Numerical Simulation For The Temperature Field Of High Power Laser Heating Silicon Material Considering The Effects By Atmospheric Thermal Blooming

The interaction between laser and material is mainly the heating of the material by laser.It changes the state and structure of material,which is mainly characterized by thermal diffusion,thermal expansion and thermal stress.During the laser processing and heat treatment,we shouldn't only consider the feature and the absorption characteristics for laser power of the material,but also the change of the parameters of laser should be considered.Linear effect and nonlinear effect arethe only two factors which will influence high power laser's transmission in the atmosphere.The linear effect mainly influence by the absorption,scattering and atmospheric turbulence effects of atmospheric gas molecules.The nonlinear effect mainly depends on the influence of atmospheric heat blooming.In this paper,we make a numerical simulation study of the temperature field affected by the intense laser considered with the atmospheric thermal blooming effect.First,based on the scalar wave equation,Lorentz-Lorenz equation,and the hydrodynamic equations of momentum conservation and conservation of energy,we built a multi parameter physical model of the laser in the atmosphere under steady thermal halo.Then,we can simulate the influence of the transmission distance and initial power on the laser power density.Secondly,the laser intensity distribution of the distortion after the thermal halo effect is obtained by the formation of thermal halo effect.The effect of atmospheric thermal halo effect on the intensity distribution of laser light is studied under the different conditions of different atmospheric wind speed,the different transmission distance of lasers through the atmosphere and the different initial laser power of lasers.Finally,we used the finite element method(FEM)to obtainthe influence of the temperature distribution characteristics of the irradiated silicon material after the thermal halo effect by changing the values of the above parameters.The result shows that,the smaller the cross wind velocity and the stronger the thermal halo and the greater the distortion of the temperature distribution.The farther the laser propagation distance in the atmosphere,the stronger the heat halo and the greater the distortion of the temperature distribution.The bigger the initial power of laser propagation in the atmosphere,the stronger the thermal halo effect and the greater the temperature distortion of the material.The mechanism of thermal action of the intense laser through the atmospheric thermal halo effect and silicon material is preliminarily revealed.