Design of real-time feedback control of vertical growth rate on EAST

Real-time feedback control of vertical growth rate, called gamma control, has been successfully applied to experimental advanced superconducting tokamak (EAST). In this paper, a new gamma control method is proposed to regulate the vertical growth rate, which is an estimator of plasma vertical instability. Thus, the gamma controller can be utilized to keep the tokamak plasma away from its unstable boundary. In this work, the main development process includes three steps: (1) real-time implementation of model-based vertical growth rate calculation, taking advantage of GPU parallel computing capability, (2) design of plasma shape response for dynamic shape control using a slight modification to the plasma boundary, and (3) development of a gamma control algorithm integrated into the EAST plasma control system (PCS). The gamma control was experimentally verified in the EAST 2019 experiment campaign. It is shown that the time evolution of the real-time vertical growth rate agrees with the target value, indicating that the real-time vertical growth rate can be regulated by gamma control.