Plastic flow and lattice dynamics experiments on shock and ramp loaded solid-state samples at extreme pressures and strain rates

Experiments are being done on high power lasers, such as the Omega laser at LLE and the Janus and NIF lasers at LLNL, to probe the solid-state plastic response of materials to high pressure (50-500 GPa), and very high strain rate deformation (1.e6 - 1.e10 1/s). Two classes of experiments will be described. Dynamic Laue diffraction experiments with a time resolution of $\sim$0.1 ns have been developed to probe the microscopic lattice response of single crystal samples to a strong shock. In particular, the time scale for the onset of plasticity and the rate of the 1D to 3D lattice relaxation are a direct measure of how rapidly dislocations can be generated and transported on sub-nanosecond time scales (lattice kinetics). Macroscopic plastic flows at high pressure and strain rate can be generated that span a few tens of nanoseconds by using the Rayleigh-Taylor or Richtmyer-Meshkov fluid instabilities. Results from both classes of experiments will be compared with simulations using various models of flow stress (strength), a multi-scale model for bcc strength, and with analytic theory, where possible.