Feedthrough and suppression of Rayleigh–Taylor and Richtmyer–Meshkov instabilities

Feedthrough is the mechanism whereby a perturbation at one interface affects the evolution of perturbations at nearby interfaces. In this paper, we identify detrimental as well as beneficial effects of feedthrough in Rayleigh–Taylor (RT) and Richtmyer–Meshkov (RM) instabilities, and define and evaluate a feedthrough effectiveness factor FRT and FRM for each instability, finding that FRM > FRT. We determine what initial conditions are required to suppress RT and RM instabilities. Asymptotic decay calls for a carefully tuned shock at an interface just as it begins to accelerate in the opposite direction. We examine freeze out and mode killing, which rely on feedthrough and require nonzero perturbations in a specific ratio at the two interfaces of a finite-thickness shell. We also present model-based predictions on feedthrough in turbulent RT and RM mixing layers. These stabilizing mechanisms may be useful in hot spot as well as shock-ignition inertial confinement fusion designs explaining, perhaps, the unpredictability and variability in the performance of nominally identical capsules, and how a poorer quality capsule can outperform a higher-quality one, as apparently happened in the recently reported National Ignition Facility experiment N221204 [Abu-Shawareb et al., Phys. Rev. Lett. 132, 065102 (2024).]