Photonic Doppler Velocimetry System for Shock Physics at UNR

Photonic Doppler Velocimetry (PDV) is a diagnostic technique used to obtain time-resolved free surface velocity profiles in shock physics experiments. A Doppler-shifted signal reflected from the free surface interferes with a reference signal, and a beat frequency is measured to infer velocity. PDV enables key measurements such as shock arrival time, spall strength, and Hugoniot elastic limit. It is also used to identify phase transformations and characterize ejecta. These measurements are related to national defense, stockpile stewardship, and planetary impacts. At the UNR, we conduct experiments relevant to shallow bubble collapse, impact vaporization, and 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 experiments. To support this need, an 8-channel heterodyne PDV system has been developed with the capability for future expansion via multiplexing.