Robust Control of the Electron Temperature Profile in DIII-D

Control of kinetic profiles is crucial to achieving a high level of plasma performance in tokamak plasmas. This requires feedback algorithms that use measurements of the plasma state in real time to determine the necessary actuator trajectories to reach the target profile. To that end, a robust control scheme has been developed for the electron temperature (T_e) profile on DIII-D. A linearized model of the dynamics of the electron temperature is derived from the heat transport equation, and the electron density profile is modeled as an uncertainty. The mixed-sensitivity H-infinity technique results in a controller that is capable of tracking a target profile near the linearization point for an expected range of uncertainty. The controller is then tested in closed-loop nonlinear simulations by using the Control Oriented Transport SIMulator (COTSIM). Preliminary predictive simulation results show that this controller is indeed capable of regulating the electron temperature profile with expected dynamic performance and robustness.

*Supported by the US DOE (DE-SC0010661, DE-FC02-04ER54698) and by the NSF GRFP (1842163).