Prevention of mode coupling by external applied resonant magnetic perturbation on the J-TEXT tokamak

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First Author:Ying He

Correspondence Author:Nengchao Wang,Da Li

Journal:Plasma Phys. Control. Fusion

Volume:65

Issue:6

Page Number:065011

DOI number:10.1088/1361-6587/acd20f

Date of Publication:2023-05-11

Abstract:Toroidal coupling between m/n = 2/1 and m/n = 3/1 modes frequently occurs in the J-TEXT, where m (n) is the poloidal (toroidal) mode number. These coupled modes destabilize each other, leading to confinement degradation and even triggering a major disruption. This paper presents two control strategies for preventing the mode coupling through the application of a proper static resonant magnetic perturbation (RMP) field. Experimental results demonstrate that moderate 2/1 RMP can suppress the small, rotating 2/1 mode thus prevent coupling between the 2/1 and 3/1 modes. The 3/1 static RMP can excite a large 3/1 locked island while leave the small 2/1 mode rotating at 8 kHz. Enlarging the frequency difference between 2/1 and 3/1 modes makes mode coupling more difficult. Both strategies can break the frequency coupling condition between the 2/1 and 3/1 modes, and hence avoid coupling and mutual destabilizing.

Links to published journals:https://doi.org/10.1088/1361-6587/acd20f