K
Kazuya Uehara
Researcher at Japan Atomic Energy Research Institute
Publications - 62
Citations - 1053
Kazuya Uehara is an academic researcher from Japan Atomic Energy Research Institute. The author has contributed to research in topics: Tokamak & Plasma. The author has an hindex of 16, co-authored 62 publications receiving 1020 citations.
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Journal ArticleDOI
Experimental Observation of the rf-Driven Current by the Lower-Hybrid Wave in a Tokamak
Takumi Yamamoto,Tsuyoshi Imai,Michiya Shimada,Norio Suzuki,Masaki Maeno,Shigeru Konoshima,T. Fujii,Kazuya Uehara,Takashi Nagashima,A. Funahashi,Noboru Fujisawa +10 more
TL;DR: In this paper, it was observed that the waves launched from a phased array antenna of four waveguides couple effectively with electrons under the condition of ε = 2.0.
Journal ArticleDOI
Observation of nonlinear coupling between small-poloidal wave-number potential fluctuations and turbulent potential fluctuations in Ohmically heated plasmas in the JFT-2M tokamak.
Yoshihiko Nagashima,Katsumichi Hoshino,Akira Ejiri,K. Shinohara,Yuichi Takase,Kazuhiro Tsuzuki,Kazuya Uehara,Hisato Kawashima,Hiroaki Ogawa,T. Ido,Y. Kusama,Y.M. Miura +11 more
TL;DR: A bispectral analysis revealed that a significant nonlinear coupling among the two types of fluctuations and the broadband background turbulent potential fluctuations occurs inside the last closed magnetic flux surface, suggesting that a nonlinear process such as the parametric-modulational instability is involved.
Journal ArticleDOI
Avoidance of qa=3 disruption by electron cyclotron heating in the JFT-2M tokamak.
Katsumichi Hoshino,M. Mori,Takumi Yamamoto,Hiroshi Tamai,Teruaki Shoji,Y.M. Miura,H. Aikawa,Satoshi Kasai,T. Kawakami,Hisato Kawashima,Masaki Maeno,Tatsuma D. Matsuda,K. Oasa,Kazuo Odajima,Hiroaki Ogawa,Toru Ogawa,T. Seike,T. Shiina,Kazuya Uehara,Toshihiko Yamauchi,Norio Suzuki,Hikosuke Maeda +21 more
TL;DR: The observed narrow suppression window suggests that the basic mechanism responsible for the suppression is direct island heating, which is much faster than the time scale of the change of the overall current profile.
Journal ArticleDOI
Steady-state tokamak operation, ITB transition and sustainment and ECCD experiments in TRIAM-1M
Hideki Zushi,Kazuo Nakamura,Kazuaki Hanada,Kohnosuke Sato,Mizuki Sakamoto,Hiroshi Idei,Makoto Hasegawa,Atsuhiro Iyomasa,Shoji Kawasaki,Hisatoshi Nakashima,A. Higashijima,T. Kuramoto,A. Tanaka,Y. Matsuo,K. Esaki,H. Akanishi,T. Sugata,H. Hoshika,K. Sasaki,N. Maezono,M. Kitaguchi,N. Imamura,N. Yoshida,Kazutoshi Tokunaga,T. Fujiwara,Mitsutaka Miyamoto,Masayuki Tokitani,Kazuya Uehara,Y. Sadamoto,Yousuke Nakashima,Yuusuke Kubota,Y. Higasizono,Yuichi Takase,Akira Ejiri,Syun'ichi Shiraiwa,Shinichiro Kado,T. Sikama,Shunji Tsuji-Iio,T. Takeda,Y. Hirooka,Katsumi Ida,Y. Nakamura,Takashi Fujimoto,Atsushi Iwamae,Takashi Maekawa,Osamu Mitarai +45 more
TL;DR: In this article, the formation and sustainment of an internal transport barrier (ITB) in enhanced current drive mode has been investigated by controlling the lower hybrid driven current profile by changing the phase spectrum.
Journal ArticleDOI
Observation of the limiter H mode in the JT-60 tokamak with lower-hybrid current drive
Shunji Tsuji,Kenkichi Ushigusa,Y. Ikeda,Tsuyoshi Imai,Itami T,M. Nemoto,Keisuke Nagashima,Yoshihiko Koide,Yasunori Kawano,T. Fukuda,Takashi Kondoh,M. Shimada,Haruki Nakamura,O. Naito,H. Yoshida,Takeo Nishitani,Hirotaka Kubo,Kenji Tobita,Y. Kusama,S. Ishida,Masayasu Sato,N. Isei,Tatsuo Sugie,Naoyuki Miya,Ryuji Yoshino,Kazuya Uehara +25 more
TL;DR: A nearly steady-state edge-localized-mode-free {ital H} mode with a duration up to 3.3 sec was established without significant impurity accumulation in limiter discharges of a tokamak with lower-hybrid current drive for the first time.