The feedout process: Rayleigh–Taylor and Richtmyer–Meshkov instabilities in uniform, radiation-driven foils

Observation of perturbation coupling between a Richtmyer–Meshkov-unstable interface on the cold surface of a radiatively-driven foil and the Rayleigh–Taylor-unstable hot surface is reported. For the 50 μm wavelength studied, the combination of pulse length and foils thickness was found to affect the strength of instability coupling. Thick (86 μm) foils with a 2.2 ns long pulse showed weak coupling between the two instabilities, while thin (35 μm) foils showed strong, fast coupling. An intermediate (50 μm) foil thickness with a cooler, 4.5 ns pulse showed a transition from weak to strong coupling during the pulse duration. Radiation-hydrodynamic simulations are in agreement with the experiments and provide insight into the coupling phenomenon.