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25 May 2005 Modeling infrared spectral intensity data from bomb detonations
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Infrared emissions from the detonation of three bomb types and four weights in a series of 56 events were recorded by a Fourier transform spectrometer in the midwave IR (1800-6000 wavenumbers) at temporal and spectral resolutions of 0.047 seconds and 16 wavenumbers, respectively. Fifteen time-resolved spectral datasets corresponding to two distinct chemical explosives were selected for this study. The detonation fireball intensities are well described as cooling greybodies, and a single Planckian distribution, modified by atmospheric absorption, has been fit to the spectra. Agreement between the model and data is within a few percent on average. However, the model underestimates the observed intensity by as much as 40% in the 2000-2200 wavenumber window and hot carbon dioxide at the surface of the fireball is a likely source of this spectral emission (spectral assignments have not yet been performed). For the statically detonated munitions, temperature curves are characterized by initial temperatures of 1685-1885 Kelvin and lifetimes of 0.91-1.24 seconds. Temperatures for some air delivered ordnance exhibited secondary maxima. Fireball areas are estimated without imagery. The model provides features which are reproducible within and characteristic of the munition type, providing promise for proposed event classification schemes. The timedependent Planckian fit residual near 2150 wavenumbers versus time provided the best discrimination between the two munition types, indicating that better understanding the non-Planckian behavior is key to the classification problem. A novel method to estimate the atmospheric transmittance function from the time-resolved fireball spectra is also developed.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kevin C. Gross, Glen P. Perram, and Ronald F. Tuttle "Modeling infrared spectral intensity data from bomb detonations", Proc. SPIE 5811, Targets and Backgrounds XI: Characterization and Representation, (25 May 2005);

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