Application of photon Doppler velocimetry for characterization of ejecta from shock-loaded samples

Abstract

We consider the problem of recovering the physical parameters of ejecta from data of photon Doppler velocimetry (PDV). The results of PDV measurements of ejecta production from shock-loaded Pb samples are presented. Shockwaves in the samples were generated by an accelerated flyer-plate. Depending on the sample thickness, the shock-breakout pressure varied from 27.5 to 43 GPa. The ejecta transport occurred in the air. The spectral profile J(ω) of heterodyne beats underlies our analysis of the experiments. The noise-free component of |J(ω)|2 is shown to obey the transport equation which accounts for multiple scattering and absorption of the probing beam in the cloud of moving particles. This provides a means for theoretical modeling of PDV data. Varying the values of the free-surface velocity and the parameters of the velocity distribution of ejecta, we fit the calculated spectrum to the PDV-measured one. We apply this method to time-resolved PDV spectra and, based on the ejecta optical model, recover the values of the free-surface velocity, the areal density, and the density-velocity distribution of ejecta.