Atmospheric TIG Arc Diagnostics with a Low Disturbance Electrostatic Probe

Abstract

The use of electrostatic probe is available and simple in atmospheric TIG arc plasma diagnostic. Usually electrostatic probe takes disturbance in arc plasma due to sweeping motion. A low disturbance electrostatic probe was developed. This probe consisted of aluminum wire and moved through arc plasma along probe’s longitudinal direction to avoid sweeping motion. And the signal collected by this probe required Abel inversion to convert into the value per 1 mm probe length. With the application of the low disturbance probe in biased condition, ion saturation current density in various sections along the axial direction of TIG arc was obtained. The result shows that half width and peak value of ion saturation current density increase with the enhance of arc current; the radius of current-carrying area can be estimated by the half width of ion saturation current density; along the axial direction of TIG arc, the radius of current-carrying area change to the minimum near cathode.