Model Validation for High-Power Laser Ignition of JA2 Propellant

Report No. ARL-TR-2044
Authors: Cohen, A.; Beyer, R. A.; McNesby, K.; Kotlar, A. J.; Whren, A.
Date/Pages: September 1999; 33 pages
Abstract: A study of JA2 ignition using high-power (3 kW) pulsed Nd: glass lasers at low loading densities was undertaken to help construct models for predicting initial pressurization in bombs at high loading densities. Comparisons were made with results of experiments using a low-power (0.1 kW) continuous wave (cw) CO2 laser. Differences in wavelength dependence of optical properties and time dependence of the laser pulse were considered. Measured infrared (IR) emission delays agreed with the calculated "reaction" delays using a condensed-phase model. The calculations are sensitive to values used for optical properties. Experiments in which laser energy and beam diameter were varied indicate that there is an upper limit on flux density values for flamespreading to occur. Exceeding the limit leads only to ablation. An understanding of the ablation process due to high-power irradiation of energetic solids is needed to predict the pressure response of solid propellant to high- power lasers.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 1999