Plasma and Fusion Research

Volume 19, 1402001 (2024)

Regular Articles

Suppression of "Edge MHD Instability of LHD" by External RMP
Shu ITO1), Kiyomasa WATANABE1,2), Yuki TAKEMURA2,3), Satoru SAKAKIBARA2,3) and Sadao MASAMUNE4)
Nagoya University, Graduate School of Engineering, Chikusa, Nagoya 464-8603, Japan
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu 509-5292, Japan
SOKENDAI (The Graduate University for Advanced Studies), Toki, Gifu 509-5292, Japan
Chubu University, Graduate School of Engineering, Kasugai, Aichi 487-8501, Japan
(Received 18 October 2023 / Accepted 20 November 2023 / Published 8 February 2024)


We experimentally investigate the effect of external resonant magnetic perturbation (RMP) on "Edge MHD instability", which is observed in a discharge with relatively low magnetic Reynolds number and middle beta in the Large Helical Device (LHD) and leads to minor collapse (rapid degradation of volum-averaged beta value by 10%). When the external RMP is small, the instability is continuously observed in a discharge, and the fluctuation amplitude decreases a little with the increment of the RMP. When the RMP is large enough, the appearance of the instability becomes intermittent, and the fluctuation amplitude rapidly decreases with the increment of the RMP. Moreover, the confinement performance degraded by the instability also recovers when the intermittent instability appears.


LHD, MHD instability, RMP, magnetic confinement, helical plasma

DOI: 10.1585/pfr.19.1402001


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