Evolution of perturbed interfaces subjected to transient accelerations*

In phenomena ranging from the expulsion of stellar core elements during supernova explosions to the degradation of the ignition hot spot during inertial confinement fusion implosions, interfaces separating plasmas of different densities undergo large, transient accelerations. Depending on the respective signs of the acceleration and density gradient, interfacial perturbations may be Rayleigh-Taylor unstable and thus experience significant growth. Although Rayleigh-Taylor analysis is well established for small-amplitude, incompressible, and constant-acceleration situations, predicting perturbation growth when departing from these conditions is more challenging. Our objective is to investigate interfacial perturbation growth driven by transient accelerations with substantial density changes. Analysis based on one-dimensional gas dynamics is used to quantify the acceleration and dilatation experienced by such interfaces, which are incorporated into one-dimensional models to characterize perturbation growth at early and late times. The modeling results are compared to simulations using an in-house, high-order accurate hydrodynamics code.