X-RAY RADIOGRAPHIC IMAGING OF HYDRODYNAMIC PHENOMENA IN RADIATION-DRIVEN MATERIALS - SHOCK PROPAGATION, MATERIAL COMPRESSION, AND SHEAR-FLOW

One- and two-dimensional, time-resolved x-ray radiographic imaging at high photon energy (5-7 keV) is used to study shock propagation, mater ial motion and compression, and the effects of shear flow in solid den sity samples which are driven by x-ray ablation with the Nova laser. B y backlighting the samples with x rays and observing the increase in s ample areal density due to shock compression, the trajectories of stro ng shocks (approximately 40 Mbars) in flight are directly measured in solid density plastic samples. Doping a section of the samples with hi gh-Z material (Br) provides radiographic contrast, allowing a measurem ent of the shock-induced particle motion. Instability growth due to sh ear flow at an interface is investigated by imbedding a metal wire in a cylindrical plastic sample and launching a shock in the axial direct ion. Time-resolved radiographic measurements are made with either a sl it-imager coupled to an x-ray streak camera or a pinhole camera couple d to a gated microchannel plate detector, providing approximately 10 m um spatial and approximately 100 ps temporal resolution.