Two-dimensional simulation of laser ablation with 235 nanosecond pulses

Abstract

A two-dimensional thermal model of nanosecond pulsed laser ablation is developed to describe the physical processes, the plasma absorption, the crater profile, and the temperature distribution on a gold target and below the surface. The surface temperature and the plasma plume are coupled to the target through the Knudsen layer at the target–vapor interface. The simulation results of crater shape have been compared with the experimental outcomes obtained by a pulsed Nd:YAG laser having 1064 nm wavelength, 235 ns duration, 70 μm spot size on the target, and pulse energy of 2.5 mJ leading to the intensity less than 109 W/cm2. According to the model results the material removal process continues for a long time after the end of pulse irradiation, about 1200 ns after the beginning of the laser pulse irradiance. This model is valid when the phase explosion does not occur; it means that the target surface temperature is less than the critical value.