Radiation hydrodynamic effects in two beryllium plates with an idealized aluminum joint

A beryllium capsule formed from two hemispherical shells with a thin bond i s one possible ignition target for the National Ignition Facility [J. A. Pa isner , Laser Focus World 30, 75 (1994)] Nonuniformities in density, opacit y, and interface position at the joint between these hemishells will initia te two-dimensional (2-D) perturbations of the shock wave and material behin d the shock as the shock passes through the shell perpendicular to the join t width. Rarefaction of material flow behind the shock front can cause the interface between the shell and joint material to oscillate in position. Th e amplitude of these oscillations may be comparable to the joint width. The evolution of these perturbations is studied by numerically simulating shoc k passage through flat beryllium plates containing aluminum joints. Using t he MIMOSA-ND code [D. Sofronov , Vopr. At. Nauki Tekh., Ser: Mat. modelirov anie fizicheskih processov 2, 3 (1990)] two different cases are calculated- a wide (10 mu m) and a narrow (1 mu m) joint of aluminum between two 150 mu m long semiinfinite beryllium plates. Both cases showed good agreement wit h an analytic representation of the oscillation behavior. For the narrow jo int, a special technique allows the calculation of mixing between the joint and surrounding material caused by the Kelvin-Helmholtz instability. (C) 1 999 American Institute of Physics. [S1070-664X(99)02411-8].