Spectroscopic measurement of temperatures in pulsed TIG welding arcs

Time resolved plasma temperatures in a pulsed tungsten-inert-gas (TIG) welding arc have been measured using optical emission spectroscopy. The peak and base pulse-averaged plasma temperatures both decrease with time after the arc ignition, and the plasma temperature decreases during the peak pulse period and increases during the base pulse period when the arc reaches the steady state. The decrease in the plasma temperature is associated with the increase in the cathode surface temperature and the decrease in the arc voltage and vice versa. The importance of the cathode surface temperature on the arc properties has been discussed.