Subpicosecond laser ablation behavior of magnesium target and crater evolution: Molecular dynamics study and experimental validation

The micro-ablation processes and morphology evolution of ablative craters on single-crystal magnesium under subpicosecond laser irradiation are investigated by MD simulations and experiments. Simulation results exhibit that the main failure mode of single-crystal Mg film irradiated by low fluence and long width pulse laser is the ejection of surface atoms which have laser-induced high stress. But under high fluence and short width pulse laser irradiation, the main damage mechanism is nucleation fracture caused by stress wave reflection and superposition at the bottom of the film. In addition, Mg[0001] has higher pressure sensitivity and is more prone to ablation than Mg[1010].The evolution equation of crater depth was established by the multi-pulse laser ablation simulation and verified by experiments. The results show that, under multiple pulsed laser irradiation, not only crater depth increases linearly with the pulse number, but also the quadratic term and constant term of the fitted crater profile curve increase linearly.