Study on the influence of side assisting gas on energy loss during CO2 laser welding based on 3D reconstruction

It is essential to acquire the electron temperature distribution of plasma plume to determine the laser energy loss caused by laser-induced plasma. In this paper, a set of synchronous high-speed cameras were positioned in different angles to obtain plasma images during CO2 laser welding process shielded by He-Ar mixed gas. The absorption coefficient and refractive index of incident laser was calculated based on the 3D distribution of laser-induced plasma. The results indicated that the temperature field of plasma core region was nonuniform while the temperature distribution was relatively smooth and uniform for plasma periphery portion. It was found that the shielding gas affected the 3D distribution of plasma, as well as the energy interaction between laser and base material. Laser energy loss caused by plasma increased with argon percentage in the shielding gas. Relatively, laser energy loss caused by refraction is slightly higher than that caused by absorption.