Probing shock-initiation of plastic-bonded explosives with a tabletop microscope

Abstract

In this study we investigate the shock-to-detonation transition (SDT) in a plastic-bonded explosive (PBX) consisting of pentaerithritol tetranitrate (PETN) with poly-dimethyl siloxane (PDMS) binder. The study uses a tabletop shock compression microscope with laser-driven flyer plates and arrays of tiny PBX charges. The PBX was shocked by 4 ns duration 0.5-4.5 km/s impacts and probed using photon Doppler velocimetry (PDV) and optical pyrometry. The PBX was initiated, hot spots were produced, and a long-lived high pressure waveform develops within 10 ns, resembling detonative shock waves. The initiated PBX continues to develop more shock energy as a function of run distance, which leads to the hypothesis that the detonation wave has not yet fully developed at the run distances studied due to some fraction of PBX not initiating. Possible methods to achieve better initiation over short run distances <0.25 mm were discussed.