LASERS IN ENGINEERING

Laser short-pulse heating of metallic surfaces results in the thermal separation of electron and lattice sub-systems. In this case, the electron temperature well in excess of the lattice site temperature results. The process is concerned in the thermal coupling of two sub-systems and the resultant energy transport equation becomes hyperbolic for the timescales of time and space considered. In the present study, analytical solutions for electron and lattice site temperatures are obtained using a perturbation method. In the analysis, a gold film is used and the laser pulse intensity is varied exponentially. The absorption mechanism is assumed to follow an exponential decay within the absorption depth of the substrate material. It is found, that temporal behaviour of the electron temperature is similar to that corresponding to the laser pulse intensity, provided that both curves have different temporal gradients. The electron temperature decays wheas the lattice site temperature increases continuously with time