Stabilization of Resistive Wall Mode Due to Shear Alfvén Resonance in a Cylindrical Plasma with a Uniform Longitudinal Flow

Abstract

Resistive wall mode (RWM) is studied in a cylindrical plasma with a uniform longitudinal plasma flow. In order to simplify the analysis, two steps current profile model is employed with a constant current density jo for the inner region 0 < r < a 0 and a constant current density j 1 for the outer region a 0 < r < a. Also the resistive shell is assumed sufficiently thin. Current profiles from peaked ones to hollow ones are simulated by changing the ratio j 1 /j 0 . Based on the incompressible MHD model, it is shown that RWM can be stabilized by adjusting the resistive wall position, when the shear Alfven resonance appears inside the plasma column, with the increase of the uniform flow velocity. In this case the free energy destabilizing the RWM is absorbed in the plasma column through the shear Alfven resonance. However, except when the RWM is close to the marginal state without a plasma flow, the flow velocity for stabilization is comparable to the sound velocity.