MHD modes destabilized by energetic ions on LHD

K. Toi, M. Isobe, M. Osakabe, F. Watanabe, K. Ogawa, S. Yamamoto, N. Nakajima, D. A. Spong, K. Ida, T. Ido, T. Ito, S. Morita, K. Nagaoka, K. Narihara, M. Nishiura, S. Ohdachi, S. Sakakibara, A. Shimizu, K. Tanaka, Y. TodoT. Tokuzawa, A. Weller

研究成果: ジャーナルへの寄稿学術誌査読

9 被引用数 (Scopus)

抄録

Energetic ion-driven magnetohydrodynamic instabilities such as Alfvén eigenmodes (AEs), energetic particle modes (EPMs), and their impacts on energetic ion confinement are being studied on the Large Helical Device (LHD). The magnetic configuration of this device is three dimensional and has negative magnetic shear over a whole radial region in the low-beta regime. Two types of toroidicity-induced Alfvén eigenmodes (TAEs) are typically observed in LHD plasmas that are heated by tangential neutral beam injection: One is localized in the plasma core region near a central TAE gap and the other is a global TAE having a radially extended eigenfunction. Core-localized TAEs with even and odd radial mode parities are often observed. The global TAE is usually observed in medium-to high-beta plasmas where broad regions with low magnetic shear are present. Helicity-induced Alfvén eigenmodes (HAEs), which exist in gaps unique to three-dimensional plasmas that have both toroidal and poloidal mode couplings, were detected for the first time. Recently, reversed magnetic shear Alfvén eigenmodes (RSAEs) having characteristic frequency sweeping were discovered in reversed magnetic shear (RS) plasmas produced by intense counterneutral beam current drive. In the RS plasma, the geodesic acoustic mode (GAM) excited by energetic ions, which is a global-type mode different from localized GAM excited by drift waves, was also detected for the first time in a helical plasma. Nonlinear couplings between RSAE and GAM modes and also between two TAEs were observed. Bursts of TAEs and EPMs often enhance radial transport and loss of energetic ions at low toroidal magnetic field (<0.75 T).

本文言語英語
ページ(範囲)186-193
ページ数8
ジャーナルFusion Science and Technology
58
1
DOI
出版ステータス出版済み - 2010
外部発表はい

!!!All Science Journal Classification (ASJC) codes

  • 土木構造工学
  • 核物理学および高エネルギー物理学
  • 原子力エネルギーおよび原子力工学
  • 材料科学一般
  • 機械工学

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