Predictive Control of the Tokamak q Profile to Facilitate Reproducibility of High-qmin Steady-State Scenarios at DIII-D
W.P. Wehner, M. Lauret, E. Schuster, J.R. Ferron, C. Holcomb, T.C. Luce, D.A. Humphreys, M.L. Walker, B.G. Penaflor and R.D. Johnson
IEEE Multi-conference on Systems and Control
Buenos Aires, Argentina, September 19-22, 2016
Abstract
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We consider control of the q profile while simultaneously regulating
the plasma stored energy for the DIII-D tokamak. The main objective is
to improve the shot-to-shot reproducibility and facilitate the
accessibility of operating conditions that have steady-state potential,
i.e. plasmas with large non-inductive current drive fractions. At
DIII-D, non-inductive current sources including electron cyclotron
current drive (ECCD) and neutral beam injection (NBI) allow the
possibility of shaping the plasma current density distribution, and
therefore enabling control of the q profile. A feedback controller is
designed in a model predictive control framework to regulate the q
profile while simultaneously regulating the plasma stored energy. The
effectiveness of the control approach is demonstrated with experiments.