Improved plasma performance on Large Helical Device

A. Komori, N. Ohyabu, H. Yamada, O. Kaneko, K. Kawahata, N. Ashikawa, P. DeVaries, M. Emoto, H. Funaba, M. Goto, K. Ida, H. Idei, K. Ikeda, S. Inagaki, N. Inoue, M. Isobe, S. Kado, K. Khlopenkov, T. Kobuchi, S. KuboR. Kumazawa, Y. Liang, S. Masuzaki, Y. Matsumoto, T. Minami, J. Miyazawa, T. Morisaki, S. Morita, S. Murakami, S. Muto, T. Mutoh, Y. Nagayama, Y. Nakamura, H. Nakanishi, K. Narihara, Y. Narushima, K. Nishimura, N. Noda, T. Notake, S. Ohdachi, Y. Oka, M. Okamoto, M. Osakabe, T. Ozaki, R. O. Pavlichenko, B. J. Peterson, A. Sagara, K. Saito, S. Sakakibara, R. Sakamoto, H. Sasao, M. Sasao, K. Sato, M. Sato, T. Seki, T. Shimozuma, M. Shoji, H. Suzuki, M. Takechi, Y. Takeiri, N. Tamura, K. Tanaka, K. Toi, T. Tokuzawa, Y. Torii, K. Tsumori, I. Yamada, S. Yamaguchi, S. Yamamoto, M. Yokoyama, Y. Yoshimura, K. Y. Watanabe, T. Watanabe, T. Watari, Y. Hamada, K. Itoh, K. Matsuoka, K. Ohkubo, T. Satow, S. Sudo, K. Yamazaki, O. Motojima, M. Fujiwara

Research output: Contribution to journalConference articlepeer-review

15 Citations (Scopus)


Since the start of the Large Helical Device (LHD) experiment, various attempts have been made to achieve improved plasma performance in LHD [A. Iiyoshi et al., Nucl. Fusion 39, 1245 (1999)]. Recently, an inward-shifted configuration with a magnetic axis position Rax of 3.6 m has been found to exhibit much better plasma performance than the standard configuration with Rax of 3.75 m. A factor of 1.6 enhancement of energy confinement time was achieved over the International Stellarator Scaling 95. This configuration has been predicted to have unfavorable magnetohydrodynamic (MHD) properties, based on linear theory, even though it has significantly better particle-orbit properties, and hence lower neoclassical transport loss. However, no serious confinement degradation due to the MHD activities was observed, resolving favorably the potential conflict between stability and confinement at least up to the realized volume-averaged beta 〈β〉 of 2.4%. An improved radial profile of electron temperature was also achieved in the configuration with magnetic islands, minimized by an external perturbation coil system for the Local Island Divertor (LID). The LID has been proposed for remarkable improvement of plasma confinement like the high (H) mode in tokamaks, and the LID function was suggested in limiter experiments.

Original languageEnglish
Pages (from-to)2002-2008
Number of pages7
JournalPhysics of Plasmas
Issue number5 II
Publication statusPublished - May 2001
Externally publishedYes
Event42nd Annual Meeting of the APS Division of Plasma Physics - Quebec, Que, Canada
Duration: Oct 23 2000Oct 27 2000

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics


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