Tearing mode stabilization by electron cyclotron resonant heating in EAST tokamak experiments

Tearing mode stabilization by electron cyclotron waves (ECWs) has been carried out inExperimental advanced superconductiong tokamak (EAST) experiments. The effects of theamount of ECW power and the radial wave deposition location on stabilizing the m/n = 2/1magnetic island are investigated, where m/n is the poloidal/toroidal mode number. The localheating is found to dominate the mode stabilization in these experiments. The stabilization ismore effective when the wave is deposited closer to the radial island location, as expected.With increasing ECW power, however, the tearing modes are not stabilized completely, andthe island width saturates at a finite width. Moreover, the island rotation frequency is found todecrease when the ECW deposition is close to the island such that the island width is reducedsignificantly. Using externally applied, rotating resonant magnetic perturbations to generateslowly rotating magnetic islands, the locked island stabilization by ECW has also beenstudied, and the island width reduction and nonuniform island rotation are observed when theisland’s center passes through the ECW deposition region

电子回旋波（electron cyclotron waves, ECWs）抑制撕裂模的相关实验已在实验先进超导托卡马克（Experimental Advanced Superconducting Tokamak, EAST）装置上开展。本研究探究了ECW功率大小与径向波沉积位置对抑制m/n=2/1磁岛的影响，其中m/n为极向/环向模数目。实验结果表明，局域加热是本实验中撕裂模稳定化的主导机制。正如预期，当波沉积位置更靠近径向磁岛位置时，稳定效果更为显著。然而，随着ECW功率提升，撕裂模无法被完全抑制，磁岛宽度会最终趋于一个有限定值。此外，当ECW沉积位置靠近磁岛且磁岛宽度被显著缩小时，观测到磁岛的旋转频率出现下降。本研究还通过外加旋转共振磁扰动（resonant magnetic perturbations）生成慢速旋转的磁岛，探究了ECW对锁定磁岛的稳定作用；当磁岛中心穿过ECW沉积区域时，观测到磁岛宽度减小且旋转呈现非均匀特性。