低扰动静电探针对TIG电弧载流区的分析

Analysis of current-carrying region of TIG arc with low-disturbing electrostatic probe

为了认识TIG电弧载流区特性,确定载流区作用范围,采用一种低扰动静电探针,测定弧柱区轴向不同截面内的悬浮探针电位及偏置探针电流.结果表明,探针施加负偏置电压时,测得的离子饱和电流,其分布半径与电弧载流区半径相当;施加正偏置电压时,测量得到电子饱和电流,通过其分布半径可确定电弧半径;沿电弧轴向,载流区和电弧半径在阳极附近最大,并向阴极递减;电弧外围负离子区对探针的作用使悬浮探针电位降低,当探针裸露长度减小为5～6 mm时,该影响可忽略.

For understanding the character of TIG arc current-carrying region and ascertaining the range of current-carrying region,a low-disturbing electrostatic probe was developed to measure the potential of probe in floating condition and the current of probe with bias voltage in various sections along the axial direction of arc.The results show that it can get the ion saturated current by probe with negative bias voltage and the electron saturated current by probe with positive bias voltage.And then the half widths of the ion saturated current peak and the electron saturated current peak can represent the radius of current-carrying region and arc including peripheral negative ion region respectively.Both of the range of current-carrying region and arc increase into widest near anode from cathode to anode along the axial direction of arc.In addition,it is found that the effect on probe caused by peripheral negative ion region of arc can reduce the potential of probe in floating condition.This effect can be neglected when the exposed length is decreased into 5-6 mm.