Current Profile Control for the Development of Consistent Discharges in DIII-D
W.P. Wehner, J.E. Barton, M.D. Boyer, E. Schuster, M.L. Walker, D.A. Humphreys, J.R. Ferron, T.C. Luce, B.G. Penaflor and R.D. Johnson
54th IEEE Conference on Decision and Control
Osaka, Japan, December 15-18, 2015
Abstract
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The number of tokamak discharges required to carry out meaningful
experiments can be significantly reduced by current profile control
in the early startup phase. The tokamak is a plasma-confinement device,
suitable for confining plasma at the requisite high temperature
necessary for initiating fusion. It is currently the most promising
device for realizing sustained fusion power generation at a commercial
grade level, though it is still in the experimental stage. Presently,
difficult to achieve plasma conditions, such as the shape of the
plasma current profile, are achieved in a trial and error fashion,
which can be a lengthy, wasteful process. In this work we make use of
model-based control techniques such as optimal feedforward control via
nonlinear programming and linearized feedback control to obtain a
target current profile at a specified time in low-confinement-mode
(L-mode) discharges. The effectiveness of the controller is
demonstrated experimentally.