Plasma-driven Rayleigh-Taylor instabilities show unusual flow strength in tin*

The Rayleigh-Taylor instability can be used to measure flow strength in solids, where the growth of perturbations is mitigated by the material's resistance to plastic flow.$^{\mathrm{1}}$ This phenomenon has been exploited to investigate the strength of various materials at high strain rates, including Cu, Fe, Ta, and Pb.$^{\mathrm{2-4}}$ Here, a Be plasma, formed by three lasers of Omega EP, drives a ramped compression pulse into a rippled Sn target to an average pressure of 1 Mbar. The growth of a rippled Sn surface against less dense CH plastic is measured using face-on radiography. We find that the growth is significantly less than predicted by a simple Steinberg-Guinan strength model. 1.Park, H.-S. \textit{et al.} Grain-Size-Independent Plastic Flow at Ultrahigh Pressures and Strain Rates. \textit{Phys. Rev. Lett.} \textbf{114}, (2015). 2.Huntington, C. M. \textit{et al.} Investigating iron material strength up to 1 Mbar using Rayleigh-Taylor growth measurements. \textit{AIP Conf. Proc.} \textbf{1793}, 110007 (2017). 3.McNaney, J. M. \textit{et al.} Measurements of Rayleigh-Taylor growth in solid and liquid copper in the Mbar regime. in \textit{Bull. of the Am. Phys. Soc.} (2019). 4.Krygier, A. \textit{et al.} Extreme Hardening of Pb at High Pressure and Strain Rate. \textit{Phys. Rev. Lett.} \textbf{123}, (2019).