Configuration flexibility and extended regimes in Large Helical Device

Recent experimental results in the Large Helical Device have indicated that a large pressure gradient can be formed beyond the stability criterion for the Mercier (high-n) mode. While the stability against an interchange mode is violated in the inward-shifted configuration due to an enhancement of the magnetic hill, the neoclassical transport and confinement of high-energy particle are, in contrast, improved by this inward shift. Mitigation of the unfavourable effects of MHD instability has led to a significant extension of the operational regime. Achievements of the stored energy of I MJ and the volume-averaged beta of 3% are representative results from this finding. A confinement enhancement factor above the international stellarator scaling ISS95 is also maintained around 1.5 towards a volume-averaged beta, (beta), of 3%. Configuration studies on confinement and MHD characteristics emphasize the superiority of the inward-shifted geometry to other geometries. The emergence of coherent modes appears to be consistent with the linear ideal MHD theory; however, the inward-shifted configuration has reduced heat transport in spite of a larger amplitude of magnetic fluctuation than the outward-shifted configuration. While neoclassical helical ripple transport becomes visible for the outward-shifted configuration in the collisionless regime, the inward-shifted configuration does not show any degradation of confinement deep in the collisionless regime (nu* < 0.1). The distinguished characteristics observed in the inward-shifted configuration help in creating a new perspective of MHD stability and related transport in net current-free plasmas. The first result of the pellet launching at different locations is also reported.

Kozo Yamazaki | Masaki Osakabe | Shigeru Inagaki | Takashi Shimozuma | Osamu Motojima | N. Ohyabu | Hiroshi Yamada | Kunizo Ohkubo | Masahiko Isobe | Osamu Kaneko | Shigeru Morita | Tokihiko Tokuzawa | Konstantin V. Khlopenkov | W. A. Cooper | Hideo Sugama | Masayuki Yokoyama | Hiroshi Idei | Y. Takeiri | Takashi Mutoh | Masahiko Emoto | Ryuhei Kumazawa | P. W. Fisher | Akio Sagara | Shin Kubo | Yoshiro Narushima | Kenji Tanaka | Yoshio Nagayama | T. Uda | Motoshi Goto | Kazuo Kawahata | Naoko Ashikawa | Noriyoshi Nakajima | Suguru Masuzaki | Larry R Baylor | I. Yamada | T. Kobuchi | T. Minami | J. Miyazawa | K. Narihara | T. Notake | Y. Oka | S. Sudo | Satoru Sakakibara | Mitsuo Shoji | H. Funaba | H. Sasao | Akio Komori | Kazuo Toi | Sadayoshi Murakami | Katsumi Ida | Masami Fujiwara | Tetsuo Seki | Tomohiro Morisaki | Sadatsugu Muto | Katsuyoshi Tsumori | T. Watari | Kiyohiko Nishimura | Yuji Nakamura | Ryuichi Sakamoto | K. N. Sato | Satoshi Ohdachi | Takashi Satow | Hideya Nakanishi | K. Kawahata | S. Murakami | A. Sagara | Tsuguhiro Watanabe | T. Morisaki | R. Sakamoto | O. Motojima | K. Watanabe | N. Ohyabu | T. Mutoh | R. Kumazawa | S. Masuzaki | T. Seki | J. Miyazawa | M. Goto | B. Peterson | N. Ashikawa | K. Saito | S. Sakakibara | T. Tokuzawa | K. Narihara | I. Yamada | A. Komori | K. Yamazaki | M. Fujiwara | T. Satow | T. Uda | L. Baylor | G. Rewoldt | H. Yamada | M. Emoto | H. Funaba | K. Ida | H. Idei | O. Kaneko | S. Kubo | T. Minami | S. Muto | Y. Nagayama | H. Nakanishi | K. Nishimura | N. Noda | T. Kobuchi | Y. Oka | M. Osakabe | T. Ozaki | H. Sasao | M. Sasao | M. Sato | T. Shimozuma | H. Suzuki | Y. Takeiri | K. Tsumori | M. Yokoyama | T. Watari | K. Ohkubo | S. Sudo | Y. Yoshimura | T. Notake | Y. Liang | H. Sugama | T. Kuroda | N. Nakajima | K. Itoh | K. Tanaka | N. Tamura | Y. Narushima | S. Inagaki | M. Shoji | Y. Xu | A. Kostrioukov | Y. Xu | Byron J. Peterson | S. Morita | K. Y. Watanabe | Y. Liang | K. Matsuoka | K. Saito | Tetsuo Ozaki | S. Yamamoto | Y. Yoshimura | N. Inoue | N. Noda | H. Suzuki | Tsutomu Kuroda | Y. Torii | K. Ikeda | S. Yamamoto | Kuninori Sato | K. Itoh | M. Sasao | Tsuguhiro Watanabe | K. Ikeda | Yuki Torii | M. Sato | G Rewoldt | A. Kostrioukov | N. Tamura | N. Inoue | S. Ohdachi | Y. Nakamura | M. Isobe | K. Matsuoka | K. Toi | K. V. Khlopenkov

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