Physical characteristics of striking arc

The striking arc of TIG touch was observed through the spectral diagnosis system. The changing phenomenon of main ionized element that provided the electrons in striking arc was found. The metallic element was the main contributor to provide the electrons at the beginning of the discharging, and then the excited shielding gas element replaced the metallic element. The electron density during the period of the arc starting was calculated by the Stark-broadened line of Hα. Through the discussion with the repeatability in relaxation phenomenon, the statistical regularity in the arc starting process was analyzed. The similar rules as above were observed via the comparison with the laser-assisted arc starting experiments and the MIG arc starting experiments. It laid the basis for further establishing the physical modeling in different stages of the striking arc and exploration for the new modes of welding arc starting.