托卡马克中等离子体破裂时的过电压研究

Overvoltage Protection for Plasma Disruption in Tokamak

为解决托卡马克放电中经常发生的等离子体破裂造成瞬间能量剧变在电源系统内的迅速传播而危及整流元件的安全且目前对破裂的预防和控制手段还不成熟的问题,对等离子体破裂时的情形进行了分析建模。电路参数的计算及MATLAB仿真发现,不同类型破裂时产生的过电压幅值和作用时间相差较大;电源系统中过电压波的传播及对整流元件影响的分析表明,一般保护难以兼顾不同类型破裂时产生的过电压冲击,因此介绍了针对等离子体破裂时产生的过电压的复合保护器,由非线性电阻和间隙组成。仿真结果和试验证明其效果良好。

The EAST Tokamak approach is considered as one of the most prospective means for research in nuclear fusion utilization. The poloidal fields of EAST includes 12 high power AC/DC converters which supply to 14 inter coupling superconducting coils respectively to generate and control the plasma, one non-linear unstable phenomenon called plasma disruption often take place in tokamak experiment, it is a sudden loss of confinement and transfer of plasma energy to the surrounding device and structure During a disruption, the instantaneous overvoltage due to energy collapse will be generated in the poloidal field power supply system which is closely coupled with. The overvoltage wave can flow through the entire power device and hence endanger the AC/DC converter components along with its quick transmission in pulse form and sometimes cause the rectifier components break down. Thus the feasible way now is to reduce the overvoltage damage effects. To cope with this problem, this paper discusses the overvoltage waveform based on mathematical model of plasma disruption and calculation with detailed circuit parameter and simulation with MATLAB program, it is found that the peak value and duration of overvoltage greatly vary from different disruption types. By analyzing the transmission on line and the effects on AC/DC converter components, it is found that it is unreliable with unitary protection for different disruption types because the disruption types in Tokamak experiments are diversified, in addition, a new method based on analysis and simulation above for overvoltage protection against plasma disruption is presented, which is comprised of non-linear resistor and clearance In this way, different disruption situations are considered and the simulation and experiment reveal that the protection effect is reliable.