Void Closure in Porous Materials Traversed by Strong Shocks*

Porous materials are widely used in high-energy-density physics (HEDP) experiments, and are also found in astrophysical systems such as asteroids. Simulations of strong shocks passing through these systems often assume that the porous material is a homogenous gas with an averaged density. Previous models of material behavior have focused on the compaction of the voids in the presence of a relatively weak shock (such as the P-α model) or for materials that are fairly low porosity (Mie-Grueisen models). Our works considers materials with high porosities, like those often used in HEDP targets, traversed by shocks that far exceed the compaction pressure for the voids. We explore when and how radiation from such shocks can heat the voids sufficiently to cause the pores to collapse prior to the arrival of the shock. Results and examples for carbon foams will be shown.