Quantitative methods for studying shock-material behavior using x-ray phase contrast imaging

Synchrotron-based x-ray phase contrast imaging (XPCI) provides direct insight into the form and behavior of shock waves; however, extracting quantitative information from the images can be difficult because of image noise and the ill-posed problem of phase retrieval. We address these challenges by studying the shock-material interface behavior of polymers and energetic materials at oblique angles. Micron resolution XPCI images of gas gun-driven shock/detonation waves are recorded at the Dynamic Compression Sector, Advanced Photon Source. We present two techniques for recovering quantitative information about the shock wave: (a) a Monte Carlo-based technique and (b) an iterative-based phase retrieval. The Monte Carlo-based technique measures changes in mass density in the surrounding regions of the shock-material interface. Its accuracy is demonstrated with comparisons to shock-polar theory and detailed hydrodynamic simulations. The iterative-based phase retrieval technique reconstructs the mass density profile across the wave front. When demonstrated on PBX 9501, we found evidence of the heterogeneous microstructure interacting and shaping the wave front. These two techniques can be applied generally to studying and developing hydrodynamic models relating to shock physics.