Measurement and Simulation of temperature field of metal targets under millisecond pulsed laser irradiation
|School||Nanjing University of Technology and Engineering|
|Course||Measuring Technology and Instruments|
|Keywords||thermal conductivity laser irradiation numerical simulation absorptioncoefficiem heat source|
In connection with the physical processes in the millisecond laser irradiation of metal targets, this paper analyzes the mechanism of interaction of the millisecond pulsed laser with metal targets and summaries some factors affect the irradiation effect of the irradiation proces s, and gives several infinite plane heat conduction equation and boundary conditions based on the heat conduction equation.According to the deduced heat conduction equation using Finite Element Analysis combined with experiment, we made a numerical simulation of the temperature of the-common metals copper, aluminum with the Me-lar-50laser parameters and the radial variation of aluminum, copper surface temperature with different energy of the same pulse width; the radial variation of aluminum, copper surface temperature with the same voltage of different pulse-width; the axial variation of aluminum, copper internal temperature field with different energy of the same pulse width; the axial variation of aluminum, copper internal temperature field with the same voltage of different pulse-width were analyzed and compared. When the pulse duration is1.5ms, the temperature change of aluminum and copper are very different, reflects the absorption coefficient affect the rise in temperature of the target, high absorption coefficient of the temperature to rise faster. By increasing the pulse width time when the energy falls below a specific value, can effectively improve the target temperature rise; when the energy exceeds a certain value by increasing the pulse width to enhance the effect of target temperature rise is not particularly obvious.After Me-lar-50laser irradiation, we conducted experiments under various situations using KLEIBER KMGA740pyrometer and got the experimental data of copper,aluminum surface temperature.Laser at the same voltage, although the pulse width of different energy,but the temperature rise after the initial trend is basically the same, the initial phase of the temperature rise curve is almost coincident, which is also consistent with the theoretical simulation results of the simulation. In the case of the same laser voltage and spot size, increasing the laser pulse can effectively enhance the effect of increase in temperature rise, large energy of a small pulse width for improving instantaneous maximum temperature after irradiation is relatively better.