Use of a fast near-infrared spectrometer for absorption and emission measurements within the expanding blast wave of a high explosive

Abstract

We demonstrate the use of a fast InGaAs array and spectrometer to measure properties related to near-infrared absorption and emission (750 nm -1500 nm) following a high explosive detonation. Using a broadband light source and a rigid absorption gauge, gas temperatures are measured at a rate of 20 kHz for a period of several milliseconds behind the blast wave from a PETN, PBXN-5, and PBXN-113 detonations. The temperature and concentration of water vapor is determined by fitting experimental transmission spectra to a simulated database. Strong emission signatures obtained during the PETN breakout event (integrated over approximately the first 20 microseconds) indicate the presence of high energy nitrogen and oxygen atoms. Measurements from water absorption at a distance of 23 cm from the PETN charge indicate temperatures decaying from 1600 K to 600 K during the first few milliseconds, and measurements of non-ideal explosives with optically thick postdetonation environments are also demonstrated. These measurements are intended to aid the development of detonation and explosive simulations. © 2012 American Institute of Physics.