Electron kinetic theory approach - one- and three-dimensional heating with pulsed laser

The modeling of laser heating process is essential for better understanding of the physical phenomena that occur as laser interacts with the workpiece. The Fourier heating model is not applicable for certain range of laser pulses. Consequently, new models of the laser heating process that eliminate this shortcoming of the Fourier heating model are needed. In the present study, a three-dimensional laser heating process based on the electron kinetic theory is introduced. The temperature profiles predicted from the kinetic theory are compared with the Fourier theory findings. The convergence of three-dimensional to one-dimensional heating is investigated. The electron kinetic theory predictions are also compared with the two-equation model results for a one-dimensional case. The study is extended to include two different laser pulse lengths. It is found that three-dimensional heating approaches its one-dimensional counterpart for the Gaussian intensity profile. As the pulse length shortens, the Fourier theory predicts higher temperatures in the surface region of the substrate as compared to that predicted from the electron kinetic theory. The temperature profiles obtained from the two-equation model and the kinetic theory are almost identical for the short pulse length employed in the present study.