Influence of window characteristics on chemical reaction zone measurements in PBX 9502

摘要

The chemical reaction zone (CRZ) describes the spatial and temporal region behind a detonation front over which explosive "reactants" are converted to products by exothermic decomposition reactions, and the flow is subsonic. The CRZ is characteristic to each explosive’s chemical composition and decomposition reaction rate(s), and can vary from 10s of ns (e.g. conventional high explosives) behind the front to μs/mm for non-ideal formulations (e.g. ammonium nitrate-fuel oil). The CRZ is often measured using optical velocimetry techniques at a windowed interface; the window affects the reaction zone dynamics due to wave interactions at the interface. PBX 9502 is a plastic- bonded high explosive of 95% 1,2,3-triamino-2,4,6-trinitrobenzene (TATB) and 5% Kel- F 800 polymer binder. In this paper, we describe the evaluation of Kel-F 800 as a novel shock impedance-matched window to PBX 9502, and provide a preliminary estimate of its optical window correction at 532 and 1550 nm. The window corrections were found to be small, a(λ) = 1.013 ± 0.034 at 532 nm, a(λ) = 1.010 ± 0.003 at 1550 nm, similar to PMMA. The CRZ of PBX 9502 was measured at LiF, PMMA, and Kel-F 800 windows. A two-step reaction previously observed at LiF is also observed with Kel-F 800, and indicates that reaction occurs over fast and slow regions, with t_(fast) = 22 ± 5 ns, and t_(slow) = 280 ± 10 ns.