Confinement characteristics of high-energy ions produced by ICRF heating in the large helical device

R. Kumazawa, K. Saito, Y. Torii, T. Mutoh, T. Seki, T. Watari, M. Osakabe, S. Murakami, M. Sasao, T. Watanabe, T. Yamamoto, T. Notake, N. Takeuchi, T. Saida, F. Shimpo, G. Nomura, M. Yokota, A. Kato, Y. Zao, H. OkadaM. Isobe, T. Ozaki, K. Narihara, Y. Nagayama, S. Inagaki, S. Morita, A. V. Krasilnikov, H. Idei, S. Kubo, K. Ohkubo, M. Sato, T. Shimozuma, Y. Yoshimura, K. Ikeda, K. Nagaoka, Y. Oka, Y. Takeiri, K. Tsumori, N. Ashikawa, M. Emoto, H. Funaba, M. Goto, K. Ida, T. Kobuchi, Y. Liang, S. Masuzaki, T. Minami, J. Miyazawa, T. Morisaki, S. Muto, Y. Nakamura, H. Nakanishi, K. Nishimura, N. Noda, S. Ohdachi, B. J. Peterson, A. Sagara, S. Sakakibara, R. Sakamoto, K. Sato, M. Shoji, H. Suzuki, K. Tanaka, K. Toi, T. Tokuzawa, K. Y. Watanabe, I. Yamada, S. Yamamoto, M. Yoshinuma, M. Yokoyama, K. Y. Watanabe, O. Kaneko, K. Kawahata, A. Komori, N. Ohyabu, H. Yamada, K. Yamazaki, S. Sudo, K. Matsuoka, Y. Hamada, O. Motojima, M. Fujiwara

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


The behaviour of high-energy ions accelerated by an ion cyclotron range of frequency (ICRF) electric field in the large helical device (LHD) is discussed. A better confinement performance of high-energy ions in the inward-shifted magnetic axis configuration was experimentally verified by measuring their energy spectrum and comparing it with the effective temperature determined by an electron slowing down process. In the standard magnetic axis configuration a saturation of the measured tail temperature was observed as the effective temperature was increased. The ratio between these two quantities is a measure of the quality of transfer efficiency from high-energy ions to a bulk plasma; when this efficiency was compared with Monte Carlo simulations the results agreed fairly well. The ratio of the stored energy of the high-energy ions to that of the bulk plasma was measured using an ICRF heating power modulation method; it was deduced from phase differences between total and bulk plasma stored energies and the modulated ICRF heating power. The measured high energy fraction agreed with that calculated using the injected ICRF heating power, the transfer efficiency determined in the experiment and the confinement scaling of the LHD plasma.

Original languageEnglish
Pages (from-to)1037-1050
Number of pages14
JournalPlasma Physics and Controlled Fusion
Issue number6
Publication statusPublished - Jun 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics


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