Combined use of High-Speed Videography and PDV Profilometry for Measuring High Speeds Flyers and Impact Shock Dynamics

Abstract

Challenges remain in understanding the dynamic forces that occur with small scale explosive detonations and the subsequent impact those forces have on flyer velocity and deformation profiles. This work presents two data acquisition techniques for probing the behavior of various materials disturbed by laser induced detonations. The physical reactions of metallic flyers and transparent acrylic are cataloged and measured. The data acquisition techniques described here are high speed videography, Photon Doppler Velocimetry Profilometry (usually referred to as PDV Profilometry). High-speed videography provides a detailed temporal view of shock wave propagation, impact pressure distribution, and plasma plume dynamics. A Shimadzu Hypervision HPV-X2 camera was used at up to 10 million frames per second. For nanosecond scale velocity measurements PDV Profilometry was used to capture flyer velocity, acceleration, and deformation. PDV profilometry is a relatively new technique, here its ability to collect 8 or more velocity profiles at up to 750 km/s from a single PDV probe is demonstrated. Measurements of a shock front induced by the collision of a super sonic flyer against the surface of an acrylic cube is observed using the high speed camera. In this acrylic collision experiment impact and shock speeds up to 10km/s are recorded. Combining these techniques, a wide variety of experiments may be undertaken and observed with remarkable clarity in the nanosecond to microsecond time domain.