High-irradiance laser ignition of explosives

A current issue important to high explosive safety is deflagration-to-detonation transitions (DDTs) in accident scenarios. In order to better understand the reactive mechanisms involved in DDT and to begin to approach the fast ignition and heating rates seen in DDT, high-irradiance (less than or equal to800W/cm 2 ) CO 2 laser ignition experiments were performed on the common high explosives octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). Reported data include time to ignition as a function of laser irradiance, energy, and ignition temperature. A simple dual ignition criteria model (DICM) was used to interpret the HMX results. The DICM requires two basic criteria for ignition: (1) a minimum surface temperature must be reached and (2) a minimum energy concentration must exist within the solid. The DICM sucessfully predicted the slope transition trend and the critical ignition energy for HMX to within 10% of the measured values. TATB had a single dependence on irradiance over the entire range of heating rates.