Numerical simulations of ultrashort laser pulse ablation and plasma expansion in ambient air

Using a self-consistent one-dimensional Cartesian Lagrangian fluid code, we modeled the ultrashort laser pulse ablation of solid aluminum and the subs equent plasma expansion in ambient air. A laser fluence of approximately 10 J/cm(2) is considered. The code axial plasma temperature and density are s trongly inhomogeneous and the maximum radiation emission generally occurs i n the front of the plasma. The code average plasma temperature is in good a greement with the experiments for all times, while larger discrepancies wit h respect to the experiments are observed at late times for the plasma dens ity. Experimental results are in reasonable agreement with the condition of thermodynamic equilibrium, which is an important assumption in the model. (C) 2001 Elsevier Science B.V. All rights reserved.