Faculty Profiles - OHNO, Noriyasu

Papers - OHNO, Noriyasu

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Lithography-Free Nanofabrication on Various Semiconductors by the Codeposition Etching Technique Reviewed International journal

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

Langmuir Vol. 40 ( 24 ) page： 12437 - 12442 2024.6

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

Scopus

PubMed

First results of multi-fluid modeling of detached hydrogen plasmas in a linear plasma device using fluid code LINDA-NU Reviewed International journal

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

Contributions to Plasma Physics Vol. 2024;e202300150 2024.6

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

Scopus

Four-dimensional conditional averaging tomography of rotating plasma ejection from cylindrical detached plasma Reviewed International journal

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

Scientific Reports Vol. 14 ( 1 ) page： 9329 2024.4

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

Scopus

PubMed

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

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 Vol. 30 ( 3 ) page： 10.1063/5.0129886 2023.3

Increased Photoelectrochemical Performance of Vanadium Oxide Thin Film by Helium Plasma Treatment with Auxiliary Molybdenum Deposition Reviewed International coauthorship

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

ADVANCED ENERGY AND SUSTAINABILITY RESEARCH Vol. 4 page： 2200141 2023.1

Structural correlation of random lasing performance in plasma-induced surface-modified galium nitride Reviewed

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

ACS Applied Optical Materials Vol. 1 page： 412 - 420 2022.12

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)) Invited Reviewed

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

Applied Surface Science Vol. 599 page： 153668 2022.10

Reduction of pulsed particle load with dynamic pressure induced by transient recycled neutral flux Reviewed International coauthorship International journal

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 Vol. 64 ( 10 ) page： 105013 2022.9

Bidirectional reflectance distribution function of recrystallized tungsten mono-block exposed to cyclic heat loading Reviewed International journal

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 Vol. 33 page： 101243 2022.9

Fuzz Growth Process under He-W Co-Deposition Conditions Reviewed International coauthorship International journal

SHEN Wanqi, KAJITA Shin, TANAKA Hirohiko, SHI Quan, OHNO Noriyasu

Plasma and Fusion Research Vol. 17 ( 0 ) page： 1302094 - 1302094 2022.8

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

Helium (He)-Tungsten (W) co-deposition experiments were conducted in the linear plasma device Co-NAGDIS at a temperature of 1223 K to observe the characteristics of fuzz growth on the W surface 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

Scopus

CiNii Research

Measurement of the Bidirectional Reflectance Distribution Function of Tungsten Surface Sputtered in Argon Plasma Reviewed

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 Vol. 17 page： 2405041 2022.5

Isotope Effect for Plasma Detachment in Helium and Hydrogen/Deuterium Mixture Plasmas Reviewed International journal

GUO Xinyue, TANAKA Hirohiko, KAJITA Shin, OHNO Noriyasu, HATTORI Shogo, SAWADA Keiji

Plasma and Fusion Research Vol. 17 ( 0 ) page： 2402027 - 2402027 2022.5

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

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

Scopus

CiNii Research

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 Reviewed International coauthorship

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

Physical Chemistry Chemical Physics Vol. 24 page： 13883 - 13896 2022.5

Changes in morphology and field emission property of nano-tendril bundles after high temperature annealing Reviewed International coauthorship International journal

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

Nuclear Materials and Energy Vol. 31 page： 101178 2022.4

An approach to implement a heat flux limit in a model for fusion relevant plasmas Reviewed International coauthorship

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

Physics of Plasmas Vol. 29 page： 32502 2022.3

Completion of JT-60SA construction and contribution to ITER Reviewed International coauthorship International journal

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 Vol. 62 ( 4 ) page： 42002 2022.3

Nitrogen Atom Density Measurements in NAGDIS-T Using Vacuum Ultraviolet Absorption Spectroscopy Reviewed

NISHIO Ryosuke, KAJITA Shin, TANAKA Hirohiko, ASAOKA Koji, TSUTSUMI Takayoshi, HORI Masaru, OHNO Noriyasu

Plasma and Fusion Research Vol. 17 ( 0 ) page： 1201004 - 1201004 2022.1

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

For the development of a high nitrogen atom density source, we produced nitrogen plasmas and measured the nitrogen atom density using vacuum ultraviolet absorption spectroscopy (VUVAS) at high neutral gas pressure (>1.5 mTorr) and discharge power (>500 W) in the NAGDIS-T, which could generate spiral-shaped dissociative recombining plasmas. It was seen that the nitrogen atom density increases with increasing neutral gas pressure and discharge power, and it reached 6.2 × 1017 m−3. In the low gas pressure case, the estimated atom density was confirmed to be consistent with that measured by the actinometry method.

DOI： 10.1585/pfr.17.1201004

Web of Science

CiNii Research

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.

Optics InfoBase Conference Papers 2022

Photoelectrochemical properties of plasma-induced nanostructured tungsten oxide Reviewed International coauthorship International journal

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

Applied Surface Science Vol. 580 page： 151979(7 pp) 2021.12

Growth of Mo Large-Scale Fiberform Nanostructures Reviewed

Kajita Shin, Okuyama Tatsuki, Tanaka Hirohiko, Ohno Noriyasu

PLASMA AND FUSION RESEARCH Vol. 16 ( 0 ) page： 1206105 - 1206105 2021.12

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

Web of Science

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