Mathematical Modeling For The Behaviors Of Laser Induced Plasma During CO₂ Laser Penetration Welding

In this paper, the generation mechanisms of the laser induced plasma and the factors that influenced the plasma were first summarized during CO2 laser penetration welding; Then the forms and the factors of the plasma that influenced the laser beam energy density were discussed. Lastly, on this basis, this influences of the plasma on the laser beam energy density were calculated.. On the one hand, by calculating the electron density field, the absorption coefficient and the refractive index of the laser induced plasma, the reasons for the metal plasma shielding were found to be not only the larger absorption but also smaller refractive index than those of the shielding gas plasma; and the case of He shielding gas was antipodal. On the other hand, by studying the energy density of the laser beam that penetrated through the plasma, Lensing effect of plasma was verified to be the major reason for the plasma shielding.