Characterization of ejecta in shock experiments with multiple light scattering

Upon impact, the free surface of a solid metal may eject a cloud of fast and fine particles. Photon Doppler Velocimetry (PDV) is one of the optical diagnostics used to characterize these ejecta. Although the technique provides a direct way to estimate the particle velocities in the single scattering...

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Bibliographic Details
Published in:Journal of applied physics 2024-02, Vol.135 (7)
Main Authors: Don Jayamanne, J. A., Burie, J.-R., Durand, O., Pierrat, R., Carminati, R.
Format: Article
Language:English
Subjects:
Computer simulation
Ejecta
First principles
Free surfaces
Impact analysis
Inelastic scattering
Inhomogeneity
Mathematical models
Multiple scatter
Optical properties
Optics
Particle size distribution
Physics
Spectrograms
Transport equations
Velocimetry
Wave scattering
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Summary:Upon impact, the free surface of a solid metal may eject a cloud of fast and fine particles. Photon Doppler Velocimetry (PDV) is one of the optical diagnostics used to characterize these ejecta. Although the technique provides a direct way to estimate the particle velocities in the single scattering regime, it has been shown that multiple scattering cannot be neglected in real ejecta. Here, we derive a model for PDV measurements starting from the first principles of wave scattering. We establish rigorously the relationship between the specific intensity and the measured signal, as well as the Radiative Transport Equation (RTE) that describes the evolution of the specific intensity upon scattering and absorption in dynamic ejecta, including the effects of inelastic scattering and inhomogeneities in the optical properties. We also establish rigorously the connection between the Monte Carlo scheme used for numerical simulations and the solution to the RTE. Using numerical simulations, we demonstrate the crucial contribution of multiple scattering to PDV spectrograms as well as the effect of statistical inhomogeneities in particle size distribution. These results could substantially impact the analysis of ejecta by PDV.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0190613