绝缘片约束TIG电弧载流区的静电探针分析

为了认识绝缘片约束TIG电弧载流区形态及电流密度的变化,采用一种低扰动静电探针,在电弧轴向不同高度截面内测定悬浮探针电位及饱和离子电流,并对不同约束程度下电位电流波形进行对比分析.结果表明,绝缘片高于弧根时,电弧不会受到绝缘片的固壁约束作用;在绝缘片的约束作用下,载流区电位梯度增大,并在绝缘片约束方向上发生收缩;载流区电流密度和温度随绝缘片约束程度增加而增大,且在靠近电弧截面中心的区域内,电弧能量更加集中.

Electrostatic probe analysis of current-carrying region in constricting TIG arc with insulating sheet

The shape and current density of current-carrying region in constricting TIG arc with insulating sheet were analyzed by the low disturbance electrostatic probe. The floating potential and ion saturation current of probe were obtained separately in sections at different location along arc axial direction. The results show that the insulating sheet is over the arc root to make the arc not be constricted; with the constriction of insulating sheet, the current-carrying region pinches in the direction of constriction and potential gradient increase. When the constriction effect on arc root is intensified, both of the current density and temperature of current-carrying region are enhanced, and the heat is much moreconcentrated near the center of current-carrying region section.