An updated technique to obtain explosive Arrhenius kinetics data on microsecond timescales

Time-to-explosion versus temperature data for explosives provide valuable Arrhenius kinetics information; this can be used for the predictive modeling of explosives response to dynamic stress scenarios and also to facilitate the design of new explosive compounds. Typical laboratory methods of obtaining these data, e.g., differential scanning calorimetry (DSC), are slow and cannot reach the high temperatures of interest (circa 1000 °C). However, Wenograd [1] heated explosives to such temperatures on a microsecond-scale inside stainless steel hypodermic needles. This was done by rapidly discharging a capacitor through the steel. He obtained the temperature by measuring the needle resistance in a Wheatstone bridge arrangement and the time to explosion from needle rupture. Based on this work, we report the development of the High Explosives Initiation Time (HEIT) test which utilizes a 250 Joule pulsed power system to heat the needles. This work extends the Wenograd approach by using optical diagnostics, computational modeling and advanced techniques to measure needle resistance and needle rupture. Arrhenius plots for novel explosive materials will be presented.

1 Wenograd, J.: ‘The behaviour of explosives at very high temperatures’, Transactions of the Faraday Society, 1961, 57, (0), pp. 1612-1620