Reversed-Field Pinch Contributions to Resistive Wall Mode Physics and Control

• Optimal feedback control of resistive-wall modes (RWM) is of common interest for toroidal fusionconcepts that use conducting walls for stabilization of ideal MHD modes. From the RWM control point of view,the RFP situation is in many respects similar to the advanced tokamak situation in the presence of very lowplasma rotation, where the most effective stabilizing mechanism is the feedback action of a set of active coils.Results from EXTRAP T2R (Sweden) and RFX-mod (Italy) RFP experiments have shown that full feedbackcontrol of multiple RWMs is possible and their deleterious effects can be completely suppressed. However it isnow important to optimize the RWM control systems both for the RFP and tokamak configuration for futureimplementation. Important aspects of optimization are effective mode identification and tracking capability,avoidance of the harmful effects of sideband modes (aliasing) in the control spectrum, minimized powerrequirements and robust controller stability. The paper describes collaborative work carried out on the two RFPexperiments. Controller models based on the mode harmonic control concept and on a state-space multipleinputmultiple-output intelligent shell concept are studied. Progress in development of optimal control schemesare presented both through experimental studies and simulations.

Ämnesord

NATURVETENSKAP  -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)

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