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, this new gamma control method is proposed to regulate vertical growth rate, which is an estimator of plasma vertical instability. So that gamma controller can be utilized to keep the tokamak plasma away from its unstable boundary. In this work, main development process includes three steps: 1) Real-time implementation of model-based vertical growth rate calculation taking advantage of GPU parallel computing capability in real time; 2) Design of plasma shape response for dynamic shape control using a slight modification to plasma boundary; 3) Development of gamma control algorithm integrated into EAST plasma control system (PCS). The experiment verification for gamma control is made in EAST 2019 experiment campaign. It is shown that time evolution of real-time vertical growth rate agrees with target value, meaning that real-time vertical growth rate can be regulated by gamma control.