Experimental Design for Late Time Multimode Rayleigh-Taylor Instability with Controlled ablation effects

The asymptotic evolution of the Rayleigh-Taylor instability (RTI) is self-similar. Multimode RTI evolves when a supernova (SN) explodes onto the circumstellar medium (CSM). In the classical RTI (CRTI) case, the late time evolution is dominated by the bubble merger mechanism and independent of the initial perturbation. On the contrary, in the ablative RTI (ARTI) case, the evolution is dominated by the bubble competition mechanism and depends on the initial perturbation. This qualitative difference between these mechanisms can impact the mix width at late times.

It was observed in a previous experiment on the national ignition facility (NIF) that high energy fluxes can alter the evolution of RTI in the single mode case. In this work we present a new platform on NIF to study this effect on the self-similar multimode case. The SN ejecta and the CSM are simulated by a dense material (plastic) and a light material (foam), respectively. In a series of shots, we can adjust the foam properties (opacity, density) and control the amount of radiation flux, which originated at the foam and ablates the plastic. We designed a direct drive and face-on radiography for measuring the bubble size statistics and can be compared to the theoretical predictions for bubble merger/competition mechanisms.