Validating methods for modeling composition gradients in planar shock experiments

<p>An interface is Rayleigh–Taylor (RT) unstable when acceleration pushes a less dense material into a more dense one, and the growth of the instability is governed partly by the Atwood number gradient. Double-shell inertial confinement fusion capsules have a foam spacer layer pushing on an inner capsule composed of a beryllium tamper and high-Z inner shell, and so have RT unstable interfaces that require benchmarking. To this end, the results of a planar shock experiment with beryllium/tungsten targets are presented. One target had the normal bilayer construction of beryllium and tungsten in two distinct layers; the second target had the beryllium grading into tungsten with a quasi-exponential profile, motivated by the potential for reduced RT growth with the gradient profile. Simulations mimic the shock profiles for both targets and match the shock velocity to within 5%. These results validate the ability of our simulations to model double-shell capsules with bilayer or graded layer Be/W inner shells, which are needed to design future experiments at the National Ignition Facility.</p>. Authors: Bradley, P. A. (ORCID:0000000162296677); Rasmus, A. (ORCID:0000000193001034); Stark, D. J. (ORCID:0000000203642733); Loomis, E. N. (ORCID:0000000320951383); Palaniyappan, S. (ORCID:0000000163771206). DOE Contract: 89233218CNA000001. Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Adaptive mesh refinement; Equations of state; Flow instabilities; Fluid mechanics; Hydrodynamics; Interferometry; Lasers; Shock testing; Shock waves; Streak cameras