Investigation of Richtmyer-Meshkov growth to study material viscosity at high pressures*

An accurate understanding of viscosity trends of materials approaching the warm dense matter regime are poorly constrained and yet are important for diverse problems including mantle dynamics of super-Earths. Mantle dynamics drive a wide range of processes that shape terrestrial planets and the viscosity of a planet’s mantle at relevant pressures (>100 GPa) is a critical transport property. A major constituent in the mantle of Earth is MgO and is thus predicted to be prevalent in the mantle of super-Earths.  This work focuses on novel experiments to measure the viscosity of MgO at lower mantle conditions. Experiments were performed on OMEGA-EP to measure the growth of a shocked interface. We present preliminary computational results and analysis. We use an in-house finite volume code with AMR and a stiffened equation of state to simulate the Richtmyer-Meshkov instability. We present features of the Richtmyer-Meshkov instability in materials with a stiffened equation of state that deviate from the impulsive model. Lastly, we discuss how the features of our simulations are used in the design and analysis of the experiments.