Feedback Control of (2,1) Mode in q$_edge\sim$2 Tokamak Plasma in RFX-MOD
POSTER
Abstract
RFX-mod is the largest reversed field pinch (R=2 m, a=0.46 m, plasma current up to 2 MA). Thanks to its great flexibility it can be operated as a 150 kA, 1 s pulse length tokamak. The real-time control system, based on 192 coils independently driven, is used therefore to actively control MHD stability also in such tokamak plasmas. Preliminary results on active control of a current-driven (2,1) mode in a ohmic discharge with ramping current, in presence of a resistive shell, will be presented. In these discharges qedge ramps down to $\sim$2, when the (2,1) mode is destabilized and then feedback controlled. Feedback control allows for stable operation at q$_edge\sim$2, which would be otherwise not possible. Future plans for an extended tokamak campaign in 2011, dedicated to MHD active control and to the interaction of external non axis-symmetric magnetic with the plasma will also be discussed.