Predictive Rotation Profile Control for the DIII-D Tokamak

W. Wehner, E. Schuster, M.D. Boyer, M.L. Walker, D.A. Humphreys

Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)

Milwaukee, WI, USA, October 23-27, 2017

Abstract

Control-oriented modeling and model-based control of the rotation profile are employed to build a suitable control capability for aiding rotation- related physics studies at DIII-D. To obtain a control-oriented model, a simplified version of the momentum balance equation is combined with empirical representa- tions of the momentum sources. The control approach is rooted in a Model Predictive Control (MPC) framework to regulate the rotation profile while satisfying constraints associated with the desired plasma stored energy and/or βN limit. Simple modifications allow for alternative control objectives, such as maximizing the plasma rotation while maintaining a specified input torque. Because the MPC approach can explicitly incorporate various types of constraints, this approach is well suited to a variety of control objectives, and therefore serves as a valuable tool for experimental physics studies. Closed-loop TRANSP simulations are presented to demonstrate the effectiveness of the control approach.