Effect of high power CO2 and Yb:YAG laser radiation on the characteristics of TIG arc in atmospherical pressure argon and helium

• Arc characteristics will be affected by CO2 laser radiation, but not by YAG laser.
• CO2 laser affects arc characteristics in Ar significantly, but negligibly in He.
• Arc column expands and temperature rises occurred between laser position and anode.
• Effects of laser radiation on arc are attributed to the divergence of IB absorption.

The effects of laser radiation on the characteristics of the DC tungsten inert gas (TIG) arc were investigated by applying a high power slab CO2 laser and a Yb:YAG disc laser. Experiment results reveal that the arc voltage–current curve shifts downwards, the arc column expands, and the arc temperature rises while the high power CO2 laser beam vertically interacts with the TIG arc in argon. With the increase of the laser power, the voltage–current curve of the arc shifts downwards more significantly, and the closer the laser beam impingement on the arc to the cathode, the more the decrease in arc voltage. Moreover, the arc column expansion and the arc temperature rise occur mainly in the region between the laser beam incident position and the anode. However, the arc characteristics hardly change in the cases of the CO2 laser–helium arc and YAG laser–arc interactions. The reason is that the inverse Bremsstrahlung absorption coefficients are greatly different due to the different electron densities of the argon and helium arcs and the different wave lengths of CO2 and YAG lasers.