脉冲YAG激光诱导放电击穿电压研究

为了研究激光诱导放电击穿的机理及在应用中减小击穿电压以降低加工风险,通过测得击穿电压随不同激光脉冲能量、极间距和工具电极（阴极）材料的关系,得出只有当单脉冲激光能量W≥0.15mJ,即激光在工件表面形成汽化的前提下才能有效放电击穿,并且当其它条件不变时,击穿电压U50随激光单脉冲能量的增大而减小。在电极材料为碳钢并保持不变的情况下,随着极间距的增大,U50升高,并随着单脉冲激光能量增大,U50升高的趋势渐缓。在其它条件不变下,改变工具电极材料（紫铜和石墨）,得出相对于石墨,使用紫铜时能有效地减小击穿电压。结果表明,增大激光单脉冲能量、减小极间距和使用逸出功小、低熔点的材料作为阴极时,能有效地减小击穿电压。

Investigation on the breakdown voltage by YAG pulse-laser guiding discharge

In this paper, the principle of laser discharge breakdown was discussed. According to the experiments, the relationships between the breakdown voltage (U50) and some factors were carried out, including the single-pulse energy, distance between the electrodes and the cathode materials. It is confirmed that the channel could be broken down, only on the base of forming the vaporization on the surface of the workpiece according to the laser, which means that the condition of the breakdown is the single-pulse energy W≥0.15mJ. The breakdown voltage would decrease with the increasing of the single-pulse energy. When the cathode material is 45# steel, U50 rises with the increase of the distance between the electrodes. And when increasing the single-pulse energy, the tread of this increasing will slow down obviously. Altering the cathode material with other conditions keep unchanged, we find out that the copper can reduce the U50, compared to graphite. In the testing conditions, the ways of reducing the U50 are increasing the single-pulse energy, decreasing the distance between the electrodes, and using smaller work function and lower melting point’s material as the cathode materials.