Shock Initiation Microscopy with High Time and Space Resolution

Will P. Bassett, Belinda P. Johnson, Lawrence Salvati, Erin J. Nissen, Mithun Bhowmick, Dana D. Dlott

Research output: Contribution to journalArticlepeer-review

Abstract

We describe studies of shock initiation and shock-to-detonation transitions in energetic materials using a tabletop shock compression microscope with nanosecond time resolution and micrometer spatial resolution. Planar input shocks with durations of 4–20 ns are produced using 0–4.5 km/s laser-launched flyer plates. Emphasis is on measurements of temperature, velocities, pressure, and microstructure using photon Doppler velocimetry (PDV), optical pyrometry and high-speed videography. Techniques are discussed for fabricating disposable shock target arrays of tiny plastic-bonded explosives (PBX), liquid and powder explosives, and single-crystal explosives for high-throughput studies. Optical temperature measurements of shocked triaminotrinitrobenzene (TATB) are discussed. Since TATB is yellow, we developed methods to correct for the blue absorption to obtain more accurate temperatures. Hot spots in shocked polymer-encased HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) crystals are observed in real-time, showing a hot spot produced in a collapsing void that ignites a deflagration. Despite the small dimensions of our explosive charges (typically 1 mm diameter and 250 μm length), we produced reproducible detonation states in solid and liquid explosives using short-duration shocks near the von Neumann spike (VNS) pressure. We show the VNS pressure is associated with a transition to high-efficiency gas production from the explosives. In studies of NM, prior to detonation, we see reaction originating at hot spots which coalesce to form a superdetonation.

Original languageEnglish (US)
Pages (from-to)223-235
Number of pages13
JournalPropellants, Explosives, Pyrotechnics
Volume45
Issue number2
DOIs
StatePublished - Feb 1 2020

Keywords

  • imaging
  • molecular explosives
  • pyrometry
  • shock compression
  • velocimetry

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

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