A theoretical approach for transient shock strengthening in high-energy-density laser compression experiments

Laser-compression experiments in high-energy-density systems typically utilize shock waves passing through a series of different materials to achieve a desired state of compression. In this study, a theoretical approach for strengthening such shock waves is examined. A method based on characteristics analysis is used to semi-analytically solve the problem of a shock passing through an intermediate region of non-uniform impedance between the experimental apparatus and the sample under study that increases the strength of the shock initially transmitted into the sample. It is shown that an exponential discretization of impedance in the intermediate region is the most efficient distribution for shock strengthening, leading to as much as a 25% increase in the pressure of the sample, significantly extending the range of achievable states in laser-driven dynamic compression experiments. The results of the analysis are verified via comparison to simulations performed with the HYADES hydrodynamics code.