Temperature measurements in a free burning arc

Spectroscopic analysis of a 100-A gas tungsten arc welding arc indicates an arc temperature of 11000K near the cathode, decreasing toward the anode to 80000K. At these temperatures, the argon gas is approximately 2 percent ionized, and the electron density and conductivity of the gas are sensitive to small changes in arc temperature. The arc temperature with a stationary molten anode is similar to that with a cooled anode. Photographs of the arc indicate an expanding plasma region with increased arc current. The axial temperature at the arc midplane follows the equation T = (7643 + 18.8 I)0K. (DLC)