Characterizing the evolution of mixing induced by Richtmyer–Meshkov instability in laser-driven reshock experiments

A reshock experiment for investigating the growth of material mixing driven by the Richtmyer–Meshkov instability has been conducted at the SG 100 kJ Laser Facility. We present a novel measurement technique for capturing the density field and the temporal evolution of the mixing width in rough aluminum subjected to reshocks under extreme conditions. The temporal evolution of the aluminum layer width obtained from backlit X-ray radiography demonstrates a sharp increase in width caused by reshocks, and simulations using the BHR-2 turbulent mixing model show excellent agreement with the measured aluminum layer width. Moreover, by utilizing a quasi-monochromatic X-ray imaging system at 5.2 keV, based on Bragg reflection from a spherically curved quartz crystal, we demonstrate direct quantification of the aluminum density field in mixed regions for the first time in a indirectly driven reshock experiment. The deviation between the calculated and actual density values is significantly less than 10% when the density of the aluminum region is below 0.7 g/cm3. The density field provides further information about variable-density turbulent mixing, which improves the constraints on simulations and enhances predictive capabilities for inertial confinement fusion target design and astrophysical shock scenarios.