High precision compensation of plasma-coupling interferences for quench detection in the TF system of EAST

The variation of plasma current in superconducting tokamak discharge produces coupling interferences to the quench detection signal, which directly influences some critical issues, such as the reliability of quench detection and the security of superconducting magnets. The previous studies have found that the plasma-coupling inductance is time-varying owing to different plasma parameters, and the conventional decoupling compensation methods cannot effectively suppress the plasma-coupling interferences. This paper investigates the interference mechanism and suppression strategy of plasma on Toroidal Field (TF) magnet quench detection signal in the Experimental Advanced Superconducting Tokamak (EAST). Based on the feedback of TF current, plasma current and poloidal beta (βp), the inversion model of dynamic compensation coefficient is established to break the limitations of fixed coefficient on the compensation effectiveness, and achieve higher compensation precision of the plasma-coupling interferences. The experimental results indicate that the high precision compensation can not only suppress the residual interferences within 10 mV to further improve the Signal-to-Noise Ratio (SNR) and reliability of EAST TF quench detection, but also provide robust assurance for the secure and stable operation of future superconducting fusion reactors.