Implementation and Testing of Model-based Optimal Control Strategies for q-profile Feedback Regulation in EAST*

Regulation of the q-profile via feedback control has been demonstrated experimentally in EAST for the first time ever. Extensive studies have shown that the q-profile, which is closely related to poloidal magnetic flux profile, is a key factor to achieving advanced tokamak operating scenarios that are characterized by improved confinement and possible steady-state operation. A general framework for real-time feedforward + feedback control of magnetic and kinetic plasma profiles has been implemented in the EAST Plasma Control System (PCS). Moreover, a first-principles-driven, control-oriented model of the poloidal magnetic flux profile evolution has been used to design a linear quadratic integral (LQI) controller for q-profile regulation in EAST. The proposed controller has been tested successfully in reference tracking and disturbance rejection experiments. These experiments constitute the first time ever a model-based, closed-loop, q-profile controller has been successfully implemented and tested in EAST.