Recent Developments in the DIII-D PCS for Integrated Plasma Control and Actuator

A. Pajares, W.P Wehner, E. Schuster, N. Eidietis, J. Barr, A. Welander, R. La Haye, A. Hyatt, J. Ferron, M. Walker, D. Humphreys

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

Portland, OR, USA, November 5-9, 2018

DIII-D experiments have tested new modifications to the DIII-D Plasma Control System to assess the capability of simultaneously regulating different aspects of the plasma dynamics under the supervision of exception handling algorithms. A first experiment sought combined central safety-factor (q0) and normalized beta (βN) control with zero neutral-beam injection (NBI) torque. Whereas NBI was employed to regulate βN, electron-cyclotron heating & current drive (ECH&CD) was used to control q0. A second experiment showed the Off-Normal & Fault Response system’s capability to monitor the plasma state and assign the authority over the ECH&CD system either to the Profile Control category (for current profile + βN control) or to the Gyrotrons category (for NTM suppression). Actuator sharing strategies were utilized. Finally, control-oriented models for the q0, q95, toroidal rotation Wf, βN and line-averaged electron density evolutions have been developed. These models have been validated using DIII-D experimental data to support future control experiments on integrated plasma-scalar regulation. Based on such models, a robust, Lyapunov-based controller has been designed and tested in simulation for a DIII-D scenario.