Simultaneous application of photon Doppler velocimetry and coherent backscattering for probing ejecta from shock-loaded samples

Abstract

We present the results of experiments on simultaneous probing of a shock-loaded layer of aluminum oxide particles by the methods of photon Doppler velocimetry (PDV) and coherent backscattering (CBS). The measurements of the angular profiles of CBS from a dynamically expanding medium are reported for the first time. The powder of particles was applied to the surface of an explosively driven steel plate. The particle velocities ranged from 0.9 to 1.3 km/s. The main characteristics of the cloud of ejected particles (the areal density, mass–velocity distribution, etc.) are recovered from the PDV and CBS probing data using an approach based on theoretical modeling of the measurement results with the transport equation. By varying the parameters of the particle cloud (the transport optical thickness and the parameters of the initial velocity distribution), it is managed to fit the dynamics of the calculated Doppler spectra and CBS angular profiles to the data of measurements in given time intervals and, thereby, recover the values of these parameters. As applied to the diagnostics of ejecta from shock-loaded samples, the CBS method is shown to provide independent data on the spatial distribution of particles over the cloud thickness. The presented results demonstrate that the joint application of PDV- and CBS-based channels of measurements to ejecta diagnostics makes it possible to halve the error in recovering the ejecta parameters compared to using PDV alone.