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Home / Publications / Journals / Fusion Science and Technology / Volume 46 / Number 1

Long-Pulse Operation and High-Energy Particle Confinement Study in ICRF Heating of LHD

Takashi Mutoh, Ryuhei Kumazawa, Tetsuo Seki, Kenji Saito, Tetsuo Watari, Yuki Torii, Norio Takeuchi, Fujio Shimpo, Goro Nomura, Mitsuhiro Yokota, Tsuguhiro Watanabe, Masaki Osakabe, Mamiko Sasao, Sadayoshi Murakami, Tomoya Saida, Hiroyuki Okada, Yuichi Takase, Atsushi Fukuyama, Naoko Ashikawa, Masahiko Emoto, Hisamichi Funaba, Pavel R. Goncharov, Motoshi Goto, Yasuji Hamada, Katsumi Ida, Hiroshi Idei, Katsunori Ikeda, Shinsaku Imagawa, Shigeru Inagaki, Mitsutaka Isobe, Takashi Kobuchi, Shin Kubo, Suguru Masuzaki, Keisuke Matsuoka, Takashi Minami, Toshiyuki Mito, Jyunichi Miyazawa, Tomohiro Morisaki, Shigeru Morita, Sadatsugu Muto, Yoshio Nagayama, Yukio Nakamura, Hideya Nakanishi, Kazumichi Narihara, Yoshiro Narushima, Kiyohiko Nishimura, Nobuaki Noda, Takashi Notake, Satoshi Ohdachi, Yoshihide Oka, Tetsuo Ozaki, Byron J. Peterson, Akio Sagara, Satoru Sakakibara, Ryuichi Sakamoto, Kuninori Sato, Motoyasu Sato, Takashi Shimozuma, Mamoru Shoji, Hajime Suzuki, Yasuhiko Takeiri, Naoki Tamura, Kenji Tanaka, Kazuo Toi, Tokihiko Tokuzawa, Katsuyoshi Tsumori, Kiyomasa Watanabe, Hiroshi Yamada, Ichihiro Yamada, Kozo Yamazaki, Masayuki Yokoyama, Yasuo Yoshimura, Mikiro Yoshinuma, Osamu Kaneko, Kazuo Kawahata, Nobuyoshi Ohyabu, Kunizo Ohkubo, Akio Komori, Shigeru Sudo, Osamu Motojima

Fusion Science and Technology / Volume 46 / Number 1 / July 2004 / Pages 175-183

Technical Paper / Stellarators

Long-pulse operation and high-energy particle confinement properties were studied using ion cyclotron range of frequency (ICRF) heating for the Large Helical Device. For the minority-ion mode, ions with energies up to 500 keV were observed by concentrating the ICRF heating power near the plasma axis. The confinement of high-energy particles was studied using the power-modulation technique. This confirmed that the confinement of high-energy particles was better with the inward-shifted configuration than with the normal configuration. This behavior was the same for bulk plasma confinement. Long-pulse operation for more than 2 min was achieved during the experimental program in 2002. This was mainly due to better confinement of the helically trapped particles and accumulation of fewer impurities in the region of the plasma core, in conjunction with substantial hardware improvements. Currently, the plasma operation time is limited by an unexpected density rise due to outgassing from the chamber materials. The temperature of the local carbon plates of the divertor exceeded 400°C, and a charge-coupled device camera observed the hot spots. The hot spot pattern was well explained by a calculation of the accelerated-particle orbits, and those accelerated particles came from outside the plasma near the ICRF antenna.

 
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