Ablated matter expansion and crater formation under the action of ultrashort laser pulse

The action of a subpicosecond laser pulse on a target made of an absorbing condensed substance is considered. The propagation of an electron heat conduction wave and the crystal lattice heating prior to the hydrodynamic expansion of the target are analyzed. In these initial interaction stages, a heated layer with a thickness of d T is formed at the target surface. The dependence of d T on the absorbed laser energy density F[J/cm2] is evaluated. The motion of ablated matter in the expansion stage is described using a numerical solution of the equations of gasdynamics and the results of molecular dynamics (MD) simulations. The MD simulations are performed using a large number (∼103) of parallel processors, which allows the number of model atoms to be increased up to a level (about 3.5 × 107) close to that encountered under real experimental conditions.