Simplified model to account for dependence of ablation parameters on temperature and phase of the ablated material

A simple theoretical model involving heat conduction equation that includes the temperature and phase dependence of material properties is presented. It describes the heating, vaporization, and physics of laser created plasma for aluminum targets in ambient gas. One-dimensional (ID) heat conduction equation is numerically solved to calculate ablation threshold, ablation depth and ablation onset time and to investigate the effect of energy, nature of surface and laser pulse shape. Results show a marked difference in ablation characteristics between with and without the temperature and phase dependence. The temperature profiles inside the target and ablated vapors at various irradiance and pulse shapes are generated. Depending on the pulse shape and irradiance a certain region inside the plume becomes critically dense and reflects the incoming laser. The distance at which this shielding occurs varies with laser intensity, with the increase in intensity the time of occurrence of shielding decreases. (C) 2003 Elsevier B.V. All rights reserved.