ELM triggering by energetic particle driven mode in wall-stabilized high- plasmas

壁安定化された高ベータプラズマにおける高エネルギー粒子駆動モードによるELM誘発

松永 剛; 相羽 信行; 篠原 孝司; 朝倉 伸幸; 諫山 明彦; 大山 直幸; JT-60チーム

Matsunaga, Go; Aiba, Nobuyuki; Shinohara, Koji; Asakura, Nobuyuki; Isayama, Akihiko; Oyama, Naoyuki; JT-60 Team

In the JT-60U high- plasmas above the no-wall limit, a triggering of an edge localized mode (ELM) by an energetic particle (EP) driven mode has been observed. This EP-driven mode is thought to be driven by trapped EPs and it has been named EP driven wall mode (EWM) on JT-60U. When the EWM appears in an ELMy H-mode phase, ELM crashes are reproducibly synchronized with the EWM bursts. The EP-driven mode has a higher repetition frequency and less energy loss than those of the natural ELM. In order to trigger an ELM by the EP-driven mode, some conditions are thought to be needed, thus an EWM with large amplitude and growth rate, and marginal edge stability. In the scrape off layer region, several measurements indicate an ion loss induced by the Emote ion loss considered as the EP loss through the edge region can increase a local pressure gradient at the pedestal region, and then affect the edge stability.