We have performed a series of highly‐instrumented experiments examining corner‐turning of detonation. A TATB booster is inset 15 mm into LX‐17 (92.5% TATB, 7.5% kel‐F) so that the detonation must turn a right angle around an air well. An optical pin located at the edge of the TATB gives the start time of the corner‐turn. The breakout time on the side and back edges is measured with streak cameras. Three high‐resolution X‐ray images were taken on each experiment to examine the details of the detonation. We have concluded that the detonation cannot turn the corner and subsequently fails, but the shock wave continues to propagate in the unreacted explosive, leaving behind a dead zone. The detonation front farther out from the corner slowly turns and eventually reaches the air well edge 180° from its original direction. The dead zone is stable and persists 7.7 μs after the corner‐turn, although it has drifted into the original air well area. Our regular reactive flow computer models sometimes show temporary failure but they recover quickly and are unable to model the dead zones. We present a failure model that cuts off the reaction rate below certain detonation velocities and reproduces the qualitative features of the corner‐turning failure.
Streak camera breakout and Fabry‐Perot interferometer data have been taken on the outer surface of 1.80 g/cm3 TATB hemispherical boosters initiated by slapper detonators at three temperatures. The slapper causes breakout to occur at 54° at ambient temperatures and 42° at −54 °C, where the axis of rotation is 0°. The Fabry velocities may be associated with pressures, and these decrease for large timing delays in breakout seen at the colder temperatures. At room temperature, the Fabry pressures appear constant at all angles. Both fresh and decade‐old explosive are tested and no difference is seen. The problem has been modeled with reactive flow. Adjustment of the JWL for temperature makes little difference, but cooling to −54 °C decreases the rate constant by 1/6th. The problem was run both at constant density and with density differences using two different codes. The ambient code results show that a density difference is probably present, but it cannot be quantified.
A femtosecond (fs) laser has been used as a tool for solving many problems involving access, machining, disassembly, inspection and avoidance of undesirable hazardous waste streams in systems containing energetic materials. Because of the unique properties of the interaction of ultrashort laser pulses with matter, the femtosecond laser can be used to safely cut these energetic materials in a precise manner without creating an unacceptable waste stream. Many types of secondary high explosives (HE) and propellants have been cut with the laser for a variety of applications ranging from disassembly of aging conventional weapons (demilitarization), inspection of energetic components of aging systems to creating unique shapes of HE for purposes of initiation and detonation physics studies. Hundreds of samples of energetic materials have been cut with the fs laser without ignition and, in most cases, without changing the surface morphology of the cut surfaces. The laser has also been useful in cutting nonenergetic components in close proximity to energetic materials.
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