Physics-model-based Control of the Plasma Current Profile Dynamics for the Development and Sustainment of Advanced Scenarios in DIII-D

J.E. Barton, M.D. Boyer, W. Shi, W.P. Wehner, E. Schuster, J.R. Ferron, M.L. Walker, D.A. Humphreys, T.C. Luce, B.G. Penaflor, R.D. Johnson

IAEA Fusion Energy Conference

Saint Petersburg, Russia, October 13-18, 2014

Abstract

DIII-D experimental results are reported to demonstrate the potential of physics-model-based q-profile control for robust and reproducible sustainment of advanced scenarios. In the absence of feedback control, variability in wall conditions and plasma impurities, as well as drifts due to external disturbances, can limit the reproducibility of discharges with simple pre-programmed scenario trajectories. The control architecture utilized is a feedforward + feedback scheme where the feedforward commands are computed off-line and the feedback commands are computed on-line. Good agreement between experimental results and simulations demonstrates the accuracy of the models employed for physics-model-based control de- sign. Additionally, the results indicate the need for integrated q-profile and normalized beta (βN ) control to further enhance the ability to achieve robust scenario execution, which is a subject of ongoing work.