Identification and control of magneto-kinetic response during advanced tokamak scenarios in DIII-D

The paper proposes a model-based control approach for the coupled evolution of the poloidal magnetic flux profile and the normalized pressure ratio β_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 β_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 β_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 β_N. Experimental results showing the performance of the proposed controller implemented in the DIII-D tokamak are presented.