Controlling X-Ray Flux in Hohlraums Using Burn-through Barriers

A technique for controlling X-ray flux in hohlraums is presented. In Indirect Drive Inertial Confinement Fusion (ICF) the soft X-rays arriving at the spherical fuel capsule are required to have a specific temporal profile and high spatial uniformity in order to adequately compress and ignite the fuel. Conventionally this is achieved by modifying the external driver, the hohlraum geometry, and the sites of interaction between the two. In this study a technique is demonstrated which may have utility in a number of scenarios, both related to ICF and otherwise, in which precise control over the X-ray flux and spatial uniformity are required. X-ray burn-through barriers situated within the hohlraum are shown to enable control of the flux flowing to an X-ray driven target. Control is achieved through the design of the barrier rather than by modification of the external driver. The concept is investigated using the one-dimensional (1-D) radiation hydrodynamics code HYADES in combination with a three-dimensional (3-D) time-dependent viewfactor code.