Development of a Robust Current Profile Feedback Controller in DIII-D
Y. Ou, E. Schuster, T. C. Luce, J. R. Ferron, M. L. Walker and D. A. Humphreys, T.A. Casper, W.H. Meyer
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Atlanta, Georgia, November 2-6, 2009
Abstract
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Setting up a suitable current profile has been demonstrated to be a
key condition for one candidate advanced tokamak scenario with
improved confinement and steady-state operation. A control-oriented
model of the current pro- file evolution in DIII-D was recently
developed for the plasma current ramp-up and early-flattop phases [1]
and used to synthesize open-loop control schemes tested both in
simulations and experiments [2]. A robust closed-loop controller is
proposed to regulate the current profile under the presence of model
uncertainties in the plasma resistivity. Using the POD/Galerkin
technique, the control-oriented PDE model is reformulated into a
low-dimensional ODE model that preserves the dominant dynamics, and
an H∞ controller is designed to minimize the regulation/tracking error.
A Corsica-based simulation assessment is presented.
[1] Y. Ou, et al., Fusion Engin. Design 82 (2007) 1153.
[2] Y. Ou, et al., Plasma Phys. Control. Fusion 50 (2008) 115001.