Faculty Profiles - OHNO, Noriyasu

Papers - OHNO, Noriyasu

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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) Reviewed Open Access

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

Nuclear Fusion Vol. 63 ( 4 ) 2023.4

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

TANAKA Hirohiko, MASUZAKI Suguru, KAWAMURA Gakushi, HAYASHI Yuki, KOBAYASHI Masahiro, SUZUKI Yasuhiro, MUKAI Kiyofumi, KAJITA Shin, OHNO Noriyasu

Plasma and Fusion Research Vol. 18 ( 0 ) page： 2402021 - 2402021 2023.3

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research

<p>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 βand the Pfirsch-Schlüter current effects.</p>

DOI： 10.1585/pfr.18.2402021

Study of the intermittent plasma structure around the divertor simulation experimental module in GAMMA 10/PDX Reviewed Open Access

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 Vol. 30 ( 3 ) page： 32501 2023.3

Structural Correlation of Random Lasing Performance in Plasma-Induced Surface-Modified Gallium Nitride Reviewed

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

ACS Applied Optical Materials Vol. 1 ( 1 ) page： 412 - 420 2023.1

Publisher：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

Scopus

Motion analysis of arc spots on tungsten fuzz by means of self-avoiding random walk model Reviewed Open Access

Hwangbo Dogyun, Nishijima Daisuke, Kajita Shin, Ohno Noriyasu

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 62 ( SA ) page： SA1007 2023.1

Field emission current from protrusion structures formed by helium plasma with various impurity gases Reviewed

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

Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV Vol. 2023-June page： 529 - 532 2023

Publisher：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

Scopus

Thermal conductivity measurement of fuzzy W using a thermoreflectance method Reviewed

Kajita S., Yagi T., Ohno N.

Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV Vol. 2023-June page： 526 - 528 2023

Publisher：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

Scopus

Use of machine learning for a helium line intensity ratio method in Magnum-PSI Reviewed International coauthorship Open Access

Kajita Shin, Iwai Sho, Tanaka Hirohiko, Nishijima Daisuke, Fujii Keisuke, van der Meiden Hennie, Ohno Noriyasu

NUCLEAR MATERIALS AND ENERGY Vol. 33 page： 101281 2022.10

Plasma induced surface nanostructure on semiconductors for the application of random laser Reviewed

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

POWER TRANSMISSION FACTOR FOR TUNGSTEN TARGET W/WO FIBER-FORM NANOSTRUCTURE IN H PLASMAS WITH HOT ELECTRON COMPONENT USING COMPACT PLASMA DEVICE AIT-PID Reviewed International journal

Takamura, S; Miyamoto, T; Ohno, N

FUSION SCIENCE AND TECHNOLOGY Vol. 63 ( 1T ) page： 225 - 228 2013.5

Simulation of dynamics of carbon dust particles in the JT-60U tokamak Reviewed International coauthorship International journal

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

JOURNAL OF NUCLEAR MATERIALS Vol. 415 ( 1 ) page： S1106 - S1110 2011.8

Dusty sheaths in plasmas with two-temperature electrons Reviewed International journal

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

DUSTY PLASMAS IN THE NEW MILLENNIUM Vol. 649 page： 277 - 280 2002

Generation of high heat flux plasma in divertor plasma simulator by ion cyclotron wave heating Reviewed International journal

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 page： 1050 - 1053 1997

Generation of high heat flux plasmas by rf heating in divertor plasma simulator NAGDIS-II Reviewed International journal

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

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

Numerical simulation study on density dependence of plasma detachment in simulated gas divertor experiments of the TPD-I device Reviewed

Ohno, N; Mori, S; Ezumi, N; Takagi, M; Takamura, S; Suzuki, H

CONTRIBUTIONS TO PLASMA PHYSICS Vol. 36 ( 2-3 ) page： 339 - 343 1996

STUDIES ON SHEATH FORMATION IN DIVERTOR PLASMAS BY COMPUTER-SIMULATION USING PARTICLES Reviewed International journal

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

CONTRIBUTIONS TO PLASMA PHYSICS Vol. 32 ( 3-4 ) page： 249 - 254 1992

Experiments on Subharmonic Waves in an Ion Beam-Plasma System Reviewed Open Access

Ono Noriyasu, Kasuya Toshiro, Tanaka Masayoshi, Komori Akio, Kawai Yoshinobu

Vol. 9 ( 1 ) page： 23 - 27 1987.7

Language：Japanese Publisher：Interdisciplinary Graduate School of Engineering Sciences, Kyushu University

Subharmonic waves are experimentally studied in detail by applying pump waves to an ion beam-plasma system. It is found that the subharmonic waves are excited in the characteristic region of the pump-wave frequency, accompanied with low-frequency fluctuations. These low-frequency fluctuations are considered to play an important role on excitation of the subharmonics.

DOI： 10.15017/17680

Open Access

CiNii Research

The effect of W surface fuzz induced by He plasma on deuterium permeation Reviewed International coauthorship

L. Li, Z. Chen, Z. Liu, Z. Gao, N. Zhang, Y. Li, C. Yin, S. Mao, H. Tanaka, N. Ohno, M. Ye

Nuclear Fusion Vol. 66 page： 016006 2025.11

「プラズマ科学のフロンティア」に挑む名古屋大学低温プラズマ科学研究センター Reviewed Open Access

大野哲靖

応用物理 Vol. 94 ( 11 ) page： 613 - 616 2025.11

TALIF measurements of atomic deuterium in toroidal divertor simulator NAGDIS-T Reviewed International journal Open Access

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

Nuclear Materials and Energy Vol. 42 2025.3

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：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

Open Access

Scopus

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Papers - OHNO, Noriyasu