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

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 (β_N) control with zero neutral-beam injection (NBI) torque. Whereas NBI was employed to regulate β_N, 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 + β_N control) or to the Gyrotrons category (for NTM suppression). Actuator sharing strategies were utilized. Finally, control-oriented models for the q₀, q₉₅, toroidal rotation W_f, β_N 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.