New Control Abilities on EAST PCS for Steady-State Operation

To accomplish experimental advanced supercon- ducting tokamak (EAST) physical targets, the plasma control system (PCS), adapted from DIII-D PCS and deployed on EAST in 2005, keeps in continuous development. Some new control abilities for steady-state operation have been achieved. To avoid the integrator linear drift in long pulse discharge, the linear rate for each integrator channel is precalculated and used to decrease the effect of the acquired raw data during shots. Another strategy applied for long pulse operation is real-time data archiving using data segment technology of MDSplus, which provides the possibility to save all data in segments without increasing the computer memory or reducing the saving frequency. For plasma high-performance and noninductive operations, the plasma beta and loop voltage control was implemented in PCS. Using low hybrid wave, the control algorithm was successfully verified in 2016 EAST campaign. Besides, another two control algorithms are integrated to reduce the divertor heat flux. One is radiation power control, which is successfully feedback controlled by using divertor inert gas puffing and mid-plane supersonic molecular beam injection. The other is quasi-snowflake shape control using PEFIT/ISOFLUX, which shows significant heat load reduction to divertor target according to the experimental result. The present EAST PCS has become a huge system capable of long pulse, high-performance advanced plasma control operation, which is ready to demonstrate ITER-like control contents.