Design an arc suppression system for the Electromagnetic Pellet Injection System

Plasma disruption can cause serious damage to tokamak devices, so disruption mitigation systems are indispensable to protect tokamak. Currently, disruption mitigation requires a high-speed impurity injection system to meet the demand due to the short disruption warning time (the minimum warning time is only 10 ms). The Electromagnetic Pellet Injection System (EMPI) can meet the requirements of short response time and high injection speed. However, arcing due to the characteristics of the EMPI itself will affect the effect of disruption mitigation. Arc suppression can increase the lifetime of this system, avoid the negative impact of impurities due to arc ablation on disruption mitigation. In this work, the influence of passive and active technology on the arc suppression effect and deceleration efficiency is explored. The typical parameter of a passive arc suppressor is Ls1=8.0 mu H, Rs1=7.5m omega. The active arc suppressor can improve its performance by minimizing the inductance Ls2 and resistance Rs2. Based on the simulation results, passive and active arc suppressors were designed, and an experimental platform was developed to test the performance. The arc suppression inductance value of the passive arc suppressor is fixed at Ls1=7.89 mu H. The passive arc suppression effect is best when the arc suppression resistance value is Rs1=6m omega, which can reduce the voltage value by about 60%.