Stabilization of the Resistive Wall Mode by a Rotating Solid Conductor

C. Paz-Soldan, M. I. Brookhart, A. T. Eckhart, D. A. Hannum, C. C. Hegna, J. S. Sarff, and C. B. Forest

Phys. Rev. Lett. 107, 245001 – Published 5 December 2011

Abstract

Stabilization of the resistive wall mode (RWM) by high-speed differentially rotating conducting walls is demonstrated in the laboratory. To observe stabilization intrinsic azimuthal plasma rotation must be braked with error fields. Above a critical error field the RWM frequency discontinuously slows (locks) and fast growth subsequently occurs. Wall rotation is found to reduce the locked RWM saturated amplitude and growth rate, with both static (vacuum vessel) wall locked and slowly rotating RWMs observed depending on the alignment of wall to plasma rotation. At high wall rotation RWM onset is found to occur at larger plasma currents, thus increasing the RWM-stable operation window.