Conceptual design of a Rayleigh–Taylor experiment to study bubble merger in two dimensions on NIF

A preliminary design of an experiment meant to investigate the evolution of multimode Rayleigh–Taylor instability (RT) is presented. This experiment is intended to provide a direct measurement of the two-dimensional bubble front evolution in the hydrodynamic regime. RT growth for the proposed design has been analyzed using one-dimensional direct numerical simulations in Hyades and models of self-similar behavior. The models predictions are compared to results obtained in two-dimensional Dafna numerical simulations, with good agreement. The proposed design assures a significant bubble-merging process (∼3–4 bubble merger generations). The design takes advantage of the National Ignition Facility (NIF) capabilities to provide a large enough laser spot area (∼0.5–1 cm2), along with a low-enough drive that preheat effects remain small.