An investigation into the initiation of hexanitrostilbene by laser-driven flyer plates

An investigation into the shock sensitivity of hexanitrostilbene (HNS) has been carried out. A Q-switched Nd:YAG laser was used to launch miniature flyer plates from substrate-backed aluminium films. The impact produces a shock with duration of the order of I ns and pressure of the order of 10 GPa. The explosive samples were pressed into PMMA cylinders to 65-78 % theoretical maximum density. The threshold laser pulse energy required to produce a flyer with sufficient velocity to cause detonation was found. A high-speed camera was used to record the entire event. Initial curvature of the streak record, for impacts just below the detonation threshold, showed that reaction started inside the column. This feature was not seen in a previous study(1). It was found that conventional HNS, with a mean particle size of approximately 25 gm, could not be detonated while fine grained HNS (sub-micron particle size) would detonate.