Model-Based Optimal Control of Core Kinetic+Magnetic Profiles and Scalar Plasma Properties in NSTX-U

H. Al Khawaldeh, B. Leard, S.T. Paruchuri, T. Rafiq, E. Schuster,

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

Spokane, WA, USA, October 17-21, 2022

Active control of key plasma properties will be necessary to achieve high-performance scenarios in NSTX-U. These scenarios, which are characterized by magnetohydrodynamic stability, improved confinement, and possible steady-state operation, rely on active shaping of the kinetic and magnetic profiles and/or active regulation of important scalar (integrated over space) properties. A response model based on the one-dimensional magnetic diffusion equation in combination with a zero-dimensional energy balance equation has been exploited in this work to synthesize some of the needed active control algorithms. The infinite dimensionality of the magnetic diffusion equation is reduced by spatial discretization and both equations are then linearized to obtain a response model for control synthesis. Model-based optimal control techniques are later used to synthesize controllers with a variety of control objectives, such as the simultaneous regulation of the safety factor profile and the plasma stored energy or the simultaneous regulation of the plasma internal inductance and the normalized beta. The controllers are tested in higher-fidelity (simulation models are more complex than those used for control synthesis) nonlinear simulations using the Control Oriented Transport SIMulator (COTSIM).

*Supported by the US DOE under DE-SC0021385