Basic Hydrodynamics of Richtmyer-Meshkov-type Growth and Oscillations in the ICF-Relevant Conditions

Abstract : In inertial confinement fusion (ICF), the possibility of ignition or high energy gain is largely determined by our ability to control the Rayleigh-Taylor (RT) instability growth in the target. The exponentially amplified RT perturbation eigenmodes are formed from all sources of the target and radiation non-uniformity in a process called seeding. This process involves a variety of physical mechanisms which are somewhat similar to the classical Richtmyer-Meshkov (RM) instability (in particular, most of them are active in the absence of acceleration), but differ from it in many ways. In the last decade, the radiographic diagnostic techniques have been developed that made direct observations of the RM-type effects in the ICF-relevant conditions possible. New experiments stimulated the advancement of the theory of the RM-type processes. The progress in the experimental and theoretical studies of such phenomena as classical RM instability in finite-thickness targets, re-shock and re-rarefaction of the RM-unstable material interfaces, ablative RM instability, feedout, and perturbation development associated with impulsive loading is reviewed.