Development of a Multi-Channel Photonic Doppler Velocimetry (PDV) System for Shock Physics Experiments at the University of Nevada, Reno

Photonic Doppler Velocimetry (PDV) is a diagnostic technique used to determine time-resolved free surface velocity profiles in shock physics experiments. By combining a Doppler-shifted reflected signal from the free surface with a reference signal, interference occurs and a beat frequency is measured to infer velocity profiles. PDV provides key measurements such as shock arrival time, spall strength, and the Hugoniot elastic limit. It is also used to identify phase transformations and characterize ejecta. These research questions arise in a range of experimental setups related to national defense, stockpile stewardship, and planetary impacts. At the University of Nevada, Reno, we conduct experiments relevant to shallow bubble collapse, impact vaporization, and the shock compression of porous and granular materials. This work utilizes both a single-stage gas/powder gun and a two-stage light gas gun, necessitating an in-house PDV system to diagnose a broad variety of test conditions. To support this need, an 8-channel heterodyne PDV system has been developed at UNR, with the capability for future expansion via multiplexing.