Studies in the nonlinear evolution of the Rayleigh-Taylor and Richtmyer-Meshkov instabilities and their role in inertial confinement fusion

Hydrodynamic instabilities, such as the Rayleigh-Taylor and Richtmyer-Meshkov instabilities, play a central role when trying to achieve net thermonuclear fusion energy via the method of inertial confinement fusion (ICF). The development of hydrodynamic instabilities on both sides of the compressed shell may cause shell breakup and ignition failure. A newly developed statistical mechanics model describing the evolution of the turbulent mixing zone from an initial random perturbation is presented. The model will be shown to compare very well both with full numerical simulations and with experiments, performed using high power laser systems, and using shock tubes. Applying the model to typical ICF implosion conditions, an estimation of the maximum allowed target, in-flight aspect ratio as a function of equivalent surface roughness, will be derived.