Identification and Control of Magneto-Kinetic Response During Advanced Tokamak Scenarios in DIII-D

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

American Control Conference

Washington, DC, USA, June 17-19, 2013

Abstract

The paper proposes a model-based control approach for the coupled evolution of the poloidal magnetic flux profile and the normalized pressure ratio beta_N. The model is determined by a system identification method which is shown to sufficiently reproduce the plasma response to variations in particular actuators. Data for model identification is collected during the plasma current flattop in a large beta_N, high-confinement scenario (H-mode) with the actuators modulated in open loop. Using this data, a linear state-space plasma response model for the poloidal magnetic flux profile and beta_N dynamics around a plasma equilibrium state is identified. An optimal state feedback controller with integral action is designed for the purpose of simultaneous control of the poloidal flux profile and beta_N. Experimental results showing the performance of the proposed controller implemented in the DIII-D tokamak are presented.