Model-based Adaptive Control of Resistive Wall Modes in DIII-D
F. Xie, E. Schuster, D. Humphreys, M. Walker, Y. In
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Atlanta, Georgia, November 2-6, 2009
Abstract
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One of the major non-axisymmetric instabilities under study in the
DIII-D tokamak is the resistive wall mode (RWM), a form of plasma kink
instability whose growth rate is moderated by the influence of a
resistive wall. The General Atomics/FARTECH DIII-D/RWM dynamic model
represents the plasma surface as a toroidal current sheet and the wall
using an eigenmode approach. We report first on the experimental
validation and reconciliation of the proposed dynamic model, which is
a required step previous to the potential imple- mentation in the
Plasma Control System (PCS) of any model-based controller. The dynamic
model is then used to synthesize an adaptive control law for the
stabilization of the RWM under time-varying β conditions. Simulation
results are presented comparing the performance of the model-based
adaptive controller and present non- model-based PD controllers.