Transition from L mode to high ion temperature mode in CHS heliotron/torsatron plasmas

K. Ida, M. Osakabe, K. Tanaka, T. Minami, S. Nishimura, S. Okamura, A. Fujisawa, K. Yamazaki, Y. Yoshimura, S. Kubo, R. Akiyama, D. S. Darrow, H. Idei, H. Iguchi, M. Isobe, S. Kado, T. Kondo, S. Lee, K. Matsuoka, S. MoritaI. Nomura, S. Ohdachi, M. Sasao, A. Shimizu, S. Takagi, C. Takahashi, S. Takayama, M. Takechi, K. Toi, K. Tsumori, T. Watari

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20 Citations (Scopus)

Abstract

A high ion temperature (Ti) mode is observed for neutral beam heated plasmas in the Compact Helical System (CHS) heliotron/torsatron. The high Ti mode plasma is characterized by a high central ion temperature, Ti(O), and is associated with a peaked electron density profile produced by neutral beam fuelling with low wall recycling. Transition from L mode to high Ti mode has been studied in CHS. Ti(0) in the high Ti mode discharges reaches 1 keV, which is 2.5 times higher than that in the L mode discharges. The ion thermal diffusivity is significantly reduced by a factor of more than 2-3 in the high Ti mode plasma. The ion loss cone is observed in neutral particle flux in the energy range 1-6 keV with a narrow range of pitch angle (90°±20°) in the high Ti mode. However, the degradation of ion energy confinement due to this loss cone is negligible.

Original languageEnglish
Pages (from-to)1649-1658
Number of pages10
JournalNuclear Fusion
Volume39
Issue numberSpecial Issu
DOIs
Publication statusPublished - 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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