Double-pulse laser ablation; Molecular dynamics; Hydrodynamics; Crater depth; Plume reheating;INDUCED BREAKDOWN SPECTROSCOPY; SIGNAL ENHANCEMENT; MOLECULAR-DYNAMICS; METAL TARGETS; SPALLATION; SINGLE

We elaborated two numerical methods, two-temperature hydrodynamics and hybrid two-temperature molecular dynamics, which take into account basic mechanisms of a metal target response to ultra short laser irradiation. The model used for the description of the electronic subsystem is identical for both approaches, while the ionic part is defined by an equation of state in hydrodynamics and by an interatomic potential in molecular dynamics. Since the phase diagram of the equation of state and corresponding potential match reasonably well, the dynamics of laser ablation obtained by both methods is quite similar. This correspondence can be considered as a first step towards the development of a self consistent combined model. Two important processes are highlighted in simulations of double-pulse ablation: (1) the crater depth decrease as a result of recoil flux formation in the nascent plume when the delay between the pulses increases; (2) the plume reheating by the second pulse that gives rise to two three-fold growth of the electron temperature with the delay varying from 0 to 200 ps. (C) 2016 Published by Elsevier B.V.