Robust Control of the Toroidal Rotation and Safety Factor Profiles in the DIII-D Tokamak
W. Shi, W. Wehner, E. Schuster, M. L. Walker, D. A. Humphreys
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Salt Lake City, Utah, USA, November 14-18, 2011
Abstract
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Because of the coupling between the different magnetic and kinetic
plasma profiles, multi-input- multi-output (MIMO) model-based
controllers are introduced to regulate the plasma rotation and safety
factor profiles around particular target profiles. The approach is
based on linear two-time-scale models identified from experimental data.
The inputs are separated into slow and fast components by a low-pass
filter that is incorporated into the overall plant. Then a singular
value decomposition (SVD) of the plasma model is carried out to decouple
the system and identify the most relevant control channels. Finally,
the H∞ technique is used to determine a stabilizing feedback controller
that minimizes the reference tracking errors and rejects disturbances
with minimal control energy. Computer simulation results illustrate the
performance of the robust profile controller, showing potential for
improved performance. Experi- mental results in DIII-D are also reported.