Effect of Operating Environment on Photonic Doppler Velocimetry Data Quality

Photonic Doppler velocimetry (PDV) is a commonly fielded laser diagnostic used to measure the velocity of a moving metal surface on dynamic experiments. PDV has continued to grow in popularity due to its ease in fielding and increased temporal resolution over past alternatives. This rapid adoption, however, may have outpaced more fundamental understandings on the failure mechanisms and stymied novel uses of this diagnostic. The presented work examines the effects of the operating environment on the quality of PDV data with hopes to provide guidance on extending its applicability to new experimental regimes.

Air, which is the traditional background environment for PDV, can sustain shockwaves that disrupt the probe and lead to data dropout. Additionally, ionization of the background gas could lead to scattering or absorption of the beam, degrading the quality of the data.

While fielding the experiment in vacuum may mitigate these effects, it could also fail to suppress a spray of metal particles that are dislodged from the surface at the beginning of the experiment, obscuring the surface and leading to noisy signals.

This work presents the results from a series of flyer plate experiments conducted in different gas environments and with different artificial dust particle parameters to systematically determine the effect of the environment on PDV’s performance. Initial results show performance is influenced more by the background pressure and the presence of metal spray rather than shock or ionization effects.