针对快放电直线脉冲变压器驱动源初级储能开关，调节开关气压，进行相同自击穿电压下不同间隙长度的开关自击穿实验。通过监测自击穿电压分布规律变化，研究开关间隙长度对开关自击穿特性的影响。结果表明，当开关间隙长度较大时，电极表面粗糙度较小，表明电极烧蚀程度较低。开关间隙长度为6 mm时，开关自击穿电压分散性达到最小，自击穿电压分布符合高斯函数，间隙长度大于6 mm时自击穿电压分布符合极限函数。适当增加开关间隙长度使自击穿电压分布失去对称性，有利于开关在低欠压比下获得更好的静态性能。针对电极结构，选择开关间隙长度为6~9 mm时能够获得最佳的静态性能。初步分析，引起开关自击穿电压分布发生改变的原因是电场强度的改变对阴极电子发射产生了影响。

The switch used in FLTD primary energystoring system is chosen as the study object. A selfbreakdown experiment of the switches with different gap length has been done at the same breakdown voltage by changing the gap pressure. The influence of the gap length on the switch performance has been researched by observing the change of the breakdown voltage distribution. The experiment result shows that, the selfbreakdown voltage dispersion at 6 mm gap is the least. Breakdown voltage distribution with the gap length equal to or less than 6 mm is similar to Gauss distribution function and it is similar to extreme distribution function with the gap length larger than 6 mm. The switch with a long gap whose breakdown voltage distribution loses the symmetry has better static performance at low working ratio. According to the electrode structure used in this paper, the gap length should be chosen between 6 mm and 9 mm to get the best static performance. The reason for the change of breakdown voltage distribution is the alteration of the electric field influencing the electron emission on cathode.