Two-dimensional gas-dynamic model of laser ablation in an ambient gas

A two-step gas-dynamic model of laser ablation in an ambient gas atmosphere is proposed. The initial 1D stage is related to ablation plume formation and describes heating, melting and evaporation of the target, the target-vapour interaction in the boundary layer, and vapour dynamics. The final 2D stage is responsible for the formation of energy and angular distributions of the ablated material. These distributions are calculated assuming local thermodynamic equilibrium. Interaction between the vapour and ambient gas is taken into account by two-component gas-dynamic equations. Numerical analysis of laser ablation in ambient gas atmosphere revealed that both kinetic energy of ablated atoms and width of their angular distribution decrease with ambient pressure. Dynamics of ablated material expansion and its energy distribution are compared with the experiment. (C) 2000 Elsevier Science B.V. All rights reserved.