Time resolving the loss of crystallinity during detonation in a secondary solid explosive

There are still significant uncertainties in our ability to predict and control detonation in secondary solid explosives which has serious implications for the safety and performance of explosives. One reason is for this uncertainty is that while chemical kinetics are well understood in gases and liquids, much less is known about how chemistry proceeds within a crystalline lattice. Secondly, events like detonation, where a bulk material can go from ambient conditions to pressures of Gigapascals (GPa) and temperatures of about 4000 kelvin (K) within nanoseconds (ns), are extremely difficult to directly observe. To better understand the role of the loss of crystallinity and how this affects temperature and chemical kinetics during a detonation, we developed a technique using visible laser scattering to probe morphology changes on a nanosecond time scale before and during a detonation. We will present our results applying this to several common secondary solid explosives, PETN, HMX and TATB, and considering steady detonation, initiation of detonation, and failure scenarios. These measurements reveal when during a detonation wave, and how fast that the initial crystals change into a less scattering dense product fluid giving new insight into the microscopic mechanism of a detonation in solid explosives.