Simulation of ultrashort double pulse laser ablation of metals

We perform a hydrodynamic simulation of laser ablation of metals to explain the results of recent experiments with subpicosecond double pulses (2 x 2 J/cm(2)). In the experiments, the time delay tau(del) between the pulses varies from 0.1 ps to 200 ps. When the delay is much shorter than the electron-ion relaxation time tau(ei) (tau(delay) << tau(ei)) the crater depth is the same as for a single pulse of energy 4 J/cm(2). For the intermediate delays (tau(delay) similar to tau(ei)) the crater depth monotonically drops. For the long delay tau(delay) >> tau(ei) the crater depth corresponds to that obtained with a single pulse. The results of the hydrodynamic two-temperature simulations performed with realistic absorption and multiphase equation of state explain the observed behavior.