Thermal analysis of metal ablation by means of femtosecond-to-nanosecond laser pulses

Based on double-temperature equation,the temperature field of metal ablation by means of femtosecond,picosecond and nanosecond laser pulses is numerically calculated with finite-difference method to describe different laser pulses ablation on metal surface.The derived results are compared with those obtained with the approximate analytical expressions and simplified equations.Then the application range scope of the different simplified equations and the reasonability of simplification are discussed.The relationship between the electron heat flux expression and the laser intensity is also analyzed.The calculation shows that the results of the simplified equations are consistent with the numerical calculation results obtained with the double-temperature equation.It is proved that the temperature of the lattice can be treated as a constant and the double-temperature equation reduces to the electron temperature equation for femtosecond scale laser pulses,the system should be described by a complete double-temperature equation for picosecond laser pulses,and that the electron and lattice temperature are equal and the model is reduced to a heat conduction equation during for nanosecond laser pulses.