This paper studies microparticle-triggered breakdown phenomena in mm-scale nitrogen gaps based on theoretical analysis and numerical simulation. Secondary electron and field emission contributions are both considered when predicting the microparticle-initiated breakdown voltage. In the present model, the ionization coefficient of the microscale discharge is modified to recognize the significant reduction in the number of collisions that occurs when a microparticle is present. The theoretical analysis indicates that small particles have little influence on the gas-gap breakdown voltage unless field-emission effects are dominant. However, when large microparticles (radius 50 μm) are present, a significant decrease (more than 20%) in the minimum breakdown voltage can be observed regardless of the particle position in the gas gap. Therefore, one should endeavor to exclude large microparticles from the discharge process. A fluid model is then used to simulate the microparticle-initiated breakdown process in a gas switch. The microparticle radius is 10 μm and the distance between the microparticle and cathode is 1 μm. It can be found that the electrode–particle microdischarge generates regions of high-density plasma that finally trigger main-gap breakdown when a voltage of 2.5 kV–3.5 kV is applied. The calculated results are consistent with our theoretical analysis. This paper provides a quantitative research method to evaluate the influence of microparticles on gas breakdown and contributes to improving gas-switch insulation performance.

本文基于理论分析和数值模拟研究了毫米尺度氮间隙中微粒触发的击穿现象。在预测微粒引发的击穿电压时，都会考虑二次电子和场发射贡献。在本模型中，微尺度放电的电离系数被修改，以识别存在微粒时发生的碰撞次数的显着减少。理论分析表明，除非场发射效应占主导地位，否则小颗粒对气隙击穿电压几乎没有影响。然而，当大微粒（半径 50 μm) 存在时，无论气隙中的粒子位置如何，都可以观察到最小击穿电压的显着降低（超过 20%）。因此，应努力将大微粒排除在放电过程之外。然后使用流体模型来模拟气体开关中微粒引发的击穿过程。微粒半径为10 μ m，微粒与阴极之间的距离为1 μ米。可以发现，当施加 2.5 kV-3.5 kV 的电压时，电极-粒子微放电会产生高密度等离子体区域，最终触发主隙击穿。计算结果与我们的理论分析一致。本文提供了一种定量研究方法来评估微粒对气体击穿的影响，有助于提高气体开关绝缘性能。