A study of the radiation of a Nd:YAG laser–MIG hybrid plasma

To study the coupling of a Nd:YAG laser beam and a MIG arc with the spectrum of the plasma, a new hollow probe method is used to collect radiation from specific points within the arc plasma. With the probe, the spatial distributions of the MIG arc radiation with and without the Nd:YAG laser hybrid plasma are collected and analyzed by a fiber spectrometer. Through analysis of the spectrum, radiation in the ultraviolet (Fe II dominated), visible (Fe I dominated) and infra (Ar I dominated) spectral zones are acquired for comparison of the difference between the MIG and Laser–MIG hybrid welding processes. The electronic temperature is calculated using the Boltzmann plot method and the electronic density is calculated using the Stark broadening method. The results show that the Laser–MIG hybrid welding processes cause the plasma energy to focus on the center of the welding arc and approach the welding pool. An ionizing duct abundant with Fe ions will be formed near the position of the impinging laser beam, which makes the welding arc stable. The electronic temperature of the Laser–MIG hybrid welding arc is a little higher than that of the MIG. The electronic density of Laser–MIG hybrid welding is higher than that of the MIG.