Faculty Profiles - OHNO, Noriyasu

Papers - OHNO, Noriyasu

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Development of net-current free heliotron plasmas in the Large Helical Device Reviewed

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 Vol. 49 page： 104015(8pp) 2009

Direct observation of cathode spot grouping using nanostructured electrode Reviewed

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

Physics Letters A Vol. 373 page： 4273-4277 2009

Discharge Bifurcation of Microwave-sustained Helium Plasma Torch at Atmospheric Pressure Reviewed

S.Takamura, M.Kando, N.Ohno

J.Plasma Fusion Res. SERIES Vol. 8 page： 910-913 2009

Statistical properties of edge plasma turbulence in the Mega-Amp Spherical Tokamak and the Large Helical Device Reviewed International coauthorship International journal

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 Vol. 32 ( 2 ) page： 898 - 901 2008.12

Deuterium retention near surface of TiO<inf>2</inf> by low-voltage D <inf>2</inf> plasma discharge Reviewed International journal

Matsunami N., Tanaka T., Ohno N., Tokitani M.

Physica Status Solidi (C) Current Topics in Solid State Physics Vol. 5 ( 4 ) page： 923 - 926 2008.12

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

Scopus

11<sup>th</sup> International Workshop on Plasma Edge Theory in Fusion Devices: Preface Reviewed International coauthorship International journal

Heikkinen J., Ohno N.

Contributions to Plasma Physics Vol. 48 ( 1-3 ) 2008.3

Intermittency and extended self-similarity in space and fusion plasma: boundary effects Reviewed

V.P.Budaev, S.Savin, L.Zelencyi, N.Ohno, S.Takamura and E.Amata

Plasma Physics and Controlled Fusion Vol. 50 page： 074014(20pp) 2008

Measurement of Plasma Properties of the Atmospheric Oxy-Combustion Flame by Using Double Probe Method Reviewed

Y.Osaka, N.Kobayashi, N.Ohno, S.Takamura, Y.Tanaka, Y.Uesugi

Contrib. Plasma Physics Vol. 48 ( 5-7 ) page： 485-490 2008

Extended self-similarity of intermittent turbulencein edge magnetized plasmas Reviewed

V.P. Budaev, N. Ohno, S.Takamura, S. Masuzaki, A. Komori, T. Morisaki

Nuclear Fusion Vol. 48 page： 24014 2008

Deuterium retention near surface of TiO2 by low-voltage D2 plasma discharge Reviewed

N.Matsunami, T.Tanaka, N.Ohno and M.Tokitani

Phys. Stat. Sol.(c) Vol. 5 ( 4 ) page： 923-926 2008

ELM propagation in the low- and high- filed-side Scrape-off Layer of the JT-60U tokamak Reviewed

N.Asakura, H.Kawashima, N.Ohno, G.Matsunaga, T.Nakano and N.Oyama

Journal of Physics; Conference Series Vol. 123 page： 012009(11pp) 2008

Statistical properties of edge plasma turbulence in the Large Helical Device Reviewed

J.M.Dewhurst, B.Hnat, N.Ohno, R.O.Dendy, S.Masuzaki, T.Morisaki and A.Komori

Plasma Physics and Controlled Fusion Vol. 50 page： 095013(15pp) 2008

Fluctuating Helium Emission in Optically Thick Divertor Plasmas Reviewed

F. B. Rosmej, N. Ohno, S. Takamura, S. Kajita

Contributions to Plasma Physics Vol. 48 page： 243-248 2008

Numerical Modeling of Behavior of Dust Made of Different Materials in Plasmas Reviewed

Y. Tanaka, A. Yu. Pigarov, R. D. Smirnov, S. I. Krasheninnikov, N. Ohno, Y. Uesugi

Contributions to Plasma Physics Vol. 48 page： 295-299 2008

Extended Self-Similarity in Edge Plasma Turbulence of Fusion Devices Reviewed

V. P. Budaev, N. Ohno, S. Takamura, S. Masuzaki, A. Komori, T. Morisaki

Contributions to Plasma Physics Vol. 48 page： 42-47 2008

Plasma Rotation Measurements by Passive Spectroscopic Method in the HYBTOK-II using a Dynamic Ergodic Divertor Reviewed

Y.Hasebe, M.Okamoto, S.Kajita, N.Ohno and S.Takamura

Plasma and Fusion Research Vol. 3 page： S1015 2008

ELM propagation in the low- and high-field-side scrape-off layer of the JT-60U tokamak Reviewed International journal Open Access

Asakura N., Kawashima H., Ohno N., Matsunaga G., Nakano T., Oyama N.

Journal of Physics: Conference Series Vol. 123 2008

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

Open Access

Scopus

Plasma-assisted laser ablation of tungsten: Reduction in ablation power threshold due to bursting of holes/bubbles Reviewed International journal Open Access

Kajita S., Ohno N., Takamura S., Sakaguchi W., Nishijima D.

Applied Physics Letters Vol. 91 ( 26 ) 2007.12

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

Open Access

Scopus

Effect of cross-field transport on H<sup>-</sup> density profile in magnetized plasmas: Comparison between measurement and simulation Reviewed International journal Open Access

Kajita S., Kado S., Ohno N., Takamura S., Kurihara K., Kuwahara Y.

Physics of Plasmas Vol. 14 ( 10 ) 2007.11

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

Open Access

Scopus

Sub-ms Laser Pulse Irradiation on Tungsten Target Damaged by Exposure to Helium Plasma Reviewed

S.Kajita, S.Takamura, N.Ohno, D.Nishijima, H.Iwakiri, N.Yoshida

Nuclear Fusion Vol. 47 page： 1358 - 1366 2007.9

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Papers - OHNO, Noriyasu