Infrared spectra of the detonation fireballs

A rapid scanning Fourier transform infrared spectrometer was used to observe the detonation of several novel munitions. The spectral signatures from different explosive compositions are discernable and may be exploited for event classification. A simplified radiative transfer model recently developed for the spectral interpretation of rapidly evolving battlespace combustion events has been extended and applied to the data from these new field tests. In particular, the fireball radius, temperature, soot combustion, and H$_{2}$O and CO$_{2}$ concentrations are determined as a function of time. The fireball radius increased from 0 to 8 meters in about 230 ms and decreased gradually over the following 1-3 s. The fireball temperature profile revealed a rapid jump to over 1800 Kelvin immediately upon detonation followed by a short oscillation as secondary combustion kinetics dominated and a longer temperature decay. Computational methods for fitting the radiative transfer model to the observed data will be discussed, with a particular emphasis on computational efficiency.