IAEA Fusion Energy Conference 2010

Proceedings of the 23rd IAEA Fusion Energy Conference
Daejeon, 11-16 October 2010

Organized by the International Atomic Energy Agency
and hosted by the Government of the Republic of Korea


(EXS/5-3) Interactions between MHD Instabilities in the Wall-stabilized High-β Plasmas

G. Matsunaga1), N. Aiba1), K. Shinohara1), Y. Sakamoto1), M. Takechi1), T. Suzuki1), N. Asakura1), A. Isayama1), N. Oyama1), M. Yoshida1), K. Kamiya1), H. Urano1), T. Nakano1), Y. Kamada1), and the JT-60 Team
1) Japan Atomic Energy Agency, Naka 311-0193, Japan

Abstract.  In the JT-60U wall-stabilized high-βN plasmas, interactions between MHD instabilities have been observed. It is observed that an energetic particle driven wall mode (EWM) triggers an edge localized mode (ELM). When the EWM appears, type-I ELM crashes are synchronized with EWM bursts. The EWM-triggered ELMs have a higher frequency and less energy release than those of usual type-I ELMs. This interaction mainly occurs when the EWM with a large amplitude appears. In the SOL region, several measurements indicate ion losses induced by the EWM. Abrupt ion losses through the edge can increase as local pressure gradient at the pedestal that determines the edge stability. Moreover, another interaction that an EWM-triggered ELM excites marginal resistive wall mode (RWM) is observed. Just after the EWM-triggered ELM, an n = 1 distortion appears and decays soon. It is considered that an impact of the induced ELM can excite the marginally stable RWM.

Full paper and slides available (PDF)