Effect of Joint and Gaps on Shock Propagation

摘要

National Ignition Facility targets, especially those made with material such as beryllium through which hydrogen doesn't permeate, may be made in sections and pieced together. Tolerances, chamfers, glue joints and fill tubes will form density mismatches which may lead to asymmetries in the capsule implosion. Such defects or perturbations also form non-linear initial conditions of interest for hydrodynamic evolution. The physics of this process is being studied in planar packages in indirect drive. Ablation driven shock waves, similar to those produced by the foot of the NIF pulse, are generated from Nova hohlraum radiation. Time resolved radiography is used to study the propagation of non-planar shock waves through a uniform material and across material interfaces in order to examine the stability of the interface. We will compare shocks propagating around 'gaps' and through 'joints' with two-dimensional numerical simulations in planar geometry.