidal device NAGDIS-T 査読有り

S.Kajita, K.Asaoka, H.Tanaka, R.Nishio, T.Tsutsumi, M.Hori, N.Ohno

JAPANESE JOURNAL OF APPLIED PHYSICS 59 巻 ( 8 ) 頁： 086002(6 pp) 2020年8月

Effect of temperature and incident ion energy on nanostructure formation on silicon exposed to helium plasma 査読有り国際共著

M.Thompson, Q.Shi, S.Kajita, N.Ohno, C.Corr

PLASMA PROCESSES AND POLYMERS 17 巻 ( 12 ) 頁： e2000126(7 pp) 2020年8月

Helium-W co-deposition layer: TEM observation and D retention 査読有り

S.Kajita, K.Asai, N.Ohno, H. Tanaka, N.Yoshida, D. Nagata, M. Yajima

JOURNAL OF NUCLEAR MATERIALS 540 巻頁： 152350 2020年7月

S.Feng, S.Kajita, T.Yoshida, N.Ohno, D.Nagata, M.Tokitani

MATERIALS RESEARCH EXPRESS 7 巻頁： 75007 2020年7月

The influence of impurities on the formation of nanocone structures on silicon surface irradiated by low energy helium plasma 査読有り

Q.Shi, S. Kajita, N. Ohno, M.Tokitani, D.Nagata, S. Feng

JOURNAL OF APPLIED PHYSICS 128 巻 ( 2 ) 頁： 23301 2020年7月

Spatiotemporal dynamics of cross-field ejection events in recombining detached plasma 査読有り

H.Tanaka, S.Kajita, H.Natsume, I.Saeki, N.Ohno

PLASMA PHYSICS AND CONTROLLED FUSION 62 巻 ( 7 ) 頁： 075011(10 pp) 2020年6月

Application of dynamic mode decomposition to rotating structures in detached linear plasmas 査読有り

H.Natsume, H. Tanaka, S. Kajita, N.Ohno

PHYSICS OF PLASMAS 27 巻 ( 4 ) 頁： 42301 2020年4月

Modifications of WNOx films by keV D and H ions 査読有り

N.Matsunami, N.Ohno, M. Tokitani, B. Tsuchiya, M. Sataka, S. Okayasu

SURFACE & COATINGS TECHNOLOGY 394 巻頁： 125798 2020年4月

Inspection of Arc Trails Formed in Stellarator/Heliotron Devices W7-X and LHD 査読有り国際共著

15 巻頁： 2402012 2020年3月

Helium irradiation effects on the surface modification and recrystallization of tungsten 査読有り国際共著

Khan A, De Temmerman G, Kajita S, Greuner H, Balden M, Hunger K, Ohno N, Hwangbo D, Tomita Y, Tokitani M, Nagata D, Yajima M

PHYSICA SCRIPTA T171 巻 ( 1 ) 頁： 14050 2020年3月

Microstructure and Retention in He-W Co-Deposition Layer 査読有り

K.Asai, N.Yoshida, N.Ohno, S.Kajita, H.Tanaka, M.Yajima, D.Nagata

PLASMA AND FUSION RESEARCH 15 巻頁： 1201004 2020年2月

Growth of nano-fibers on HCP-metals by He plasma irradiation 査読有り

S.Kajita, T.Nojima, Y.Yamamoto, N.Yoshida, T.Okuyama, T.Kuwabara, N.Ohno

JAPANESE JOURNAL OF APPLIED PHYSICS 59 巻 ( SH ) 頁： SHHA03 2020年2月

First EMC3-EIRENE modelling of JT-60SA edge plasmas with/without resonant magnetic perturbation field 査読有り国際共著

H.Tanaka, G.Kawamura, K.Hoshino, M.Kobayashi, G.Matsunaga, Y.Suzuki, T.Lunt, Y.Feng, N.Ohno

CONTRIBUTIONS TO PLASMA PHYSICS 60 巻 ( 5-6 ) 頁： e201900114 2020年2月

Dynamics of the changes in the parameters of the arc plasma during the destruction of a helium-induced tungsten fuzz by arc pulses 査読有り国際共著

S. A.Barengolts , D.Hwangbo , S.Kajita , N.Ohno , V. P.Frolova , A. G.Nikolaev , E. M.Oks , D. L.Shmelev , M. M.Tsventoukh , G. Yu Yushkov

NUCLEAR FUSION 60 巻 ( 4 ) 頁： 44001 2020年2月

Photocatalytic application of helium plasma induced nanostructured tungsten oxides 査読有り

S.Feng, S.Kajita, Y.Tomita, T.Yoshida, N.Ohno

JAPANESE JOURNAL OF APPLIED PHYSICS 59 巻 ( SA ) 頁： SAAB04(6 pp) 2019年11月

Helium-plasma–induced straight nanofiber growth on HCP metals 査読有り

S.Kajita, T.Nojima, T.Okuyama, Y.Yamamoto, N.Yoshida, N.Ohno

Acta Materialia 181 巻頁： 342 - 351 2019年10月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 Acta Materialia Inc. Low-energy helium (He) plasma irradiations were conducted on ruthenium (Ru) and rhenium (Re), which have hexagonal close packed (HCP) crystal structures. Growth of linear shaped fiberform nanostructures were identified on the surfaces of the both metals after the He plasma irradiation. We also conducted He plasma irradiation while Re particles were deposited on tungsten substrate; 3-mm-thick large scale fiberform nanostructures were grown on the surface. The crystal orientation was analyzed using diffraction patterns of Re and Ru nanofibers together with detailed transmission electron microscope observations. It was found that the growth of linear nanofibers has a preferential crystal orientation in the growth direction and it is always in the c-direction of the HCP crystals. Potential growth processes and mechanisms are proposed based on the experimental observations.

DOI： 10.1016/j.actamat.2019.09.053

Field Emission From Nanostructured Tendril Bundles 査読有り国際共著

D.Sinelnikov, D.Bulgadaryan, D.Hwangbo, S.Kajita, V.Kumaev, N.Ohno

IEEE TRANSACTIONS ON PLASMA SCIENCE 47 巻 ( 11 ) 頁： 5186 - 5190 2019年10月

Kinetics of deuterium penetration into neutron-irradiated tungsten under exposure to high flux deuterium plasma 査読有り

M. Yajima, Y. Hatano, N. Ohno, T. Kuwabara, T. Toyama, M. Takagi, K. Suzuki

Nuclear Materials and Energy 21 巻頁： 100699 2019年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 The Authors The objective of this study is to investigate the effects of neutron (n) irradiation on hydrogen isotope transport in tungsten (W). W samples were irradiated with neutrons in a fission reactor and then exposed to high flux deuterium (D) plasma at 563 K in a linear plasma device. The fraction of D release increased with increasing exposure time. In addition, the D retention in n-irradiated W increased in proportion to the square root of the plasma exposure time. These observations were explained by increase in the penetration depth of D with filling up displacement damages acting as strong trapping sites.

DOI： 10.1016/j.nme.2019.100699

Application of Ion Sensitive Probe to High Density Plasmas in Magnum-PSI 査読有り国際共著

Y.Hayashi, N.Ohno, H.van der Meiden, J.Scholten, S.Kajita, J.van der Berg, R.Perillo, J.Vernimmen, T.Moragan

PLASMA AND FUSION RESEARCH 14 巻頁： 1202135(3 pp) 2019年7月

Spatial and temporal measurement of recombining detached plasmas by laser Thomson scattering 査読有り

S. Kajita, H. Ohshima, H. Tanaka, M. Seki, H. Takano, N. Ohno

PLASMA SOURCES SCIENCE & TECHNOLOGY 28 巻頁： 105015 (9pp) 2019年7月

Photocatalytic decomposition of ethylene using He plasma induced nano-TiO<inf>2</inf> 査読有り

S.Kajita, Y.Tomita, E.Yasunaga, T.Yoshida, K.Miyaguchi, H.Tanaka, N.Ohno

Japanese Journal of Applied Physics 58 巻頁： 070903(4 pp) 2019年6月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 The Japan Society of Applied Physics. Ethylene decomposition via photocatalytic reaction using ultra-violet light was performed using an oxidized titanium (Ti) sheet and/or thin film samples fabricated by helium (He) plasmas treatments. We prepared nanostructured Ti samples formed by He plasma irradiation and additional thin film deposited samples using radio frequency magnetron sputtering. The samples prepared in this study had a slightly lower photocatalytic activity compared to the thin film deposited on tungsten nanostructure samples previously reported; the anatase formation was solely identified on Ti sheet samples and is hopeful for further improvement of photocatalytic activity of plasma treated titania.

DOI： 10.7567/1347-4065/ab2830

Fabrication of a nanostructured TiO<inf>2</inf> photocatalyst using He plasma-irradiated tungsten and ethylene gas decomposition 査読有り

Y.Tomita, S.Kajita, E.Yasunaga, T.Yoshida, N.Ohno, H.Tanaka

Japanese Journal of Applied Physics 58 巻 ( SE ) 頁： SEEG01(6 pp) 2019年5月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 The Japan Society of Applied Physics. Decomposition of ethylene gas by a photocatalyst is an environmentally friendly and sustainable process. We fabricated titanium dioxide thin films deposited on nanostructured tungsten substrates formed by exposure to helium plasma and evaluated their photocatalytic performance. The nanostructures were maintained even after sputtering and annealing, and the proportion of tungsten inside the thin film increased with increasing oxidation temperature. The photocatalytic activity was improved due to formation of the nanostructure.

DOI： 10.7567/1347-4065/ab09c8

Investigation of recombination front region in detached plasmas in a linear divertor plasma simulator 査読有り国際共著

N.Ohno, M.Seki, H.Ohshima, H.Tanaka, S.Kajita, Y.Hayashi, H.Natsume, H.Takano, I.Saeki, M.Yoshikawa, H.van der Meiden

Nuclear Materials and Energy 19 巻頁： 458 - 462 2019年5月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

We have investigated detailed plasma structure around the recombination front region (RFR), where volume electron-ion recombination (EIR) strongly occurs in detached plasmas, by using two-dimensional (2D) movable probe system as well as laser Thomson scattering diagnostics. The 2D distribution of electron density, electron temperature, and plasma potential around the RFR, has been revealed for the first time. The spatial distribution of the particle loss rate due to EIR estimated from electron temperature and electron density profiles indicated that the three-dimensional structure of the RFR adopts a cone structure. Furthermore, in the peripheral region of the RFR, the radial profile of the electron density was widened locally with increasing cross-field transport caused by plasma fluctuation. From the heat transport analysis of electrons, it was found that the thermal relaxation process between electrons and ions is important for the cooling of electrons, and that the convection of electrons regulates electron heat transport near the RFR.

DOI： 10.1016/j.nme.2019.03.010

Generation of Spiral Shape Nitrogen Recombining Plasma for Atomic Nitrogen Source 査読有り

K. Asaoka, N. Ohno, Y. Hayashi, S. Kajita, and H. Tanaka

Plasma and Fusion Research 14 巻頁： 3401069(4 pp) 2019年4月

Characterization of He induced nanostructures using SEM image analysis 査読有り

H.Tanaka, S.Kajita, N.Ohno

Plasma and Fusion Research 14 巻 ( Specialissue2 ) 頁： 3402049(6 pp) 2019年4月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 The Japan Society of Plasma Science and Nuclear Fusion Research. Helium induced nanostructures on tungsten were characterized by applying basic statistical analysis techniques to scanning electron microscope (SEM) images. As the analysis targets, pinhole- and fuzz-dominant surfaces irradiated with different ion fluences were employed. Although two-dimensional Fourier analysis of the normalized brightness of SEM images clarified several characteristic features, their differences are small to distinguish the dominant nanostructures. On the other hand, probability density functions (PDFs) of the normalized brightness indicate that hole- and fuzz-dominant surfaces have long tail and Gaussian-like shape, respectively. By using several indexes with considering the black and white saturation, it was found that kurtosis and Kullback- Leibler divergence could provide reasonable judgement as the characterization index.

DOI： 10.1585/pfr.14.3402049

Synergistic effect of nitrogen and hydrogen seeding gases on plasma detachment in the GAMMA 10/PDX tandem mirror 査読有り

N.Ezumi, T.Iijima, M.Sakamoto, Y.Nakashima, M.Hirata, M.Ichimura, R.Ikezoe, T.Imai, T.Kariya, I.Katanuma, J.Kohagura, R.Minami, T.Numakura, M. Yoshikawa, S. Togo, MD S.Islam, MD M.Islam, K.Nojiri, A.Terakado, S.Jang, Y.Kinoshita, T.Mikami, S.Yamashita, T.Yoshimoto, T.Hara, A.Hatayama, K.Ichimura, S.Kado, S.Masuzaki, T.Nakano, N.Ohno, K. Sawada, H. Tanaka, A.Tonegawa and R.Perillo

Nuclear Fusion 59 巻頁： 060030 2019年4月

Ignition and Behavior of Arc Spots on Helium Irradiated Tungsten under Fusion Relevant Condition 査読有り

S.Kajita, D.Hwangbo, N.Ohno

IEEE Transactions on Plasma Science 47 巻 ( 8 ) 頁： 3909 - 3916 2019年4月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 1973-2012 IEEE. In nuclear fusion reactors, unipolar arcing is a longstanding plasma surface interaction issue. In this paper, short summaries of morphology changes by helium plasma irradiation under fusion relevant conditions and ignition of arcing on the He irradiated surfaces are given. Helium plasma irradiation leads to surface morphology changes, and arcing can be ignited on the surface in response to pulsed heat load accompanied by plasma instabilities. Then, we focused on arcing ignited on large-scale fiberform nanostructures (LFNs) formed with deposition of metallic particles together with helium-ion irradiation. Dusts release from the arc spot and the amount of material erosion are discussed based on the experiments.

DOI： 10.1109/TPS.2019.2908193

Analysis of indefinite divertor footprint with proper orthogonal decomposition in hydrogen/deuterium plasmas in LHD 査読有り

H.Tanaka, S.Masuzaki, G.Kawamura, M.Kobayashi, Y.Suzuki, T.Morisaki, N.Ohno LHD Experimental Group

Nuclear Materials and Energy 19 巻頁： 378 - 383 2019年3月

Increased energy absorption into W due to the metal deposited layer from an ELM-like pulsed plasma 査読有り

T.Nakamori, N.Ohno, H.Tanaka, S.Kajita, Y.Kikuchi, T.Akiyama

Plasma and Fusion Research 14 巻頁： 1401051(5 pp) 2019年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 The Japan Society of Plasma Science and Nuclear Fusion Research. It is important in divertor physics research to investigate thermal response process of beryllium deposited tungsten to high transient heat load such as ELMs. We investigated the heat load on aluminum-coated tungsten by comparing the measured back surface temperature and calculation results of the one-dimensional heat conduction equation. When the plasma power was low enough so that the evaporation did not occur sufficiently, the heat load on the aluminum-coated tungsten was higher than the virgin tungsten. It was caused by the reduction in the energy reflection coefficient due to the formation of aluminum layer. The results suggested that the beryllium deposited layer adversely affects the heat load on the divertor plate when the heat load was not high such as Grassy-ELM.

DOI： 10.1585/pfr.14.1401051

Double-probe measurement in recombining plasma using NAGDIS-II 査読有り

Y. Hayashi, H. Nishikata, N. Ohno, S. Kajita, H. Tanaka, H. Ohshima, M. Seki

Contributions to Plasma Physics 59 巻 ( 7 ) 頁： e201800088 2019年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim We have studied the validity of the double-probe method in recombining plasmas. Electron temperature (Te) measured with a double probe was quantitatively evaluated by taking into account the influences of plasma potential fluctuation, plasma resistivity, and electron density fluctuation on the current–voltage characteristics. Differential potential fluctuation and plasma resistivity between two electrodes have a minor effect on Te especially when the inter-distance is small (typically 1 mm). Scattering of measured Te due to the density fluctuation was sufficiently suppressed by making the data acquisition time long (typically 4 s) and taking the average. There is a good agreement between Te measured with the optimized double-probe method and that with laser Thomson scattering diagnostics.

DOI： 10.1002/ctpp.201800088

Development of Thomson scattering measurement system for Upstream plasmas in the NAGDIS-II device 査読有り

H.Takano, H.Ohshima, S.Kajita, H.Tanaka, N.Ohno

Plasma and Fusion Research 14 巻 ( Specialissue1 ) 頁： 2405031(4 pp) 2019年2月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 The Japan Society of Plasma Science and Nuclear Fusion Research. A new laser Thomson scattering (LTS) measurement system in the upstream region of the linear plasma device NAGDIS-II is established in addition to the recently introduced LTS in the downstream. Further, horizontal distributions of the electron temperature and electron density were compared with those obtained from the Langmuir probe, indicating plasma disturbance due to the insertion of the probe head. We discuss the variation of the electron energy distribution function at upstream and downstream in the recombining plasma.

DOI： 10.1585/pfr.14.2405031

Growth of membrane nanostructures on W co-deposition layer 査読有り

S. Kajita, N. Yoshida, S. Kawaguchi, H. Tanaka, N. Ohno, D. Nagata, M. Tokitani

Nuclear Materials and Energy 18 巻頁： 339 - 344 2019年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 The Authors Large-scale mm thick fiberform nanostructures are grown when materials are subjected to high flux helium ions with tungsten particles (ions and neutrals) precipitation. Observations of the large-scale fiberform nanostructures (LFNs) were conducted by scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. In particular, this study focuses on membrane nanostructures. Membranes that contain He bubbles were always observed when LFNs covered the surface. We discuss the growth process of the membrane structures based on detailed observations.

DOI： 10.1016/j.nme.2019.02.004

Spatiotemporal Structure of Hα Emission from the Detached Plasma in GAMMA 10/PDX 査読有り

H.Tanaka, M.Sakamoto, N.Ezumi, A.Terakado, K.Nojiri, T.Mikami, Y.Kinoshita, K.Kobayashi, M.Yoshikawa, J. Kohagura, N.Ohno

Plasma and Fusion Research: Regular Articles 14 巻頁： 2402036(5 pp) 2019年2月

Growth process of nano-tendril bundles with sputtered tungsten 査読有り

D. Hwangbo, S. Kajita, H. Tanaka, and N. Ohno

Nuclear Materials and Energy 18 巻頁： 250 - 257 2019年1月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 The Authors Nano-tendril bundles (NTBs) were generated in DC He plasma with impurity gas-seeding (Ne and N 2 ) under sputtering-dominated conditions. NTB morphologies were characterized using the net erosion yield of samples. NTBs’ height and area were analyzed and ion fluence dependence was discussed. For both impurities, the number of NTBs increased steadily with increasing the fluence. It was revealed that NTB can be generated newly and continuously regardless of ion fluence. Surface observations suggested that micro-protrusions can evolve into NTBs. The effect of re-deposition of W was discussed based on SEM observations. Line-of-sight deposition seemed to play a key role of W feeder to enable NTBs to grow greater.

DOI： 10.1016/j.nme.2019.01.008

Proton scattering from tungsten fuzz

Multipoint measurements employing a microwave interferometer and a Langmuir probe in the detached linear plasma 査読有り

H. Natsume, H. Tanaka, S. Kajita, M. Yoshikawa, M. Seki, H. Ohshima, and N. Ohno

AIP ADVANCES 9 巻頁： 015016 (6pp) 2019年1月

Influence of heavier impurity deposition on surface morphology development and sputtering behavior explored in multiple linear plasma devices 査読有り国際共著

D.Nishijima, A.Kreter, M.Baldwin, D.Borodin, A.Eksaeva, D.Hwangbo, S.Kajita, M.Miyamoto, N.Ohno, M.Patino, A.Psopieszczyk, M.Rasinski, T.Schlummer, A.Terra, R.P.Doerner

NUCLEAR MATERIALS AND ENERGY 18 巻頁： 67 - 71 2019年1月

Spatiotemporal Structure of H alpha Emission from the Detached Plasma in GAMMA 10/PDX 査読有り

H.Tanaka, M.Sakamoto, N.Ezumi, A.Terakado, K.Nojiri, T.Mikami, Y.Kinoshita, K.Kobayashi, M.Yoshikawa, J. Kohagura, N.Ohno

PLASMA AND FUSION RESEARCH 14 巻 ( Specialissue1 ) 頁： 2402036(5 pp) 2019年1月

Effect of Damage Introduction and He Existence on D Retention in Tungsten by High Flux D Plasma Exposure 査読有り

Yasuhisa Oya, Keisuke Azuma, Akihiro Togari, Moeko Nakata, Qilai Zhou, Mingzhong Zhao, Tatsuya Kuwabara, Noriyasu Ohno, Miyuki Yajima, Yuji Hatano, Takeshi Toyama

Lecture Notes in Networks and Systems 53 巻 ( 8 ) 頁： 89 - 96 2019年

D. Bulgadaryan, D. Sinelnikov, V. Kurnaev, S. Kajita, D. Hwangbo, N. Ohno

Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 434 巻頁： 9 - 12 2018年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

© 2018 Elsevier B.V. Tungsten fuzz is a nanostructure formed on tungsten surface under helium plasma impact. In this work, we investigate this structure using the scattering of keV-energy protons. Energy spectra of scattered protons have double-peak shape that corresponds to the scattering from fuzz and underlying pure tungsten. The energy losses of protons in fuzz are estimated as the difference between primary beam energy and the energy corresponding to the local minimum between two peaks. Computer simulations with SRIM code also demonstrate double-peak shape of energy spectra of protons scattered from fuzzy target. Fuzz and pure tungsten stopping powers for protons are compared and fuzz density relative to pure tungsten is estimated and discussed. Evolution of H+energy spectra during fuzz irradiation by Ar+beam is measured and discussed.

DOI： 10.1016/j.nimb.2018.07.038

Plasma exhaust and divertor studies in Japan and Europe broader approach, DEMO design activity 査読有り国際共著

N.Asakura, K.Hoshino , H.Utoh, Y.Someya, S.Suzuki, C.Bachmann, H.Reimerdes, R.Wenninger, H.Kudo, S.Tokunaga, Y.Hommai, Y.Sakamoto, R.Hiwatari, K.Tobita, Jeong-Ha You, G.Federici, K.Ezato, Y.Seki, ...N.Ohno

Fusion Engineering and Design 136 巻頁： 1214 - 1220 2018年11月

Characterized divertor footprint profile modification with the edge pressure gradient in the Large Helical Device 査読有り

Tanaka H., Masuzaki S., Kawamura G., Kobayashi M., Suzuki Y., Motojima G., Murase T., Morisaki T., Ohno N.

Plasma Physics and Controlled Fusion 60 巻 ( 12 ) 頁： 125001 2018年10月

Morphologies of co-depositing W layer formed during He plasma irradiation 査読有り

Kajita Shin, Kawaguchi Shota, Yoshida Naoaki, Ohno Noriyasu, Tanaka Hirohiko

NUCLEAR FUSION 58 巻 ( 10 ) 頁： 106002 2018年10月

One-Step Plasma Synthesis of Nb<inf>2</inf>O<inf>5</inf> Nanofibers and their Enhanced Photocatalytic activity 査読有り

S.Kajita, F.Mimuro, T.Yoshida, N.Ohno, N.Yoshida

ChemPhysChem 19 巻 ( 23 ) 頁： 3237 - 3246 2018年9月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Fiberform nanostructured niobium (Nb) was fabricated by one step helium (He) plasma irradiation. He ion implantation formed He nano-bubbles on a Nb plate and led to formation of protrusions while migrating in Nb matrix; fiberform nanostructures (FN) were grown when the fluence became high (>1026 m−2). The necessary conditions for the formation of Nb FN were revealed to be the surface temperature range of 900–1100 K and the incident ion energy higher than 70 eV. The sample was oxidized at 573–773 K in an air atmosphere, and Pt nanoparticles were photo-deposited on the Nb2O5 samples. The surface was analyzed by scanning electron microscope, transmission electron microscope, x-ray photoelectron spectroscopy, and ultraviolet-visible spectrophotometry. Photocatalytic activity of the fabricated materials was studied using methylene blue (MB) decolorization process. An enhanced photocatalytic performance was identified on FN Nb2O5 substrate with Pt deposition.

DOI： 10.1002/cphc.201800769

Growth of nano-tendril bundles on tungsten with impurity-rich He plasmas 査読有り

Hwangbo Dogyun, Kajita Shin, Ohno Noriyasu, McCarthy Patrick, Bradley James W, Tanaka Hirohiko

NUCLEAR FUSION 58 巻 ( 9 ) 頁： 096022 2018年9月

Thomson Scattering Measurement of Two Electron Temperature Components in Transition to Detached Plasmas 査読有り

Ohshima Hiroshi, Kajita Shin, Tanaka Hirohiko, Ohno Noriyasu, Van der Meiden Hennie J

PLASMA AND FUSION RESEARCH 13 巻頁： 1201099 2018年8月

Effect of the Nanostructured Layer Thickness on the Dynamics of Cathode Spots on Tungsten 査読有り国際共著

Sergey A. Barengolts, Vadim G. Mesyats, Mikhail M. Tsventoukh, Shin Kajita, Dogyun Hwangbo, Noriyasu Ohno

IEEE Transactions on Plasma Science 46 巻 ( 11 ) 頁： 4044 - 4050 2018年8月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE Transactions on Plasma Science

IEEE Experimental data on the effect of the thickness of a nanostructured layer present on the surface of a tungsten cathode on its arcing properties have been analyzed. It has been shown that if the nanostructured layer is not completely destroyed as a result of the operation of a cathode spot cell, the spot ``sinks'' in the layer, the spot cells group together, and the trajectory of the spot motion becomes ``entangled.'' To interpret the experimental results, the grouping of arc spot cells was simulated using a random walk model based on the Monte Carlo method into which an attractive force was introduced and assuming that the cell plasma density, i.e., the cell initiation probability, is proportional to 1/r&#x00B2;, where r is the distance between two spot cells. It has been demonstrated that spot cells are entangled, forming a group and moving together when the attractive force between them is strong enough. When this force decreases and the directionality of the cells increases as the cathode spot shifts to a lower thickness region of the nanostructured layer, the velocity of motion of the spot increases and its trace left on the surface becomes narrower.

DOI： 10.1109/TPS.2018.2859953

Blob- and hole-like structures outstanding during the transition from attached to detached divertor states in GAMMA 10/PDX 査読有り

Tanaka, H, Sakamoto, M, Ezumi, N, Nojiri, K, Terakado, A, Mikami, T, Kinoshita, Y, Kobayashi, K, Yoshikawa, M, Kohagura, J, Ohno, N

PHYSICS OF PLASMAS 25 巻 ( 8 ) 頁： 082505(6 pp) 2018年8月

Localized spiraling plasma ejection contributing the ion-flux broadening in the detached linear plasma 査読有り

Tanaka, H, Takeyama, K, Yoshikawa, M, Kajita, S, Ohno, N, Hayashi, Y

PLASMA PHYSICS AND CONTROLLED FUSION 60 巻 ( 7 ) 頁： 075013 2018年7月

Ignition and erosion of materials by arcing in fusion-relevant conditions 査読有り

Hwangbo Dogyun, Kajita Shin, Barengolts Sergey A, Tsventoukh Mikhail M, Kawaguchi Shota, Mesyats Vadim G, Ohno Noriyasu

CONTRIBUTIONS TO PLASMA PHYSICS 58 巻 ( 6-8 ) 頁： 608 - 615 2018年7月

Helium line emission spectroscopy in recombining detached plasmas 査読有り

Shin Kajita, Kensuke Suzuki, Hirohiko Tanaka, Noriyasu Ohno

Physics of Plasmas 25 巻 ( 6 ) 頁： 063303 2018年6月

Nanostructure Growth on Rhodium/Ruthenium by the Exposure to He Plasma 査読有り

Tomohiro NOJIMA, Shin KAJITA, Naoaki YOSHIDA, Shota KAWAGUCHI, Noriyasu OHNO, Hirohiko TANAKA, Masayuki TOKITANI, Daisuke NAGATA, Tsuyoshi AKIYAMA, Takashi YAGI

Plasma and Fusion Research 13 巻頁： 3406064 2018年6月

Mode Structure Analysis of Detached Plasmas with 2D Images 査読有り

Kajita Shin, Tanaka Hirohiko, Ohno Noriyasu, Onda Takuya

PLASMA AND FUSION RESEARCH 13 巻頁： 1402033(5 pp) 2018年5月

Fabrication of photocatalytically active vanadium oxide nanostructures via plasma route 査読有り

Shin Kajita, Tomoko Yoshida, Noriyasu Ohno, Yusuke Ichino, Naoaki Yoshida

Journal of Physics D: Applied Physics 51 巻 ( 21 ) 頁： 215201 2018年4月

Fuzzy nanostructure growth on precious metals by He plasma irradiation 査読有り

Shin Kajita, Tomohiro Nojima, Yudai Tomita, Noriyasu Ohno, Hirohiko Tanaka, Naoaki Yoshida, Miyuki Yajima, Tsuyoshi Akiyama, Masayuki Tokitani, Takashi Yagi

Surface and Coatings Technology 340 巻頁： 86 - 92 2018年4月

Pulsation Effects of Incident Ion Energy on W Fuzz Growth 査読有り

Kajita Shin, Kawaguchi Shota, Hwangbo Dogyun, Tanaka Hirohiko, Ohno Noriyasu

PLASMA AND FUSION RESEARCH 13 巻頁： 1205001 2018年1月

Measurement of He neutral temperature in detached plasmas using laser absorption spectroscopy 査読有り

Aramaki M., Tsujihara T., Kajit S., Tanaka H., Ohno N.

AIP Advances 8 巻 ( 1 ) 頁： 015308 2018年1月

Analysis of ELM stability with extended MHD models in JET, JT-60U and future JT-60SA tokamak plasmas 査読有り

Aiba N., Pamela S., Honda M., Urano H., Giroud C., Delabie E., Frassinetti L., Lupelli I., Hayashi N., Huijsmans G.T.A., Litaudon X., Abduallev S., Abhangi M., Abreu P., Afzal M., Aggarwal K.M., Ahlgren T., Ahn J.H., Aho-Mantila L., Airila M., Albanese R., Aldred V., Alegre D., Alessi E., Aleynikov P., Alfier A., Alkseev A., Allinson M., Alper B., Alves E., Ambrosino G., Ambrosino R., Amicucci L., Amosov V., Sundén E.A., Angelone M., Anghel M., Angioni C., Appel L., Appelbee C., Arena P., Ariola M., Arnichand H., Arshad S., Ash A., Ashikawa N., Aslanyan V., Asunta O., Auriemma F., Austin Y., Avotina L., Axton M.D., Ayres C., Bacharis M., Baciero A., Baião D., Bailey S., Baker A., Balboa I., Balden M., Balshaw N., Bament R., Banks J.W., Baranov Y.F., Barnard M.A., Barnes D., Barnes M., Barnsley R., Wiechec A.B., Orte L.B., Baruzzo M., Basiuk V., Bassan M., Bastow R., Batista A., Batistoni P., Baughan R., Bauvir B., Baylor L., Bazylev B., Beal J., Beaumont P.S., Beckers M., Beckett B., Becoulet A., Bekris N., Beldishevski M., Bell K., Belli F., Bellinger M., Belonohy , Ayed N.B., Benterman N.A., Bergsåker H., Bernardo J., Bernert M., Berry M., Bertalot L., Besliu C., Beurskens M.

Plasma Physics and Controlled Fusion 60 巻 ( 1 ) 2018年1月

記述言語：日本語出版者・発行元：Plasma Physics and Controlled Fusion

The stability with respect to a peelingballooning mode (PBM) was investigated numerically with extended MHD simulation codes in JET, JT-60U and future JT-60SA plasmas. The MINERVA-DI code was used to analyze the linear stability, including the effects of rotation and ion diamagnetic drift (w∗i), in JET-ILW and JT-60SA plasmas, and the JOREK code was used to simulate nonlinear dynamics with rotation, viscosity and resistivity in JT-60U plasmas. It was validated quantitatively that the ELM trigger condition in JET-ILW plasmas can be reasonably explained by taking into account both the rotation and w∗i effects in the numerical analysis. When deuterium poloidal rotation is evaluated based on neoclassical theory, an increase in the effective charge of plasma destabilizes the PBM because of an acceleration of rotation and a decrease in w∗i. The difference in the amount of ELM energy loss in JT-60U plasmas rotating in opposite directions was reproduced qualitatively with JOREK. By comparing the ELM affected areas with linear eigenfunctions, it was confirmed that the difference in the linear stability property, due not to the rotation direction but to the plasma density profile, is thought to be responsible for changing the ELM energy loss just after the ELM crash. A predictive study to determine the pedestal profiles in JT-60SA was performed by updating the EPED1 model to include the rotation and w∗i effects in the PBM stability analysis. It was shown that the plasma rotation predicted with the neoclassical toroidal viscosity degrades the pedestal performance by about 10% by destabilizing the PBM, but the pressure pedestal height will be high enough to achieve the target parameters required for the ITER-like shape inductive scenario in JT-60SA.

DOI： 10.1088/1361-6587/aa8bec

Enhanced growth of large-scale nanostructures with metallic ion precipitation in helium plasmas 査読有り

Shin Kajita, Shota Kawaguchi, Noriyasu Ohno, Naoaki Yoshida

Scientific Reports 8 巻頁： 56 2018年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nature Publishing Group

Helium plasma irradiation on metal surfaces leads to the formation of metallic fuzzy nanostructures accompanied by the growth of helium bubbles in metals. The mechanism of the growth process, its impact for fusion devices, and potential application have been explored. Here we show enhanced growth of large-scale fuzz by precipitating additional metallic particles during helium plasma irradiation. The growth rate of the fuzzy structures became orders of magnitude greater than conventional fuzz growth
in an hour of irradiation, 1 mm-thick visible tungsten and molybdenum fuzzy fur structures covered a tungsten metal substrate. Additional precipitation of metallic ions breaks the bottleneck diffusion process
moreover, further acceleration in the growth rate could have occurred if the electric sheath shape was influenced by the grown structure and the electric field that formed around the structure started collecting ions.

DOI： 10.1038/s41598-017-18476-7

Morphology Changes of Platinum and Tungsten Carbide by He Plasma Irradiation 査読有り

Tomita Yudai, Kajita Shin, Ohno Noriyasu, Tanaka Hirohiko, Ichino Yusuke

PLASMA AND FUSION RESEARCH 13 巻頁： 3406074 2018年

Recent progress of divertor simulation research using the GAMMA 10/PDX tandem mirror 査読有り

Nakashima Y, Ichimura K, Islam M. S, Sakamoto M, Ezumi N, Hirata M, Ichimura M, Ikezoe R, Imai T, Kariya T, Katanuma I, Kohagura J, Minami R, Numakura T, Yoshikawa M, Iijima T, Islam M. M, Nojiri K, Shimizu K, Terakado A, Togo S, Asakura N, Fukumoto M, Hatayama A, Hirooka Y, Kado S, Kubo H, Masuzaki S, Matsuura H, Nakano T, Nagata S, Nishino N, Ohno N, Sagara A, Sawada K, Shoji M, Tonegawa A, Ueda Y

NUCLEAR FUSION 57 巻 ( 11 ) 2017年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

This paper describes the recent progress in divertor simulation research using the GAMMA 10/PDX tandem mirror towards the development of divertors in fusion reactors. During a plasma flow generation experiment in the end cell of the GAMMA 10/PDX, ICRF heating in the anchor cell successfully extended the particle flux up to 3.3 1023 m2 s-1. Superimposing the short pulse of the ECH also attained a maximum heat flux of ∼30 MW m-2. We have succeeded in achieving and characterizing the detachment of the high-temperature plasma, which is equivalent to the SOL plasma of tokamaks, by using the divertor simulation experimental module (D-module) in the GAMMA 10/PDX end cell, in spite of using a linear device with a short magnetic field line connection length. Various gases (Ar, Xe, Ne and N2) are examined to evaluate the effect of radiation cooling against the plasma flow at the MW m-2 level in the divertor simulation region and the following results are obtained: (i) Xe gas was most effective in the reduction of heat and particle fluxes (1%, 3%, respectively) and has a stronger effect on electron cooling (down to ∼1.6 eV) in the used gas species. (ii) Ne gas was less effective. On the other hand, (iii) N2 gas showed more favorable effects than Ar in the lower pressure range. These results will contribute to the progress in detached plasma operation and in clarifying the radiation cooling mechanism towards the development of future divertors.

DOI： 10.1088/1741-4326/aa7cb4

Development of a Compact Divertor Plasma Simulator for Plasma-Wall Interaction Studies on Neutron-Irradiated Materials 査読有り

N.Ohno, T.Kuwabara, M.Takagi, R.Nishimura, M.Yajima, A.Sagara, T.Toyama, K.Suzuki, H.Kurishita, T.Shikama, Y.Hatano, N.Yoshida

PLASMA AND FUSION RESEARCH 12 巻 ( 0 ) 頁： 1405040 - 1405040 2017年10月

担当区分：筆頭著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：社団法人プラズマ・核融合学会

We have developed a compact divertor plasma simulator (CDPS) that can produce steady-state deuterium and/or helium plasmas with densities above ∼ 1018 m−3 for Plasma-Wall Interaction (PWI) studies of neutronirradiated materials. The maximum particle flux is about 1022 m−2s−1. The CDPS was installed and is being operated in the radiation-controlled area of the International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University. We are able to control sample temperature within uncertainty of 5◦C during plasma exposure by adjusting the cooling air flow rate to the sample holder. The CDPS has a sample-carrier system, which makes it possible to transfer a plasma-irradiated sample from the sample holder to an infrared heater for analysis using thermal desorption spectroscopy (TDS) without exposing it to the air. This avoids the oxidation of the sample and minimizes the time between the end of plasma exposure and TDS analysis. An ITER-like tungsten (W) sample (A.L.M.T. Corp.), which has been irradiated by neutrons to 0.06 dpa in a fission reactor, was exposed to a deuterium plasma in the CDPS. The experimental results clearly show that the total deuterium retention in the neutron-irradiated W sample increases significantly in comparison with a pristine W, as demonstrated by broadening of the TDS spectrum at high temperatures.

DOI： 10.1585/pfr.12.1405040

Studies of power exhaust and divertor design for a 1.5 GW-level fusion power DEMO 査読有り

N.Asakura, K.Hoshino, S.Suzuki, S.Tokunaga, Y.Someya, H.Utoh, H.Kudo, Y.Sakamoto, R.Hiwatari, K.Tobita, K.Shimizu, K.Ezato, Y.Seki, N.Ohno, Y.Ueda, Joint Special Team for DEMO Design

Nuclear Fusion 57 巻頁： 126050(12 pp) 2017年10月

Plasma Exhaust and Divertor Studies in JA and EU Broader Tokamak Fusion Reactor Approach, DEMO Design Activity 査読有り

Nobuyuki Asakura, Kazuo Hoshino, Hiroyasu Utoh, Yoji Someya, Satoshi Suzuki, Christian Bachmann, Holger Reimerdes, Hironobu Kudo, Shinsuke Tokunaga, Yuki Homma, Yoshiteru Sakamoto, Ryoji Hiwatari, Ronald Wenninger, Kenji Tobita, Noriyasu Ohno,Gianfranco Federici, Koichiro Ezato, Yohji Seki, Noriyasu Ohno, Yoshio Ueda

2017年9月

Extension of the operational regime of the LHD towards a deuterium experiment 査読有り

Takeiri Y., Morisaki T., Osakabe M., Yokoyama M., Sakakibara S., Takahashi H., Nakamura Y., Oishi T., Motojima G., Murakami S., Ito K., Ejiri A., Imagawa S., Inagaki S., Isobe M., Kubo S., Masamune S., Mito T., Murakami I., Nagaoka K., Nagasaki K., Nishimura K., Sakamoto M., Sakamoto R., Shimozuma T., Shinohara K., Sugama H., Watanabe K. Y., Ahn J. W., Akata N., Akiyama T., Ashikawa N., Baldzuhn J., Bando T., Bernard E., Castejon F., Chikaraishi H., Emoto M., Evans T., Ezumi N., Fujii K., Funaba H., Goto M., Goto T., Gradic D., Gunsu Y., Hamaguchi S., Hasegawa H., Hayashi Y., Hidalgo C., Higashiguchi T., Hirooka Y., Hishinuma Y., Horiuchi R., Ichiguchi K., Ida K., Ido T., Igami H., Ikeda K., Ishiguro S., Ishizaki R., Ishizawa A., Ito A., Ito Y., Iwamoto A., Kamio S., Kamiya K., Kaneko O., Kanno R., Kasahara H., Kato D., Kato T., Kawahata K., Kawamura G., Kisaki M., Kitajima S., Ko W. H., Kobayashi M., Kobayashi S., Kobayashi T., Koga K., Kohyama A., Kumazawa R., Lee J. H., Lopez-Bruna D., Makino R., Masuzaki S., Matsumoto Y., Matsuura H., Mitarai O., Miura H., Miyazawa J., Mizuguchi N., Moon C., Morita S., Moritaka T., Mukai K., Muroga T., Muto S., Mutoh T., Nagasaka T., Nagayama Y., Nakajima N., Nakamura Y., Nakanishi H., Nakano H., Nakata M., Narushima Y., Nishijima D., Nishimura A., Nishimura S., Nishitani T., Nishiura M., Nobuta Y., Noto H., Nunami M., Obana T., Ogawa K., Ohdachi S., Ohno M., Ohno N., Ohtani H., Okamoto M., Oya Y., Ozaki T., Peterson B. J., Preynas M., Sagara S., Saito K., Sakaue H., Sanpei A., Satake S., Sato M., Saze T., Schmitz O., Seki R., Seki T., Sharov I., Shimizu A., Shiratani M., Shoji M., Skinner C., Soga R., Stange T., Suzuki C., Suzuki Y., Takada S., Takahata K., Takayama A., Takayama S., Takemura Y., Takeuchi Y., Tamura H., Tamura N., Tanaka H., Tanaka K., Tanaka M., Tanaka T., Tanaka Y., Toda S., Todo Y., Toi K., Toida M., Tokitani M., Tokuzawa T., Tsuchiya H., Tsujimura T., Tsumori K., Usami S., Velasco J. L., Wang H., Watanabe T. -H., Watanabe T., Yagi J., Yajima M., Yamada H., Yamada I., Yamagishi O., Yamaguchi N., Yamamoto Y., Yanagi N., Yasuhara R., Yatsuka E., Yoshida N., Yoshinuma M., Yoshimura S., Yoshimura Y.

Nuclear Fusion 57 巻 ( 10 ) 2017年8月

Erosion of nanostructured tungsten by laser ablation, sputtering and arcing 査読有り

Dogyun Hwangbo, Shota Kawaguchi, Shin Kajita, Noriyasu Ohno

Nuclear Materials and Energy 12 巻頁： 386 - 391 2017年8月

Measuring temperature effects on nano-bubble growth in tungsten with grazing incidence small angle X-ray scattering 査読有り

Matt Thompson, Russ Doerner, Noriyasu Ohno, Nigel Kirby, Patrick Kluth, Daniel Riley, Cormac Corr

Nuclear Materials and Energy 12 巻頁： 1294 - 1297 2017年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Elsevier Ltd

W samples were exposed to He plasma in the MAGPIE, NAGDIS-II and PISCES-A across a range of sample temperatures between 473–1123 K. GISAXS was used to quantify the effect of plasma fluence and W surface temperature on He nano-bubble size distributions. In NAGDIS-II at 873 K nano-bubbles are exponentially distributed with mean diameters μ=0.64±0.01nm, similar to the value of μ=0.62±0.01nmfound for the MAGPIE plasma device at the much lower temperature of 473 K. Above ∼900 K nano-bubbles followed an approximately exponential distribution with μ &gt
0.72 nm demonstrating a significant increase in nano-bubble sizes at higher temperatures.

DOI： 10.1016/j.nme.2016.11.025

A Particle-In-Cell approach to particle flux shaping with a surface mask 査読有り

Kawamura G, Ohno N, Takamura S, Tomita Y

NUCLEAR MATERIALS AND ENERGY 12 巻頁： 297 - 301 2017年8月

Toroidally symmetric/asymmetric effect on the divertor flux due to neon/nitrogen seeding in LHD 査読有り

Tanaka H., Kawamura G., Masuzaki S., Kobayashi M., Akiyama T., Peterson B. J., Mukai K., Sano R., Dai S. Y., Sakamoto R., Morisaki T., Ohno N.

NUCLEAR MATERIALS AND ENERGY 12 巻頁： 241 - 246 2017年8月

Molecular activated recombination in divertor simulation plasma on GAMMA 10/PDX 査読有り

Sakamoto M, Terakado A, Nojiri K, Ezumi N, Nakashima Y, Sawada K, Ichimura K, Fukumoto M, Oki K, Shimizu K, Ohno N, Masuzaki S, Togo S, Kohagura J, Yoshikawa M

NUCLEAR MATERIALS AND ENERGY 12 巻頁： 1004 - 1009 2017年8月

Fractality and growth of He bubbles in metals 査読有り

Shin Kajita, Atsushi M. Ito, Noriyasu Ohno

Physics Letters, Section A: General, Atomic and Solid State Physics 381 巻 ( 29 ) 頁： 2355 - 2362 2017年8月

Field emission from metal surfaces irradiated with helium plasmas 査読有り国際共著

Dogyun Hwangbo, Shin Kajita, Noriyasu Ohno, Dmitry Sinelnikov

IEEE Transactions on Plasma Science 45 巻 ( 8 ) 頁： 2080 - 2086 2017年8月

Effects of modified surfaces produced at plasma-facing surface on hydrogen release behavior in the LHD 査読有り

Nobuta Y, Masuzaki S, Tokitani M, Ashikawa N, Nagata D, Yoshida N, Oya Y, Yajima M, Motojima G, Kasahara H, Miyamoto M, Ohno N, Yamauchi Y

NUCLEAR MATERIALS AND ENERGY 12 巻頁： 483 - 487 2017年8月

Behavior of 23S metastable state He atoms in low-temperature recombining plasmas 査読有り

S.Kajita, T.Tsujihara, M.Aramaki, H.van der Meiden, H.Oshima, N.Ohno, H.Tanaka, R.Yasuhara, T.Akiyama, K.Fujii, T.Shikama

Physics of Plasmas 24 巻頁： 073301(8 pp) 2017年6月

Influence of expanding and contracting magnetic field configurations on detached plasma formation in a linear plasma device 査読有り

Y.Hayashi, N.Ohno, S.Kajita, H.Tanaka

Physics of Plasmas 24 巻頁： 062509(8 pp) 2017年6月

Recent progress of the JT-60SA project 査読有り国際共著国際誌

Shirai H., Barabaschi P., Kamada Y., Maksoud W.A., Aiba N., Akiyama T., Alonso J., Angioni C., Arai T., Arakawa H., Ardellier F., Artaud J.F., Asakura N., Ashikawa N., Barbato E., Barrera G., Baruzzo M., Baulaigue O., Beaufils S., Bécoulet M., Benkadda S., Benoit F., Bettini P., Beurskens M., Bierwage A., Boboc A., Boccaccini L., Bolzonella T., Bonne F., Borba D., Botija J., Bourdelle C., Brolatti G., Bruschi A., Bucalossi J., Cabrera-Pérez S., Canton A., Cardella A., Carvalho I., Challis C., Chapman I., Chiba S., Ciazynski D., Cismondi F., Clement-Lorenzo S., Coccoluto G., Cocilovo V., Coda S., Coelho R., Coletti A., Collin B., Conway G., Corato V., Costa P., Crisanti F., Cristofani C., Cruz N., Cucchiaro A., Dairaku M., Davis S., Day C., de Baar M., de la Luna E., De Tommasi G., De Vellis A., De Vries P., Decker J., Decool P., Delrez C., Di Pace L., Di Pietro E., Disset G., Donati A., Douai D., Dougnac H., Duchateau J.L., Duglue D., Dumas N., Dunai D., Ejiri A., Endo Y., Enoeda M., Falchetto G., Farina D., Farthing J., Fejoz P., Fernandez P., Ferro A., Fiamozzi-Zignani C., Fietz W., Figini L., Frello G., Frosi P., Fujita T., Fukuda T., Fukumoto M., Fukuyama A., Furukawa M., Furukawa M.

Nuclear Fusion 57 巻 ( 10 ) 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

The JT-60SA project has been implemented for the purpose of an early realization of fusion energy. With a powerful and versatile NBI and ECRF system, a flexible plasma-shaping capability, and various kinds of in-vessel coils to suppress MHD instabilities, JT-60SA plays an essential role in addressing the key physics and engineering issues of ITER and DEMO. It aims to achieve the long sustainment of high integrated performance plasmas under the high β N condition required in DEMO. The fabrication and installation of components and systems of JT-60SA procured by the EU and Japan are steadily progressing. The installation of toroidal field (TF) coils around the vacuum vessel started in December 2016. The commissioning of the cryogenic system and power supply system has been implemented in the Naka site, and JT-60SA will start operation in 2019. The JT-60SA research plan covers a wide area of issues in ITER and DEMO relevant operation regimes, and has been regularly updated on the basis of intensive discussion among European and Japanese researchers.

DOI： 10.1088/1741-4326/aa5d01

Measurement of Poloidal Flow Profiles Using a Mach Probe Array in HYBTOK-II Tokamak with RMP Fields 査読有り

Okamoto Masaaki, Sakakibara Satoru, Yoshimoto Naoya, Ohno Takuya, Ohno Noriyasu

PLASMA AND FUSION RESEARCH 12 巻頁： 1202027 2017年6月

Observations of sustained phase shifted magnetic islands from externally imposed m/n=1/1 RMP in LHD 査読有り国際共著

Narushima Y., Sakakibara S., Suzuki Y., Watanabe K. Y., Ohdachi S., Takemura Y., Yoshinuma M., Ida K., Castejon F., Lopez-Bruna D., Hegna C. C., Kobayashi M., Tanaka H., Akiyama T., Ohno N.

NUCLEAR FUSION 57 巻 ( 7 ) 頁： 076024 2017年5月

Molecular activated recombination in divertor simulation plasma on GAMMA 10/PDX 査読有り

M.Sakamoto, A.Terakado, K.Nojiri, N.Ezumi, Y.Nakashima, K.Sawada, Ichimura, M.Fukumoto, N.Ohno, S.Masuzaki, S.Togo, Kohagura, M.Yoshikawa

Nuclear Materials and Energy 12 巻頁： 1004-1009 2017年5月

Increase in the energy absorption of pulsed plasma by the formation of tungsten nanostructure 査読有り

D. Sato, N. Ohno, F. Domon, S. Kajita, Y. Kikuchi, I. Sakuma

Nuclear Fusion 57 巻 ( 6 ) 頁： 066028(8 pp) 2017年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2017 IAEA, Vienna. The synergistic effects of steady-state and pulsed plasma irradiation to material have been investigated in the device NAGDIS-PG (Nagoya DIvertor Simulator with Plasma Gun). The duration of the pulsed plasma was ∼0.25 ms. To investigate the pulsed plasma heat load on the materials, we developed a temperature measurement system using radiation from the sample in a high time resolution. The heat deposited in response to the transient plasma on a tungsten surface was revealed by using this system. When the nanostructures were formed by helium plasma irradiation, the temperature increase on the bulk sample was enhanced. The result suggested that the amount of absorbed energy on the surface was increased by the formation of nanostructures. The possible mechanisms causing the phenomena are discussed with the calculation of a sample temperature in response to the transient heat load.

DOI： 10.1088/1741-4326/aa67ad

Tailoring of fuzzy nanostructures on porous tungsten skeleton by helium plasma irradiation 査読有り

Kajita Shin, Tanaka Hirohiko, Ohno Noriyasu

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 3 ) 頁： 030303(4 pp) 2017年3月

Plasma detachment in linear devices 査読有り

Ohno N.

PLASMA PHYSICS AND CONTROLLED FUSION 59 巻 ( 3 ) 頁： 034007(9 pp) 2017年3月

Localized Density Fluctuation in the Downstream of Detached Plasma 査読有り

Takeyama Kohei, Ohno Noriyasu, Yoshikawa Masayuki, Tanaka Hirohiko, Kajita Shin

PLASMA AND FUSION RESEARCH 12 巻 ( 1 ) 頁： 1202007 2017年2月

Transverse motion of a plasma column in a sheet plasma 査読有り

Onda Takuya, Kajita Shin, Iijima Takaaki, Tonegawa Akira, Ohno Noriyasu, Tanaka Hirohiko

CONTRIBUTIONS TO PLASMA PHYSICS 57 巻 ( 2 ) 頁： 87 - 93 2017年2月

In Situ TEM Observation of Helium Bubbles Collapsing on Nanostructured Tungsten during Annealing 査読有り

M. Yajima, N. Yoshida, S. Kajita, and N. Ohno

Plasma and Fusion Research 11 巻頁： 1206125 2016年12月

Measurement of heat diffusion across fuzzy tungsten layer 査読有り

S.Kajita, T.Yagi, K.Kobayashi, M.Tokitani, N.Ohno

Results in Physics 6 巻頁： 877-878 2016年11月

Enhancement of photocatalytic activity of TiO2 by plasma irradiation 査読有り

S.Kajita, T.Yoshida, N.Ohno, T.Ishida, D.Kitaoka

Japanese Journal of Applied Physics 55 巻頁： 106202(5 pp) 2016年9月

Plasma detachment study of high density helium plasmas in the Pilot-PSI device 査読有り

Y.Hayashi, K.Jesko, H.J.van der Meiden, J.W.M.Vernimmen, T.W.Morgan, N.Ohno, S.Kajita, M.Yoshikawa, S.Masuzaki

Nuclear Fusion 56 巻頁： 126006(13 pp) 2016年9月

Fuzzy nanostructure growth on Ta/Fe by He plasma irradiation 査読有り

S.Kajita, T.Ishida, N.Ohno, D.Hwangbo, T.Yoshida

Scientific Reports 6 巻頁： 30380 2016年7月

Statistical Analysis of Particle Flux Flowing into the End-Target in between Atached and Detached Sttes in the Linear Divertor Plasma Simulator NAGDIS-II 査読有り

H.Tanaka, N.Ohno, T.Onda, K.Takeyama, S.Kajita, T.Kuwabara, Y.Tsuji

Contrib. Plasma Phys. 56 巻 ( 6-8 ) 頁： 723-728 2016年6月

Measurement of thermophysical property of plasma forming tungsten nanofiber layer 査読有り

S.Kajita, T.Yagi, K.Kobayashi, M.Tokitani, N.Ohno

Japanese Journal of Applied Physics 55 巻頁： 056203(5 pp) 2016年4月

Dynamics of three-dimensional radiative structures during RMP assisted detached plasmas on the large helical device and its comparison with EMC3-EIRENE modeling 査読有り国際共著

Shwetang N. Pandya, Byron J. Peterson, Masahiro Kobayashi, Katsumi Ida, Kiyofumi Mukai, Ryuichi Sano, Junichi Miyazawa, Hirohiko Tanaka, Suguru Masuzaki, Tsuyoshi Akiyama, Gen Motojima, Noriyasu Ohno

Nuclear Fusion 56 巻 ( 4 ) 頁： 046002 2016年3月

Strong Reduction of Ion Flux to a Target Plate in a Magnetically Contracting Detached Plasma 査読有り

Y.Hayashi, H.Nishikata, N.Ohno, S.Kajita

Plasma and Fusion Research: Rapid Communications 11 巻頁： 1202005(2 pp) 2016年2月

Plasma flow in peripheral region of detached plasma in linear plasma device 査読有り

Y.Hayashi, N.Ohno, S.Kajita, H.Tanaka

Physics of Plasmas 23 巻頁： 012511(7 pp) 2016年1月

Arc tracks on nanostructured surfaces after microbreakdowns 査読有り

D.Sinelnikov, D.Bulgadaryan, D.Hwangbo, S.Kajita, D.Kolodko, V.Kurnaev, N.Ohno

Journal of Physics:Conference Series 748 巻頁： 012012(6 pp) 2016年

Detailed Analysis of Plasma Resistivity in Detached Recombining Plasmas 査読有り

H.Nishikata, Y.Hayashi, N.Ohno, S.Kajita, T.Kuwabara

Contrib. Plasma Phys. 56 巻 ( 6-8 ) 頁： 717-722 2016年

Modeling of Linear Divertor Plasma Simulator Experiments with Three-dimensional Target Structure by Using EMC3-EIRENE Code 査読有り

T.Kubawara, H.Tanaka, G.Kawamura, N.Ohno, H.Nishikata, M.Kobayashi, Y.Feng

Contrib. Plasma Phys. 56 巻 ( 6-8 ) 頁： 598-603 2016年

Effects of Modified Surfaces Produced at Plasma-Facing Surface on Hydrogen Isotopes and Helium Release Behavior in the LHD 査読有り

Y.Nobuta, S.Masuzaki, M.Tokitani, D.Nagata, N.Ashikawa, N.Yoshida, Y.Oya, M.Yajima, G.Motojima, H.Kasahara, M.Miyamoto, N.Ohno

IAEA proccedings 頁： MPT/P5-19(9 pp) 2016年

Photon Trapping Effects in DEMO Divertor Plasma 査読有り

K. Hoshino, K. Sawada, R. Idei, S. Tokunaga, N. Asakura, K. Shimizu, and N. Ohno

Contrib. Plasma Phys. 56 巻頁： 657-662 2016年

Investigation of arcing on fiber-formed nanostructured tungsten by pulsed plasma during steady state plasma irradiation 査読有り

M. Yajima, N. Ohno, S. Kajita, G. De Temmerman, K. Bystrov, S. Bardin

Fusion Engineering and Design 112 巻頁： 156-161 2016年

Vacuum Breakdown from Nanostructured Fuzzy Surfaces 査読有り国際共著国際誌

Sinelnikov D., Bulgadaryan D., Hwangbo D., Kajita S., Kolodko D., Kurnaev V., Ohno N.

PROCEEDINGS OF THE 27TH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM (ISDEIV), VOL 1 頁： 68 - 71 2016年

Morphology and optical property changes of nanostructured tungsten in LHD 査読有り

S.Kajita, T.Akiyama, N.Yoshida, M.Tokitani, M.Yajima, N.Ohno

Plasma and Fusion Research 10 巻頁： 1402083(9 pp) 2015年12月

Sulfur K-edge XANES for methylene blue in photocatalytic reaction over WO<inf>3</inf> nanomaterials 査読有り国際誌

K. Komori, T. Yoshida, T. Nomoto, M. Yamamoto, C. Tsukada, S. Yagi, M. Yajima, S. Kajita, N. Ohno

Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 365 巻頁： 35 - 38 2015年12月

Increase in the work function of W/WO3 by helium plasma irradiation 査読有り

S.Kajita, A.Ohta, T.Ishida, K.Makihara, T.Yoshida, N.Ohno

Japanese Journal of Applied Physics 54 巻頁： 126201(6 pp) 2015年11月

3D effects of edge magnetic field configuration on divertor/scrape-off layer transport and optimization possibilities for a future reactor 査読有り国際共著国際誌

M. Kobayashi, Y. Xu, K. Ida, Y. Corre, Y. Feng, O. Schmitz, H. Frerichs, F. L. Tabares, T. E. Evans, J. W. Coenen, Y. Liang, A. Bader, K. Itoh, H. Yamada, Ph Ghendrih, G. Ciraolo, D. Tafalla, A. Lopez-Fraguas, H. Y. Guo, Z. Y. Cui, D. Reiter, N. Asakura, U. Wenzel, S. Morita, N. Ohno, B. J. Peterson, S. Masuzaki

Nuclear Fusion 55 巻 ( 10 ) 頁： 104021 2015年9月

記述言語：英語出版者・発行元：Nuclear Fusion

© 2015 IAEA, Vienna. This paper assesses the three-dimensional (3D) effects of the edge magnetic field structure on divertor/scrape-off layer transport, based on an inter-machine comparison of experimental data and on the recent progress of 3D edge transport simulation. The 3D effects are elucidated as a consequence of competition between transports parallel () and perpendicular () to the magnetic field, in open field lines cut by divertor plates, or in magnetic islands. The competition has strong impacts on divertor functions, such as determination of the divertor density regime, impurity screening and detachment control. The effects of magnetic perturbation on the edge electric field and turbulent transport are also discussed. Parameterization to measure the 3D effects on the edge transport is attempted for the individual divertor functions. Based on the suggested key parameters, an operation domain of the 3D divertor configuration is discussed for future devices.

DOI： 10.1088/0029-5515/55/10/104021

Initiation of arcing on tungsten surface exposed to steady state He Plasmas 査読有り

S.Kajita, Y.Noiri, N.Ohno

Physica Scripta 90 巻 ( 9 ) 頁： 095604(7 pp) 2015年8月

Development of Impurity Seeding and Radiation Enhancement in the Helical Divertor of LHD 査読有り

K.Mukai, S.Masuzaki, B.Peterson, T.Akiyama, M.Kobayashi, H.Tanaka, S.Pandya, R.Sano, G.Motojima, N.Ohno, T.Morisaki, C.Suzuki, I.Murakami, J.Miyazawa, N.Tamura, S.Yoshimura, I.Yamada, R.Yasuhara, H.Funaba, K.Tanaka

Nuclear Fusion 55 巻頁： 83016(9 pp) 2015年7月

Overview of transport and MHD stability study:focusing on the impact of magnetic field topology in the Large Helical Device 査読有り

K. Ida, K. Nagaoka, S. Inagaki, H. Kasahara, T. Evans, M. Yoshinuma, K. Kamiya, S. Ohdach, M. Osakabe, M. Kobayashi, S. Sudo1,, K. Itoh, T. Akiyama, M. Emoto, A. Dinklage, X. Du, K. Fujii, M. Goto, T. Goto, M. Hasuo, C. Hidalgo, K. Ichiguchi, A. Ishizawa, M. Jakubowski, G. Kawamura, D. Kato, S. Morita, K. Mukai, I. Murakami, S. Murakami, Y. Narushima, M. Nunami, N. Ohno, N. Pablant, S. Sakakibara, T. Seki, T. Shimozuma, M. Shoji, K. Tanaka, T. Tokuzawa, Y. Todo, H. Wang, M. Yokoyama, H. Yamada, Y. Takeiri, T. Mutoh, S. Imagawa, T. Mito, Y. Nagayama, K.Y. Watanabe, N. Ashikawa, H. Chikaraishi, A. Ejiri, M. Furukawa, T. Fujita, S. Hamaguchi, H. Igami1, M. Isobe, S. Masuzaki, T. Morisaki, G. Motojima, K. Nagasaki, H. Nakano, Y. Oya, C. Suzuki, Y. Suzuki, R. Sakamoto, M. Sakamoto, A. Sanpei, H. Takahashi, H. Tsuchiya, M. Tokitani, Y. Ueda, Y. Yoshimura1, S. Yamamoto, K. Nishimura, H. Sugama, T. Yamamoto, H. Idei, A. Isayama, S. Kitajima, S. Masamune, K. Shinohara, P.S. Bawankar, E. Bernard, M. von Berke, H. Funaba, X.L. Huang, T. Ii, T. Ido, K. Ikeda, S. Kamio, R. Kumazawa, T. Kobayashi, C. Moon, S. Muto, J. Miyazawa, T. Ming, Y. Nakamura, S. Nishimura, K. Ogawa, T. Ozaki, T. Oishi, M. Ohno, S. Pandya, A. Shimizu, R. Seki, R. Sano, K. Saito, H. Sakaue, Y. Takemura, K. Tsumori, N. Tamura, H. Tanaka, K. Toi, B. Wieland, I. Yamada, R. Yasuhara, H. Zhang2, O. Kaneko, A. Komori and Collaborators

Nuclear Fusion 55 巻 ( 10 ) 頁： 104018 2015年7月

Sulfur E-edge XANES for methylene blue in photocatalytic reaction over WO3 nanomaterials 査読有り

K.Komori, T.Yoshida, T.Nomoto, M.Yamamoto, C.Tsukada, S.Yagi, M.Yajima, S.Kajita, N.Ohno

Nuclear Instruments and Methods in Physics Research B 365 巻頁： 35-38 2015年7月

Molecular dynamics and Monte Carlo hybrid simulation for fuzzy tungsten nanostructure formation 査読有り

A.M.Ito, A.Takayama, Y.Oda, T.Tamura, R.Kobayashi, T.Hattori, S.Ogata, N.Ohno, S.Kajita, M.Yajima, Y.Noiri, Y.Yoshimoto, S.Saito, S.Takamura, T.Murashima, M.Miyamoto, H.Nakamura

Nuclear Fusion 55 巻 ( 7 ) 頁： 073013 2015年6月

Growth of multifractal tungsten nanostructure by He bubble induced directional swelling 査読有り

S.Kajita, N.Yoshida, N.Ohno, Y.Tsuji

New Journal of Physics 17 巻頁： 043038(14 pp) 2015年4月

Influence of Deuterium Retention on Secondary Electron Emission from Graphite under Deuterium Plasma Exposure 査読有り

T.Kaneko, N.Ohno, Y.Nakamura, M.Yamagiwa, N.Matsunami, S.Kajita, M.Takagi

Plasma and Fusion Research: Regular Articles 10 巻頁： 1402009(5 pp) 2015年3月

Nanostructure growth by helium plasma irradiation to tungsten in sputtering regime 査読有り

Y.Noiri, S.Kajita, N.Ohno

Journal of Nuclear Materials 463 巻 ( C ) 頁： 285 - 288 2015年1月

Flow damping due to stochastization of the magnetic field 査読有り

K.Ida, M.Yoshinuma, H.Tsuchiya, T.Kobayashi, C.Suzuki, M.Yokoyama, A.Shimizu, K.Nagaoka, S.Inagaki, K.Itoh & the LHD Experiment Group (36th author)

Nature Communications 2015年1月

Hybrid simulation research on formation mechanism of tungsten nanostructure induced by helium plasma irradiation 査読有り

A.M. Ito, A.Takayama, Y.Oda, T.Tamura, R.Kobayashi, T.Hattori, S.Ogata, N.Ohno, S.Kajita, M.Yajima, Y.Noiri, Y.Yoshimoto, S.Saito, S.Takamura, T.Murashima, M.Miyamoto, H.Nakamura

Journal of Nuclear Materials 463 巻頁： 109 - 115 2015年1月

Multi-pin Langmuir probe measurement for identification of blob propagation characteristics in the Large Helical Device 査読有り

H.Tanaka, S.Masuzaki, N.Ohno, T.Morisaki, Y.Tsuji, LHD Experiment Group

Journal of Nuclear Materials 463 巻頁： 761-764 2015年

Evolution of radiation profiles during detached plasmas and radiative collapse in LHD 査読有り

S.N.Pandya, B.J.Peterson, M.Kobayashi, K.Mukai, R.Sano, H.Tanaka, S.Masuzaki, J.Miyazawa, T.Akiyama.G.Motojima N.Ohno

Journal of Nuclear Materials 463 巻頁： 551-554 2015年

Nanostructure growth by helium plasma irrdaition to tungsten in sputtering regime 査読有り

Y.Noiri, S.Kajita, N.Ohno

Journal of Nuclear Materials 463 巻頁： 285-288 2015年

Progress of divertor simulation research toward the realization of detached palsam using a large tandem mirror device 査読有り

Y.Nakashima, H.Takeda, K.Ichimura, K.Hosoi, K.Oki, M.Sakamoto, M.Hirata, M.Ichimura, R.Ikezoe, T.Imai, M.Iwamoto, Y.Hosoda, I.Katanuma, T.Kariya, S.Kigure, J.Kohagura, R.Minami, T.Numakura, S.Takahashi, M.Yoshikawa, N.Asakura, M.Fukumoto, A.Hatayama, Y.Hirooka, S.Kado, H.Kubo, S.Masuzaki, H.Matsuura, S.Nagata, N.Nishino, N.Ohno, A.Sagara, T.Shikama, M.Shoji, A.Tonegawa, Y.Ueda

Journal of Nuclear Materials 463 巻頁： 537-540 2015年

Impact of 3D magnetic field structure on boundary and divertor plasmas in stellarator /heliotron devices 査読有り

M.Kobayasahi, Y.Feng, Y.Xu, F.L.Tabares, K.Ida, O.Schmitz, T.E.Evans, H.Frerichs, Y.Liang, A.bader, K.Itoh, H.Yamada, Ph.Ghendrih, G.Ciraolo, D.Tafalla, A.Lopez-Fraguas, H.Y.Guo, Z.Y.Cui, D.Reiter, N.Asakura, U.Wenzel, S.Morita, N.Ohno, B.J.Peterson, S.Masuzaki

Journal of Nuclear Materials 463 巻頁： 2-10 2015年

Global helium particle balance in LHD 査読有り

G.Motojima, S.Masuzaki, M.Tokitani, H.Kasahara, Y.Yoshimura, M.Kobayashi, R.Sakamoto, T.Morisaki, J.Miyazawa, T.Akiyama, N.Ohno, T.Mutoh, H.Yamada, LHD Experiment Group

Journal of Nuclear Materials 463 巻頁： 1080-1083 2015年

Radiated power distributions in impurity-seeded plasmas in LHD 査読有り

T.Morisaki, K.Oyama, N.Tamura, S.Masuzaki, T.Akiyama, G.Motojima, J.Miyazawa, B.J.Peterson, N.Ohno, H.Yamada, LHD Experiment Group

Journal of Nuclear Materials 463 巻頁： 640-643 2015年

Simulation Study of Power Load with Impurity Seeding in Advanced Divertor "Short Super-X Divertor" for a Tokamak Reactor 査読有り

N.Asakura, K.Hoshino, K.Shimizu, K.Shinya, H.Utoh, S.Tokunaga, K.Tobita, N.Ohno

Journal of Nuclear Materials 463 巻頁： 1238-1242 2015年

Influence of external resonant magnetic perturbation field on edge plasma of small tokamak HYBTOK-II 査読有り

Y.Hayashi, Y.Suzuki, N.Ohno, M.Okamoto, Y.Kikuchi, S.Sakakibara, K.Watanabe, Y.Takemura

Journal of Nuclear Materials 463 巻頁： 463-466 2015年

In-situ measurement of deuterium retention in W under plasma exposure 査読有り

T. Watanabe, T. Kaneko, N. Matsunami, N. Ohno, S. Kajita, T. Kuwabara

Journal of Nuclear Materials 463 巻頁： 1049-1052 2015年

CORRELATION ANALYSIS OF 3-4 KILOHERTZ CORE AND EDGE DENSITY FLUCTUATIONS IN THE GAMMA 10 TANDEM MIRROR DEVICE 査読有り

H. Tanaka, M. Sakamoto, K. Furutachi, K. Oki, M. Mizuguchi, Y. Nagatsuka, M. Yoshikawa, R. Nohara, M. Yoshikawa, J. Kohagura, N. Ohno, and Y. Tsuji

Fusion Sci. Tech. 68 巻頁： 125-129 2015年

Influence of Deuterium Retention on Secondary Electron Emission from Graphite under Deuterium Plasma Exposure 査読有り

T.Kaneko, N.Ohno, Y.Nakamura, M.Yamagiwa, N.Matsunami, S.Kajita, M.Takagi

Plasma and Fusion Research 10 巻頁： 1402009(5 pp) 2015年

Arc spot grouping: An entanglement of arc spot cells 査読有り

S.Kajita, D.Hwangbo, N.Ohno, M.M.Tsventoukh, S.A.Barengolts

Journal of Applied Physics 116 巻頁： 233302 2014年12月

Current Activities in the Interactive Joint Research at Tohoku University - Advanced Evaluation of Radiation Effects on Fusion Materials - 査読有り

H.Kurishita, M.Hatakeyama, M.Narui, S.Matsuo, T.Shikama, K.Tada, N.Ohno, T.Takeuchi, Y.Hatano, M.Nishiura, Y.Nakashima, H.Watanabe, K.Tokunaga, T.Hino, Y.Ueda, T.Muroga, A.Sagara, O.Kaneko

Plasma and Fusion Research 9 巻頁： 3405136（4 pp) 2014年9月

Compact and high-particle-flux thermal-lithium-beam probe system for measurement of two-dimensional electron density profile 査読有り

Y.Shibata, T.Manabe, S.Kajita, N.Ohno, M.Takagi, H.Tsuchiya, T.Morisaki

Rev. Sci. Instrum. 85 巻頁： 93510(6 pp) 2014年9月

Application of Nanostructured Tungsten Fabricated by Helium Plasma Irradiation for Photoinduced Decolorization of Methylene Blue 査読有り

K.Komori, T.Yoshida, S.Yagi, H.Yoshida, M.Yajima, S.Kajita, N.Ohno

e-J.Surf.Sci.Nanotech.(e-Journal of Surface Science and Nanotechnology) 12 巻頁： 343-348 2014年7月

Fractality of self-grown nanostructured tungsten by He plasma irradiation 査読有り

S.Kajita, Y.Tsuji, N.Ohno

Physics Letters A 378 巻頁： 2533-2538 2014年7月

In situ observation of structural change of nanostructured tungsten during annealing 査読有り

M.Yajima, N.Yoshida, S.Kajita, M.Tokitani, T.Baba, N.Ohno

Journal of Nuclear Materials 449 巻 ( 1-3 ) 頁： 9-14 2014年6月

Influence of plasma-neutral collisions on probe measurements in atmospheric pressure plasmas 査読有り国際誌

Contributions to Plasma Physics 54 巻 ( 3 ) 頁： 304 - 307 2014年4月

In situ measurement of deuterium retention in graphite under successive exposure to deuterium and hydrogen plasmas 査読有り

N.Ohno, Y.Nakamura, M.Yamagiwa, T.Kaneko, N.Matsunami, S.Kajita, M.Takagi

Phys. Scr. T159 巻頁： 014053(4 pp) 2014年4月

A plasma source driven predator-prey like mechanism as a potential cause of spiraling intermittencies in linear plasma devices 査読有り

D.Reiser, N.Ohno, H.Tanaka, L.Vela

Physics of Plasmas 21 巻頁： 032302(10 pp) 2014年3月

Surface modification of titanium using He plasma 査読有り

S.Kajita, D.Kitaoka, N.Ohno, R.Yoshihara, N.Yoshida, T.Yoshida

Applied Surface Science 303 巻頁： 438-445 2014年3月

Thermal response of nanostructured tungsten 査読有り

S.Kajita, G.De Temmerman, T.Morgan, S.van Eden, T. de Kruif, N.Ohno

Nuclear Fusion 54 巻頁： 033005(10 pp) 2014年2月

Helium plasma irradiation on single crystal tungsten and undersized atom doped tungsten alloys 査読有り国際誌

Kajita Shin, Yoshida Naoaki, Ohno Noriyasu, Hirahata Yuki, Yoshihara Reiko

PHYSICA SCRIPTA 89 巻 ( 2 ) 2014年2月

Optical design for divertor Thomson scattering system for JT-60SA 査読有り

S.Kajita, A.Enokuchi, T.Hatae, K.Itami, T.Hamano, S.Kado, N.Ohno, N.Takeyama

Fusion Engineering and Design 89 巻 ( 1 ) 頁： 69-76 2014年1月

Helium plasma irradiation on single crystal tungsten and undersized atom doped tunsten alloys 査読有り

S.Kajita, N.Yoshida, N.Ohno, Y.Hirahata, R.Yoshihara

Phys. Scr. 89 巻頁： 025602(7 pp) 2014年1月

Modified Power Transmission Factor of Tungsten in Plasmas with Hot Electron Component 査読有り

S.Takamura, S.Ono, N.Ohno

Contrib. Plasma Phys. 54 巻 ( 4-6 ) 頁： 474-478 2014年

Transition in velocity and grouping of arc spot on different nanostructured tungsten electrodes 査読有り

Hwangbo D.

Results in Physics 4 巻頁： 33 - 39 2014年

Spectroscopic Study and Motion Analysis of Arc Spot Initiated on Nanostructured Tungsten 査読有り

D.Hwangbo, S.Kajita, M.Osaka, N.Ohno

Jpn. J. Appl. Phys. 52 巻頁： 11NC02(6 pp) 2013年11月

Low-energy helium irradiation on in-vessel mirror materials 査読有り

S.Kajita, M.Tokitani, T.Saeki, N.Ohno, N.Yoshida

Journal of Nuclear Materials 442 巻 ( 1-3, Supplement 1 ) 頁： S515-S519 2013年11月

Helium effects on tungsten surface morphology and deuterium retention 査読有り

Y.Ueda, H.Y.Peng, H.T.Lee, N.Ohno, S.Kajita, N.Yoshida, R.Doerner, G.De Temmerman, V.Alimov, G.Wright

Journal of Nuclear Materials 442 巻 ( 1-3 ) 頁： S267-S272 2013年11月

Properties of deposited layer formed by interaction with Be seede D-He mixture plasma and tungsten 査読有り

K.Tokunaga, M.J.Baldwin, D.Nishijima, R.P.Doerner, S.Nagata, B.Tsuchiya, H.Kurishita, T.Fujiwara, K.Araki, Y.Miyamoto, N.Ohno, Y.Ueda

Journal of Nuclear Materials 442 巻 ( 1-3 ) 頁： S313-S319 2013年11月

Characterization of Gun Plasma Penetrated into a Steady State Plasma Device 査読有り

S.Kajita, T.Akiyama, T.Nihashi, M.Osaka, N. Ohno, Y.Kikuchi, I.Sakuma, M.Nagata

IEEE TRANSACTIONS ON PLASMA SCIENCE 41 巻 ( 11 ) 頁： 3122-3128 2013年11月

Field emission property of nanostructured tungsten formed by helium plasma irradiation 査読有り

Kajita S.

Fusion Engineering and Design 88 巻 ( 11 ) 頁： 2842 - 2847 2013年11月

Progress of the JT-60SA project 査読有り国際共著国際誌

Kamada Y., Barabaschi P., Ishida S., Abdel Maksoud W., Aiba N., Akino N., Akiyama T., Alonso J., Angioni C., Arai T., Arakawa H., Ardellier F., Artaud J., Asakawa S., Asakura N., Ashikawa N., Balaguer D., Barbato E., Barrera G., Baruzzo M., Baulaigue O., Bayetti P., Bécoulet M., Benkadda S., Benoit F., Besi U., Beurskens M., Boccaccini L., Bolzonella T., Borba D., Botija J., Bourdelle C., Brolatti G., Bruschi A., Bucalossi J., Cara P., Challis C., Chantant M., Chapman I., Chesny P., Chiba S., Ciayznski D., Cismondi F., Cocilovo V., Coletti R., Coletti A., Collins B., Conway G., Corato V., Costa P., Cucchiaro A., Dael A., Davis S., Day C., De Baar M., Decool P., Della Corte A., Delrez C., De Vries P., Decker J., Di Zenobio A., Di Pace L., Di Pietro E., Disset G., Donati A., Douai D., Dougnac H., Drotziger S., Duchateau J.L., Duglue D., Dumas N., Ejiri A., Endo Y., Farina D., Fernandez P., Ferro A., Fietz W., Figini L., Fslchetto G., Fujita T., Fukuda T., Fukumoto M., Fukuyama A., Furukawa M., Furukawa M., Gaio E., Garcia J., Garzotti L., Gauthier E., Genini L., Geraud A., Ginoulhiac G., Giruzzi G., Gomez Carrasco B., Gonde R., Goniche M., Gouat P., Gros G., Haga S.

Nuclear Fusion 53 巻 ( 10 ) 2013年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

The JT-60SA project implemented by Japan and Europe is progressing on schedule towards the first plasma in March 2019. After careful R&D, procurements of the major components have entered their manufacturing stages. In parallel, disassembly of JT-60U has been completed on time, and the JT-60SA tokamak assembly is expected to start in January 2013. The JT-60SA device, a highly shaped large superconducting tokamak with a variety of plasma control actuators, has been designed in order to contribute to ITER and to complement ITER in all the major areas of fusion plasma development necessary to decide DEMO reactor construction. Detailed assessments and prediction studies of the JT-60SA plasma regimes have confirmed these capabilities: using ITER- and DEMO-relevant plasma regimes, heating conditions, and its sufficiently long discharge duration, JT-60SA enables studies on magnetohydrodynamic stability at high beta, heat/particle/momentum transport, high-energy ion physics, pedestal physics including edge localized mode control, and divertor physics. By integrating these studies, the project provides 'simultaneous and steady-state sustainment of the key performance characteristics required for DEMO' with integrated control scenario development.

DOI： 10.1088/0029-5515/53/10/104010

Control of 3D edge radiation structure with resonant magnetic perturbation fields applied to the stochastic layer and stabilization of radiative divertor plasma in LHD 査読有り

M. Kobayashi, S. Masuzaki, I. Yamada, Y. Narushima, C. Suzuki, N. Tamura, B. J. Peterson, S. Morita, C. F. Dong, N. Ohno, S. Yoshimura, Y. Feng, M. Goto, K. Sato, T. Akiyama, K. Tanaka

Nuclear Fusion 53 巻 ( 9 ) 2013年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

It is found that resonant magnetic perturbation (RMP) fields have a stabilizing effect on the radiating edge plasma, realizing stable sustainment of radiative divertor (RD) operation in the Large Helical Device (LHD). Without RMP, thermal instability leads to radiative collapse. Divertor power load is reduced by a factor of 3-10 during the RMP-assisted RD phase, while maintaining relatively good core plasma confinement with confinement enhancement factor . It has also been demonstrated that the RMP field itself can initiate transition to RD operation by increasing perturbation strength, while keeping constant density and injection power. The results show a possibility of a new control knob for divertor power load in a 3D magnetic field configuration. It is also found that after the transition to RD, the energy confinement enhancement factor based on ISS04 scaling increases by a factor of 1.4 compared with the attached phase. The operation range of the RMP-assisted RD is identified in terms of RMP strength and radial location of the resonance layer of the RMP. A 3D edge radiation structure is analysed using the edge transport code EMC3-EIRENE and the results are compared with experiments. The comparison indicates that the application of RMP modulates the 3D edge radiation structure such that an intense radiation appears around the X-point of the m/n = 1/1 island in the case with RMP, while it is located at the inboard side without RMP. © 2013 IAEA, Vienna.

DOI： 10.1088/0029-5515/53/9/093032

Growth Annealing Equilibrium of Tungsten Nanostructures by Helium Plasma Irradiation in Non Eroding Regimes 査読有り

S.Kajita, N.Ohno, M.Yajima, J.Kato

Journal of Nuclear Materials 440 巻 ( 1-3 ) 頁： 55-62 2013年9月

Influence of crystal orientation on damages of tungsten exposed to helium plasma 査読有り

N.Ohno, Y.Hirahata, M.Yamagiwa, S.Kajita, M.Takagi, N.Yoshida, R.Yoshihara, T.Tokunaga, M.Tokitani

Journal of Nuclear Materials 438 巻頁： S879-S882 2013年7月

Study of Hydrogen Isotopes Behavior in Carbon Based Materials with In-Situ Ion Beam Analysis under Plasma Exposure 査読有り

Y.Nakamura, M.Yamagiwa, T.Kaneko, N.Matsunami, N.Ohno, S.Kajita, M.Takagi, M.Tokitani, S.Masuzaki

Journal of Nuclear Materials 438 巻頁： S1036-S1039 2013年7月

Tritium retention in nanostructured tungsten with large effective surface area 査読有り

M.Yajima, Y.Hatano, S.Kajita, J.Shi, M.Hara, N.Ohno

Journal of Nuclear Materials 438 巻頁： S1142-S1145 2013年7月

Enhancement of multi-pulse laser induced damage threshold on Cu mirror under vacuum condition 査読有り

S.Kajita, R.Yasuhara, M.Sato, N.Ohno, M.Tokitani, N.Yoshida

Optics Express 21 巻 ( 14 ) 頁： 17275-17284 2013年7月

Development of steady/transient dual plasma irradiation device using a plasma gun 査読有り

S.Kajita, N.Ohno, T.Akiyama, T.Nihashi, T.Uchiyama, M.Osaka, Y.Kikuchi, M.Nagata

Journal of Nuclear Materials 438 巻頁： S707-S710 2013年7月

Edge and divertor plasma measurements with ion sensitive and Mach probes in LHD 査読有り

Y.Hayashi, N.Ezumi, S.Masuzaki, H.Tanaka, M.Kobayashi, K.Sawada, N.Ohno, the LHD Experiment Group

Journal of Nuclear Materials 438 巻頁： S1228-S1231 2013年7月

Tritium retention in nanostructured tungsten with large effective surface area 査読有り

M.Yajima, Y.Hatano, S.Kajita, J.Shi, M.Hara, N.Ohno

Journal of Nuclear Materials 438 巻頁： S1142-S1145 2013年7月

Study of hydrogen isotopes behavior in carbon based materials with in situ ion beam analysis under plasma exposure 査読有り

Y. Nakamura, M. Yamagiwa, T. Kaneko, N. Matsunami, N. Ohno, S. Kajita, M. Takagi, M. Tokitani, S. Masuzaki

Journal of Nuclear Materials 438 巻頁： S1036-S1039 2013年7月

Influence of crystal orientation on damages of tungsten exposed to helium plasma 査読有り

N.Ohno, Y.Hirahata, M.Yamagiwa, S.Kajita, M.Takagi, N.Yoshida, R.Yoshihara, T.Tokunaga, M.Tokitani

Journal of Nuclear Materials 438 巻頁： S879-S882 2013年7月

Thermal radiation characteristics and direc evidence of tungsten cooling on the way to nanostructure formation on its surface 査読有り

S.Takamura, T.Miyamoto, N.Ohno

Journal of Nuclear Materials 438 巻頁： S814-S817 2013年7月

Recent results of divertor simulation research using an end-cell of a large tandem mirror device 査読有り

Y. Nakashima, H. Takeda, K. Ichimura, K. Hosoi, M. Sakamoto, M. Hirata, M. Ichimura, R. Ikezoe, T. Imai, T. Ishii, T. Kariya, I. Katanuma, J. Kohagura, R. Minami, T. Numakura, H. Ueda, M. Yoshikawa, N. Asakura, T. Furuta, A. Hatayama, et al.(N.Ohno No.27)

Journal of Nuclear Materials 438 巻頁： S738-S741 2013年7月

Kinetic effect of high energy ions on the temperature profile in the boundary plasma region 査読有り

N.Ezumi, Y.Hayashi, K.Todoroki, K.Okazaki, H.Tanaka, S.Masuzaki, N.Ohno

Journal of Nuclear Materials 438 巻頁： S472-S474 2013年7月

Divertor heat and particle control experiments on the large helical device 査読有り

S. Masuzaki, M.Kobayashi, T.Akiyama, N.Ohno, T.Morisaki, et al.

Journal of Nuclear Materials 438 巻頁： S133-S138 2013年7月

Properties of deposited layer formed by interaction with Be seeded D-He mixture plasma and tungsten 査読有り国際共著国際誌

Tokunaga K., Baldwin M.J., Nishijima D., Doerner R.P., Nagata S., Tsuchiya B., Kurishita H., Fujiwara T., Araki K., Miyamoto Y., Ohno N., Ueda Y.

Journal of Nuclear Materials 442 巻 ( 1-3 SUPPL.1 ) 2013年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Materials

Be-seeded, high-flux, deuterium/helium mixture plasma exposure experiments on tungsten target materials have been performed to simulate ITER all tungsten divertor erosion/modification and deposition phenomena. The exposure conditions are kept fixed at a typical low-ion-energy of 60 eV and a flux of 3-6 × 1022/m2/s. Sample temperature is 1123 K and plasma exposure times spanning 1050-10,100 s are explored. The typical ratio of He/D ions is 0.2 and Be content is 0.2%. A He-induced nanostructure layer is formed on the exposure surfaces of tungsten materials and the surface of the nanostructure is covered by a thin layer of Be and O. A fraction of the re-eroded Be from the target is deposited on a glassy carbon plate with line of sight to the tungsten target. Rutherford backscattering spectrometry analyses show that the Be redeposit layer is in the form of laminae. Small amounts of Mo, W and C are also found in the redeposited Be layer. Elastic recoil detection analyses show that D, He and H are also included in the redeposited Be layer. © 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2013.05.006

Field Emission Property of Nanostuructured Tungsten Formed by Helium Plasma Irradiation 査読有り

S.Kajita, N.Ohno, Y.Hirahata, M.Hiramatsu

Journal of Fusion Engineering and Design 88 巻頁： 2842-2847 2013年6月

Power Transmission Factor for Tungsten Target W/WO Fiber-form Nanostructure in He Plasmas with Hot Electron Component using Compact Plasma Device AIT-PID 査読有り

S.Takamura, T.Miyamoto, N.Ohno

Transactions of Fusion Science and Technology 63 巻頁： 225-228 2013年5月

Investigation of Advanced Divertor Magnetic Configuration for Demo Tokamak Reactor 査読有り

N.Asakura, K.Shinya, K.Tobita, K.Hoshino, K.Shimizu, H.Utoh, Y.Someya, M.Nakamura, N.Ohno, M.Kobayashi, H.Tanaka

Transactions of Fusion Science and Technology 63 巻 ( 1T ) 頁： 70-75 2013年5月

Impact of arcing on carbon and tungsten: from the observations in JT-60U, LHD and NAGDIS-II 査読有り

S.Kajita, M.Fukumoto, M.Tokitani, T.Nakano, Y.Noiri, N.Ohno, S.Masuzaki, S.Takamura, N.Yoshida, Y.Ueda

Nuclear Fusion 53 巻頁： 053013(9 pp) 2013年4月

Helium plasma implantation on metals: Nanostructure formation and visible-light photocatalytic response 査読有り

S.Kajita, T.Yoshida, D.Kitaoka, R.Etoh, M.Yajima, N.Ohno, H.Yoshida, N.Yoshida, Y.Terao

Journal of Applied Physics 113 巻頁： 134301(8 pp) 2013年4月

Assessment of multi-pulse laser-induced damage threshold of metallic mirrors for Thomson scattering system 査読有り

M.Sato, S.Kajita, R.Yasuhara, N.Ohno, M.Tokitani, N.Yoshida, Y.Tawara

Optics Express 21 巻 ( 8 ) 頁： 9333-9342 2013年4月

Comparison of damages on tungsten surfac exposed to noble gas plasmas 査読有り

M.Yajima, M.Yamagiwa, S.Kajita, N.Ohno et al.

Plasma Science & Technol. 15 巻頁： 282-286 2013年3月

Two-dimensional visualization of excitation temperature and chemical species in divertor plasmas: Trace CD molecules by chemical sputtering of fusion plasma reactor wall 査読有り

Z.Cui, K.Kodama, M.Yamamoto, Q.Shen, M.Yoshimi, S.Kajita, N.Ohno, K.Kitagawa

Microchemical Journal 106 巻頁： 174-179 2013年1月

Influence of the Probe Electrode on Probe Measurements for Atmospheric Pressure Microwave Plasma Torch 査読有り国際誌

Ezumi N., Kodama N., Akahane K., Shiozawa S., Sawada K., Ohno N.

Contributions to Plasma Physics 53 巻 ( 1 ) 頁： 81 - 85 2013年1月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Contributions to Plasma Physics

In this study, in order to clarify the influence of a probe electrode during probe measurements of an atmospheric pressure microwave plasma, simultaneous observations of probe current and the change of plasma shape using a high-speed camera have been done. Fast and random repetitions of attachment and detachment of the plasma torch to the probe electrode have been observed. It is found that the response time is related to ion sound speed. Different behaviors of the plasma torch for a floating metal electrode or an insulator have been observed. Probe current-voltage characteristics show asymmetric double probe shape © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/ctpp.201310014

First Principles Investigation on Trapping of Multiple Helium Atoms within a Tungsten Monovacancy 査読有り

A.Takayama, A.M.Ito, S.Saito, N.Ohno, H.Nakamura

Japanese Journal of Applied Physics 52 巻頁： 01AL03(4 pp) 2013年

Deuterium Atomic Density Estimation in Recombining Plasmas Using Self-Absorption Spectroscopy 査読有り

S.Kajita, T.Nishiwaki, N.Ohno, K.Sawada, M.Takagi

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 8 巻 ( 1 ) 頁： 1-6 2013年

Intermittent transport in edge plasma with a 3-D magnetic geometry in the Large Helical Device 査読有り

H.Tanaka, S.Masuzaki, N.Ohno, T.Morisaki, Y.Tsuji, the LHD Experiment Group

Journal of Nuclear Materials 438 巻頁： S563-S566 2013年

Observation of Arc Spots Initiated on Nanostructured Tungsten 査読有り

S.Kajita, N.Ohno, S.Takamura

IEEE TRANSACTIONS ON PLASMA SCIENCE 41 巻 ( 8, Part 2 ) 頁： 1889-1895 2013年

Extension of operation regimes and investigation of three-dimensional currentless plasmas in the Large Helical Device 査読有り

O.Kaneko, H.Yamada, S.Inagaki, M.Jakubowski, S.Kajita, et al.(N.Ohno is the 104th author))

Nucl. Fusion 53 巻頁： 104015(11 pp) 2013年

First-Principles Investigation on Trapping of Multiple Helium Atoms within a Tungsten Monovacancy 査読有り

A.Takayama, A.M.Ito, S.Saito, N.Ohno, H.Nakamura

Jpn. J. Appl. Phys. 52 巻頁： 01AL023(4 pp) 2013年

Effect of resistivity profile on current decay time of initial phase of current quench in neon-gas-puff inducing disruptions of JT-60U 査読有り

S.Kawakami, Y.Shibata, K.Y.Watanabe, N.Ohno, A.Isayama, T.Takizuka, Y.Kawano, M.Okamoto

Physics of Plasmas 20 巻頁： 112507(6 pp) 2013年

Degradation of optical reflectivity of in-vessel mirror materials by helium bombardment 査読有り

S.Kajita, M.Tokitani, T.Saekim N.Ohno, N.Yoshida

J. Nucl. Mater. 417 巻頁： 838-841 2013年

Behavior of Plasma Response Field in Detached Plasma 査読有り国際誌

NARUSHIMA Yoshiro, KOBAYASHI Masahiro, AKIYAMA Tsuyoshi, SAKAKIBARA Satoru, MASUZAKI Suguru, ASHIKAWA Naoko, OHNO Noriyasu

Plasma and Fusion Research 8 巻 ( 0 ) 頁： 1402058 - 1402058 2013年

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：プラズマ・核融合学会

Sustaining a detached plasma is important for the reduction of the heat load on a divertor. The externally controlled methods such as gas puffing in the divertor region, etc. have been studied for maintaining detached plasmas. In the recent LHD experiments, a resonant magnetic perturbation (RMP) is utilized to establish the detached plasma, which is one of the candidates to reduce the divertor heat load. The finite plasma response field has been detected when the RMP is imposed, and its behavior is investigated from the viewpoint of the magnetic island dynamics. A parameter of the phase difference, Δθ (defined as the phase difference between the plasma response field and the RMP), changes from antiphase to in-phase while the plasma transits from the attached to the detached states. Finally, when the Δθ reaches at certain critical value, Δθcrit, the plasma enters the detached state. Since this critical value does not have a dependency on plasma beta and collisionality, Δθcrit seems to be a threshold to establish the detached plasma. From the viewpoint of magnetic island dynamics, the behavior of Δθ approaching in-phase implies the "trend" of island growth. The detached plasma might be established in the case of the tendency for the plasma response field to reinforce the island width.

DOI： 10.1585/pfr.8.1402058

Thermal radiation characteristics and direct evidence of tungsten cooling on the way to nanostructure formation on its surface 査読有り国際誌

Takamura S., Miyamoto T., Ohno N.

Journal of Nuclear Materials 438 巻 ( SUPPL ) 2013年

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Materials

The physical properties of tungsten with nanostructure on its surface are investigated focusing on the thermal radiation and cooling characteristics. First, direct evidence of substantial W surface cooling has been clearly shown with use of a very thin thermocouple inserted into W target, which solves an uncertainty associated with a radiation thermometer. Second, the above measurements of W surface temperature make it possible to estimate quantitatively the total emissivity from which we may evaluate the radiative power through the Stefan-Boltzmann equation, which is very important for mitigation evaluation of a serious plasma heat load to the plasma-facing component. © 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2013.01.176

Preliminary experiments on the vertical stability with helical coils in a small tokamak, HYBTOK-II 査読有り国際誌

Hatakeyama S., Shibata Y., Kawakami S., Tsutsui H., Tsuji-Iio S., Shimada R., Ohno N., Akiyama T., Suzuki Y., Watanabe K.

39th EPS Conference on Plasma Physics 2012, EPS 2012 and the 16th International Congress on Plasma Physics 1 巻頁： 285 - 288 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：39th EPS Conference on Plasma Physics 2012, EPS 2012 and the 16th International Congress on Plasma Physics

In summary, we proposed saddle shaped stellarator system for vertical mode in toka-mak. These preliminary results demonstrate the feasibility of vertical stability, even if only two selected coils which are localized at one side of the torus. However as noted earlier, the experiment were conducted with the circular cross-section tokamak which is stable vertically. Further work is needed to confirm the improvement in the vertical stability in elongated tokamaks. In addition, very large coil current comparable to the plasma current are needed in our system. In order to reduce the current, future work also should focus on optimal configuration of the coils.

Blob/Hole Generation in the Divertor Leg of the Large Helical Device 査読有り

H.Tanaka, N.Ohno, Y.Tsuji, S.Kajita, S.Masuzaki, M.Kobayashi, T.Morisaki, A.Komori and the LHD Experimental Group

Plasma and Fusion Research 7 巻頁： 1402152(6 pp) 2012年11月

Fatal Damages due to Breakdown on a Diagnostic Mirror Located outside the Vacuum Vessel in JT-60U 査読有り

S.Kajita, T.Hatae, T.Sakuma, S.Takamura, N.Ohno, K.Itami

Plasma and Fusion Research 7 巻頁： 2405121(4 pages) 2012年9月

Optical properties of nanostructured tungsten in near infrared range 査読有り

S.Kajita, N.Ohno, T.Yokochi, N.Yoshida, R.Yoshihara, S.Takamura, T.Hatae

Plasma Physics and Controlled Fusion 54 巻頁： 105015(7 pages) 2012年9月

Superimposition of Pulses to Steady Arc Discharge in Toroidal Divertor Simulator 査読有り

S.Kajita, T.Uchiyama, N.Ohno

Plasma and Fusion Research 7 巻頁： 1405100(6 pages) 2012年7月

Statistical Analysis of the Spatial Behavior of Plasma Blobs Around the Plasma Column in a Linear Plasma Device 査読有り

H.Tanaka, N.Ohno, Y.Tsuji, K.Okazaki, S.Kajita

Contrib. Plasma Phys. 52 巻 ( 5-6 ) 頁： 424 - 428 2012年6月

Effect of Externally Applied Resonance Magnetic Perturbation on Current Decay during Tokamak Disruption 査読有り

Y.Kanazawa, Y.Shibata, M.Okamoto, N.Ohno, S.Kajita

Plasma and Fusion Research 7 巻頁： 1202049(2 pages) 2012年6月

Effect of neutral pressure on the He plasma flow measurement in a linear device 査読有り国際共著

E.-K.Park, H.-J.Woo, K.-S.Chung, H.Tanaka, S.Kajita, N.Ohno

Current Applied Physics 12 巻頁： 1479 - 1502 2012年5月

Transition in Plasma Fluctuation between Attached and Detached Plasmas 査読有り

K.Okazaki, H.Tanaka, N.Ohno, S.Kajita

Plasma and Fusion Research 7 巻頁： 1201033(2 pages) 2012年4月

Arcing on tungsten subjected to helium and transients: ignition conditions and erosion rates 査読有り国際誌

Kajita Shin, Ohno Noriyasu, Yoshida Naoaki, Yoshihara Reiko, Takamura Shuichi

PLASMA PHYSICS AND CONTROLLED FUSION 54 巻 ( 3 ) 2012年2月

TEM analysis of high temperature annealed W nanostructure surfaces 査読有り国際誌

Kajita Shin, Yoshida Naoaki, Yoshihara Reiko, Ohno Noriyasu, Yokochi Takanori, Tokitani Masayuki, Takamura Shuichi

JOURNAL OF NUCLEAR MATERIALS 421 巻 ( 1-3 ) 頁： 22 - 27 2012年2月

Anisotropic Graphite Erosion in Low-Temperature and high-Density Deuterium Plasma 査読有り

M.Teraoka, N.Ohno, S.Kajita, T.Nishiwaki, A.M.Ito, H.Nakamura

Jpn. J. Appl. Phys. 51 巻頁： 01AB03 (5pp) 2012年1月

Near Infrared Radiation from Heated Nanostructured Tungsten 査読有り

S.Kajita, T.Yokochi, N.Ohno, T.Kumano

Jpn. J. Appl. Phys. 51 巻頁： 01AJ03 (5pp) 2012年1月

Measurement of ion and electron temperatures in plasma blobs by using an improved ion sensitive probe system and statistical analysis methods 査読有り国際誌

K. Okazaki, H. Tanaka, H. Tanaka, N. Ohno, N. Ezumi, Y. Tsuji, S. Kajita

Review of Scientific Instruments 83 巻 2012年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

We have measured ion temperature as well as electron temperature in plasma blobs observed in a linear plasma device by using an improved ion sensitive probe. Current-voltage characteristics of the ion sensitive probe inside and outside plasma blobs were re-constructed with a conditional sampling method. It is clearly found that both ion and electron temperatures in plasma blobs decrease more slowly in a cross-field direction than those in a bulk plasma without plasma blobs. © 2012 American Institute of Physics.

DOI： 10.1063/1.3681778

Electric Field at a Plasma-Facing Wall for a Two-Temperature Electron Distribution 査読有り

Y.Tomita, G.Kawamura, M.Ueno, N.Ohno, Z.H.Huang, Y.D.Pan, L.W.Yan

Contrib. Plasma Phys. 52 巻 ( 5-6 ) 頁： 484-489 2012年

Thermionic Energy Converter System Using Heat Flux in Divertor Region 査読有り

D.Oikawa, N.Ohno, S.Kajita, M.Takagi, S.Masuzaki, M.Tokitani, K.Asano

Plasma and Fusion Research 7 巻頁： 1405050(8 pages) 2012年

Conditions for the Release of a Metallic Dust Particle from a Plasma-Facing Wall 査読有り

M.Ueno, N.Ohno, Y.Tomita, G.Kawamura

Contrib. Plasma Phys. 52 巻 ( 5-6 ) 頁： 478-483 2012年

Effects of fibre-form nanostructures on particle emissions from a tungsten surface in plasmas 査読有り

S.Takamura, T.Miyamoto, N.Ohno

Nuclear Fusion 52 巻頁： 123001(8 pages) 2012年

Validation of the current decay model in the initial phase of current quench in high disruptive discharges of JT-60U 査読有り国際誌

Shibata Y., Watanabe K., Ohno N., Okamoto M., Isayama A., Kurihara K., Oyama N., Nakano T., Kawano Y., Sugihara M.

38th EPS Conference on Plasma Physics 2011, EPS 2011 - Europhysics Conference Abstracts 35 2 巻頁： 1628 - 1631 2011年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：38th EPS Conference on Plasma Physics 2011, EPS 2011 - Europhysics Conference Abstracts

The validation of current decay model during the current quench was investigated in high (3p disruptive discharges on JT-60U. It is experimentally confirmed that the electron temperature does not play an important role in the determination of the current decay time in the initial phase of current quench and that values obtained from L/R model are two orders of magnitude larger than the experimental current decay time. The current decay time predicted by the modified L/R model, in which the time derivative of plasma inductance is taken into account, is in fairly good agreement with the experimental data. In future work, we need to perform the MHD equilibrium code for free-boundary condition such as DINA [5] and TSC [6] code under the axisymmetric assumption in order to clear up the determination mechanism of time derivative of plasma inductance.

Recent progress of tungsten R&D for fusion application in Japan 査読有り国際誌

Ueda Y., Lee H.T., Ohno N., Kajita S., Kimura A., Kasada R., Nagasaka T., Hatano Y., Hasegawa A., Kurishita H., Oya Y.

Physica Scripta T T145 巻 2011年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physica Scripta T

The status of ongoing research projects of tungsten R&D in Japan is summarized in this paper. For tungsten material development, a new improved fabrication technique, the so-called superplasticity-based microstructural modification, is described. This technique successfully improved fracture strength and ductility at room temperature. Recent results on vacuum plasma spray W coating and W brazing on ferritic steels and vanadium alloys are explained. Feasibility of these techniques for the manufacture of the blanket is successfully demonstrated. The latest findings on the effect of neutron damage in tungsten on T retention and on the change in mechanical and electrical properties are described. Retention characteristics for neutron-damaged W were different compared to those for ion-damaged W. Upon neutron irradiation, tungsten alloys containing transmutation elements of W (Re and Os) show changes in properties that are different compared with those shown by pure W. The effects of mixed plasma exposure (D/He/C) are described. Both D/He and D/C mixed ion irradiations significantly affect ion-driven permeation in W. He bubble dynamics play a key role in nano-structure formation on the W surface. © 2011 The Royal Swedish Academy of Sciences.

DOI： 10.1088/0031-8949/2011/T145/014029

Deuterium retention in Fe <inf>2</inf>O <inf>3</inf> under low-energy deuterium-plasma exposure 査読有り国際誌

Matsunami N., Sogawa T., Sakuma Y., Ohno N., Tokitani M., Masuzaki S.

Physica Scripta T T145 巻 2011年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physica Scripta T

Stainless steel (SUS) is used as the structure material in nuclear fusion devices. Heating and O 2 plasma discharge are considered for the removal of tritium. Oxide layer growth is anticipated on heating SUS at a high temperature in low-pressure residual O 2 gas. When O 2 plasma discharge is performed, oxygen plasma reaches the structure material and iron oxides such as Fe 2O 3 are formed. Thus, a knowledge of the retention behavior of hydrogen isotopes or deuterium (D) in the oxide layers is important in designing the devices. We investigated D retention in Fe 2O 3 films and the influence of Fe 2O 3 crystal structure on D retention and found that D retention in γ-Fe 2O 3 (cubic-maghemite) is larger than that in α-Fe 2O 3 (hexagonal-hematite). The results for Fe 2O 3 are compared with those for SUS and Fe. © 2011 The Royal Swedish Academy of Sciences.

DOI： 10.1088/0031-8949/2011/T145/014042

TEM observation of the growth process of helium nanobubbles on tungsten: Nanostructure formation mechanism 査読有り国際誌

Kajita Shin, Yoshida Naoaki, Yoshihara Reiko, Ohno Noriyasu, Yamagiwa Masato

JOURNAL OF NUCLEAR MATERIALS 418 巻 ( 1-3 ) 頁： 152 - 158 2011年11月

Helium bubble formation on tungsten in dependence of fabrication method 査読有り国際誌

Yamagiwa Masato, Kajita Shin, Ohno Noriyasu, Takagi Makoto, Yoshida Naoaki, Yoshihara Reiko, Sakaguchi Wataru, Kurishita Hiroaki

JOURNAL OF NUCLEAR MATERIALS 417 巻 ( 1-3 ) 頁： 499 - 503 2011年10月

Nanoscale surface morphology of tungsten materials induced by Be-seeded D-He plasma exposure 査読有り国際誌

Tokunaga K., Baldwin M. J., Doerner R. P., Nishijima D., Kurishita H., Fujiwara T., Araki K., Miyamoto Y., Ohno N., Ueda Y.

JOURNAL OF NUCLEAR MATERIALS 417 巻 ( 1-3 ) 頁： 528 - 532 2011年10月

Exfoliation of the tungsten fibreform nanostructure by unipolar arcing in the LHD divertor plasma 査読有り国際誌

Tokitani M., Kajita S., Masuzaki S., Hirahata Y., Ohno N., Tanabe T.

NUCLEAR FUSION 51 巻 ( 10 ) 2011年10月

Development of Nanostructured Black Metal by Self-Growing Helium Bubbles for Optical Application 査読有り国際誌

Kajita Shin, Saeki Tsubasa, Hirahata Yuki, Yajima Miyuki, Ohno Noriyasu, Yoshihara Reiko, Yoshida Naoaki

JAPANESE JOURNAL OF APPLIED PHYSICS 50 巻 ( 8 ) 頁： 08JG01 2011年8月

Investigation on the effect of temperature excursion on the helium defects of tungsten surface by using compact plasma device 査読有り

S.Takamura, T.Miyamoto, Y.Tomida, T.Minagawa, N.Ohno

Journal of Nuclear Materials 415 巻頁： S100-S103 2011年8月

Exposure of tungsten nano-structure to TEXTOR edge plasma 査読有り国際共著

Y.Ueda, K.Miyata, Y.Ohtsuka, H.T.Lee, M.Fukumoto, S.Brezinsek, J.W.Coenen, A.Kreter, A.Litnovsky, V.Philipps, B.Schweer, G.Sergienko, T.Hirai, A.Taguchi, Y.Torikai, K.Sugiyama, T.Tanabe, S.Kajita, N.Ohno, The TEXTOR team

Journal of Nuclear Materials 415 巻 ( 1 ) 頁： S92 - S95 2011年8月

Divertor simulation experiment and its future research plan making use of a large tandem mirror device 査読有り国際誌

Nakashima Y., Takeda H., Hosoi K., Yonenaga R., Katanuma I., Ichimura K., Ichimura M., Imai T., Ishii T., Kariya T., Kiwamoto Y., Minami R., Miyata Y., Ozawa H., Shidara H., Yamaguchi Y., Yoshikawa M., Asakura N., Hatayama A., Higashizono Y., Kado S., Masuzaki S., Nishino N., Ohno N., Ueda Y.

Journal of Nuclear Materials 415 巻 ( 1 SUPPL ) 2011年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Materials

Divertor simulation study has been started as a new research plan, by making best use of a large linear plasma device. The experiment of generating the plasma flow with high heat and particle flux was successfully performed at an end-mirror exit of the GAMMA 10 tandem mirror. In typical hot-ion-mode plasmas, the heat-flux density of 0.6 MW/m2 and the particle-flux density of 1022 particles/s m2 were simultaneously achieved in the case of only ICRF heating and superimposing the 300 kW ECH pulse attained the peak value of the net heat-flux up to 8 MW/m2 on axis. The above experimental results and the simulation analysis of ICRF heating using the Fokker-Planck code give a clear prospect of generating the required performance for divertor studies by building up the plasma heating systems to the end-mirror cell. Detailed behavior of the plasma flow and the future research plan are also described. © 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2010.11.081

Motion of unipolar arc spots ignited on a nanostructured tungsten surface 査読有り

S.Kajita, S.Takamura, N.Ohno

Plasma Physics and Controlled Fusion 53 巻 ( 7 ) 頁： 074002 2011年5月

Molecular Dynamics Simulation of Hydrogen Injection onto Diamond Surfaces 査読有り

H.Nakamura, A.M.Ito, S.Saito, A.Takayama, Y.Tamura, N.Ohno, S.Kajita

JAPANESE JOURNAL OF APPLIED PHYSICS 50 巻 ( 1 ) 頁： 01AB04(4 pages) 2011年1月

Molecular Dynamics Simulation of Chemical Vapor Deposition of Amorphous Carbon: Dependence on H/C Ratio of Source Gas 査読有り

A.M.Ito, A.Takayama, S.Saito, N.Ohno, S.Kajita, H.Nakamura

JAPANESE JOURNAL OF APPLIED PHYSICS 50 巻 ( 1 ) 頁： 01AB01(6 pages) 2011年1月

Formation of Metallic Nanostructure by Helium Plasma Irradiation 査読有り

Kajita Shin, Saeki Tsubasa, Hirahata Yuki, Ohno Noriyasu

JAPANESE JOURNAL OF APPLIED PHYSICS 50 巻 ( 1 ) 頁： 01AH02 2011年1月

Practical selection of emission lines of He I to determine the photon absorption rate 査読有り

S.Kajita, N.Ohno

Review of Scientific Instruments 82 巻頁： 023501(5 pages) 2011年

Formation and decay processes of Ar/He microwave plasma jet at atmospheric gas pressure 査読有り

S.Takamura, S.Amano, T.Kurata, H.Kasada, J.Yamamoto, M.A.Razzak, G.Kushida, N.Ohno, M.Kando

Journal of Applied Physics 110 巻頁： 043301 (8 pages) 2011年

Deuterium retention in Fe2O3 under low-energy deuterium-plasma exposure 査読有り

N.Matsunami, T.Sogawa, Y.Sakuma, N.Ohno, M.Tokitani, S.Masuzaki

Physica Scripta T145 巻頁： 014042 (4pp) 2011年

In situ measurement of hydrogen isotope retention using a high heat flux plasma generator with ion beam analysis 査読有り

M.Yamagiwa, Y.Nakamura, N.Matsunami, N.Ohno, S.Kajita, M.Takagi, M.Tokitani, S.Masuzaki, A.Sagara and K.Nishimura

Physica Scripta T145 巻頁： 014032 (5pp) 2011年

Recent progress of tungsten R&D for fusion application in Japan 査読有り

Y.Ueda, H.T.Lee, N.Ohno, S.Kajita, A.Kimura, R.Kasada, T.Nagasaka, Y.Hatano, A.Hasegawa, H.Kurishita and Y.Oya

Physica Scripta T145 巻頁： 014029 (6pp) 2011年

Beryllium erosion induced by transient heat loads and subsequent reactions in a deuterium plasma 査読有り

S.Kajita, D.Nishijima, R.Doerner, K.Umstadter, J.Yu, N.Ohno, Y.Ueda

Journal of Nuclear Materials 420 巻頁： 252-257 2011年

Study of Plasma Current Decay in the Initial Phase of High Poloidal Beta Disruptions in JT-60U 査読有り国際誌

SHIBATA Yoshihide, MATSUNAGA Go, KAMADA Yutaka, SUGIHARA Masayoshi, WATANABE Kiyomasa, OHNO Noriyasu, OKAMOTO Masaaki, ISAYAMA Akihiko, KURIHARA Kenichi, OYAMA Naoyuki, NAKANO Tomohide, KAWANO Yasunori

Plasma and Fusion Research ( 6 ) 頁： 1302136 - 1302136 2011年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：社団法人プラズマ・核融合学会

In order to validate some current decay models during the current quench, the plasma current decay time was studied using the experimental plasma resistance and inductance in high poloidal beta, βp, disruptions in JT-60U. The plasma resistance and inductance were evaluated from an equilibrium calculation code and the measurement value of a magnetic sensor, the electron temperature evaluated by using ECE measurement and the electron density measured by FIR interferometer. In high βp disruptions, it was found that the electron temperature at the plasma center just after current quench starts was approximately 1-4 keV under almost the same current decay time observed during the initial phase of current quench. This result indicates that the electron temperature itself plays no major role in the determination of the current decay time in the initial phase of current quench. Moreover, the current decay time predicted by a modified L/R model [Y. Shibata et al., Nucl. Fusion 50, 025015 (2010)], in which the time derivative of plasma inductance was considered, was in good agreement with the experimental current decay time, while the values obtained from the conventional L/R model were two orders of magnitude larger than the experimental results.

DOI： 10.1585/pfr.6.1302136

Midterm summary of Japan-US fusion cooperation program TITAN 査読有り国際誌

Muroga T., Sze D.K., Okuno K., Terai T., Kimura A., Kurtz R.J., Sagara A., Nygren R., Ueda Y., Doerner R.P., Sharpe J.P., Kunugi T., Morley N.B., Hatano Y., Sokolov M.A., Yamamoto T., Hasegawa A., Katoh Y., Ohno N., Tokunaga K., Konishi S., Fukada S., Calderoni P., Yokomine T., Messadek K., Oya Y., Hashimoto N., Hinoki T., Hashizume H., Norimatsu T., Shikama T., Stoller R.E., Tanaka K.A., Tillack M.S.

Fusion Science and Technology 60 巻 ( 1 ) 頁： 321 - 328 2011年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Science and Technology

Japan-US cooperation program TITAN (Tritium, Irradiation and Thermofluid for America and Nippon) started in April 2007 as 6-year project. This is the summary report at the midterm of the project. Historical overview of the Japan-US cooperation programs and direction of the TITAN project in its second half are presented in addition to the technical highlights.

DOI： 10.13182/FST11-A12373

Deuterium uptake in iron oxide (Fe<inf>2</inf>O<inf>3</inf>) under D <inf>2</inf>+-plasma exposure 査読有り国際誌

Sogawa T., Matsunami N., Ohno N., Tokitani M., Masuzaki S.

AIP Conference Proceedings 1321 巻頁： 274 - 277 2010年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AIP Conference Proceedings

We have studied implantation of low-energy deuterium ions into Fe 2O3 films and deuterium (D)-uptake in Fe2O 3 films, which were prepared by oxidation of Fe sheets in air at 400°C for 20 min. X-ray diffraction (XRD) shows that the films are mixture of hexagonal α-Fe2O3 (hematite) and cubic γ-Fe2O3 (maghemite). According to Rutherford backscattering spectroscopy (RBS) of 1.8 MeV H+, the composition is found to be crudely stoichiometric (Fe:O=2:3). The samples were subjected to D2+-plasma exposure using AC-glow discharge. The amount of D-uptake in Fe2O3 is evaluated to be ∼6×10 16cm2 for AC voltage of 1.5 kV in 0.4 Torr of D 2 gas for 15 min. The amount of D-uptake in Fe2O 3 appears to be larger by a factor of three than that in Fe. Comparisons of XRD patterns and RBS spectra before and after D2+-plasma exposure show no appreciable change of the crystalline structure, quality and composition. © 2010 American Institute of Physics.

DOI： 10.1063/1.3548377

2D Measurement of Edge Plasma Dynamics by Using High-Speed Camera Based on HeI Line Intensity Ratio Method 査読有り

Ohno N., Miyamoto K., Kodama K., Kajita S., Kitagawa K.

CONTRIBUTIONS TO PLASMA PHYSICS 50 巻 ( 10 ) 頁： 962 - 969 2010年11月

Enhancement of cross-field transport into the private region of detached-divertor in Large Helical Device 査読有り

H. Tanaka, N. Ohno, Y. Tsuji, S. Kajita, S. Masuzaki, M. Kobayashi, T. Morisaki, H. Tsuchiya, A.Komori, and LHD Experimental Group

Physics of Plasmas 17 巻頁： 102509(8pages) 2010年10月

Nanostructured Black Metal: Novel Fabrication Method by Use of Self-Growing Helium Bubbles 査読有り

S.Kajita, T.Saeki, N.Yoshida, N.Ohno, A.Iwamae

Applied Physics Express 3 巻頁： 085204-1-3 2010年7月

2D Statistical Analysis of Non-Diffusive Transport under Attached and Detached Plasma Conditions of the Linear Divertor Simulator 査読有り

H.Tanaka, N.Ohno, Y.Tsuji, S.Kajita

CONTRIBUTIONS TO PLASMA PHYSICS 50 巻 ( 3-5 ) 頁： 256 - 266 2010年5月

Basic Study on the Generation of RF Plasmas in Premixed Oxy-combustion with Methane 査読有り国際共著国際誌

Y.Osaka, N.Kobayashi, M.A.Razzak, N.Ohno, S.Takamura, Y.Uesugi

Plasma and Fusion Research ( 5 ) 頁： 010 2010年3月

記述言語：英語出版者・発行元：社団法人プラズマ・核融合学会

Oxy-combustion generates a high temperature field (above 3000 K), which is applied to next generation power plants and high temperature industrial technologies because of N2 free processes. However, the combustion temperature is so high that the furnace wall may be fatally damaged. In addition, it is very difficult to control the heat flux and chemical species' concentrations because of rapid chemical reactions. We have developed a new method for controlling the flame by electromagnetic force on this field. In this paper, we experimentally investigated the power coupling between the premixed oxy-combustion with methane and radio frequency (RF) power through the induction coil. By optimizing the power coupling, we observed that the flame can absorb RF power up to 1.5 kW. Spectroscopic measurements also showed an increase in the emission intensity from OH radicals in the flame, indicating improved combustibility.

DOI： 10.1585/pfr.5.010

Study of current decay time during disruption in JT-60U tokamak 査読有り

Y.Shibata, K.Y.Watanabe, M.Okamoto, N.Ohno, A.Isayama, K.Kurihara, T.Nakano, N.Oyama, Y.Kawano, G.Matsunaga, S.Sakakibara, M.Sugihara, Y.Kamada and the JT-60U team

Nuclear Fusion 50 巻頁： 025015 (7pp) 2010年

Formation Condition of Fiberform Nanostructured Tungsten by Helium Plasma Exposure 査読有り

W. Sakaguchi, S. Kajita, N. Ohno, et al.

Plasma Fusion Research 5 巻頁： S1023(5pages) 2010年

Design study of the divertor Thomson scattering system for JT-60SA 査読有り

S. Kajita, T. Hatae, K. Itami, N. Ohno, T. Nakano

J. Plasma Fus. Res. Series 9 巻頁： 157-162 2010年

2D Measurement of Edge Plasma Dynamics by Using High-Speed Camera Based on HeI Line Intensity Ratio Method 査読有り

N.Ohno, K.Miyamoto, K.Kodama, S.Kajita, K.Kitagawa

Contrib. Plasma Physics 50 巻 ( 10 ) 頁： 962-969 2010年

Deepening of Floating Potential for Tungsten Target Plate on the way to Nanostructure Formation 査読有り

S.Takamura, T.Miyamoto and N.Ohno

Plasma and Fusion Research: Rapid Communications 5 巻頁： 039(2 pages) 2010年

Compact Plasma Device for PWI Studies 査読有り

S.Takamura, T.Tsujikawa, Y.Tomida, K.Suzuki, T.Minagawa, T.Miyamoto, N.Ohno

J. Plasma Fusion Res. SERIES 9 巻頁： 441-445 2010年

2D Statistical Analysis of Non-Diffusive Transport under Attached and Detached Plasma Conditions of the Linear Divertor Simulator 査読有り

H.Tanaka, N.Ohno, Y.Tsuji, S.Kajita

Contrib. Plasma Physics 50 巻 ( 3-5 ) 頁： 256-266 2010年

Self-Affine Fractality of Bifurcating Arc Trail in Magnetized Plasma 査読有り

Shin KAJITA, Noriyasu OHNO, Yoshiyuki TSUJI, Hirohiko TANAKA, and Shuichi TAKAMURA

Journal of the Physical Society of Japan 79 巻 ( 5 ) 頁： 054501(7 pages) 2010年

Fluid Mechanical Characteristics of Microwave Discharge Jet Plasmas at Atmospheric Gas Pressure 査読有り

S.Takamura, S.Saito, G.Kushida, M.Kando, N.Ohno,

IEEJ Trans. FM 130 巻 ( 5 ) 頁： 493-500 2010年

Comparison with Surfaces of Diamond and Graphite for Adsorption of Hydrogen 査読有り

H.Nakamura, A.Ito, S.Saito, Y.Tamura, S.Fujiwara, N.Ohno, S.Kajita

Proceedings of ITC19, 2009 1 巻 2010年

Tungsten blow-off in response to the ignition of arcing: revival of arcing issue in future fusion devices 査読有り

S.Kajita, S.Takamura, N.Ohno

J. Nuclear Mater. 2010年

Recent progress in understanding the behavior of dust in fusion devices 査読有り

S.I.Krasheninnikov, A.Yu Pigarov, R.D.Smirnov, M.Rosenberg, Y.Tanka, D.J.Benson, T.K.Soboleva, T.D.Rognlien, D.A.Mendis, B.D.Bray, D.L.Rudakov, J.H.Yu, W.P.West, A.L.Roquemore, C.H.Skinner, J.L.Terry, B.Lipschultz, A.Bader, R.S.Granetz, C.S.Pitcher, N.Ohno, S.Takamura, S.Masuzaki, N.Ashikawa, M.Shiratani, M.Tokitani, R.Kumazawa, N.Asakura, T.Nakano, A.J.Litnovsky, R.Maqueda and the LHD Experimental Group

Plasma Physics and Controlled Fusion 50 巻 ( 12 ) 頁： 124054(13 pp) 2010年

Degradation of optical reflectivity of in-vessel mirror materials by helium bombardment 査読有り

S.Kajita, T.Saeki, N.Ohno, M.Tokitani, T.Hatae, W.Sakaguchi

J. Nuclear Mater. 2010年

Comparison of Hydrogen Adsorption on Diamond and Graphite Surfaces 査読有り国際誌

NAKAMURA Hiroaki, ITO Atsuhi M., SAITO Seiki, TAMURA Yuichi, FUJIWARA Susumu, OHNO Noriyasu, KAJITA Shin

Plasma and Fusion Research ( 5 ) 頁： S2072 - S2072 2010年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：社団法人プラズマ・核融合学会

By a classical molecular dynamics (CMD) simulation with a modified Brenner's reactive empirical bond-order (REBO) potential, we found that graphite with zigzag (1010) and armchair (1120) edge states is destroyed more easily than other structures, i.e., graphite with the (0001) surface, and diamond with the (100), (111), (120), and (110) surfaces. Experimental results indicated that graphite is eroded under hydrogen atom injection with Ein = 0.3 eV, and that diamond is not eroded under the same conditions. Our simulation results are consistent with these experimental results. We also reveal the temperature and saturation dependence of the surface structure of carbon crystals.

DOI： 10.1585/pfr.5.S2072

Steady-State Operation Scenario and the First Experimental Result on QUEST 査読有り国際誌

HANADA Kazuaki, MAEKAWA Takashi, KISHIMOTO Yasuaki, ISHIGURO Masaki, YOSHINAGA Tomokazu, IGAMI Hiroe, NISHINO Nobuhiro, HONMA Hiroshi, KAWASAKI Shoji, NAKASHIMA Hisatoshi, HIGASHIJIMA Aki, SATO Kohnosuke, HIGASHIZONO Yuta, ANDO Akira, ASAKURA Nobuyuki, EJIRI Akira, HIROOKA Yoshihiko, ISHIDA Akio, KOMORI Akio, MATSUKAWA Makoto, MOTOJIMA Osamu, OGAWA Yuichi, ZUSHI Hideki, OHNO Noriyasu, ONO Yasushi, PENG Martin, SUDO Shigeru, YAMADA Hiroshi, YOSHIDA Naoaki, YOSHIDA Zensho, NAKAMURA Kazuo, SAKAMOTO Mizuki, IDEI Hiroshi, HASEGAWA Makoto, TAKASE Yuichi, MITARAI Osamu

Plasma and Fusion Research ( 5 ) 頁： S1007 - S1007 2010年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：社団法人プラズマ・核融合学会

QUEST focuses on the steady state operation of the spherical tokamak by controlled PWI and electron Bernstein wave current drive. One of the main purposes of QUEST is an achievement of long duration discharge with MW-class injected power. As the result, QUEST should be operated in the challenging region on heat and particle handling. To do the particle handling, high temperature all metal wall up to 623 K and closed divertors are planned, which is to realize the steady-state operation under recycling ratio, R = 1. This is a dispensable check to DEMO, because wall pumping should be avoided as possible in the view of tritium retention. The QUEST project will be developed in increment step such as, I. low β steady state operation in limiter configuration, II. low β steady state operation in divertor configuration, III. relatively high β steady state operation in closed divertor configuration. Phase I in the project corresponds to these two years, and final goal of phase I is to make full current drive plasma up to 20 kA. Closed divertor will be designed and tested in the Phase II. QUEST is running from Oct., 2008 and the first results are introduced.

DOI： 10.1585/pfr.5.S1007

Formation process of tungsten nanostructure by the exposure to helium plasma under fusion relevant plasma conditions 査読有り

S.Kajita, W.Sakaguchi, N.Ohno, N.Yoshida, T.Saeki

Nuclear Fusion 49 巻頁： 095005(6pp) 2009年8月

Development of Divertor Plasma Simulators with High Heat Flux Plasmas and its Application to Nuclear Fusion Study : A Review 査読有り国際誌

OHNO Noriyasu, KAJITA Shin, TAKAGI Makoto, TAKAMURA Shuichi

IEEJ transactions on electrical and electronic engineering : official journal of the Institute of Electrical Engineering of Japan / = 電気学会 4 巻 ( 4 ) 頁： 476 - 487 2009年7月

Ray tracing simulation for radiation trapping of the He I resonance transition in a linear plasma device 査読有り国際共著

S.Kajita, D.Nishijima,E.M.Hollmann, N.Ohno

Physics of Plasmas 16 巻頁： 063303 2009年6月

Investigation of detached recombining deuterium plasma and carbon chemical erosion in the toroidal divertor simulator NAGDIS-T 査読有り

K.Yada, N.Matsui, N.Ohno, S.Kajita, S.Takamura, M.Takagi

Journal of Nuclear Materials 390-391 巻頁： 290 - 294 2009年6月

Spherical cauliflower-like carbon dust formed by interaction between deuterium plasma and graphite target and its internal structure 査読有り国際誌

Ohno N., Yoshimi M., Tokitani M., Takamura S., Tokunaga K., Yoshida N.

JOURNAL OF NUCLEAR MATERIALS 390-91 巻頁： 61 - 64 2009年6月

Deuterium retention in tungsten oxide under low energy D<inf>2</inf>+ plasma exposure 査読有り国際誌

Matsunami N., Ohno N., Tokitani M.

Journal of Nuclear Materials 390-391 巻 ( 1 ) 頁： 693 - 695 2009年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Materials

W is a candidate for plasma facing material and oxide layers are highly anticipated on W surface. We have studied deuterium (D) retention in tungsten oxide (WO3) films and thermal release of deuterium. WO3 films, prepared by oxidation of W metal sheet, were exposed to D2 plasma under AC glow discharge at the applied voltage V up to a few kV and DC discharge. D-retention in W has been studied for comparison. The amount of D retained in the WO3 films and W were analyzed by detecting α particles from the nuclear reaction, D(3He, α)p, using 0.7 MeV 3He+ ions. We find that D-uptake in WO3 film is much larger than in W. According to thermal desorption, release of D2 occurs at ∼180 and 450 °C. © 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2009.01.191

Erratum: Comparison of He I line intensity ratio method and electrostatic probe for electron density and temperature measurements in NAGDIS-II (Physics of Plasmas (2006) 13 (013301)) 査読有り国際誌

Kajita S., Ohno N., Takamura S., Nakano T.

Physics of Plasmas 16 巻 ( 2 ) 2009年3月

Prompt ignition of a unipolar arc on helium irradiated tungsten 査読有り

S.Kajita, S.Takamura and N.Ohno

Nuclear Fusion 49 巻頁： 032002(4pp) 2009年2月

Development of Divertor Plasma Simulators with High Heat Flux Plasmas and Its Application to Nuclear Fusion Study 査読有り

大野哲靖

IEEJ Transactions 4 頁： 476 - 487 2009年

Visualized blow-off from helium irradiated tungsten in response to ELM-like heat load 査読有り

S.Kajita, N.Ohno, W.Sakaguchi, M.Takagi

Plasma and Fusion Research 4 巻頁： 004(6 pages) 2009年

In situ reflectivity of tungsten mirrors under helium plasma exposure 査読有り

W.Sakaguchi, S.Kajita, N.Ohno, M.Takagi

Journal of Nuclear Materials 頁： doi:10.1016/j.jnucmat.2009.01.276 2009年

Statistical analysis to the SOL plasma fluctuation in JT-60U 査読有り

N. Asakura, N. Ohno, H. Tanaka, H. Kawashima, T. Nakano

J.Nucl. Mater. 390-391 巻頁： 364-367 2009年

Effects of tungsten surface conditions on carbon deposition 査読有り

Y. Ueda, M. Fukumoto, A. Yamawaki, Y. Soga, Y. Ohtsuka, S. Brezinsek, T. Hirai, A. Kirschner, A. Kreter, A. Litnovsky, V. Philipps, A. Pospieszczyk, B. Schweer, G. Sergienko, T. Tanabe, K. Sugiyama, K. Ohya, N. Ohno and The TEXTOR team

J.Nucl. Mater. 390-391 巻頁： 44-48 2009年

Deuterium retention in Tungsten Oxyside under low-voltage D2+ plasma exposure 査読有り

N.Matsunami, N.Ohno and M.Tokitani

J.Nucl. Mater. 390-391 巻頁： 693-695 2009年

Development of net-current free heliotron plasmas in the Large Helical Device 査読有り

A.Komori, H.Yamada, S.Sakakibara, O.Kaneko, K.Kawahata, T.Mutoh, N.Ohyabu, S.Imagawa, K.Ida, Y.Nagayama, T.Shimozuma, K.Y.Watanabe, T.Mito, M.Kobayashi, K.Nagaoka, R.Sakamoto, N.Yoshida, S.Ohdachi, N.Ashikawa, Y.Feng, T.Fukuda, H.Igami, S.Inagaki, H.Kasahara, S.Kubo, R.Kumazawa, O.Mitarai, S.Murakami, Y.Nakamura, M.Nishiura, T.Hino, S.Masuzaki, K.Tanaka, K.Toi, A.Weller, M.Yoshinuma, Y.Narushima, N.Ohno, T.Okamura, N.Tamura, K.Saito, T.Seki, S.Sudo, H.Tanaka, T.Tokuzawa, N.Yanagi, M.Yokoyama, Y.Yoshimura, T.Akiyama, H.Chikaraishi, M.Chowdhuri, M.Emoto, N.Ezumi, H.Funaba, L.Garcia, P.Goncharov, M.Goto, K.Ichiguchi, M.Ichimura, H.Idei, T.Ido, S.Iio, K.Ikeda, M.Irie, A.Isayama, T.Ishigooka, M.Isobe, T.Ito, K.Ito, A.Iwamae, S.Hamaguchi, T.Hamajima, S.Kitajima, S.Kado, D.Kato, T.Kato, S.Kobayashi, K.Kondo, S.Masamune, Y.Matsumoto, N.Matunami, T.Minami, C.Michael, H.Miura, J.Miyazaa, N.Mizuguchi, T.Morisaki, S.Morita, G.Motojima, I.Murakami, S.Muto, K.Nagasaki, N.Nakajima, Y.Nakamura, H.Nakanishi, H.Nakano, K.Narihara, A.Nishimura, H.Nishimura, K.Nishimura, S.Nishimura, N.Nishino, T.Notake, T.Obana, K.Ogawa, Y.Oka, T.Ohishi, H.Okada, K.Okuno, K.Ono, M.Osakabe, T.Osako, T.Ozaki, B.J.Peterson, H.Sakaue, M.Sasao, S.Satake, K.Sato, M.Sato, A.Shimizu, M.Shiratani, M.Shoji, H.Sugama, C.Suzuki, Y.Suzuki, K.Takahata, H.Takahashi, Y.Takase, Y.Takeiri, H.Takenaga, S.Toda, Y.Toda, M.Tokitani, H.Tsuchiya, K.Tsumori, H.Urano, E.Veshchev, F.Watanabe, T.Watanabe, T.H.Watanabe, I.Yamada, S.Yamada, O.Yamagishi, S.Yamaguchi, S.Yoshimura, T.Yoshinaga and O.Motojima

Nuclear Fusion 49 巻頁： 104015(8pp) 2009年

Direct observation of cathode spot grouping using nanostructured electrode 査読有り

S.Kajita, N.Ohno, S.Takamura, Y.Tsuji

Physics Letters A 373 巻頁： 4273-4277 2009年

Discharge Bifurcation of Microwave-sustained Helium Plasma Torch at Atmospheric Pressure 査読有り

S.Takamura, M.Kando, N.Ohno

J.Plasma Fusion Res. SERIES 8 巻頁： 910-913 2009年

High temperature irradiation damage of carbon materials studies by laser Raman spectroscopy 査読有り

M.Yoshida, T.Tanabe, N.Ohno, M.Yoshimi, S.Takamura

Journal of Nuclear Materials 386-388 巻頁： 841-843 2009年

*Development of Divertor Plasma Simulators with High Heat Flux Plasmas and its Application to Nuclear Fusion Study: A Review 査読有り

N.Ohno, S.Kajita, M.Takagi, S.Takamura

TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING IEEJ Trans. 4 巻頁： 476,487 2009年

Formation and mitigation of fiberform nanostructured tungsten by helium and sub-ms laser pulse irradiations 査読有り

S.Kajita, W.Sakaguchi and N.Ohno

Plasma Devices and Operations 17 巻頁： 165,173 2009年

Statistical analysis of fluctuation characteristics at high- and low-field sides in L-mode SOL plasmas of JT-60U 査読有り

H.Tanaka, N.Ohno, N.Asakura, Y.Tsuji, H.Kawashima, S.Takamura, Y.Uesugi and the JT-60U Team

Nuclear Fusion 49 巻頁： 65017 2009年

*Spherical cauliflower-like carbon dust formed by interaction between deuterium plasma and graphite target and its internal structure 査読有り

N.Ohno, M.Yoshimi, M.Tokitani, S.Takamura, K.TOkunaga, N.Yoshida

Journal of Nuclear Materials 頁： doi:10.1016/j.jnucmat.2009.01.051 2009年

Statistical properties of edge plasma turbulence in the Mega-Amp Spherical Tokamak and the Large Helical Device 査読有り国際共著国際誌

Dewhurst J., Hnat B., Ohno N., Dendy R., Masuzaki S., Morisaki T., Komori A., Dudson B., Counsell G., Kirk A.

35th EPS Conference on Plasma Physics 2008, EPS 2008 - Europhysics Conference Abstracts 32 巻 ( 2 ) 頁： 898 - 901 2008年12月

Deuterium retention near surface of TiO<inf>2</inf> by low-voltage D <inf>2</inf> plasma discharge 査読有り国際誌

Matsunami N., Tanaka T., Ohno N., Tokitani M.

Physica Status Solidi (C) Current Topics in Solid State Physics 5 巻 ( 4 ) 頁： 923 - 926 2008年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physica Status Solidi (C) Current Topics in Solid State Physics

We have investigated deuterium (D) uptake in TiO2 (rutile) films under exposure of low-energy D2+ ions and thermal release of D from TiO2 films. The amount of deuterium in the films was analysed by means of nuclear reaction analysis, D(3He, α)p. D-uptake under AC-glow discharge in D2 pressure of ∼90 Pa is compared with that under DC-discharge with well-defined energy of D 2+ ions in D2 pressure of ∼0.1 Pa. The results imply that the effective energy of D2+ ions in AC-glow discharge is much lower than the energy derived from the applied voltage. The results are also compared with those for Ti sheet exposed to low-energy D2+ ions. We find that D-release temperature from TiO2 is considerably lower than from Ti, though D-uptake in TiO2 is smaller than in Ti. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.

DOI： 10.1002/pssc.200778343

11th International Workshop on Plasma Edge Theory in Fusion Devices: Preface 査読有り国際共著国際誌

Heikkinen J., Ohno N.

Contributions to Plasma Physics 48 巻 ( 1-3 ) 2008年3月

Measurement of Plasma Properties of the Atmospheric Oxy-Combustion Flame by Using Double Probe Method 査読有り

Y.Osaka, N.Kobayashi, N.Ohno, S.Takamura, Y.Tanaka, Y.Uesugi

Contrib. Plasma Physics 48 巻 ( 5-7 ) 頁： 485-490 2008年

Intermittency and extended self-similarity in space and fusion plasma: boundary effects 査読有り

V.P.Budaev, S.Savin, L.Zelencyi, N.Ohno, S.Takamura and E.Amata

Plasma Physics and Controlled Fusion 50 巻頁： 074014(20pp) 2008年

Extended self-similarity of intermittent turbulencein edge magnetized plasmas 査読有り

V.P. Budaev, N. Ohno, S.Takamura, S. Masuzaki, A. Komori, T. Morisaki

Nuclear Fusion 48 巻頁： 24014 2008年

Deuterium retention near surface of TiO2 by low-voltage D2 plasma discharge 査読有り

N.Matsunami, T.Tanaka, N.Ohno and M.Tokitani

Phys. Stat. Sol.(c) 5 巻 ( 4 ) 頁： 923-926 2008年

ELM propagation in the low- and high- filed-side Scrape-off Layer of the JT-60U tokamak 査読有り

N.Asakura, H.Kawashima, N.Ohno, G.Matsunaga, T.Nakano and N.Oyama

Journal of Physics; Conference Series 123 巻頁： 012009(11pp) 2008年

Statistical properties of edge plasma turbulence in the Large Helical Device 査読有り

J.M.Dewhurst, B.Hnat, N.Ohno, R.O.Dendy, S.Masuzaki, T.Morisaki and A.Komori

Plasma Physics and Controlled Fusion 50 巻頁： 095013(15pp) 2008年

Fluctuating Helium Emission in Optically Thick Divertor Plasmas 査読有り

F. B. Rosmej, N. Ohno, S. Takamura, S. Kajita

Contributions to Plasma Physics 48 巻頁： 243-248 2008年

Numerical Modeling of Behavior of Dust Made of Different Materials in Plasmas 査読有り

Y. Tanaka, A. Yu. Pigarov, R. D. Smirnov, S. I. Krasheninnikov, N. Ohno, Y. Uesugi

Contributions to Plasma Physics 48 巻頁： 295-299 2008年

Extended Self-Similarity in Edge Plasma Turbulence of Fusion Devices 査読有り

V. P. Budaev, N. Ohno, S. Takamura, S. Masuzaki, A. Komori, T. Morisaki

Contributions to Plasma Physics 48 巻頁： 42-47 2008年

Plasma Rotation Measurements by Passive Spectroscopic Method in the HYBTOK-II using a Dynamic Ergodic Divertor 査読有り

Y.Hasebe, M.Okamoto, S.Kajita, N.Ohno and S.Takamura

Plasma and Fusion Research 3 巻頁： S1015 2008年

ELM propagation in the low- and high-field-side scrape-off layer of the JT-60U tokamak 査読有り国際誌

Asakura N., Kawashima H., Ohno N., Matsunaga G., Nakano T., Oyama N.

Journal of Physics: Conference Series 123 巻 2008年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physics: Conference Series

In JT-60U, the filament structure of Edge Localized Modes (ELMs) is measured at three poloidal locations, and their temporal evolution is investigated at the inner (high magnetic-field-side, HFS) SOL as well as outer (low magnetic-field-side, LFS) SOL. At the inner SOL, filament structure with 7-8 temporal multi-peaks in ion-saturation probe signals and other diagnostics is, for the first time, measured close to the sepatratrix. The delay of the first peak after the start of MHD activity is faster than the characteristic time of the parallel convection from the outer midplane, and the Mach numbers of the plasma parallel flow reach ion sonic levels. These results show that ELM filaments extend from the outer to the inner plasma edge, and that a part of the filaments are ejected into the inner SOL. The toroidal mode numbers (n) and poloidal width of the filaments (δz) are evaluated from the interval of the multi-peaks and duration of each peak, yielding n ∼ 18-44 and δz ∼ 2-6 cm on the HFS SOL, while n and δz are comparable on the LFS SOL. After the multi-peaks appear, flow reversal of the SOL plasma toward is observed over a wide region of the inner SOL. © 2008 IOP Publishing Ltd.

DOI： 10.1088/1742-6596/123/1/012009

Plasma-assisted laser ablation of tungsten: Reduction in ablation power threshold due to bursting of holes/bubbles 査読有り国際誌

Kajita S., Ohno N., Takamura S., Sakaguchi W., Nishijima D.

Applied Physics Letters 91 巻 ( 26 ) 2007年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Letters

Nanosecond laser ablation of tungsten (W) exposed to helium plasma is investigated using optical emission spectroscopy. Submicrometer-sized holes/bubbles are formed on the surface of W when it was exposed to the helium plasma at a sufficiently high temperature (1500-1600 K). The emissions from a virgin W (before the helium plasma irradiation) cannot be detected when the fluence is <1 J cm2; however, the threshold fluence for the detection of neutral W emission after it was exposed to the helium plasma is ∼0.2 J cm2. The physical mechanism of laser-induced bursting of holes/bubbles is proposed for achieving a significant reduction in ablation power threshold. © 2007 American Institute of Physics.

DOI： 10.1063/1.2824873

Effect of cross-field transport on H- density profile in magnetized plasmas: Comparison between measurement and simulation 査読有り国際誌

Kajita S., Kado S., Ohno N., Takamura S., Kurihara K., Kuwahara Y.

Physics of Plasmas 14 巻 ( 10 ) 2007年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics of Plasmas

The radial density profile of negative hydrogen ions in magnetized plasma is investigated in the divertor simulator MAP (Material and plasma)-II [S. Kado et al., J. Plasma Fusion Res. 71, 810 (2005)] by measurement and numerical simulation. The laser photodetachment method is used to evaluate the H - density by considering the influence of the magnetic field. The density of H- has a hollow profile and exhibits a peak in the peripheral region, though the electron density and temperature exhibit a peak at the center of the plasma column. The density profile of H- does not agree with the calculation result obtained from, the rate equation, in which the local production and extinction rates are balanced, under the present experimental condition. To understand the behavior of negative ions, their trajectories are calculated by numerically solving the equation of motion by considering the effect of collisions. The negative ion density profile calculated from the particle simulation agrees well with the measured negative ion density profile. It is shown that the cross-field H- transport due to the radial electric field with the assistance of the elastic collisions plays an important role in enhancing the negative ion density in the peripheral region. © 2007 American Institute of Physics.

DOI： 10.1063/1.2789559

Sub-ms Laser Pulse Irradiation on Tungsten Target Damaged by Exposure to Helium Plasma 査読有り

S.Kajita, S.Takamura, N.Ohno, D.Nishijima, H.Iwakiri, N.Yoshida

Nuclear Fusion 47 巻頁： 1358 - 1366 2007年9月

Integrated view of disruption dynamics on internal electromagnetic and plasma structures in the small tokamak HYBTOK-II 査読有り

M. Okamoto, S. Takamura, N. Ohno, S. Kajita, Y. Kikuchi, Y. Uesugi, T. Ozeki, Y. Kawano, M. Sugihara

Nuclear Fusion 47 巻頁： 1106 - 1111 2007年8月

Surface modification at tungsten and tungsten coated graphite due to low energy and high fluence plasma and laser pulse irradiation 査読有り国際誌

Ohno N., Kajita S., Nishijima Dai, Takamura S.

JOURNAL OF NUCLEAR MATERIALS 363 巻頁： 1153 - 1159 2007年6月

Modeling of Dust-particle Behavior for Different Materials in Plasmas 査読有り

Y.Tanaka, A.Yu.Pigarov, R.D.Smirnov, S.I.Krasheninnikov, N.Ohno, Y.Uesugi

Physics of Plasmas 14 巻頁： 52504 2007年5月

Systematic Analysis of Current Decay Time during Disruption in HYBTOK-II Tokamak 査読有り

M.Okamoto, N.Ohno, S.Takamura

Plasma and Fusion Research 3 巻頁： 6 2007年

Effect of Cross-field Transport on H-Density Profile in Magnetized Plasmas: Comparison Between Measurement and Simulation 査読有り

S.Kajita, S.Kado, N.Ohno, K.Kurihara, Y.Kuwahara, S.Takamura

Physics of Plasmas 14 巻頁： 103503 2007年

Plasma-assisted Laser Ablaion of Tungsten: Reduction in Ablation Power Threshold Due to Bursting of Holes/Bubbles 査読有り

S.Kajita, N.Ohno, S.Takamura, W.Sakaguchi, D.Nishijima

Applied Physics Letters 9191 巻頁： 261501 2007年

Development of Tungsten Materials for Plasma Facing Components in Japan 査読有り

Y.Ueda, N.Ohno, S.Kajita, H.Kurishita, H.Iwakiri et al

Fusion Science and Technology 52 巻頁： 513-520 2007年

Overview of JT-60U results for the Development of a Steady-state Advanced Tokamak Scenario 査読有り

H.Takenaga, the JT-60 Team

Nuclear Fusion 47 巻頁： S563-S578 2007年

Structural Bifurcation of Microwave Helium Jet Discharge at Atmospheric Pressure 査読有り

S.TAKAMURA, M.KITOH, T.SOGA, H.TAKASHIMA, Y.NISHINO, S.HAYAKAWA, Y.BAN, T.YUHKI, M.KANDO, N.OHNO

Plasma and Fusion Research 3 巻頁： 12 2007年

High density plasma generation by RF ohmic discharge in toroidal divertor simulator NAGDIS-T 査読有り

M. Nagase, H. Masuda, N. Ohno, S. Takamura and M. Takagi

Journal of Nuclear Materials 363-365 巻頁： 611-615 2007年

High Density Plasma Generation by RF Ohmic Discharge in Toroidal Divertor Simulator NAGDIS-T 査読有り

M.Nagase, H.Masuda, N.Ohno, S.Takamura, M.Takagi

J. Nucl. Mater. 363-365 巻頁： 611-615 2007年

Dynamic Interaction between Disruptive Plasma and Wall in the Small Tokamak HYBTOK-II 査読有り

M.Okamoto, T.Yamada, T.Hiraishi, Y.Kikuchi, N.Ohno, S.Takamura

J. Nucl. Mater. 363-365 巻頁： 1076-1080 2007年

Alleviation of Damaged Tungsten Having Helium Holes/Bubbles by Use of Transient Heat Load 査読有り

S.Kajita, S.Takamura, N.Ohno, T.Nishimoto

Plasma Fusion Research 2 巻頁： 9 2007年

Plasma-surface Interaction, Scrape-off Layer and Divertor Physics: Implications for ITER 査読有り

B.Lipschultz, X.Bonnin, G.Counsell, A.Kallenbach, A.Kukushkin, K.Krieger, A.Leonard, A.Loarte, .Neu, R.A.Pitts, T.Rognlien, J.Roth, C.Skinner, J.L.Terry, E.Tsitrone, D.Whyte, S.Zweben, N.Asakura, D.Coster, R.Doerner, R.Dux, G.hendrih, A.Herrmann, J.Hu, S.Krasheninnikov, G.Kirnev, A.Kreter, V.Kurnaev, B.LaBombard, S.Lisgo, T.Nakano, N.Ohno, H.D.Pacher, J.Paley, Y.Pan, G.Pautasso, V.Philipps, V.Rohde, D.Rudakov, P.Stangeby, S.Takamura, T.Tanabe, Y.Yang, S.Zhu

Nuclear Fusion 47 巻頁： 1189-1205 2007年

Extended Steady-state and High-beta Regimes of Net-current Free Heliotron Plasmas in the Large Helical Device 査読有り

O.Motojima, H.Yamada, A.Komori, N.Ohyabu, T.Mutoh, O.Kaneko, K.Kawahata, T.Mito, K.Ida, S.Imagawa, Y.Nagayama, T.Shimozuma, K.Y.Watanabe, S.Masuzaki, J.Miyazawa, T.Morisaki, S.Morita, S.Ohdachi, N.Ohno, K.Saito, S.Sakakibara, Y.Takeiri, N.Tamura, K.Toi, M.Tokitani, M.Yokoyama, M.Yoshinuma, K.Ikeda, A.Isayama, K.Ishii S.Kubo, S.Murakami, K.Nagasaki, T.Sekim K.Takahata, H.Takenaga and the LHD Experimental Group

Nuclear Fusion 47 巻頁： S668-S676 2007年

Alleviation of Helium Holes/Bubbles on Tungsten Surface by Use of Transient Heat Load 査読有り国際誌

KAJITA Shin, TAKAMURA Shuichi, OHNO Noriyasu, NISHIMOTO Tentaro

Plasma and Fusion Research ( 2 ) 頁： 9 - 9 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：社団法人プラズマ・核融合学会

The alleviation effect of transient heat load on helium holes/bubbles has been demonstrated using ruby laser pulses for the transient heat source in the divertor simulator NAGDIS-II. It is shown that the holes and bubbles disappeared following the irradiation of the ruby laser pulses, while the surface roughness was significantly enhanced by the irradiation of the Nd:YAG laser pulses. Based on the numerically calculated temperature in the specimen, the physical mechanism causing this difference is discussed particularly in terms of pulse width (0.6 ms for ruby laser without a Q-switch and 5 ns for Nd:YAG laser with a Q-switch).

DOI： 10.1585/pfr.2.009

Plasma response on penetration of external rotating helical magnetic field in HYBTOK-II tokamak edge plasma 査読有り国際誌

Budaev V.P., Pankratov I.M., Takamura S., Ohno N., Kajita S., Takagi M., Matsuno H., Okamoto M., Hosoi S., Hasebe Y., Yamada T., Omelchenko A.Y., Olshansky V.V.

33rd EPS Conference on Plasma Physics 2006, EPS 2006 2 巻頁： 1548 - 1551 2006年12月

Intermittency in laboratory and space plasmas: Comparative study of multifractal statistics 査読有り国際共著国際誌

Budaev V., Savin S., Zelenyi L., Takamura S., Ohno N., Shevyrev N.

33rd EPS Conference on Plasma Physics 2006, EPS 2006 1 巻頁： 344 - 347 2006年12月

Reduction of laser power threshold for melting tungsten due to subsurface helium holes 査読有り国際誌

Kajita Shin, Nishijima Dai, Ohno Noriyasu, Takamura Shuichi

JOURNAL OF APPLIED PHYSICS 100 巻 ( 10 ) 2006年11月

Modification of the damping rate of the oscillations of a dust particle levitating in a plasma due to the delayed charging effect 査読有り国際共著国際誌

Pustylnik M.Y., Ohno N., Takamura S., Smirnov R.

Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 74 巻 ( 4 ) 2006年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physical Review E - Statistical, Nonlinear, and Soft Matter Physics

Dependence of the damping rate of the oscillations of the dust particles levitating in the sheath on the plasma parameters is investigated both theoretically and experimentally. Significant deviations of the damping rate from the values predicted by the Epstein formula are found in the experiment. The delayed charging effect is applied for the theoretical explanation of the experimental results. Qualitative agreement between the theoretical and experimental data is obtained. © 2006 The American Physical Society.

DOI： 10.1103/PhysRevE.74.046402

Superdiffusion and multifractal statistics of edge plasma turbulence in fusion devices 査読有り国際共著国際誌

Budaev V.P., Takamura S., Ohno N., Masuzaki S.

Nuclear Fusion 46 巻 ( 4 ) 2006年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

The edge plasma turbulence in the T-10 tokamak, the HYBTOK-II tokamak, the linear machine NAGDIS-II and the Large Helical Device have been studied. The fluctuations in the plasma density have been analysed in terms of the multifractal formalism revisited with wavelets. In most of the cases considered, the edge density fluctuations demonstrate multifractal statistics, i.e. the scaling behaviour of the absolute moments is described by a convex function with non-trivial self-similarity properties. The multifractality factor defined in the multiplicative cascade model is a relevant parameter for characterizing the edge plasma turbulence. The multiplicative cascade process has a 'coarse' time scale T ∼ 50-200 ms iterating towards finer scales. This time scale is referred to as an integral correlation scale. The self-similarity parameters have been observed to depend on the edge plasma condition. The correlation and transport properties have been analysed regarding the multifractality parameter. The diffusion transport coefficient in an edge plasma is not a trivial function of multifractality parameters. © 2006 IAEA, Vienna.

DOI： 10.1088/0029-5515/46/4/S10

Comparison of HeI Line Intensity Ratio Method and Electrostatic Probe for Electron Density and Temperature Measurements in NAGDIS-II 査読有り

S.Kajita, N.Ohno, S.Takamura, T.Nakano

Physics of Plasmas 13 巻頁： 013301(9pages) 2006年1月

Charactersitics of rf inductive plasma in oxy-combustion

Yugo Osaka, Noriyuki Kobayashi, M.A.Razzak, Noriyasu Ohno, Shuichi Takamura

The 4th International Conference on Combustion, Incineration/Pyrolysis and Emission Control, September 26-29, 2006, Kyoto, Japan 1 巻 2006年

Fundamental research on plasma-assisted combustion by applying rf power

Yugo Osaka, Noriyuki Kobayashi, M.A.Razzak, Noriyasu Ohno, Shuichi Takamura

11th Asian Pacific Confederation of Chemical Engineering Congress, August 27-30, 2006 Kuala Lumpur, Malaysia 1 巻 2006年

Dust Formation and Transport in the Divertor Plasma Simulators

N.Ohno, M.Miyoshi, T.Yamada, M.Pustylnik, S.Kajita, S.Takamura

7th Workshop ont Fine Particle Plasma, NIFS, oki, Japan December, 15-16, 2006(招待講演) 1 巻 2006年

Two-dimensional measurement of plasma dynamics with an ICCD fast camera based on HeI line intensity ratio method

N.Yamamoto, K.Miyamoto, K.Kitagawa, S.Kajita, M.Okamoto, N.Ohno

16th International Toki Conference on Advanced Imaging and Plasma Diagnostics, Toki, Gifu, Japan, Dec. 5-8, 2006 頁： 6-15 2006年

Imaging of tungsten impurity ejected from damaged material due to transient heat load

S.Kajita, N.Ohno, S.Takamura

16th International Toki Conference on Advanced Imaging and Plasma Diagnostics, Toki, Gifu, Japan, Dec. 5-8, 2006 頁： 4-01 2006年

ELM Propagation and Fluctuations Characteristics in H- and L-mode SOL Plasmas on JT-60U

N.Asakura, N.Ohno, H.Kawashima, H.Miyoshi, G.Matsunaga, N.Oyama, S.Takamura, Y.Uesugi, M.Takechi, T.Nakano, H.Kubo

21st IAEA Fusion Energy Conference, Chengdu, China, Oct. 16-21, 2006 頁： EX/9-2 2006年

Integrated View of Disruption Dynamics on Internal Electromagnetic and Plasma Structures in the small tokamak HYBTOK-II

M.Okamoto, S.Takamura,N.Ohno, S.Kajita, Y.Kikuchi, Y.Uesugi, T.Ozeki, Y.Kawano, M.Sugihara

21st IAEA Fusion Energy Conference, Chengdu, China, Oct.16-21,2006 頁： EX/P8-14 2006年

Super Dense Core Plasma due to Internal Diffusion Barrier in LHD

N.Ohyabu, .Morisaki, S.Masuzaki, R.Sakamoto, M.Kobayashi, J.Miyazawa, M.SHoji, T.Akiyama, N.Ashikawa, M.Emoto, H.Funaba, P.Goncharov, M.Goto, J.H.Harris, Y.Hirooka, K.Ichiguchi, T.Ido, K.Itoh, H.Igami, K.Ikeda, S.Inagaki, H.KAsahara, T.Kobuchi, S.Kubo, R.Kumazawa, S.Morita, S.Muto, K.Nagaoka, N.Nakajima, Y.Nakamura, H.Nakanishi, K.Nariharam Y.Narushima, M.Nishiura, T.Notake, S.Ohdachi, N.Ohno, Y.Oka, M.Osakabe, T.Ozaki, B.J.Peterson, K.Saito, S.Sakakibara, R.Sanchez, H.Sanuki, K.Sato, T.Seki, A.SHimizu, H.SUgama, C.Suzuki, Y.Suzuki, Y.Takeiri, K.Tanaka, N.Tamura, K.TOi, T.Tokuzawa, S.TOda, K.Tsumori, I.Yamada, O.Yamagishi, M.Yokoyama, S.Yoshimura, Y.Yoshimura, M.Yoshinuma, K.Ida, T.Shimozuma, K.Y.Watanabe, Y.Nagayama, O.Kaneko, T.Mutoh, K.Kawahata, H.Yamada, A.Komori, S.Sudo, O.Motojima

21st IAEA Fusion Energy Conference, Chengdu, China, Oct.16-21, 2006 頁： EX/8-1 2006年

Bursty Fluctuation Characterisitics in SOL/Divertor Plasmas of Large Helical Device

N.Ohno, S.Masuzzaki, V.P.Budaev, H.Miyoshi, S.Takamura, T.Morisaki, N.Ohyabu, A.Komori

21st IAEA Fusion Energy Conference, Chengdu, China, Oct 16-21, 2006 頁： EX/P4-20 2006年

Extended Steady-State and High=beta Regimes of Net-Current Free Heliotron Plasmas in the Large Helical Device

O.Motojima, H.Yamada, A.Komori, O.Kaneko, K.Kawahata, T.Mito, T.Mutoh, N.Ohyabu K.Ida, S.Imagawa, Y.Nagayama, T.Shimozuma, K.Y.Watanabe, S.Masuzakim J.Miyazawa, S.Morita, S.Ohdachi, N.Ohno, K.Saito, S.Sakakibara, Y.Takeiri, N.Tamura, K.Toi, M.Tokitani, M.Yokoyama, M.Yoshinuma, K.Ikeda, A.Isayama, K.Ishii, S.Kubo, S.Murakami, K.Nagasaki, T.Seki, K.Takahata, H.Takenaga, LHD Experimental Group

21st IAEA Fusion Energy Conference, Chengdu, China, Oct.16-21. 2006 頁： OV/2-1 2006年

Plasma-surface interaction, scrape-off layer and divertor physics: Implications for ITER

B.Lipschultz, X.Bonnin, A.Kukushkin, A.Leonard, J.Roth, E.Tsitrone, D.Whyte, N.Asakura, D.Coster, G.Counsell, R.Doerner, R.Dux, G.Federici, M.Fenstermacher, W.Fundamenski, P.Ghendrih, A.Hermann, J.Hu, A.Kallenbach, S.Kasheninnikov, K.Krieger, G.Krienev, A.Kreter, B.Kurnaev, B.LaBombard, S.Lisgom A.Loarte, T.Nakano, R.Neu, N.Ohno, H.Pacher, J.Paley, Y.Pan, G.Pautasso, V.Philipps, R.Pitts, V.Riccardo, V.Rohde, D.Rudakov, P.Stangeb, S.Takamura, T.Tanabe, Y.Yang, S.Zhu

21st IAEA Fusion Energy Confernece, Chnegdu, China, Oct.16-21, 2006 頁： IT/1-4 2006年

Effects of transient heat load on tungsten surface having sub-micron helium holes and bubbles

S.Kajita, N.Ohno, S.Takamura

33rd EPS Conference on Plasma Phys. Rome, 19-23 June 2006 ECA 30I 巻頁： 4.137 2006年

Plasma Response on Penetraton of External Rotating Helical Magnetic Field in HYBTOK-II Tokamak Edge Plasma

V.P.Budaev, I.M.Pankratov, S.Takamura, N.Ohno, S.Kajita, M.Takagi, H.Matsuno, M.Okamoto, S.Hosoi, Y.Hasebe, T.Yamada, A.Ya.Omelchenko, V.V.Olshansky

33rd EPS Conference on Plasma Phys. Rome, 19-23 June 2006 ECA 30I 巻頁： 4.109 2006年

Intermittency in laboratory and space plasma: comparative study of multifractal statistics

V.P.Budaev, S.P.Savin, L.M.Zelenyi, S.Takamura, N.Ohno, N.Shevyrev

33rd EPS Conference of Plasma Phys. Rome, 19-23 June 2006 ECA 30I 巻頁： 1.064 2006年

Investigation and Application of the Line Intensity Ratio Method for the Measurement of Electron Density and Temperature

S.Kajita, T.Hiraishi, N.Ohno, M.Okamoto, T.Nakano, S.Takamura

13th International Congress on Plasma Physics, Kiev, May 22-26, 2006 頁： A151p 2006年

Dynamic Interaction between Disruptive Plasma and Wakk in the Small Tokamak HYBTOK-II

M.Okamoto, T.Yamada, T.Hiraishi, Y.Kikuchi, N.Ohno, S.Takamura

17th PSI Conference, Heifei, China, May 22-26, 2006 頁： 2-15 2006年

High Density Plasma Generation by RF Ohmic Discharge in Toroidal Divertor Simulator NAGDIS-T

M.Nagase, H.Matsuda, N.Ohno, S.Takamura, M.Takagi

17th PSI Conference, Heifei, China, May 22-26, 2006 頁： 3-16 2006年

Carbon Dust Formation and Chemical Erosion Process in High Density Deuterium Plasmas in the Linear Divertor Simulator

Y.Miyachi, M.Yoshimi, N.Ohno, S.Takamura

17th PSI Conference, Heifei, China, May 22-26, 2006 頁： 2-50 2006年

Fundamental study on the control of oxy-combustion by rf non-equilibrium plasma 査読有り

Y.Osaka, N.Kobayashi, M.A.Razzak, N.Ohno, S.Takamura

Fluid and heat engineering research 41 巻頁： 5-12 2006年

Formation of Nanostructured Tungsten with Arborescent Shape due to Helium Plasma Irradiation 査読有り

S.Takamura, N.Ohno, D.Nishijima, S.Kajita

Plasma Fusion Res. 1 巻頁： 051(2pages) 2006年

Reduction of Laser Threshold for Melting Tungsten due to Subsurface Helium Holes 査読有り

S.Kajita, D.Nishijima, N.Ohno, S.Takamura

J. Appl. Phys. 100 巻頁： 103304(10 pages) 2006年

Modification of the Damping Rate of the Oscillation of a Dust Particle levitating in a Plasma Due to the Delayed Charging Effect 査読有り

M.Y.Pustylnik, N.Ohno, S.Takamura, R.Smirnov

Phys. Rev. E 74 巻頁： 046402(9pages) 2006年

Analysis on Relation between Magnetic Structure and Bursty Fluctuation in SOL/Divertor Plasma of LHD 査読有り

N.Ohno, S.Masuzaki, H.Miyoshi, S.Takamura, V.P.Budaev, T.Morisaki, N.Ohyabu, A.Komori

Contrib. Plasma Physics 46 巻頁： 692-697 2006年

Numerical Analysis on Generation of High Density Plasmas in the Toroidal Device NAGDIS-T for SOL and Divertor Simulation Studies 査読有り

M.Nagase, S.Takamura, N.Ohno, H.Masuda, H.Kitahara, M.Takagi

Contrib. Plasma Physics 46 巻頁： 557-562 2006年

Control of Energetic Electron Component in a Magnetically Confined Diffusion Ar Plasma 査読有り

M.Pustylnik, N.Ohno, S.Takamura

Japanese Journal of Applied Physics 45 巻 ( 2A ) 頁： 926-932 2006年

Validity of Electron Temperature Measurement by Using Boltzmann Plot Method in Radio Freauency Inductive Discharge in the Atmospheric Pressure Range 査読有り

N.Ohno, M.Razzak, H.Ukai, S.Takamura, Y.Uesugi

Plasma Fusion Res. 1 巻頁： 028(9pages) 2006年

The Effect of the Rotating Helical Fields on the Plasma Edge in the HYBTOK-II Tokamak 査読有り

V.P.Budaev, I.M.Pankratov, S.Takamura, N.Ohno, M.Takagi, H.Matsuno, M.Okamoto, S.K.Saha

Nucl. Fusion 46 巻頁： S175-S180 2006年

Fast Ignition and Mode Transition of Radio Frequency Induction Plasmas at Atmospheric Pressure using tungsten Pin Electrode Array 査読有り

M.Razzak, S.Takamura, N.Ohno

Plasma Fusion Res. 1 巻頁： 006/Letters(3pages) 2006年

Assessment of Meander-Line Antenna covered with Dielectric Material for LHW Heating 査読有り

H.Matsuno, S.Takamura, S.Hosoi, N.Ohno

Plasma & Fusion Res. 1 巻頁： 0009(6pages) 2006年

Fast Initiation and Mode Transition of Radio Frequency Induction Plasmas at Atmospheric Pressure Using Tungsten Pin Electrodes Array 査読有り国際誌

RAZZAK M. Abdur, TAKAMURA Shuichi, OHNO Noriyasu

Plasma and Fusion Research ( 1 ) 頁： 6 - 6 2006年

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：社団法人プラズマ・核融合学会

The effects of using an array of tungsten pin electrodes on the ignition dynamics of radio frequency (rf) discharges generated by inductively coupled plasma (ICP) technique at atmospheric pressure are investigated experimentally. The experimental observations reveal that the array of tungsten pin electrodes successfully enhance the initial discharges maintained by the strong electrostatic field with stable and fast ignition, which enables us to sustain efficient rf induction plasmas at atmospheric pressure range.

DOI： 10.1585/pfr.1.006

Validity of Electron Temperature Measurement by Using Boltzmann Plot Method in Radio Frequency Inductive Discharge in the Atmospheric Pressure Range 査読有り国際誌

OHNO Noriyasu, RAZZAK M. Abdur, UKAI Hiroshi, TAKAMURA Shuichi, UESUGI Yoshihiko

Plasma and Fusion Research ( 1 ) 頁： 28 - 28 2006年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：社団法人プラズマ・核融合学会

The validity of electron temperature measurement using the Boltzmann plot method was investigated in a radio frequency (rf) inductive discharge in the atmospheric pressure range. Since the Boltzmann plot method requires local thermal equilibrium (LTE), the parameter regions of electron temperature and electron density, in which the Boltzmann plot method is applicable, were analyzed in terms of a comparison of the spontaneous emission and collisional excitation to the excited states. It is observed that in our rf-inductive plasma near the atmospheric pressure range the Boltzmann plot method does not provide an exact measurement of electron temperature because of relatively low electron density, which does not satisfy the calculation criteria. An alternative method employing a combination of the Stark broadening measurement and the Saha-Boltzmann equation was demonstrated to more accurately determine the plasma parameters (electron temperature and electron density).

DOI： 10.1585/pfr.1.028

Design of a novel T-lclimmittance conversion circuit for dynamic and non-linear loads 査読有り国際共著国際誌

Razzak M.A., Takamura S., Ohno N., Uesugi Y.

Proceedings of 4th International Conference on Electrical and Computer Engineering, ICECE 2006 頁： 13 - 16 2006年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Proceedings of 4th International Conference on Electrical and Computer Engineering, ICECE 2006

In recent years, the immittance conversion topology [1] has become attractive as a novel power conversion strategy because of its features that a constant voltage source is converted to a constant current source and vice versa. However, the design of an ideal immittance circuit in the high-power (∼kW) and high-frequency (∼MHz) range is practically very important, especially when apply to a dynamic and non-linear load such as induction plasma. In this article, the design and development of an ideal T-LCL immittance circuit is reported. The performance of the designed immittance circuit is analysed by using a time-varying inductive plasma load.

DOI： 10.1109/ICECE.2006.355278

Optimum generation of high heat flux toroidal plasmas by RF ohmic discharge 査読有り国際誌

Masuda H., Kitahara H., Nagase M., Ohno N., Takamura S., Takagi M.

32nd EPS Conference on Plasma Physics 2005, EPS 2005, Held with the 8th International Workshop on Fast Ignition of Fusion Targets - Europhysics Conference Abstracts 3 巻頁： 1946 - 1949 2005年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：32nd EPS Conference on Plasma Physics 2005, EPS 2005, Held with the 8th International Workshop on Fast Ignition of Fusion Targets - Europhysics Conference Abstracts

We have developed a new toroidal divertor plasma simulator, NAGDIS-T (NAGoya DIvertor plasma Simulator with Toroidal magnetic configuration). Plasma is generated by RF Joule discharge. In order to obtain high density plasmas relevant to divertor plasmas in fusion devices, we investigate the optimum condition of RF Joule discharge by varying gas pressure and driving frequency. The experimental result shows that the optimum condition strongly depends on these parameters. Copyright © (2005) by the European Physical Society (EPS).

High-Z Dust Generation on Tungsten Surfaces due to Synergetic Erosion of Deuterium/Helium Plasma Exposures 査読有り

西島大, 天野浩嗣, 大野哲靖, 吉田直亮, 高村秀一

プラズマ・核融合学会誌 = Journal of plasma and fusion research 81 巻 ( 9 ) 頁： 703 - 707 2005年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：社団法人プラズマ・核融合学会

Low-energy and high-flux plasma exposures on tungsten surfaces result in blister/hole formation. Subsequent He plasma exposure at 2,000 K on the blister-rich surface forms a hole structure on the surface, including the blister surface, and some blisters collapse due to recrystallization and bubble formation on the blister skin. Grain ejections were observed after deuterium plasma exposure at 550 K on a W surface on which a hole structure had formed due to He pre-exposure at 1,600 K.

DOI： 10.1585/jspf.81.703

Efficient Radio Frequency Inductive Discharges in Near Atmospheric Pressure Using Immittance Conversion Topology 査読有り

Razzak M. Abdur, 高村秀一, 上杉喜彦, 大野哲靖

プラズマ・核融合学会誌 = Journal of plasma and fusion research 81 巻 ( 3 ) 頁： 204 - 211 2005年3月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：社団法人プラズマ・核融合学会

A radio frequency (rf) inductive discharge in atmospheric pressure range requires high voltage in the initial startup phase and high power during the steady state sustainment phase. It is, therefore, necessary to inject high rf power into the plasma ensuring the maximum use of the power source, especially where the rf power is limited. In order to inject the maximum possible rf power into the plasma with a moderate rf power source of few kilowatts range, we employ the immittance conversion topology by converting a constant voltage source into a constant current source to generate efficient rf discharge by inductively coupled plasma (ICP) technique at a gas pressure with up to one atmosphere in argon. A novel T-LCL immittance circuit is designed for constant-current high-power operation, which is practically very important in the high-frequency range, to provide high effective rf power to the plasma. The immittance conversion system combines the static induction transistor (SIT)-based radio frequency (rf) high-power inverter circuit and the immittance conversion elements including the rf induction coil. The basic properties of the immittance circuit are studied by numerical analysis and verified the results by experimental measurements with the inductive plasma as a load at a relatively high rf power of about 4 kW. The performances of the immittance circuit are also evaluated and compared with that of the conventional series resonance circuit in high-pressure induction plasma generation. The experimental results reveal that the immittance conversion circuit confirms injecting higher effective rf power into the plasma as much as three times than that of the series resonance circuit under the same operating conditions and same dc supply voltage to the inverter, thereby enhancing the plasma heating efficiency to generate efficient rf inductive discharges.

DOI： 10.1585/jspf.81.204

Characteristic changes of deuterium retention on tungsten surfaces due to low-energy helium plasma pre-exposure 査読有り

Nishijima D, Sugimoto T, Iwakiri H, Ye MY, Ohno N, Yoshida N, Takamura S

JOURNAL OF NUCLEAR MATERIALS 337 巻 ( 1-3 ) 頁： 927 - 931 2005年3月

Hydrogen Blister Formation on Cold-Worked Tungsten with Layered Structure 査読有り

D.Nishijima, T.Sugimoto, M.Ye, N.Ohno, S.Takamura

Jpn. J. Appl. Phys. 44 巻 ( 1A ) 頁： 380-382 2005年

Further Roughing of Tungsten Surface due to Transient Heat Load by Laser Irradiation during Helium Plasma Exposure 査読有り

S.Kajita, D.Nishijima, N.Ohno, S.Takamura

J. Plasma Fusion Res. 81 巻頁： 745-746 2005年

High-Z Dust Generation on Tungsten Surface due to Synergetic Erosion of Deuterium/Helium Plasma Exposure 査読有り

D.Nishijima, K.Amano, N.Ohno, N.Yoshida, S.Takamura

J. Plasma Fusion Res. 81 巻頁： 703-707 2005年

Suppression of Blister Formation and Deuterium Retention on Tungsten Surface due to Mechanical Polishing and Helium Pre-exposure 査読有り

D.Nishijima, H.Iwakiri, K.Amano, M.Y.Ye, N.Ohno, K.Tokunaga, N.Yoshida, S.Takamura

Nucl. Fusion 45 巻頁： 669-674 2005年

Efficient Radio Frequency Inductive Discharge in Hear Atmospheric Pressure Using Imittance Conversion Topology 査読有り

M.A.Razzak, S.Takamura, Y.Uesugi, N.Ohno

J. Plasma Fusion Res. 81 巻 ( 3 ) 頁： 204-211 2005年

Characterstic changes of deuterium rentention on tungsten surfaces due to low-energy helium plasma pre-exposure 査読有り

D.Nishijima, T.Sugimoto, H.Iwakiri, M.Y.Ye, N.Ohno, N.Yoshida, S.Takamura

Journal of Nuclear Materials 337-339 巻頁： 927-931 2005年

Carbon dust formation from re-deposited layers in high-density hydrogen/helium plasmas in the NAGDIS-II device 査読有り

N.Ohno, Y.Kobayashi, T.Sugimoto, S.Takamura

Journal of Nuclear Materials 337-339 巻頁： 35-39 2005年

Neutral helium line emission for edge plasma conditions 査読有り

F.B.Rosmej, R.Stamm, S.Fritzsche, H.Capes, M.Koubiti, Y.Marandet, V.S.Lisitsa, N.Ohno, S.Takamura, D.Nishijima

Journal of Nuclear Materials 337-339 巻頁： 1101-1105 2005年

Formation mechanism of bubbles and holes on tungsten surface with low-energy and high-flux helium plasma irradiation in NAGDIS-II 査読有り

Dai. Nishijima, M.Y.Ye, N.Ohno, S.Takamura

J. Nucl. Mater. 329-333 巻頁： 1029-1033 2005年

Micron-Bubble Formation on Polycrystal Tungsten due to Low-Energy and high-Flux Helium Plasma Exposure 査読有り

D.Nishijima, M.Miyamoto, H.Iwakiri, M.Ye, N.Ohno, K.Tokunaga, N.Yoshida, S.Takamura

Nuclear Fusion 46 巻頁： 561-564 2005年

Overview of JT-60U progress towards steady-state advanced tokamak 査読有り

S.Ide, N.Ohno, JT-60U Team

Nuclear Fusion 45 巻頁： S48-S62 2005年

Transition from electrostatic-to-electromagnetic mode in a radio-frequency Ar inductively coupled plasma in atmospheric pressure 査読有り国際誌

Razzak MA, Kondo K, Uesugi Y, Ohno N, Takamura S

JOURNAL OF APPLIED PHYSICS 95 巻 ( 2 ) 頁： 427 - 433 2004年1月

Proposal of Modeified Child-Langmuir Formula Describing Space-Charge Limited Current in Plasma 査読有り

Y.Hagino, N.Ohno, S.Takamura

Contrib. Plasma Phys. 44 巻 ( 1-3 ) 頁： 144-149 2004年

Visualization of Intermittent Blobby Plasma Transport in Attached and Detached Plasmas of the NAGDIS-II 査読有り

N.Ohno, K.Furuta, S.Takamura

J. Plasma Fusion Res. 80 巻 ( 4 ) 頁： 275-276 2004年

Moving-Surface Plasma-Facing Components for Particle Control in Steady State Magnetic Fusion Devices 査読有り

Y.Hirooka, H.Fukushima, N.Ohno, S.Takamura

Fusion Science and Technology 45 巻頁： 60-64 2004年

Reconstruction of Velocity Distribution of density Bursts by Wavelet Analysis in the Linear Divertor Simulator NAGDIS-II 査読有り

N.Ohno, V.P.Budaev, K.Furuta, H.Miyoshi, S.Takamura

Contrib. Plasma Phys. 44 巻 ( 1-3 ) 頁： 222-227 2004年

Space-Charge Limited Current from Plasma-Facing Material Surface 査読有り

S.Takamura, N.Ohno, M.Y.Ye, T.Kuwabara

Contrib. Plasma Phys. 44 巻 ( 1-3 ) 頁： 126-137 2004年

Proposal of modified Child-Langmuir formula describing space-charge limited current in plasma 査読有り国際誌

Hagino Y, Ohno N, Takamura S

CONTRIBUTIONS TO PLASMA PHYSICS 44 巻 ( 1-3 ) 頁： 144 - 149 2004年

Proof-of-principle experiments on the concept of moving-surface plasma-facing components - Hydrogen recycling over a titanium-gettered rotating drum 査読有り国際誌

Hirooka Y., Fukushima H., Ohno N., Takamura S.

Fusion Engineering and Design 65 巻 ( 3 SPEC. ) 頁： 413 - 421 2003年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Engineering and Design

In the magnetic fusion community much attention has recently been directed to particle control in the existing confinement experiments, as it is recognized that the core plasma performance can directly be affected by the edge conditions. However, it is still true that there is no clear strategy to cope with the needs for steady-state reactor operation. That is that, due to the saturation nature, wall conditioning such as boronization is not applicable for fuel and impurity particles control in steady-state devices, requiring a start from enabling concepts development. As a possible solution, the concept of moving-surface plasma-facing components (MS-PFCs) was proposed in our previous work and in the present work proof-of-principle experiments have been conducted. In this concept, the plasma-facing surface is mechanically circulated out-of-pile for regeneration of particle capturing capabilities by coating getter films on it. A prototypical MS-PFC test unit has been constructed for these proof-of-principle experiments, employing a rotating copper drum as the moving surface and titanium as the getter material. It has been indicated that, from Hα light intensity data taken in front of the rotating target, relative to no getter cases, approximately 6% reduced hydrogen recycling has been achieved at steady state. In support of these data, a first-order particle balance model predicts a 7% reduction in hydrogen recycling. © 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0920-3796(03)00011-5

Ion temperature measurement using an ion sensitive probe in the LHD divertor plasma 査読有り国際誌

Ezumi N., Masuzaki S., Ohno N., Uesugi Y., Takamura S.

Journal of Nuclear Materials 313-316 巻 ( SUPPL. ) 頁： 696 - 700 2003年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Materials

The first reliable measurement of ion temperature in the divertor plasma of the Large Helical Device has been done by using an ion sensitive probe. The satisfactory current-voltage characteristics of the ion collector for evaluating the ion temperature were obtained at the outer part of the divertor leg. Furthermore, simultaneous ion and electron temperature measurements were successfully done in this part. The results show that the ion temperature is higher than the electron temperature in the part. There is a possibility that the profiles of the evaluated ion temperature which shows relatively higher than the electron temperature at the outside of divertor leg are qualitatively explained by particle's orbits around the edge and divertor region. © 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3115(02)01364-8

Experimental evaluation of space charge limited emission current from tungsten surface in high density helium plasma 査読有り国際誌

Hagino Y., Ohno N., Takamura S., Ye M.

Journal of Nuclear Materials 313-316 巻 ( SUPPL. ) 頁： 675 - 678 2003年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Materials

The experimental evaluation of space charge limited emission current from tungsten surface in high density helium plasma was done. It was found that the space charge limited current from the tungsten target plate saturated with an increase in sheath voltage. The space charge effect was predicted on the basis of boundary conditions of zero electric field on the material surface.

DOI： 10.1016/S0022-3115(02)01381-8

25aB37P 高熱流トロイダル・ダイバータプラズマ模擬試験装置の製作と性能試験(真空・第一壁・材料,炉設計) 査読有り

非接触再結合プラズマ中の揺動特性査読有り

大野哲靖、田中直行、高村秀一

7 巻 ( 10 ) 頁： 1093-1101 2003年

Transition from Electrostatic to Electromagnetic Mode in a Radio Frequency Ar Induction Plasma in Atmospheric Pressure 査読有り

M.A.Razzak, K.Kondo, Y.Uesugi, N.Ohno, S.Takamura

J. Appl. Phys. 95 巻 ( 2 ) 頁： 427-433 2003年

Intermittent structures in the high field side boundary of the HYBTOK-II tokamak 査読有り

V.P.Budaev, S.Takamura, Y.Kikuchi, Y.Uesugi, N.Ohno

Czechoslovak Journal of Phys 53 巻 ( 10 ) 頁： 863-868 2003年

Formation and dynamics of very deep negative potential well in the small tokamak device CSTN-IV 査読有り

H.Kojima, Y.Fukuzawa, T.Manabe, S.Takamura, T.Okada, N.Ohno

Czechoslovak Journal of Phys. 53 巻 ( 10 ) 頁： 895-902 2003年

プラズマと接する固体表面からの空間電荷制限放出電流査読有り

高村秀一、大野哲靖

放電研究 46 巻 ( 3 ) 頁： 2-22 2003年

Proof of principle experiments on the concept of moving-surface plasma-facing components-hydrogen recycling over a titanium-gettered ratating drum 査読有り

Y.Hirooka, H.Fukushima, N.Ohno, S.Takamura

Fusion Engineering and Design 6 巻頁： 413-421 2003年

Blister formation on tungsten surface under low energy and high flux hydrogen plasma irradiation in NAGDIS-I 査読有り

M.Y.Ye, H.Kanehara, S.Fukuta, N.Ohno, S.Takamura

Journal of Nuclear Materials 313-316 巻頁： 72-76 2003年

Incident ion energy dependence of bubble formation on tungsten surface with low energy and high flux helium plasma irradiation 査読有り

D.Nishijima, M.Y.Ye, N.Ohno, S.Takamura

Journal of Nuclear Materials 313-316 巻頁： 97-101 2003年

Experimental evaluation of space charge limited emission current from tungstn surface in high density helium plasma 査読有り

Y.Hagino, N.Ohno, S.Takamura, M.Y.Ye

Journal of Nuclear Materials 313-316 巻頁： 675-678 2003年

Ion temperature measurement using an ion sensitie probe in the LHD divertor 査読有り

N.Ezumi, S.Masuzaki, N.Ohno, Y.Uesugi, S.Takamura, LHD Experimental Group

Journal of Nuclear Materials 313-316 巻頁： 696-700 2003年

High-quality video streaming system for plasma diagnostics using super SINET 査読有り

M.Emoto, K.Watanabe, S.Masuzaki, N.Ohno, H.Okade

Rev. Sci. Instrum. 74 巻頁： 1766 2003年

Self-consistent dusty sheaths in plasmas with two-temperature electrons 査読有り

Yu.I.Chutov, O.Kravchenko, A.Pshenychnyj, R.Smirnov, K.Asano, N.Ohno, S.Takamura, Y.Tomita

Physics of Plasmas 10 巻 ( 2 ) 頁： 546-552 2003年

Fluctuation Characteristics in Detached Recombining Plasmas

N.Ohno, N.Tanaka, S. Takamura, V.Budaev

AIP Conference Proceedings 669 巻頁： 240-243 2003年

Edge Plasma Turbulence in Fusion Devices: Bursty Behavior and Fractal Properties

V.P.Budaev, S.Takamura, N.Ohno, A.Komori, S.Masuzaki, G.S.Kirnev, S.A.Grashin

30th EPS Conference on Contr. Fusion and Plasma Phys., St. Petersburg, 7-11 July 2003 ECA 27A 巻頁： 3.174 2003年

Intermittent Structures in the High Field Side Boundary of the HYBTOK-II Tokamak

V.P.Budaev, S.Takamura, Y.Kikuchi, Y.Uesugi, N.Ohno

30th EPS Conference on Contr. Fusion and Plasma Phys., St. Petersburg, 7-11 July 2003 ECA 27A 巻頁： 3.173 2003年

Surface Morphology of Tungsten Irradiated by Low-Energy and High-Flux Steady State Helium Plasma

D.Nishijima, M.Y.Ye, N.Ohno, S.Takamura

30th EPS Conference on Contr. Fusion and Plasma Phys., St.Petersburg, 7-11 July 2003 ECA 27-A 巻頁： 2.163 2003年

Structural Dynamics of Deep Negative Potential Well Formation in Small Tokamak Device CSTN-IV

H.Kojima, Y.Fukuzawa, T.Manabe, N.Ohno, S.Takamura

30th EPS Conference on Contr. Fusion and Plasma Phys., St.Petersburg, 7-11 July 2003 ECA 27A 巻頁： 2.130 2003年

Experimental Observation and Statistical Analysis of Density Bursts in the Linear Divertor Simulator NAGDIS-II

N.Ohno, K.Furuta, H.Miyoshi, S.Takamura, V.P.Budaev

30th EPS Conference on Contr. Fusion and Plasma Phys., St. Petersburg, 7-11 July 2003 ECA 27A 巻頁： 2.154 2003年

Influence of the Ion Beam on the Behavior of Dust Particles Trapped in an Ion Sheath

T.Murakami, M.Sawai, T.Misawa, N.Ohno, S.Takamura

AIP Conference Proceedings 669 巻頁： 101-104 2003年

Sound Wave Propagation in Gases at Low Pressure

T.Tonogaki, N.Ohno, S.Takamura, A.Tsushima

AIP Conference Proceedings 669 巻頁： 113-116 2003年

25aA28P LHD周辺プラズマにおける密度揺動の統計的解析(ヘリカル) 査読有り

三好秀暁, 高村秀一, 大野哲靖, 増崎貴, 小森彰夫, Budaev V.P.

プラズマ・核融合学会年会予稿集 ( 20 ) 2003年

空重希, 北原弘義, 大野哲靖, 上杉喜彦, 高村秀一

プラズマ・核融合学会年会予稿集 ( 20 ) 2003年

25aB11P 低エネルギー高粒子束水素プラズマ照射による低温高融点金属表面におけるブリスタ形成実験(真空・第一壁・材料,炉設計) 査読有り

杉本喬紀, 大野哲靖, 高村秀一

プラズマ・核融合学会年会予稿集 ( 20 ) 2003年

26aA40P トカマク装置を用いた電極バイアスによる電位井戸の形成(トカマク) 査読有り

福澤祐馬, 小島寛樹, 岡田享大, 大野哲靖, 高村秀一, 井口哲夫

プラズマ・核融合学会年会予稿集 ( 20 ) 2003年

28aA17P プラズマ-シース境界に捕捉された微粒子の不安定振動に対する高温電子成分の影響(慣性核融合、プラズマ基礎・応用) 査読有り

小林篤弘, 今里香恵, 大野哲晴, 高村秀一

プラズマ・核融合学会年会予稿集 ( 20 ) 2003年

27pB22P 接触・非接触プラズマ中の揺動特性(ミラー・CT等) 査読有り

古田賢寛, 大野哲靖, 高村秀一

プラズマ・核融合学会年会予稿集 ( 20 ) 2003年

Generation and characteristics of a detached recombining plasma and its dynamic behaviour-a bridge between fusion plasmas and low-temperature ionized gases 査読有り国際誌

Takamura S, Ohno N, Nishijima D, Uesugi Y

PLASMA SOURCES SCIENCE & TECHNOLOGY 11 巻 ( 3A ) 頁： A42 - A48 2002年8月

Characteristics of detached plasmas associated with electron-ion and molecular assisted recombinations in NAGDIS-II 査読有り国際共著国際誌

Nishijima D., Wenzel U., Ohsumi K., Ohno N., Uesugi Y., Takamura S.

Plasma Physics and Controlled Fusion 44 巻 ( 5 ) 頁： 597 - 610 2002年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plasma Physics and Controlled Fusion

Recombination in a helium and helium-hydrogen plasma was experimentally investigated in the linear divertor simulator NAGDIS-II. To identify the physical mechanisms, electron-ion recombination (EIR) and molecular assisted recombination (MAR), the plasma parameters in the recombining region have been measured. We used spectroscopic techniques on the basis of continuum emission and line emission from highly excited levels due to EIR and Langmuir probes. The dependence of the plasma parameters on the neutral pressure in a pure helium plasma and in a helium-hydrogen mixture shows clearly that recombination is caused by different processes in the two cases. In a pure helium plasma a roll-over and a following decrease of the electron density as well as a monotonic decrease of the electron temperature down to 0.1 eV were observed when increasing the helium pressure. Here EIR is the recombination mechanism. Conversely, when hydrogen is added to the helium plasma, the electron density decreases monotonically while the central electron temperature remains above 1 eV. This particular behaviour in the helium-hydrogen plasma can only be explained by the dominant action of MAR.

DOI： 10.1088/0741-3335/44/5/307

26aB13P 低エネルギー・高粒子束ヘリウムプラズマのタングステンへの照射(真空・第一壁・材料) 査読有り

Response to "comment on 'dynamic behaviors of dust particles in the plasma-sheath boundary'" [Phys. Plasmas 9, 1057 (2002)] 査読有り国際誌

Takamura S., Ohno N., Misawa T., Nunomura S.

Physics of Plasmas 9 巻 ( 3 ) 2002年3月

Proposal of Flexible Atomic and Molecular Process Management for Monte Carlo Impurity Transport Code Based on Object Oriented Method 査読有り

K.Asano, N.Ohno, S.Takamura

Contrib. Plasma Physics 42 巻頁： 157-162 2002年

Generation and characteristics of detached recombining plasma and its dynamic behaviour - a bridge between fusion plasmas and low-temperature ionized gases 査読有り

S.Takamura, N.Ohno, D.Nishijima, Y.Uesugi

Plasma Sources Sci. Technol. 11 巻 ( 3A ) 頁： A42-A4 2002年

Response to Comment on "Dynamic Behaviours of Dust Particles in the Plasma Sheath Boundary" 査読有り

S.Takamura, N.Ohno, T.Misawa, S.Nunomura

Physics of Plasmas 9 巻頁： 1060-1061 2002年

Characteristics of Detached Plasmas Associated with Electron-Ion and Molecular Assisted Recombination in NAGDIS-II 査読有り

D.Nishijima, U.Wenzel, K.Ohsumi, N.Ohno, Y.Uesugi, S.Takamura

Plasma Physics Controlled Fusion 44 巻頁： 597-610 2002年

Parametric Excitation of a Dust Particle Trapped in a Plasma-Sheath Boundary 査読有り

N.Ohno, M.Sawai, T.Misawa, K.Asano, S.Takamura

Physica Scripta T98 巻頁： 81-86 2002年

Analysics of Detached Recombining Plasmas by Collisional-Radiative Model with Energetic Electron Component 査読有り

N.Ohno, M.Motoyama, S.Takamura

Contrib. Plasma Physics 42 巻頁： 419-424 2002年

Heat Pulse in a Simulated Divertor Plasmas

Y.Uesugi, S.Takamura, K.Ohsumi, N.Ohno, D.Nishijima

29th EPS Conference on Contr. Fusion and Plasma Phys., Montroux, Switzerland, 17-21 June 2002 ECA 26B 巻頁： 1.087 2002年

西島大, 叶民友, 大野哲靖, 高村秀一

プラズマ・核融合学会年会予稿集 ( 19 ) 2002年

Analysis of detached recombining plasmas by collisional-radiative model with energetic electron component 査読有り国際誌

Ohno N, Motoyama M, Takamura S

CONTRIBUTIONS TO PLASMA PHYSICS 42 巻 ( 2-4 ) 頁： 419 - 424 2002年

28pB09 空間電荷制限領域におけるプラズマと接する固体表面からの熱電子放出の実験的評価(真空・第一壁・材料) 査読有り

萩野喜晴, 叶民友, 大野哲靖, 高村秀一

プラズマ・核融合学会年会予稿集 ( 19 ) 2002年

26pA07 交流トカマク放電によるプラズマ熱流を用いた熱電子放出(プラズマ基礎・応用II) 査読有り

真鍋俊治, 小島寛樹, 福澤祐馬, 大野哲靖, 高村秀一

プラズマ・核融合学会年会予稿集 ( 19 ) 2002年

26aB18P 移動表面式プラズマ対向機器による粒子制御の原理検証実験(真空・第一壁・材料) 査読有り

廣岡慶彦, 福島宝寿, 大野哲靖, 高村秀一

プラズマ・核融合学会年会予稿集 ( 19 ) 2002年

直線型プラズマ装置を用いた高融点金属材料の損耗・再堆積モデル実験査読有り

大野哲靖, 高村秀一

プラズマ・核融合学会誌 = Journal of plasma and fusion research 77 巻 ( 9 ) 頁： 864 - 868 2001年9月

担当区分：筆頭著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：プラズマ・核融合学会

Erosion and redeposition processes of molybdenum, a high-Z material, were investigated in the linear plasma device TPD-I. Comparison between the experimental results and numerical analysis with a 3D Monte Carlo simulation code indicated that the observed erosion profile could be explained by taking account of the effect of prompt redeposition of high-Z material.

Static and dynamic behaviour of plasma detachment in the divertor simulator experiment NAGDIS-II 査読有り国際共著国際誌

Ohno N., Nishijima D., Takamura S., Uesugi Y., Motoyama M., Hattori N., Arakawa H., Ezumi N., Krasheninnikov S., Pigarov A., Wenzel U.

Nuclear Fusion 41 巻 ( 8 ) 頁： 1055 - 1065 2001年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

A comprehensive investigation has been performed of the static and dynamic behaviour of detached recombining plasmas in the linear divertor plasma simulator NAGDIS-II. For stationary plasma detachment, the transition from electron ion recombination (EIR) to molecular activated recombination (MAR) has been observed by injecting hydrogen gas into high density helium plasmas. The particle loss rate due to MAR is found to be comparable to that of EIR. Experiments have also been performed by the injection of a plasma heat pulse produced by RF heating into the detached helium plasma to demonstrate the dynamic behaviour of volumetric plasma recombination. Negative spikes in the Balmer series line emission were observed and found to be similar to the so called negative ELM observed in tokamak divertors. Observed Balmer spectra were analysed in detail using the collisional-radiative model. A rapid increase of the ion flux to the target plate was observed associated with the re-ionization of the highly excited atoms generated by EIR.

DOI： 10.1088/0029-5515/41/8/309

Evidence for the importance of radial transport in plasma detachment in the Nagoya University Divertor Simulator (NAGDIS-II) 査読有り国際誌

Hollmann E., Whyte D., Nishijima D., Ohno N., Uesugi Y., Ezumi N.

Physics of Plasmas 8 巻 ( 7 ) 頁： 3314 - 3320 2001年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics of Plasmas

Measurements of ion and electron temperatures have been performed in detaching helium -hydrogen plasmas in a linear divertor simulator experiment using spectroscopy, a Langmuir probe, and an omegatron mass spectrometer. Detachment in these plasmas is characterized by a significant (≈20×) reduction in the central plasma flux at the target plate as the target region neutral pressure is increased from 2 to 12 mTorr. The data indicate that partially detached gas-target plasmas consist of a hot (Te≈5 eV) core region along the axis of the plasma column, surrounded by a cold (Te ≈0.1 eV) halo region of recombining plasma. At Te = 5 eV, plasma recombination is negligible compared with ionization; these experiments therefore provide evidence that detachment is primarily caused by radial transport and by a gradual drop in the ionization source as the temperature of the core region drops below 5 eV. © 2001 American Institute of Physics.

DOI： 10.1063/1.1372664

Dynamic behavior of detached recombining plasmas during ELM-like plasma heat pulses in the divertor plasma simulator NAGDIS-II 査読有り国際誌

Uesugi Y, Hattori N, Nishijima D, Ohno N, Takamura S

JOURNAL OF NUCLEAR MATERIALS 290 巻頁： 1134 - 1137 2001年3月

Evaluation of electron temperature in detached recombining plasmas 査読有り国際共著国際誌

Nishijima D., Wenzel U., Motoyama M., Ohno N., Takamura S., Krasheninnikov S.

Journal of Nuclear Materials 290-293 巻頁： 688 - 691 2001年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Materials

Detailed spectroscopic measurements have been carried out in the linear divertor plasma simulator, NAGDIS-II in order to acquire the accurate evaluation of the electron temperature, which leads to a deeper understanding of the characteristics of detached recombining plasmas. Electron temperature in the detached recombining plasmas was evaluated by two different spectroscopic methods, using continuum emission and a series of line emission from highly excited levels, giving different electron temperatures. The reasons are discussed based on the effects of energetic electrons.

DOI： 10.1016/S0022-3115(00)00528-6

Experimental observation of vertically polarized transverse dust-lattice wave propagating in a one-dimensional strongly coupled dust chain 査読有り国際誌

Misawa T., Ohno N., Asano K., Sawai M., Takamura S., Kaw P.K.

Physical Review Letters 86 巻 ( 7 ) 頁： 1219 - 1222 2001年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physical Review Letters

The existence of transverse dust-lattice wave (T-DLW) propagating in a one-dimensional strongly coupled dust chain levitated in dc argon plasma at low gas pressure was assessed. Both parts of the complex wave number were measured in the experiments. The real part showed that the T-DLW propagation as a backward wave.

DOI： 10.1103/PhysRevLett.86.1219

27aA01 [招待講演]非接触プラズマにおける再結合過程とその動的応答(プラズマ基礎・応用) 査読有り

Experimental Observation of Vertically Polarized Transverse Dust Lattice Wve Propagating in a One Dimensional Strongly Coupled Dust Chain 査読有り

T.Misawa, N.Ohno, K.Asano, M.Sawai, S.Takamura, P.K.Kaw

Physcal Review Letters 86 巻 ( 7 ) 頁： 1219-1222 2001年

Evaluation of Electron Teperature in Detached Recombining Plasma 査読有り

D.Nishijima, U.Wenzel, M.Motoyama, N.Ohno, S.I.Krasheninnikov, S.Takamura

Journal of Nuclear Materials 290-293 巻頁： 688-691 2001年

小特集「プラズマ対向面での損耗・再堆積研究の進展」3.直線型プラズマ装置を用いた高融点金属材料の損耗・再堆積モデル実験

大野哲靖、高村秀一

プラズマ・核融合学会誌 77 巻 ( 9 ) 頁： 864-868 2001年

Influence of Plasma Resistance and Fluctuation on Probe Characeteristics in Detached Recombining Plasmas 査読有り

N.Ohno, N.Tanaka, N.Ezumi, D.Nishijima, S.Takamura

Contib. Plasma Physics 41 巻頁： 473-480 2001年

Static and Dynamic Behaviors of Detached Plasma in Divertor Simulator NAGDIS-II 査読有り

S.Takamura, N.Ohno, Y.Uesugi, D.Nishijima, K.Ohsumi, M.Motoyama, N.Hattori, N.Ezumi, S.Krasheninnikov, A.Pigarov, U.Wenzel

Journal of Plasma and Fusion Research SERIES 4 巻頁： 138-145 2001年

Dynamic Behaviors of Dust Particles in the Plasma-Sheath Boundary 査読有り

S.Takamura, T.Misawa, N.Ohno, S.Nunomura, M.Sawai, K.Asano, P.K.Kaw

Physics of Plasmas 8 巻 ( 5 ) 頁： 1886-1892 2001年

プラズマと接する固体表面からの空間電荷制限電流査読有り

桑原竜弥、大野哲靖、高村秀一、叶民友

77 巻 ( 5 ) 頁： 464-475 2001年

Evidence for the Importance of Radial Transport in Plasma Detacment in the Nagoya University Divertor Simulator(NAGDIS-II) 査読有り

E.M.Hollmann, D.G.Whyte, D.Nishijima, N.Ohno, Y.Uesugi, N.Ezumi

Physics of Plasmas 8 巻 ( 7 ) 頁： 3314-3320 2001年

*Static and Dynamic Behavior of Plasma Detachment in the Divertor Simulator Experiment NAGDIS-II 査読有り

N.Ohno, D.Nishijima, S.Takamura, Y.Uesugi, M.Motoyama, N.Hattori, H.Arakawa, N.Ezumi, S.Krasheninnikov, A.Pigarov, U.Wenzel

Nuclear Fusion 41 巻 ( 8 ) 頁： 1055-1065 2001年

Modifications of Tungsten Surface under Low Ionic Energy and High Flux Plasma Irradiation

K.Moriguchi, S.Fukuta, M.Y.Ye, N.Ohno, S.Takamura

Proc. of XXV International Conference on Phenomena in Ionized Gases, Nagoya, Japan 頁： 83-84 2001年

Dynamic Response of Detached Recombining Plasmas to ELM-Like Plasma Heat Pulse Produced by RF Heating

K.Ohsumi, D.Nishijima, N.Ohno, Y.Uesugi, S.Takamura

Proc. of XXV International Conference on Phenomena in Ionized Gases, Nagoya, Japan 頁： 195-196 2001年

Influence of Supra-Thermal Electrons on Propagation of Transverse Dust Lattice Wave

T.Misawa, K.Asano, M.Sawai, N.Ohno, S.Takamura

Proc. of XXV International Conference on Phenomena in Ionized Gases, Nagoya, Japan 頁： 65-66 2001年

MD Particle Simulation on Dust Lattice Wave

K.Asano, T.Misawa, N.Ohno, S.Takamura, S.Vladimirov

Proc. of XXV International Conference on Phenomena in Ionized Gases, Nagoya, Japan 頁： 61-62 2001年

Fluctuations in Detached Recombining Plasmas

N.Tanaka, N.Ohno, S.Takamura

Proc. of XXV International Conference on Phenomena in Ionized Gases, Nagoya, Japan 頁： 345-346 2001年

大野哲靖, 高村秀一, 上杉喜彦, 西島大輔, 大住光一, 田中直行, 嶋崎弘志

プラズマ・核融合学会年会予稿集 ( 18 ) 2001年

30pA17P イオンセンシティブプローブを用いたPSI-2プラズマのイオン温度計測(プラズマ計測) 査読有り

江角直道, 大野哲靖, 高村秀一, 勝俣五男, 増崎貴, Kiss'ovski Zh., Bohmeyer W., Fussmann G., PSI-2実験グループ PSI-2実験グループ

プラズマ・核融合学会年会予稿集 ( 18 ) 2001年

29pA20P 移動表面式プラズマ対向機器による粒子制御の原理検証実験(加熱/炉設計) 査読有り

福島宝寿, 廣岡慶彦, 大野哲靖, 高村秀一

プラズマ・核融合学会年会予稿集 ( 18 ) 2001年

28aB15P ホイッスラー波により生成されたELM様熱パルスに対する非接触再結合プラズマの動的応答(加熱/炉設計) 査読有り

大住光一, 西島大輔, 大野哲靖, 上杉喜彦, 高村秀一

プラズマ・核融合学会年会予稿集 ( 18 ) 2001年

27pA12P 非接触再結合プラズマ中の揺動計測(2)(プラズマ基礎・応用) 査読有り

田中直行, 大野哲靖, 高木誠, 高村秀一, Budaev V.

プラズマ・核融合学会年会予稿集 ( 18 ) 2001年

27pA11P 時間依存衝突幅射コードと流体コードによる非接触プラズマの動的挙動解析(プラズマ基礎・応用) 査読有り

嶋崎弘志, 大野哲靖, 高村秀一

プラズマ・核融合学会年会予稿集 ( 18 ) 2001年

Influence of plasma resistance and fluctuation on probe characteristics in detached recombining plasmas 査読有り国際誌

Ohno N., Tanaka N., Ezumi N., Nishijima D., Takamura S.

Contributions to Plasma Physics 41 巻 ( 5 ) 頁： 473 - 480 2001年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Contributions to Plasma Physics

In order to find the causes of the strong anomaly of current-voltage characteristics of Langmuir probe observed in detached recombining plasmas in a linear divertor plasma simulator, NAGDIS-II, we have investigated plasma resistance along a magnetic field and potential fluctuations in the detached recombining plasmas. Simple calculation on the ratio between the plasma length, at which plasma resistance and resistance of ion sheath formed around a probe tip become equal, and an electron collection length indicates that the evaluation of electron temperature Te becomes inaccurate at Te of less than 0.6 eV when plasma density and neutral pressure are 1.0 × 1018 m-3 and 10 mtorr, respectively. The potential fluctuation in detached recombining plasmas was found to be so large compared to Te/e, which can also modify the probe characteristics.

DOI： 10.1002/1521-3986(200109)41:5<473::AID-CTPP473>3.0.CO;2-8

Peter C. Stangeby著, The Plasma Boundary of Magnetic Fusion Devices (Institute of Physics Publishing, Bristol and Philadelphia, B5版, 717頁, 2000年, ￡125, $195, ハードカバー) 査読有り

大野哲靖

プラズマ・核融合学会誌 = Journal of plasma and fusion research 76 巻 ( 10 ) 2000年10月

Detached Recombining Plasmas in relation to Volumetric Hydrogen Recycle in Hydrogen Recycling at Plasma Facing Materials, ed. by C.H.Wu

S.Takamura, N.Ohno, N.Ezumi, D.Nishijima, S.I.Krasheninnikov, A.Yu. Pigarov

NATO Science Series, II. Mathematics, Physics and Chemistry, Vol. 1, Kluwer Academic Publishers 1 巻頁： 59-66 2000年

Fundamental Processes of Plasma Heat Flow through Sheaths to Material Surfaces in Recent Research Development in Plasmas Vol.1-2000

S.Takamura, M.Y.Ye, N.Ohno, Y.Uesugi

Transworld Research Network, 2000, pp.41-64 頁： 41-64 2000年

Fundamental Process of Plasma Heat Flow through Sheaths to Material Surfaces in Recent Research Development in Plasmas 査読有り

S.Takamura, M.Y.Ye, N.Ohno, Y.Uesugi

Transworld Research Network 頁： 41-64 2000年

Dynamic Behavior of Detached Recombining Plasmas during ELM-like Plasma Heat Pulse in the Diverotr Plasma Simulator NAGDIS-II 査読有り

Y.Uesugi, N.Hattori, D.Nishijima, N.Ohno, S.Takamura

Journal of Nuclear Materials 290-293 巻頁： 1134-1137 2000年

Effects of Condensible Impurities on the Erosion Behavior of the Plasma-Facing Materials 査読有り

N.Ohno, S.Uno, Y.Hirooka, S.Takamura

Journal of Nuclear Materials 290-293 巻頁： 299-302 2000年

低ガス圧プラズマにおけるクーロン結晶の生成と浮遊位置制御査読有り

三沢達也、布村正太、浅野和仁、大野哲靖、高村秀一

電気学会論文誌A 120-A 巻 ( 2 ) 頁： 180-185 2000年

Modifications of Tungsten Surface Irradiated by Low Energy and High Flux Helium Plasma 査読有り

M.Y.Ye, S.Fukuta, N.Ohno, S.Takamura, K.Tokunaga, N.Yoshida

Journal of Plasma and Fusion Research SERIES 3 巻頁： 265-269 2000年

2-D PIC Simulation on Space-Charge Limited Emission Current from Plasma-Facing Components 査読有り

K.Asano, N.Ohno, M.Y.Ye, S.Fukuta, S.Takamura

Contib. Plasma Physics 40 巻頁： 478-483 2000年

Dynamic Behavior of Detached Recombining Plasmas for Plasma Heat Pulse in the Diverotr Simulator NAGDIS-II 査読有り

N.Ohno, D.Nishijima, M.Motoyama, N.Hattori, Y.Uesugi, S.Takamura, U.Wenzel

Journal of Plasma and Fusion Research SERIES 3 巻頁： 202-205 2000年

Application of Strongly Ionized AC Tokamak Plasma for Synthesis of TiN Thin Films 査読有り

M.Y.Ye, O.Matsuda, N.Ohno, Y.Uesugi, M.Takagi, S.Takamura

Vacuum 59 巻頁： 55-62 2000年

Observation of Transverse Dust Lattice Wave Excited by Unstable Vertical Oscillations of Dust Particles in an Ion Sheath with Low Gas Pressure 査読有り

T.Misawa, S.Nunomura, N.Ohno, S.Takamura

Japan Journal of Applied Physics 39 巻頁： L511-L553 2000年

Detached Recombining Plasmas in relation to Volumetric Hydrogen Recycle 査読有り

S.Takamura, N.Ohno, N.Ezumi, D.Nishijima, S.I.Krasheninnikov, A.Yu.Pigarov

Hydrogen Recycling at Plasma Facing Materials, ed. by Ch.H.Wu, NATO Science Series, II. Mathematics, Physics and Chemistry, Kluwer Academic Pubilishers 1 巻頁： 59-66 2000年

Dynamic Behaviors of Dust Particles in the Plasma-Sheath Boundary

S.Takamura, T.Misawa, N.Ohno, S.Nunomura, M.Sawai, K.Asano, P.K.Kaw

42nd Annual Meeting of the Division of Plasma Physics of the American Physical Society, combined with ICPP2000, Quebec, Canada 1 巻 2000年

Recombination Plasmas in the ASDEX Upgrade Divertor and the Divertor Simulator NAGDIS-II

U.Wenzel, R.Pugno, K.Schmidtmann, N.Hattori, D.Nishijima, N.Ohno, S.Takamura, Y.Uesugi

Proc. of 27th EPS Conf. on Controlled Fusion and Plasma Physics, Budapest, Hungary 24B 巻頁： 1192-1195 2000年

Bubble Formation in Tungsten Surface during Low Energy and High Flux Helium/Hydrogen Plasma Irradiation

M.Y.Ye, S.Fukuta, N.Ohno, S.Takamura

Proc. of Japan/US Workshop(00FT5-1) on High Heat Flux Components and Plasma Surface Interactions for Next Fusion Devices, Osaka, Japan 1 巻頁： 288-298 2000年

2-D PIC simulation on space-charge limited emission current from plasma-facing components 査読有り

Asano K, Ohno N, Ye MY, Fukuta S, Takamura S

CONTRIBUTIONS TO PLASMA PHYSICS 40 巻 ( 3-4 ) 頁： 478 - 483 2000年

24aH-12 プラズマ対向壁からの熱電子放出に関する2次元PICシミュレーション査読有り

浅野和仁, 大野哲靖, 叶民友, 福田真哉, 高村秀一

日本物理学会講演概要集 55 巻 ( 0 ) 2000年

23aD-4 プラズマ-シース境界に捕捉された微粒子群の外部強制振動に対する応答査読有り

澤井美樹, 三沢達也, 大野哲靖, 高村秀一

日本物理学会講演概要集 55 巻 ( 0 ) 2000年

25aXG-10 プラズマ-シース境界に捕捉された : 微粒子群の外部強制振動に対する応答(2) 査読有り

澤井美樹, 三沢達也, 大野哲靖, 高村秀一

日本物理学会講演概要集 55 巻 ( 0 ) 2000年

27pA10P 直線型ダイバータプラズマ模擬実験装置NAGDIS-IIにおける非接触プラズマの径方向分布計測(プラズマ基礎・応用) 査読有り

西島大輔, 大野哲靖, 上杉喜彦, 高村秀一

プラズマ・核融合学会年会予稿集 ( 17 ) 2000年

27pA08P 非接触再結合プラズマ中の揺動計測(プラズマ基礎・応用) 査読有り

大野哲靖, 田中直行, 西島大輔, 高村秀一

プラズマ・核融合学会年会予稿集 ( 17 ) 2000年

5.最近の実験的なトピックス 5.1ダイバータプラズマ中の分子活性化再結合過程査読有り

大野哲靖

プラズマ・核融合学会誌 = Journal of plasma and fusion research 75 巻 ( 10 ) 頁： 1162 - 1168 1999年10月

出版者・発行元：社団法人プラズマ・核融合学会

Molecular processes in detached divertor plasmas, especially molecular activated recombination processes, are briefly reviewed. Several reaction chains related to the volumetric recombination process, that are associated with the vibrationally excited hydrogen molecule are explained. Experimental observations of the molecular activated recombination are also reported.

DOI： 10.1585/jspf.75.1162

動画を用いたプラズマダイナミックスの研究-II 動画システムを備えた三次元分子動力学シミュレーションコードの開発とそれを用いたプラズマ中微粒子群の解析査読有り

浅野和仁, 布村正太, 三沢達也, 大野哲靖, 高村秀一

プラズマ・核融合学会誌 = Journal of plasma and fusion research 75 巻 ( 10 ) 1999年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：プラズマ・核融合学会

直流バイアスされた電極上面のシースプラズマの境界において形成される微粒子群の解析のためにJAVAによる動画システムと結合した分子動力学シミュレーションプログラムを開発した. ここではそのコードを公開して概要を述べるとともに,計算例として漏斗型多層構造形成に関するシミュレーションおよび微粒子を媒体とした横波,縦波の伝搬に関するシミュレーション結果を紹介する.

4. 核融合装置におけるプラズマ・表面相互作用 4.1 周辺プラズマ物理と原子・分子過程査読有り

大野哲靖

プラズマ・核融合学会誌 = Journal of plasma and fusion research 75 巻 ( 4 ) 頁： 378 - 383 1999年4月

出版者・発行元：社団法人プラズマ・核融合学会

Edge plasma physics and atomic-molecular processes relating to plasma heat flow to material surfaces are discussed. The local heat flow was found to be enhanced by a thermal contraction induced by cross-field potential variation in a plasma, resulting in hot spot formation on the plasma-facing materials due to nonlinear thermal bifurcation induced by thermoelectron emission. Also examined is the recombination enhancement due to the vibrationally excited hydrogen molecule generated from material surfaces in detached plasma with molecular activated recombination.

DOI： 10.1585/jspf.75.378

Molecular activated recombination in detached recombining plasmas - Reply 査読有り国際共著国際誌

Ohno N, Ezumi N, Takamura S, Krasheninnikov SI, Pigarov AY

PHYSICAL REVIEW LETTERS 82 巻 ( 10 ) 頁： 2216 - 2216 1999年3月

Two-dimensional structure of the detached recombining helium plasma associated with molecular activated recombination 査読有り国際共著国際誌

Nishijima D., Ezumi N., Kojima H., Ohno N., Takamur S., Krasheninnikov S., Pigarov A.

Journal of Nuclear Materials 266 巻頁： 1161 - 1166 1999年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Materials

The structural change of the detached plasmas associated with the molecular activated recombination (MAR) has been studied in a high density helium plasma with helium or hydrogen puff in the linear divertor plasma simulator, NAGDIS-II. The ion particle flux with the hydrogen gas puff starts to decrease in the upstream region close to the plasma source, compared to that with the helium puff. The reduction of the ion particle flux along the magnetic field is found to depend on the plasma density. With the hydrogen gas puff, the attenuation of the ion particle flux is getting smaller as increasing plasma density, which is opposite tendency in pure helium detached plasma where the conventional electron-ion recombination (EIR) is dominating.

DOI： 10.1016/S0022-3115(98)00565-0

Contribution of molecular activated recombination to hydrogen plasma detachment in the divertor plasma simulator NAGDIS-II 査読有り国際共著国際誌

Ezumi N., Nishijima D., Kojima H., Ohno N., Takamura S., Krasheninnikov S., Pigarov A.

Journal of Nuclear Materials 266 巻頁： 337 - 342 1999年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Materials

We have performed experiments on detached hydrogen plasmas associated with molecular activated recombination (MAR) in a linear divertor plasma simulator. Reductions of the ion particle flux and heat load to the target plate were clearly observed in hydrogen plasmas with the hydrogen gas puff. Detailed analysis of Balmer series spectra with the Collisional-Radiative Atomic-Molecular data (CRAMD) code shows that MAR mainly appears as a weak dependence of the Balmer series emission intensities on experimental conditions in detached hydrogen plasmas. The plasma conditions necessary to obtain plasma detachment through MAR or EIR (electron ion recombination including the radiative and three-body recombination) in tokamak divertors are also discussed.

DOI： 10.1016/S0022-3115(98)00533-9

23pB21p 高周波加熱により生成される熟パルス入射に対する非接触プラズマの動的応答(慣性核融合/加熱) 査読有り

Hot spot formation on electron-emissive target plate with plasma potential variation across magnetic field 査読有り国際誌

Ye MY, Kudose K, Kuwabara T, Ohno N, Takamura S

JOURNAL OF NUCLEAR MATERIALS 266 巻頁： 742 - 746 1999年3月

小特集「プラズマ原子・分子過程の展望」5.最近の実験的なトピックス　5.1ダイバータプラズマ中の分子活性化再結合過程

大野哲靖

プラズマ・核融合学会誌 75 巻 ( 10 ) 頁： 1162-1168 1999年

Hot Spot Formation on Electron-Emissive Target Plate with Plasma Potential Variation acoss Magnetic Field 査読有り

M.Y.Ye, K.Kudose, T.Kuwabara, N.Ohno, S.Takamura

Journal of Nuclear Materials 266-269 巻頁： 1001-1004 1999年

Simulation on Structure and Dynamic Behavior of Dust Particles in a Direct Current Plasma Sheath 査読有り

K.Asano, N.Ohno, S.Takamura

Journal of Plasma and Fusion Research 75 巻 ( 10 ) 頁： CD-ROM 1999年

Instability of Dust Particles in a Coulomb Crystal due to Delayed Charging 査読有り

S.Nunomura, T.Misawa, N.Ohno, S.Takamura

Physical Review Letters 83 巻 ( 10 ) 頁： 1970-1973 1999年

Dynamic response of detached recombining plasmas to plasma heat pulse in a divertor simulator 査読有り

N.Ohno, M.Tanaka, N.Ezumi, D.Nishijima, S.Takamura, S.I.Krasheninnikov, A.Yu.Pigarov, J.Park

Physics of Plasmas 6 巻 ( 6 ) 頁： 2486-2494 1999年

Two-dimensional structure of the detached recombining plasmas associated with molecular acivated recombination 査読有り

D.Nishijima, N.Ezumi, H.Kojima, N.Ohno, S.Takamura, S.I.Krasheninnikov, A.Yu.Pigarov

Journal of Nuclear Materials 266-269 巻頁： 1161-1166 1999年

Contribution of molecular activated recombination to hydrogen plasma detachment in the divertor plasma simulator, NAGDIS-(]G0002[) 査読有り

N.Ezumi, D.Nishijima, H.Kojima, N.Ohno, S.Takamura, S.I.Krasheninnikov, A.Yu,Pigarov

Journal of Nuclear Materials 266-269 巻頁： 337-342 1999年

小特集「多様なPSI現象」4.核融合装置におけるプラズマ・表面相互作用　4.1周辺プラズマ物理と原子・分子過程

大野哲靖

プラズマ・核融合学会誌 75 巻 ( 4 ) 頁： 378-383 1999年

小特集「プラズマ原子・分子過程の展望」5.最近の実験的なトピックス5.1ダイバータプラズマ中の分子活性化再結合過程

大野哲靖

プラズマ・核融合学会誌 75 巻 ( 10 ) 頁： 1162-1168 1999年

Modification of Tungsten Surface Irradiated by Low Energy and High Flux Helium Plasma

M.Y.Ye, S.Fukuta, N.Ohno, S.Takamura, K.Tokunaga, N.Yoshida

Proc. of 2nd IAEA TCM on Steady-State Operation of Magnetic Fusion Devices, Vol.II FURKU Report 99-05 II 巻頁： 611-617 1999年

Application of Strongly Ionized AC Tokamak Plasma for Synthesis of TiN Thin Films

M.Y.Ye, O.Matsuda, N.Ohno, Y.Uesugi, M.Takagi, S.Takamura

The 2nd Int. Symposium on Applied Plasma Science, Osaka, Japan, 1999, Proc. of ISAPS99, Advances in Applied Plasma Science 2 巻頁： 23-28 1999年

Instabilities of Dust Particles Levitated in an Ion Sheath with Low Gas Pressure

T.Misawa, S.Nunomura, K.Asano, N.Ohno, S.Takamura

Proc. 2nd Int. Conf. on the Physics of Dusty Plasmas, ICPDP-99, in "Frontiers in Dusty Plasmas", Hakone Elsevier 巻頁： 465-468 1999年

Structural Formation and Stability of Coulomb Clouds in Medium through Low Gas Pressure Range

S.Takamura, N.Ohno, S.Nunomura, T.Misawa, K.Asano

Proc. 2nd Int. Conf. on the Physics of Dusty Plasmas, ICPDP-99, in "Frontiers in Dusty Plasmas",Hakone, Elsevier 巻頁： 337-344 1999年

Ion Temperature Measurement and Energy Balance in Detached Plasmas in the Divertor Simulator, NAGDIS-II

D.Nishijima, D.G.Whyte, Y.Uesugi, N.Ohno, N.Ezumi, Y.Hirohashi, H.Arakawa, S.Takamura, I. Katsumata

Proc. 26th EPS Conf. on Controlled Fusion and Plasma Physics, Maastricht, Europhysics Conference Abstracts 23J 巻頁： 485-488 1999年

服部徳文, 今井貴博, 西島大輔, 大野哲靖, 上杉喜彦, 高村秀一

プラズマ・核融合学会年会予稿集 ( 16 ) 1999年

25pB6 NAGDIS-II中の径方向電場の中性ガス圧依存性とイオン加熱(プラズマ基礎/RFP) 査読有り

大野哲靖, 西島大輔, 上杉喜彦, WHYTE D G, 高村秀一

プラズマ・核融合学会年会予稿集 ( 16 ) 1999年

26pA1p 非接触再結合プラズマ中における輻射輸送の効果(プラズマ基礎/壁相互作用) 査読有り

荒川弘志, 西島大輔, 大野哲靖, 高村秀一

プラズマ・核融合学会年会予稿集 ( 16 ) 1999年

Structures of Detached Plasmas with High Heat Flow in a Strong Magnetic Field 査読有り

ニシジマダイスケ, エズミナオミチ, アオキコウジ, オオノノリヤス*, タカムラシュウイチ**

東北大学研究所報告. (工学), 流体科学研究所 10 巻頁： 157 - 166 1998年3月

*Experimental Evidence of Molecular Activated Recombination in Detached Recombining Plasmas 査読有り

N.Ohno, N.Ezumi, S.Takamura, S.I.Krasheninnikov, A.Yu.Pigarov

Physical Review Letters 81 巻 ( 4 ) 頁： 818-821 1998年

Static and Dynamic Erosion Behavior of TiC Coated Graphite in High Heat Flux Plasma 査読有り

S.Takamura, K.Hayashi, N.Ohno, K.Morita

Journal of Nuclear Materials 258-263 巻頁： 961-966 1998年

Confinement and Structure of Electrostatically Coupled Dust Clouds in a Direct Current Plasma-Sheath 査読有り

S.Nunomura, N.Ohno, S.Takamura

Physics of Plasmas 5 巻頁： 3517-3523 1998年

Heat Flow through Plasma Sheaths 査読有り

S.Takamura, M.Y.Ye, T.Kuwabara, N.Ohno

Physics of Plasma 6 巻 ( 6 ) 頁： 2151-2158 1998年

Anomaly of Langmuir Probe Characteristics in Detached Recombining Plasma 査読有り

N.Ezumi, N.Ohno, K.Aoki, D.Nishijima, S.Takamura

Contributions to Plasma Physics 38 巻 ( S ) 頁： 31-37 1998年

Particle simulation on multiple dust layers of coulomb cloud in cathode sheath edge 査読有り

K.Asano, S.Nunomura, T.Misawa, N.Ohno, S.Takamura

Czechoslovak Journal of Physics 48 巻頁： 239-244 1998年

Simulation and experiment on detached plasmas in the linear divertor simulator NAGDIS-(]G0002[) 査読有り

N.Ohno, N.Ezumi, D.Nishijima, S.Takamura

Czechoslovak Journal of Physics 48 巻頁： 127-136 1998年

Enhancement of plasma heat flow to the conductive divertor plate associated with cross-field potential variation and thermoelectron emission 査読有り

T.Kuwabara, K.Kudose, M.Y.Ye, N.Ohno, S.Takamura

Contributions to Plasma Physics 38 巻 ( 1-2 ) 頁： 349-354 1998年

Numerical Simulation on Structure of Detached Helium Plasmas with Hydrogen and Helium Gas Puff in NAGDIS-II 査読有り

D.Nishijima, N.Ezumi, K.Aoki, N.Ohno, S.Takamura

Contributions to Plasma Physics 38 巻 ( 1/2 ) 頁： 55-60 1998年

Erosion Characteristics of High-Temperature Metal-Carbon Composite Materials under High-Flux Plasma Irradiation

N.Ohno, S.Takamura

Proc. of Japan/US Workshop(98FT5-01) on High Heat Flux Components and Plasma Surface Interactions for Next Fusion Devices, Toki, Japan, 1998 頁： 474-483 1998年

Change in Detached Helium Plasma's Structure Associated with Molecular Activated Recombination

D.Nishijima, N.Ezumi, H.Kojima, N.Ohno, S.Takamura

Proc. of 1998 International Congress on Plasma Physics combined with 25th EPS Conference on Controlled Fusion and Plasma Physics, Praga, Czech 頁： 23-26 1998年

Space-Charge Limited Emission Current from Material Surface in a Plasma

Y.M.Ye, T.Shimada, T.Kuwabara, N.Onno, S.Takamura

Proc. of 1998 International Congress on Plasma Physics combined with 25th EPS Conference on Controlled Fusion and Plasma Physics, Praga, Czech 頁： 7-10 1998年

Observation of Trapping and Fluctuation of a Dust Could at a Very Low Gas Pressure

S.Nunomura, T.Misawa, K.Asano, N.Ohno, S.Takamura

Proc. of 1998 International Congress on Plasma Physics combined with 25th EPS Conference on Controlled Fusion and Plasma Physics, Praga, Czech 頁： 114-117 1998年

Deposition of TiN Thin Films with Strongly Ionized Plasmas in high Duty AC Tokamak Discharge

M.Y.Ye, O.Matsuda, N.Ohno, M.Takagi, Y.Uesugi, S.Takamura

Proc. of 1998 International Congress on Plasma Physics combined with 25th EPS Conference on Controlled Fusion and Plasma Physics, Praga, Czech 頁： 2509-2512 1998年

31a-YQ-3 漏斗形多層構造微粒子雲の観測査読有り

三沢達也, 布村正太, 浅野和仁, 大野哲靖, 高村秀一

日本物理学会講演概要集 53 巻 ( 0 ) 1998年

Experimental evidence of molecular activated recombination in detached recombining plasmas 査読有り国際共著国際誌

Ohno N., Ezumi N., Takamura S., Krasheninnikov S.I., Pigarov A.Y.

Physical Review Letters 81 巻 ( 4 ) 頁： 818 - 821 1998年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physical Review Letters

Molecular activated recombination (MAR) has been clearly observed for the first time in a divertor plasma simulator. A small amount of hydrogen gas puffing into a helium plasma strongly reduced the ion particle flux along the magnetic field, although the conventional radiative and three-body recombination processes were quenched. Careful comparison of the observed helium Balmer spectra with collisional radiative atomic and molecular data indicates that the population distribution over the atomic levels with relatively low principal quantum numbers can be well explained by taking the MAR effects into account. © 1998 The American Physical Society.

DOI： 10.1103/PhysRevLett.81.818

Erosion and Redeposition Processes of Molybdenum with Oblique Incidence of Magnetic Field 査読有り

小島昌博, 井戸康広, 江角直道, OHNO Noriyasu, TAKAMURA Shuichi

プラズマ・核融合学会誌 = Journal of plasma and fusion research 73 巻 ( 4 ) 頁： 452 - 459 1997年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：プラズマ・核融合学会

Erosion and redeposition processes have been investigated using a linear plasma device and a Monte Carlo simulation code. Argon plasmas were irradiated on a molybdenum substrate with an oblique incidence of magnetic field. The erosion distributions depending on the direction of magnetic field are clearly observed. Numerical code analysis gives a qualitative explanation for the erosion profiles by considering the effect of prompt redeposition of high Z material. However, we have still quantitative differences for their erosion and redeposition rates.

Effects of ion flow by ExB drift on dust particle behavior in magnetized cylindrical electron cyclotron resonance plasmas 査読有り国際誌

Nunomura S, Ohno N, Takamura S

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 36 巻 ( 2 ) 頁： 877 - 883 1997年2月

Effects of Ion Flow by E * B Drift on Dust Particle Behavior in Magnetized Cylindrical Electron Cyclotron Resonance Plasmas.

Nunomura Shota, Ohno Noriyasu, Takamura Shuichi

Japanese Journal of Applied Physics 36 巻 ( 2 ) 頁： 877 - 883 1997年

記述言語：英語出版者・発行元：The Japan Society of Applied Physics

Interactions between poloidal ion flow associated with E× B drift and dust particles have been investigated in magnetized cylindrical electron cyclotron resonance plasmas, in which radial electric field is controlled by a biased ring-shaped electrode. The dust particles are spun out and removed from the plasma due to poloidal ion drag force, even when the inward electric force on the dust particles is larger than the gravitational force. This indicates the possibility of using a new method to remove the dust particles from the processing plasma. On the other hand, in order to sustain the dust particles in the plasma, the effects of this poloidal ion flow should be substantially reduced by the friction between the dust particles and neutral gas.

DOI： 10.1143/jjap.36.877

Study of hot tungsten emissive plate in high heat flux plasma on NAGDIS-I 査読有り

M.Y.Ye, N.Ohno, S.Takamura

Journal of Nuclear Materials 241-243 巻頁： 349-352 1997年

Effects of Ion Flow by 丑X(]G1388[) Drift on Dust Particle Behaviour in Magnetizat Cylindrical Electron Cyclotron 査読有り

S.Nunomura, N.Ohno, S.Takamura

Japan Journal of Applied Physics 36 巻頁： 877-883 1997年

Observation of the Structure and its Formation Process of a New Volumetric Coulomb Cloud Composed of Different Multiple Dust Layers 査読有り

S.Nunomura, N.Ohno, S.Takamura

Japan Journal of Applied Physics 36 巻頁： L949-951 1997年

Density threshold for plasma detachment in gas target 査読有り

N.Ezumi, S.Mori, N.Ohno, S.Takamura, H.Suzuki, J.Park

Journal of Nuclear Materials 241-243 巻頁： 349-352 1997年

講座「プラズマにおけるカオス現象の観測と実験解析II」3.シースに関連したカオス３　2.準周期ルート

大野哲靖

プラズマ・核融合学会誌 73 巻 ( 8 ) 頁： 827-833 1997年

Structure of Detached Plasmas with High Heat Flow in a Strong Magnetic Field

D.Nishijima, N.Ezumi, K.Aoki, N.Ohno, S.Takamura

International Symposium on Plasma and Flow Simulation for Materials Processing, Sendai, Japan, 1997, Reports of the Institute of Fluid Science Tohoku University 10 巻頁： 157-166 1997年

講座「プラズマにおけるカオス現象の観測と実験解析I」2.プラズマにおけるカオス　2.2カオスの解析手法

大野哲靖

プラズマ・核融合学会誌 73 巻 ( 7 ) 頁： 682-687 1997年

Studies on Plasma-Gas Interactions in Powerful High Heat Flux Plasma Device NAGDIS-II

N.Ezumi, N.Ohno, Y.Uesugi, J.Park, S.Watanabe, S.A.Cohen, S.Krasheninnikov, A.Yu. Pigarov, M.Takagi, S.Takamura

Proc. of 20th EPS Conference on Controlled Fusion and Plasma Physics, Bercgtesgardenm Germany, 1997 頁： 1225-1228 1997年

Static and Dynamic Erosion Behavior of TiC Coated Graphite in High Heat Flux Plasma

S.Takamura, K.Hayashi, N.Ohno, K.Morita

8th International Conference on Fusion Reactor Materials, Sendai, Japan, 1997 1 巻 1997年

Structure and Dynamic Behavior of a Coulomb Cloud Composed of Different Multiple Dust Layers

S.Nunomura, T.Misawa, K.Asano, N.Ohno, S.Takamura

39th Annual Meeting fo the Division of Plasma Physics of the American Physical Society, Pittsburgh, USA, 1997 1 巻 1997年

Heat Flows through Plasma Sheaths

S.Takamura, M.Y.Ye, T.Kuwabara, N.Ohno

39th Annual Meeting of the Division of Plasma Physics of the American Physical Society, Pittsburgh, USA, 1997 1 巻 1997年

Plasma Heat FLow through Plasma Sheath with Electron Emission and Plasma Poe\tental Variation across Magnetic Field

M.Y.Ye, K.Kudose, T.Kuwabara, N.Ohno, S.Takamura

7th Asia Pacific Physics Conference, Beijing, China, 1997 1 巻 1997年

Numerical Analysis on Fine Particle's Behavior in an Ion-Beam Plasma System

N.Ohno, M.Nakamura, S.Nunomura, S.Takamura

Proc. of 23th Inernational Conference on Phenomena in Ionized Gases, Toulouse, France 1997 頁： 196-197 1997年

Full AC Tokamak Discharge in A Small Research Device CSTN-AC

S.Takamura, K.Hayashi, Y.Marushita, K.Tashiro, Y.Uesugi, N.Ohno, K.Sakurai, M.Kobayashi, M.Takagi, O.Mitarai

Proc. of 20th EPS Conference on Controlled Fusion and Plasma Physics, Bercgtesgardenm Germany, 1997 頁： 1225-1228 1997年

Suppression of secondary electron emission from the material surfaces with grazing incident magnetic field in the plasma 査読有り国際誌

Takamura S, Mizoshita S, Ohno N

PHYSICS OF PLASMAS 3 巻 ( 12 ) 頁： 4310 - 4312 1996年12月

Nonlinear interactions between high heat flux plasma and electron-emissive hot material surface 査読有り国際誌

Ye MY, Masuzaki S, Shiraishi K, Takamura S, Ohno N

PHYSICS OF PLASMAS 3 巻 ( 1 ) 頁： 281 - 292 1996年1月

Particle in Cell Simulation on Thermoelectron Emission from Hot Target Plate 査読有り

N.Ohno, E.Shimizu, S.Takamura

Contributions to Plasma Physics 36 巻 ( 2-3 ) 頁： 386-390 1996年

Numerical Simulation Study on Density Dependence of Plasma Detachment in Simulated Gas Divertor Experiments of The TPD-I Device 査読有り

N.Ohno, S.Mori, N.Ezumi, M.Takagi, S.Takamura, H.Suzuki

Contributions to Plasma Physics 36 巻 ( 2-3 ) 頁： 339-343 1996年

Characterization of gaseous carbon plasma in a low-temperature tokamak discharge 査読有り

O.Matsuda, N.Ohno, S.Takamura

Plasma Source Science and Technology 5 巻頁： 356-362 1996年

Suppression of Secondary Electron Emission From the Material Surfaces with Grazing Incident Magnetic Field in th Plasma 査読有り

S.Takamura, S.Mizoshita, N.Ohno

Physics of Plasma 3 巻 ( 12 ) 頁： 4310-4312 1996年

Static and Dynamic Characteristics of Plasma Detachment in Gas Target Scheme

N.Ezumi, M.Tanaka, S.Mori, N.Ohno, M.Takagi, S.Takamura, H.Suzuki

Proc. of the 1996 International Conference on Plasma Physics, Nagoya, Japan 頁： 614-617 1996年

Control of Dust Particles' Behavior by Using Ion Flow

S.Nunomura, M.Nakamura, N.Ohno, S.Takamura

International Conference on the Physics of Dusty Plasmas, Goa, India, 1996, "Advances in Dusty Plasmas" ed. by PO.K.Shukla, D.A Mendis and T.Desai, World Scientific Publishing Co., Singapore 1 巻 1996年

Generation of Dustyt Plasma in a Double-Plasma Device

M.Nakamura, S.Nunomura, H.K.Malik, N.Ohno, S.Takamura

Proc. of the 1996 International Conference on Plasma Physics, Naoya Japan 頁： 1982-1985 1996年

Characterization of Gaseous Carbon Plasma in a Low-Temperature Tokamak Discharge as Processing Plasma

O.Matsuda, N.Ohno, S.Takamura

Proc. of the 1996 International Conference on Plasma Physics, Naoya Japan 頁： 1814-1817 1996年

Impurtity Generation, Transport and Redeposition at Plasma Boundary

M.Kojima, Y.Ido, N.Ezumi, N.Ohno, S.Takamura

Proc. of the 1996 International Conference on Plasma Physics, Naoya Japan 頁： 1402-1405 1996年

Physical Mechanism of Plasma Heat Flow into Electron-Emissive Hot Material Surface

M.Y.Ye, T.Kuwabara, N.Ohno, S.Takamura

Proc. of the 1996 International Conference on Plasma Physics, Naoya Japan 頁： 1398-1401 1996年

Plasma Heat Contraction on Conducting Plate due to Plasma Potential Variation across the Magnetic Field

T.Kuwabara, K.Kudose, M.Y.Ye, N.Ohno, S.Takamura

Proc. of the 1996 International Conference on Plasma Physics, Naoya Japan 頁： 1386-1389 1996年

High Heat Flux Plasma Generator for New Divertor Plasma Simulator in Nagoya University

S.Narita, N.Ezumi, N.Ohno, Y.Uesugi, S.Takamura

Proc. of the 1996 International Conference on Plasma Physics, Naoya Japan 頁： 1362-1365 1996年

Comprehensive Studies on Secondary Electron Emission from Material Surface in Magnetized Plasma

S.Takamura, S.Mizoshita, K.Shiraishi, N.Ohno

Proc. of the 1996 International Conference on Plasma Physics, Nagoya, Japan 頁： 610-613 1996年

Temperature Dependence of Ti Sputtering Yield from TiC Composite Material under High Heat Flux Plasma Irradiation

K.Hayashi, N.Ohno, S.Takamura, K.Morita

Proc. of the 1996 International Conference on Plasma Physics, Nagoya, Japan 頁： 1410-1413 1996年

Full AC Plasma Current Operation in the CSTN-AC Tokamak

K.Hayashi, Y.Marushita, K.Tashiro, N.Ohno, S.Takamura, O.Mitarai, K.Sakurai, S.Satoh T.Kuwabara

Proc. of the 1996 International Conference on Plasma Physics, Nagoya, Japan 頁： 1246-1249 1996年

1p-YM-5 微粒子の挙動に対するプラズマ流の影響(プラズマ物理・核融合(プラズマ基礎)) 査読有り

布村正太, 中村守秀, 大野哲靖, 高村秀一

日本物理学会講演概要集. 年会 51 巻 ( 0 ) 1996年

電界制御による微粒子プラズマの生成査読有り

布村正太, 古橋一能, 大野哲靖, 高村秀一

電気学会研究会資料. EP, プラズマ研究会 1995 巻 ( 31 ) 頁： 51 - 58 1995年5月

Reduction of Plasma heat flow to a simulated divertor target plate by ponderomotive force 査読有り

S.Masuzaki, N.Ohno, S.Takamura

Journal of Nuclear Materials 220-222 巻頁： 1112-1115 1995年

Gas target experiments high heat flux plasma of the TPD-I device 査読有り

N.Ohno, S.Masuzaki, M.Takagi, S.Takamura, K.Ishii

Journal of nuclear materials 220-222 巻頁： 279-283 1995年

Heat Transport and Associated Surface Phenomena at the Plasma-Material Interface in Heat and Mass Transfer under Plasma Condition

S.Takamura, N.Ohno

Begell House, Inc., 頁： 245-252 1995年

Experimental Study on Plasma Heat Flow to Plasma Facing Materials 査読有り

S.Masuzaki, N.Ohno, S.Takamura

Journal of Nuclear Materials 223 巻頁： 173-178 1995年

Monte Carlo Simulation on Active Helium-Ash Exhaust by Divertor Biasing 査読有り

T.Kuwabara, M.Kojima, N.Ohno, Y.Uesugi, S.Takamura, Y.Yamamura

Journal of Nuclear Materials 220-222 巻頁： 1001-1004 1995年

Secondary electron emission from solid surface in an oblique magnetic field 査読有り

S.Mizoshita, K.Shiraishi, N.Ohno, S.Takamura

Journal of Nuclear Materials 220-222 巻頁： 488-492 1995年

Heat Transport and Associated Surface Phenomena at the Plasma-Material Interface 査読有り

S.Takamura, N.Ohno

"Heat and Mass Transfer under Plasma Condition" ed by P. Fan chais, M. Boubs and J. Vander Mullen, Begell House 頁： 245-251 1995年

Sensitive Detection of Probing Electron Transport and Magnetic Field Structure in Toroidal Plasma Configuration 査読有り

S.Sakurai, N.Ohno, S.Takamura

Japanese Journal of Applied Physics 33 巻 ( 2 ) 頁： 1161-1168 1994年

Detection of Electron Beam Orbits in a Tokamak Configuration with External Helical Magnetic Field 査読有り

S.Sakurai, N.Ohno, S.Takamura

Journal of Plasma and Fusion Research 70 巻 ( 2 ) 頁： 173-178 1994年

Gas Target Experiments in High Heat Flux Plasma of the TPD-I Device

N.Ohno, S.Masuzaki, S.Mori, N.Ezumi, M.Takagi, S.Takamura

36th Annual Meeting APS Division of Plasma Physics, Minneapolis, USA 1994 巻 1994年

Dynamic CT System for Visible Light Emission from Tokamak Plasma with Charge Coupled Detectors 査読有り

尾田善洋, Takamura Shuichi, Uesugi Yoshihiko, Ohno Noriyasu

プラズマ・核融合学会誌 69 巻 ( 3 ) 頁： p250 - 257 1993年3月

担当区分：最終著者記述言語：英語出版者・発行元：プラズマ・核融合学会

A tomographic reconstruction system with five channels for visible light emission has been developed and applied to observe the visible light emission from HYBTOK-II tokamak plasma. A compact and low cost computed tomography (CT) system with a good spatial and time resolution was established using an array of charge coupled devices. The shuttering capability of the CT system is 300 μs. A rapid change of the emission profile due to the deviation from the tokamak equilibrium was successfully followed. Present CT system with five CCD cameras enables us to recognize a local increment of the visible light emission due to the plasma arcing, which is difficult to observe with the conventional three camera CT system, which is often employed for fusion plasma diagnostics.

Gaseous Silicon Plasma Generated by a Low-Temperature Tokamak Discharge 査読有り

平松健司, 高村秀一, 大野哲靖

プラズマ・核融合学会誌 69 巻 ( 2 ) 頁： p121 - 128 1993年2月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：プラズマ・核融合学会

Gaseous silicon plasma is generated in a hydrogen gas environment by use of a plasmaassisted Si arc in a tokamak discharge with a low electronic temperature (≦10eV) , a high electron density (～ 10^<12>cm^<-3>) , and a low hydrogen gas pressure (～10^<-5> Torr) . On arcing, the spectral lines of Si II, Si III and Si IV ions as well as Si H radicals have been observed. Using the comparison spectroscopic method with no need of absolute measurement of line intensity, doubly ionized silicon ions are observed to be dominant, and the ionic density is estimated to be 10^<11>～10^<12>cm^<-3>. The slllcon hydrogen plasma thus produced Is useful and has a potential for plasma processing, such as a-Si:H synthesis.

Dynamical CT System for visible Light Emission From Tokamak Plasma with Charge Coupled Defectors 査読有り

Y.Oda, Y.Uesugi, S.Takamura, N.Ohno

Journal of Plasma and Fusion Research 69 巻 ( 3 ) 頁： 250-257 1993年

Sheath Voltage on Carbon Surface in a Hydrogen Plasma with Hot Electrons 査読有り

K.Shiraishi, N.Ohno, S.Takamura

Journal of Plasma and Fusion Research 69 巻 ( 11 ) 頁： 1371-1377 1993年

Chaotic Behavior Driven by an External Periodic Oscillation in a Current-Carrying Unstable Ion Sheath 査読有り

N.Ohno, A.Komori, M.Kono, Y.Kawai

Physics of Fluids B 5 巻 ( 3 ) 頁： 796-805 1993年

Experimental and Theoretical Study on Plasma Heat Flow to Plasma Facing Materials

S.Masuzaki, H.Konnno, N.Ohno, S.Takamura

Proc. of 20th EPS Conference on Controlled Fusion and Plasma Physics, Lisboa 743-746 巻 1993年

BIFURCATION PHENOMENA IN AN EMISSIVE PLATE - SIMULATED DIVERTOR PLASMA SYSTEM 査読有り

TAKAMURA S, OHNO N, SHIRAISHI K, MASUZAKI S

JOURNAL OF NUCLEAR MATERIALS 196 巻頁： 448 - 451 1992年12月

SHEATH FORMATION ON CARBON AND REFRACTORY-METALS IN A PLASMA WITH ENERGETIC ELECTRONS 査読有り国際誌

SHIRAISHI K, OHNO N, UESUGI Y, TAKAMURA S

JOURNAL OF NUCLEAR MATERIALS 196 巻頁： 745 - 749 1992年12月

INTERMITTENCY DURING TRANSITION BETWEEN STATIONARY AND PERIODIC STATES IN PLASMAS 査読有り国際誌

KOMORI A, OHNO N, YAMAURA T, KAWAI Y

PHYSICS LETTERS A 170 巻 ( 6 ) 頁： 439 - 442 1992年11月

Sheath Formation on Carbon and and Refractory Metals in a Plasma with Energetic Electrons 査読有り

K.Shiraishi, N.Ohno, Y.Uesugi, S.Takamura

Journal of Nuclear Materials 196-198 巻頁： 745-749 1992年

Gaseous Silicon Plasma Generated by a Low-Temperatue Tokamak Discharge 査読有り

K.Hiramatsu, N.Ohno, S.Takamura

Jouranl of Plasma and Fusion Research 69 巻 ( 2 ) 頁： 121-128 1992年

Studies on Sheath Formation in Divertor Plasmas by Computer Simulation Using Particle 査読有り

N.Ohno, S.Masuzaki, H.Konno, S.Takamura

Contributions to Plasma Physics 3 巻 ( 3-4 ) 頁： 249-354 1992年

高熱流プラズマの生成とその高速掃引プローブ計測システムによる計測査読有り

増崎貴、大野哲靖、高木誠、高村秀一

電気学会論文誌A 112 巻 ( 11 ) 頁： 913-921 1992年

Intermittency During Transition Between Stationary and Periodic States of Plasmas 査読有り

A.Komori, N.Ohno, T.Yamaura, Y.Kawai

Physics Letter A 170 巻 ( 6 ) 頁： 439-442 1992年

Bifurcation Phencomena in an Emissive Plate-Simulated Divertor Plasma System 査読有り

S.Takamura, N.Ohno, K.Shiraishi, S.Masuzaki

Journal of Nuclear Materials 196-198 巻頁： 448-451 1992年

Numerical Study of Potential Formation and Negative Resistance in a Currnet Carrying Ion Sheath

N.Ohno, A.Komori, Y.Kawai, S.Takamura

Proc. of 1992 International Conference on Plasma Physics, Innsbruck, Austria 頁： 1807-1810 1992年

26p-C-7 準周期ルートによるイオンシースのカオス査読有り

小森彰夫, 大野哲靖, 河野光雄, 田中雅慶, 河合良信

秋の分科会予稿集 1992 巻 ( 0 ) 1992年

Averaging effect of radical particle profile by the scanning plasma method in SiH<inf>4</inf>Ar plasmas 査読有り国際誌

Fujiyama H., Kawasaki H., Matsuda Y., Ohno N.

Materials Science and Engineering A 140 巻 ( C ) 頁： 569 - 575 1991年7月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Materials Science and Engineering A

A new plasma-enhanced chemical vapour deposition (PECVD) method has been developed for preparation of large-area uniform hydrogenated amorphous silicon (aSi:H) thin films. Detailed two-dimensional profiles of both charged particles and radical particles have been measured in magnetized multielectrode glow discharge plasmas in 10% SiH4Ar gas. The detailed profiles of SiH* and Ar I emissions had two peaks in the negative glow and cathode sheath regions but, for Hα emission, only one peak was observed in the cathode sheath region. It was verified that large-area uniform profiles of not only plasmas but also SiH* emission could be realized in the presence of modulated crossed magnetic and electric fields. By using this scanning plasma method (SPM), inhomogeneities for both profiles of plasma and SiH* (413.5 nm) emission intensity have improved to less than 2.5% near the substrate outside the discharge region. The thickness profile of prepared a-Si:H thin film has also been unified to less than 4.8% by SPM. © 1991.

DOI： 10.1016/0921-5093(91)90480-B