Implementation and Initial Testing of a Model Predictive Controller for Safety Factor Profile and Energy Regulation in the EAST Tokamak

The tokamak, a potential candidate for realizing nuclear fusion energy on Earth, uses strong magnetic fields to confine a hot ionized gas (plasma) in a toroidal vacuum chamber. The ability of tokamaks to run in high-performance modes of operation demands advanced control capabilities to regulate the spatial distribution (profile) of several plasma properties such as the safety factor q. A model predictive control (MPC) approach has been followed to further advance such control capabilities for the EAST tokamak. The proposed controllers have the capability of simultaneously regulating the q-profile and the plasma stored energy W by controlling the plasma current I-p, the individual powers of four neutral beam injectors (NBI1L, NBI1R, NBI2L, NBI2R), and the powers of two lower hybrid wave sources with different frequencies (2.45 GHz, 4.60 GHz). An active-set algorithm has been employed to solve the Quadratic Programming (QP) problem arising from the MPC formulation. Initial experimental tests of the MPC show that the real-time optimization is successfully carried out within the time constraints imposed by the dynamics of the plasma.