Growth of interfacial and vortex core instabilities from equatorial defects in a hydrodynamic double-shell ICF analogue

Double-shell capsules are a promising concept for achieving volume ignition in inertial-confinement fusion experiments due to a low convergence ratio and lower predicted ignition temperatures than single-shell capsules. Unlike single-shell capsules, however, which are spherically symmetric other than the fill tube region, double-shell capsules (currently) require an equatorial assembly joint that is known to produce substantial asymmetry in the implosion due to the deposition of baroclinic vorticity by the imploding shock, thus resulting in the growth of perturbations. In this work, we use numerical simulations of a simplified hydrodynamic double-shell analogue to investigate the instabilities that develop at the assembly joint, with particular emphasis on the dynamics of the vortex cores that emerge from late-time interfacial instabilities. We characterize the growth of interfacial and vortex core instabilities and quantify the resultant mixing. We hypothesize that, depending on the properties of the assembly joint, the translation of vortex rings may play a substantial role in mixing, and that the Crow instability may be one mechanism for their generation.