Experimental results of tantalum material strength at high pressure and high strain rate

Abstract

We are studying material strength at high pressures (>1 Mbar) and high strain rates (10 6 -10 8 sec -1 ) in Ta using the Omega laser. The Ta sample is maintained well below the melt temperature using a quasi-isentropic ramped drive based on a reservoir-gap-sample configuration. The strength is inferred from measurements of the growth of pre-imposed sinusoidal ripples on the sample via the Rayleigh-Taylor (RT) instability. The material strength can greatly suppress RT growth rate via an effective lattice viscosity (H. S. Park, et al., Phys. Rev. Lett. 104, 135504 (2010)). Our recent experiments measure the Ta RT growth in face-on radiography configuration. We find that the recently developed multi-scale dynamic material strength model matches our measured Ta RT strength data well, whereas the other constituent strength models disagree with our experimental observations.