Electron kinetic theory approach for picosecond laser pulse heating

Nonequilibrium heating occurs in a metallic substrate as the heating time a pproaches the electron-phonon energy relaxation time. In this case the Four ier heating model fails to predict the correct temperature rise in the surf ace vicinity of the substrate. Consequently, the heating process needs to b e examined at the microscopic level. In this study, laser picoseconds pulse heating of gold is considered. The governing transport equation is derived introducing an electron kinetic theory approach. The resulting high-order differential equation describing the energy transport is decomposed into tw o differential equations similar to those in the two-equation model. The pr edictions of the electron kinetic theory approach are compared with the two -equation model results for different values of the thermophysical properti es of the substrate. It is found that for particular values of mean-free pa th and the fraction of excess electron energy transfer to lattice site, bot h predictions are identical. Moreover, the material response to heating pul se is very sensitive as the values of the thermophysical properties of the substrate change.