Optical depth measurements of fireballs from aluminized high explosives

Spatially and temporally resolved attenuation of 532 nm light by fireballs from aluminized high explosives is determined using photometric and imaging methods. For all measurements, the absorbance is found to peak during the early period of high reactivity of post-detonation gases. The characteristic attenuation length is less than 1 cm during the peak absorption period, and remains on the order of centimeters until a significant decrease in optical depth occurs about 160 μs after the detonation. These results suggest that, for gram-scale and larger aluminized charges, the optically thick assumption will most likely be valid for the period in which fireball luminosity is significant.