Two-dimensional simulation of laser ablation with 235 nanosecond pulses

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 mu m spot size on the target, and pulse energy of 2.5 mJ leading to the intensity less than 10(9) W/cm(2). 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. (C) 2014 Laser Institute of America.