Differential analysis for temperature distribution diagnostics of arc current-carrying region with low disturbance electrostatic probe

The differential analysis of low disturbance electrostatic probe was developed for local micro-measurement of TIG arc current-carrying region temperature. The temperature of TIG arc current-carrying region can be solved by ion saturation current of electrostatic probe. Furthermore the temperature distribution in different welding current and arc length can be also obtained. The results show that the variation trend of TIG arc current-carrying region temperature acquired by probe, which agrees with results of spectroscopic method; because of cool disturbance of probe, the temperature solved by ion saturation current is lower than temperature measured by spectroscopic method; the distribution width of TIG arc current-carrying region temperature reduce to the smallest near cathode along the arc axial direction; the temperature rises to maximum at the center of TIG arc current-carrying region cross section along arc radial direction, and there is a region with higher temperature near cathode; when the welding current decreased, the highest temperature of TIG arc current-carrying region would be lowered, meanwhile the current-carrying region temperature distribution width reduced, and then the high temperature region near cathode tends to shrink along arc axis; the longer arc length cause spatial range of charged particles enlarged, this gives arise to expand distribution width of TIG arc current-carrying region temperature, but the highest temperature of TIG arc current-region would not change.