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Author: Shikui Cheng
Requested Type: Pre-Selected Invited
Submitted: 2018-02-05 00:24:37

Co-authors: P. Zhu, D. Banerjee

Contact Info:
University of Science and Technology of China
96, Jinzhai Road
Hefei, Anhui   230026

Abstract Text:
Toroidal flow is generally known to have stabilizing effects on high-n edge localized modes. Here n is the toroidal mode number. Our previous two-fluid MHD calculations find that such a stabilizing effect can be significantly enhanced by increasing the plasma density, which is consistent with observations from EAST experiments. However, in EAST experiments, the smaller sized ELMs preferably occur in presence of the counter-NBI drive where toroidal flows are in the negative (opposite to current) direction. In this work, the preferred flow direction for the enhanced stabilization of ELMs due to increased plasma density is studied in both limiter-typed and divertor-typed (EAST) tokamaks using the initial value code NIMROD. Preliminary calculation results show that in the presence of negative toroidal flow, higher plasma density provides stronger stabilizing effects on high-n ELMs in both types of tokamaks than in the presence of positive toroidal flow. The new finding may help explain why the ELM mitigation and suppression are more favourably achieved in the higher plasma density regime in presence of negative toroidal rotation during recent EAST experiments.