Self-consistent treatment of stabilization of resistive wall instabilities in reversed field pinches by radio-frequency waves

Abstract

Stabilization of resistive wall magnetohydrodynamic (MHD) instabilities by the force applied by injected radio-frequency (rf) waves is investigated, including the self-consistent effect of the MHD perturbation upon the rf waves in the plasma. This effect leads to the generation of Alfvénic disturbances at the frequency of the rf waves and at the wavelength (in the magnetic surface) of the MHD instability. Stabilization of the ideal external kink instability in the reversed field pinch is considered. If the self-consistent response is neglected, rf waves are confined to the thin vacuum and edge regions, and provide a restoring force which stabilizes the resistive wall instability at moderate rf wave amplitude. However, the generation of Alfvén disturbances causes the rf waves to penetrate deeply into the plasma, eliminating the stabilization.