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