Multiple Imaging Characteristics of Plasma in Laser-Tungsten Inert Gas Arc Hybrid Welding

The multi-imaging characteristics of CO2 laser-tungsten inert gas (TIG) arc hybrid welding plasma are observed by a high-speed camera with a self-made multi-imaging system. The research results show that three regions of the same plasma with decreasing area and increasing light intensity can be obtained at the same time by multiple imaging technology. The color of plasma gradually changes from blue and white to red in argon shielded hybrid welding, and the metal vapor plasma and argon arc plasma can't be distinguished. Since the second imaging, helium arc plasma is almost invisible, and the remaining metal plasma is still bright white. The less linear spectrum of helium radiation in the visible region (relatively weak light intensity) is the main reason why metal plasma can be distinguished clearly in helium protection; the metal plasma and shielding gas plasma are not fully mixed in hybrid welding. And the morphology of the metal plasma can be obvious influenced by the arc plasma.