电弧电场强度对激光等离子体引燃TIG电弧性能的影响

以峰值时间为10 ms的CO2脉冲激光进行TIG电弧的引弧试验,并采用高速摄像观察了激光等离子体引燃TIG电弧过程中的等离子体形态.结果表明,成功引燃TIG电弧的必要条件之一是必须使激光等离子体在电场作用下向阴极（钨极）方向偏移,致使激光等离子体与阴极接触产生热电子发射和场致发射并形成自持放电.在此基础上,为了探索激光等离子体引燃TIG电弧过程中电弧电场强度的影响,通过改变TIG电弧钨极形状、高度、激光与钨极相对位置等物理试验的方法,进一步分析了不同电场强度对CO2激光等离子体引燃TIG电弧引弧特性的影响规律.

Effect of electric-field intensity on laser induced plasma triggering arc discharge in TIG arc

A pulsed CO2 laser whose pulsed width is 10 ms was used to ignite the TIG arc,and a high-speed visual sensing system was established to detect the process of laser induced plasma triggering arc discharge and the shape of plasma.The experimental results show that,when the laser plasma contacts the cathode(tungsten rod) under action of electric field,which results in producing thermionic emission and field emission,the TIG arc forms self-maintaining discharge and is ignited.Furthermore,in order to investigate the influence of electric-field intensity in TIG arc on the performance of laser plasma triggering arc,the influence of main factors,such as tungsten electrode-tip shape,the height and the distance between electrode and laser etc.,on the performance for laser plasma triggering arc discharge were analyzed.