Two-temperature hydrodynamics of laser-generated ultrashort shock waves in elasto-plastic solids

Femtosecond laser is a unique tool for generation of ultrashort shock waves producing very high deformation rates in target materials. It was recently found in experiment and molecular dynamics (MD) simulation that in splitting two-wave regime the elastic precursor can have longitudinal stress nearly 30 times as large as the conventional Hugoniot elastic limit. To study different regimes of shock-wave propagation including generation, interaction, and attenuation of leading super-elastic shock and following plastic wave, we developed an elasto-plastic model of solid combined with its EoS. Response of the model to ultrafast deposition of laser energy was simulated using our two-temperature hydrodynamics (2T-HD) code, which takes into account nonequilibrium of electron and ion subsystems and significant electron pressure at early stage of evolution. Results of 2T-HD simulation of plastic and super-elastic shock-wave propagation in Al and Ni at later stage are in good agreement with corresponding MD simulations. Simulation results are discussed and compared with recent experimental observations of high-speed super-elastic shock waves.