利用高重频YAG激光作用在固体表面所产生的等离子体使工件和电极之间在电压远低于击穿阈值的条件下产生放电。实验结果显示 ,放电坑基本上呈火山坑形 ,既有单坑结构 ,也有多坑结构 ,其形貌受到放电波形、电源极性、放电介质等因素的影响。放电坑表面形貌的规律是 :①除了涂油时的阳极放电坑是单坑结构以外 ,其他条件下的放电坑都是复合多坑结构 ;②单坑结构呈火山坑形 ,坑底为圆弧形 ,熔凝物堆积在坑的边缘 ,多坑结构则是一个大的放电坑中有多个凸起尖峰

When a high repetitive rate YAG laser pulse acts on a meta surface used as onc of two electrodes,a plasma plume is profuced, and a discharge occurs between the electrodes at a voltage far below breakdown threshold.So the discharge is controlled by the laser pulse,It is shown that the discharge pit on the metal surface is crater-like,and the shape is determined by current waveeform,electrical polarity and medium between electrodes.The pattern of the discharge pit has the as following behaviior:1) In most cases,the pit is called multi-pit which means ir consists of many small pits or craters.In only one case,the pit is called simple pit which means the pit is one ctater,when the workpicce is anode and civered by a thiin iul film.2) Simple pit is like a volcanic crater,its bottom is atch-shaped with resolidified metal piled up on edge of pit.The multi-pit is a big pit with many small peaks in it.