Suppression of error-field-induced magnetic islands by Alfven resonance effect in rotating plasmas

摘要

Error-field penetration is numerically studied in cylindrical tokamak geometry with plasma rotation. For a static error field, non-rotating magnetic islands are generated in the steady state. The penetrated perturbed magnetic flux is effectively reduced by the plasma rotation at small resistivity. Twin current sheets are formed at the Alfven resonance positions when the plasma rotation is fast enough, and thereby the error-field penetration is significantly changed. The electromagnetic torque increases linearly in the plasma rotation velocity especially at high rotation velocity and low resistivity regime, which agrees with previous theoretical prediction, although the linear scaling can be easily affected if the Alfven resonance is located close to the plasma edge. The electromagnetic torque in this regime does not depend on the resistivity. For high beta or small resistivity plasmas, the resultant volume-integrated electromagnetic torque, which brakes the plasma rotation, becomes maximum at very small, almost zero experimentally, rotation velocity.