Rayleigh-Taylor strength measurements on Pb using indirect and direct drive at the National Ignition Facility

Laser-driven Rayleigh-Taylor (RT) experiments provide a unique tool for measuring the dynamic strength of materials under extreme conditions. At the National Ignition Facility (NIF), RT strength measurements have been performed using in-situ face-on x-ray radiography, which requires a large physics package (5 mm x 5 mm). Previously, to achieve uniform acceleration of such a large package, an indirect drive with a hohlraum was used. However, hohlraum physics add complexities in design such as low conversion efficiency, complex pulse shaping, and high target fabrication costs that can be addressed by a direct-drive platform. At NIF, 16 laser beams are incident on an ablator, and its drive uniformity is addressed by using 3.2 mm phase plates. Using this advanced platform, we investigate the RT growth of lead (Pb) and its strength at 300 GPa, by comparing experimental results with hydrodynamic simulations. Additionally, our results from this platform are compared with previously published results obtained using the indirect-drive platform [1]. This comparative analysis will provide valuable insights for designing future experiments probing material strength at extreme conditions.



[1] A. Krygier et al., Phys. Rev. Lett., 123 (2019) 205701.