Study of hohlraum-driven shocks at Omega EP for dual-species, dynamic radiography.

Radiography of cm-scale dynamic objects is an important diagnostic tool for high energy density physics or high-explosives, where it is important to capture material evolution under extreme conditions at ns-scale times. By simultaneously using different probing species we believe that co-analysis of radiographic data can yield more information than from single species probing. A practical way to generate multi-species probes is with high-energy, high-intensity lasers. Our group has achieved radiography of a static object simultaneously using x-rays and protons at the Omega EP laser facility. We are working to extend these efforts to radiographing a dynamic object.

The beams at Omega EP that can be used to drive a dynamic object are in nearly the same plane and direction as one of the beams that generates one of the radiographic species, and orthogonal to the other. This geometry does not allow for symmetric views, so a hohlraum was designed as a driver to produce a vertical shock through a physics package. The hohlraum was driven by a 6.8 kJ, 4-ns long laser pulse, and the velocity of the shock moving through several physics packages was measured using VISAR (Velocity Interferometer System for Any Reflector). Here we present details of the design and the results of the analysis of the data using the Igor procedure written by Marius Millot and complementary 1D simulations using the LANL multi-physics code FLAG. Simultaneous radiography with two species of the dynamic event was captured recently and presented as well.