中文摘要：

采用扫描电子显微镜（SEM）观察了纳米Cu阴极在峰值电流为10A的小击穿电流下首击穿后的阴极表面烧蚀形貌，发现纳米Cu的阴极斑点从产生到熄灭期间的运动（即短程运动）并不是随机的，而是有一定取向的；进一步通过和常规Cu首击穿烧蚀形貌对比，分析了产生有向运动的原因。结果表明：纳米Cu阴极斑点的短程有向运动有利于电弧分散，细化晶粒是减轻烧蚀的一种途径。

英文摘要：

By using a Scanning Electron Microscope （SEM）, the tracks of cathode spots on the surface of nanocrystalline Cu cathode produced after the first discharge with peak current of 10 A was investigated. It is found that the movement of cathode spots is sub-directed rather than random. The reason is explained in comparison with conventional Cu. It is suggested that sub-directed walking of cathode spots on the surface of nanocrystalline Cu is beneficial to the diffusion of cathode spots which is responsible for cathode erosion.