Revisiting burn rates of high explosive powders confined at high pressures

Predictive models of chemical reaction and burning in secondary high explosives (HEs) rely on decades-old experimental results for calibration and validation. We have successfully reproduced an experiment to determine the rate of deflagration (burning) in HMX confined at high pressure in a diamond anvil cell, originally reported by Esposito et al. (2003). The resulting burn rates are broadly consistent with the Esposito et al. study. However, due to diagnostic limitations, all previous experiments were limited to 1-dimensional streak images that were lacking in experimental detail, and it is unclear what reaction they observed. For the first time, we have imaged the deflagration reaction of HMX as a 2D movie using a fast framing camera (100 ns interframe time). We observe four distinct phases of reaction, each with its own characteristic rate, which were not resolved in the previous data.