Abstract
New methods of triggering arc discharge using a plume and a plasma channel in a tungsten inert gas (TIG) arc welding system were demonstrated. The plume and the plasma channel were produced by pulsed laser focusing on an aluminum alloy plate (anode) under a tungsten rod (cathode). The plume was ejected from the laser focusing spot. The plasma channel was generated by gas breakdown in laser beam path. To avoid oxidation, argon (Ar) or helium (He) gas is usually used to shield the rod and molten metal of the workpiece from air. Therefore, formation of the plume and the plasma channel was performed in Ar or He gas. The disadvantages of the conventional triggering methods that require high-frequency generation, high-voltage pulse, or may cause sticking of the rod to the plate are removed in the new methods. The minimum laser energy required for the triggering using the plume and the plasma channel was investigated. Results in this study indicated that laser energy required for the triggering using the plume in Ar gas was lower than that in He gas and that laser energy required for the triggering using the plasma channel in Ar gas was lower than that using the plume in Ar gas. It was found that plasma channel formed by pulsed laser focusing in Ar gas is preferable for triggering arc discharge in the TIG arc welding system.
