Modeling of thin film explosive boiling—surface evaporation and electron thermal conductivity effect

Abstract

Phase transition in a thin liquid Al film during its rapid (sub) nanosecond homogeneous heating is studied in the framework of molecular dynamics simulation with electron thermal conductivity. The results are compared with our previous results without consideration of electron thermal conductivity. Surface evaporation leads to surface cooling and this effect is more pronounced at lower heating rates in the case without electron thermal conductivity. For the case with electron thermal conductivity, the obtained results suggest the existence of four different regimes of film behavior depending on the heating rate: quasi-stationary surface evaporation regime with relatively small fluctuations at the low heating rates, explosive (volume) boiling which is initiated as growth of a single fluctuation, spinodal decomposition with many fluctuations growing simultaneously and supercritical fluid expansion with no pronounced fluctuations at the high heating rates. Our calculations also show that the duration and magnitude of the explosive boiling pressure pulse, which occurs at the threshold heating rate, are about 0.3 ns and one third of the critical pressure value, respectively. Information of this kind is needed to determine the optimal conditions for the measurement of the critical parameters of different materials in laser ablation experiments.