Shock State Distributions in Porous Tantalum Using Multipoint PDV

Heterogenous materials under shock compression can be expected to reach different shock states throughout the material according to local differences in microstructure. Here, a compact, multiple-beam focusing optic assembly is used with Photonic Doppler Velocimetry (PDV) to interrogate the shock response of porous tantalum films following plate impact. The spatial distribution of particle velocity is compared to results obtained using a set of defocused PDV beams. Both methods measure velocity distributions with the same average but different variance. Comparison to mesoscopically-resolved, hydrodynamics simulations shows that the focused PDV array more accurately measures the velocity distribution arising from the pore structure.