介质表面高功率微波击穿中释气现象的数值模拟研究

建立了一个简单的高功率微波(HPM)介质表面击穿释气模型,并采用PIC(partiele-in-cell)-MCC(Monte Carlo collisions)方法,通过自行编写的介质表面击穿数值模拟程序对不同释气条件下的介质表面HPM击穿过程进行了数值模拟研究,得到了击穿过程中电子数量等的时间图像和不同释气速度下的击穿延迟时间.模拟结果表明,对于具有一定时间宽度的HPM脉冲,当介质表面气体脱附速度较小时,由于介质表面气体层形成太慢而不会发生击穿;只有当脱附速度大于一定值时,击穿才会发生且击穿延迟时间在一定范围内随着脱附速度的增加而缩短.最后,将数值模拟得到的介质表面HPM击穿数据,与单极性表面击穿的实验诊断图像进行了对比,两者的发展趋势符合很好. 关键词： 释气现象 介质表面击穿 高功率微波 数值模拟

Numerical simulation of outgassing in the breakdown on dielectric surface irradiated by high power microwave

A simple outgassing model for dielectric surface breakdown due to the high power microwave (HPM) irradiation was establised. By using the PIC (particle-in-cell)-MCC(Monto Carlo collisions) method, the numerical simulation program of the dielectrics surface breakdown was developed, and the simulation of breakdown for different outgassing speeds was performed. The temporal evolution of the electron number and delay time of the process of breakdown in the case of different outgassing speeds were obtained. The numerical results show that when the speed of outgassing is small, the breakdown does not occur for an HPM pulse of a given duration, because the formation of the gas layer on the dielectric surface is slow. When the speed of outgassing is greater than a certain value, the breakdown occurs and the breakdown delay time shortens with the gas desorption rate increasing in a certain range. Finally, the numerical simulation results were compared with the experimental results of the direct current dielectric surface breakdown, and the trends of their development agree very well.