The initiation of fine grain pentaerythritol tetranitrate by laser-driven flyer plates

Charges of pentaerythritol tetranitrate (PETN) were impacted by laser-driven flyer plates launched from substrate backed aluminum films. The flyers were produced by single pulses from a Q-switched Nd:YAG laser. The aluminum flyers were between 3 and 5 mu m thick, had diameters of 1 mm, and achieved velocities up to 8 km s-1. The stresses were intense but of only nanosecond duration. This falls into an interesting regime since the shock thickness of a few microns is of the order of typical hot-spot sizes and less than the grain size of conventional explosive powders. Ultrafine PETN (similar to 1 mu m grain size) was readily initiated, whereas conventional, 135 sieve PETN with a grain size of 106 mu m was not, although limited reaction was observed in some cases. Environmental scanning electron microscopy was carried out to help elucidate the differences in behavior. (C) 2000 American Institute of Physics. [S0021-8979(00)09213-6].