Application of photon Doppler velocimetry for quantifying the transverse non-uniformity of ejecta from shock-loaded samples

We present the results of applying photon Doppler velocimetry (PDV) to diagnose transversely non-uniform particle ejection from the surface of shock-loaded samples. The feasibility of measuring the spatial period of non-uniformity by means of oblique PDV probing is demonstrated. To model the jets of ejected mass, a powder of corundum particles (Al2O3) was applied to the grooved surface of an explosively driven aluminum plate. The particle velocity in the jets ranged from 2 to 3.5 km/s. The collimators of the PDV system were oriented both parallel and at an angle (up to 45°) to the direction of particle motion. In the case of oblique probing, the experimental time-resolved spectrograms acquire a periodic structure, which, as shown in our study, is unambiguously related to the spatial scale of the transverse non-uniformity of the ejecta. The experimental concept and conditions are substantiated by preliminary theoretical calculations of Doppler spectra and hydrodynamic simulations of jet generation. The calculations of spectra are also used to recover values of the ejecta parameters from the PDV measurement data. The possibility of applying oblique PDV probing to metal samples with a realistic surface profile is discussed.