Abstract
A swept-wavelength external cavity quantum cascade laser (ECQCL) is used to perform standoff detection of combustion gases in a plume generated from an outdoor high-explosive (HE) open detonation. The swept-ECQCL system was located at a standoff distance of 830 m from a 41 kg charge of LX-14 (polymer-bonded high explosive) and was used to measure the infrared transmission/absorption through the post-detonation plume as it propagated through the beam path. The swept-ECQCL was operated continuously to record broadband absorption spectra at a 200 Hz rate over a spectral range from 2050 to 2230 cm−1 (4.48–4.88 μm). Fitting of measured spectra was used to determine time-resolved column densities of CO, CO2, H2O, and N2O. Analysis of visible video imagery was used to provide timing correlations and to estimate plume dimensions, from which gas mixing ratios were estimated. Measured emission factors and modified combustion efficiency show good agreement with previously reported values.
Highlights
Measurement of gas species and their concentrations produced from detonations of high explosives (HEs) is important for optimizing explosives’ performance, validating thermochemical models of detonation and combustion, and understanding shortand long-term effects of released gases on the environment
The results show that this new measurement technique is promising for standoff detection of multiple gases in plumes generated from open detonation (OD) or open burning (OB) activities
The approximate retroreflector position is indicated by the black square region of interest (ROI) in the figure
Summary
Measurement of gas species and their concentrations produced from detonations of high explosives (HEs) is important for optimizing explosives’ performance, validating thermochemical models of detonation and combustion, and understanding shortand long-term effects of released gases on the environment. Laboratory experiments performed using small quantities of explosives detonated in enclosed chambers are important, especially for research and method development, but these small-scale tests often do not reproduce the conditions or end-results occurring in larger-scale ODs. measurements of larger-scale OD events provide critical testing and validation information not available otherwise. Quantification of gas concentrations for many trace gas species and particulates produced from HE detonations can be performed by collecting air samples of the post-detonation region followed by laboratory or online analysis. Trace gases are typically analyzed using laboratory-based gas chromatography and/or mass spectrometry (GC/MS). CO2 is typically measured using nondispersive infrared sensors (e.g., LI-COR instruments) and CO is scitation.org/journal/jap typically measured using electrochemical sensors, either on static collected samples or through continuous sampling to measure dynamics (time responses are ∼1–10 s for CO2 and ∼20–30 s for CO).
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call