Multivariable Model-based Shape Control for the National Spherical Torus Experiment (NSTX)
W. Shi, E. Schuster, M. L. Walker, D. A. Humphreys, D. Gates, E. Kolemen
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Chicago, Illinois, November 8-12, 2010
Abstract
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Because of the coupling between the different geometrical parameters,
multi-input-multi-output (MIMO) model-based shape controllers are
necessary to achieve the very stringent plasma shape requirements in
highly-efficient tokamaks. Leveraging the availability of rtEFIT, we
propose a robust model-based MIMO controller to provide real-time
shaping and position control of the plasma in NSTX. The proposed
controller is composed of three loops that transform the shape control
problem into a tracking problem. A singular value decomposition of the
plasma model is carried out to define the weights associated to the
tracking errors. The H∞ technique is used to minimize the tracking
errors and optimize input efforts. Computer simula- tion results
illustrate the performance of the robust shape controller, showing the
potential for improving the performance of present non-model-based
controllers.