Pulsed laser heating - Fourier and electron kinetic theory approaches

Abstract

Laser surface pulse heating of engineering metals is in demand in the metal industry and investigation into laser pulse heating becomes fruitful in this regard. Application of Fourier theory to heat conduction due to high power laser irradiation may give closed form solution to the problem. On the other hand, the heat flux through a given plane depends on the electron energy distribution through the material and at the scale of distance required to examine the problem, the material can no longer be considered as being homogeneous continuum, therefore, errors may occur when considering the Fourier theory in laser heating process. The problem requires to be examined in the quantum field. The present study examines the pulse laser heating process when considering both Fourier conduction and electron-kinetic theory approaches. Analytical solution to Fourier conduction equation is obtained for intensity exponential pulses while numerical scheme is introduced to solve the heat transfer equation resulted from kinetic theory approach. It is found that both Fourier and electron kinetic theory approaches result in similar temperature profiles for the pulses having the same energy content. In the case of electron kinetic theory approach the rise time for surface temperature to reach the melting point is shorter than that obtained from the analytical solution.