Richtmyer-Meshkov Instability Modulation and Phase Transition in Gas Gun Experiments

The Richtmyer-Meshkov instability (RMI) occurs in elastic-plastic materials when a shock wave of sufficient pressure passes through a free surface often results in the creation of a narrow jet. We modulate RMI in gas gun experiments by modifying geometry and property of the free and impact surfaces of the copper, iron, and PMMA targets. The sample free surface has various shapes including sinusoidal and square waves, as well as V-shaped grooves, to generate the RMI jet. To modulate RMI jetting and investigate effects caused by phase transition, we explore various buffer designs such as channels, blocks, and graded density layers, on both the target and the impactor. The results of these experiments are consistent with hydrodynamic simulations. We will present velocity, optical and X-ray shadow graphic data from these experiments and provide direct comparisons with simulation results.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. We gratefully acknowledge the LLNL LDRD Program for partial funding support of this research under Project No. 21-SI-006.