The initiation of high surface area Pentaerythritol Tetranitrate using fiber-coupled laser-driven flyer plates

摘要

A system for launching flyer plates using a Q-switched Nd:YAG laser has been developed for shock initiation of secondary explosives. Flyer plates have been launched at velocities exceeding 4 km s~(-1). These flyers produce sub-nanosecond duration shocks in excess of 30 Gpa on impact. Flyer planarity and integrity have been studied by impacting polymethylmethacrylate (PMMA) windows and using a high-speed streak camera to record the light generated. Analysis of this data has provided an insight of the key mechanisms and enabled the system attributes to be controlled and optimized for explosive initiation. Pentaerythritol Tetranitrate (PETN) has been tested with specific surface areas (SSA) ranging from 12,700 cm~2 g~(-1) to 25,100 cm~2 g~(-1) and the effect of SSA on initiation threshold in this extremely short duration shock regime is examined. A minimum surface area size for initiation is evident. Calculations show that the pulse width is on the order of the particle size. We observed partial reactions in some firings, and we propose a mechanism to explain this. We then evaluate P~2 τ for PETN initiated by laser driven flyer plates. The critical energy fluence calculated is compared to published values and discussed for similar systems.