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A VISAR interferometer was used to study the reaction zone in steady-state detonation waves in pressed TNETB at different initial densities (1.23-1.71 g/cm 3 ) and degrees of dispersion (5 and 80 µm) of the initial powdered high explosive (HE). The initial density range in which a pressure rise was observed instead of the theoretically predicted chemical spike is shown to depend on the degree of dispersion of the HE. The unusual change in the parameters in the reaction zone is explained by the heterogeneous structure of pressed HEs, whose decomposition has a local nature and proceeds partially at the compression wave front. A technique for recording wave profiles using LiF windows was developed, which confirmed that all qualitative features observed when using aluminum foils ≈200 µm thick and a water window reliably reflect the detonation wave structure.Key words: pressed explosive TNETB, density, degree of dispersion, detonation wave structure, reaction zone without a chemical spike, VISAR laser interferometer, LiF window.The decomposition kinetics of pressed high explosives (HEs) in detonation is determined by the heterogeneous structure of the charges. Changes in the degree of dispersion, pressing conditions, and other factors leading to changes in the concentration and size distributions of the potential reaction centers can lead to a sudden change in the macrokinetics and qualitative changes in the reaction zone structure [1]. This is obvious if one takes into account that detonation processes are usually considered theoretically for a homogeneous medium whereas in experiments mean parameters are recorded. In this approach, the Mach front width is finite and is determined by the same heterogeneities as hot spots, i.e., the processes in the front determine the initial reaction rate and the amount of HE that reacted at these hot spots during compression. The classical Zel'dovich-Neumann-Döring (ZND) detonation theory [2] eliminates HE decomposition at the front but, nevertheless, it is frequently suitable for a

Articles you may be interested inSimulation of the detonation process of an ammonium nitrate based emulsion explosive using the lee-tarver reactive flow model AIP Conf.Abstract. Laser interferometer VISAR was used for investigation of the reaction zone structure and determination of detonation parameters in two different kinds of explosives based on ammonium nitrate: emulsion explosives and composite explosives with plastic binder. The influence of ammonium particles size, structure and charge diameter on detonation velocity and distribution of parameters inside of the reaction zone has been investigated for composite explosives. The effect of aging time of emulsion matrix with different storage time was found.

Experimental studies of the reaction zone structure in hexanitrohexaazaisowurtzitane (CL-20) at different initial densities with a multichannel VISAR laser interferometer have been carried out. It is shown that the flow in the reaction zone corresponds to the Zeldovich-von Neumann-Döring theory with a characteristic reaction time of 50 ns. The dependence of the detonation velocity on the initial density is well approximated by a similar line for HMX with a charge diameter of 20 mm. With a decrease in diam-eter to 4 mm, a sharp drop in the detonation parameters of CL-20 has been recorded. The initiation of detonation under shockwave action is investigated, and the comparison of data for CL-20 and PETN has shown that their shockwave sensitivity is quite close. The experiments on the acceleration of thin steel plates by detonating CL-20 charges have been performed, and it is found that its accelerating ability is higher than that of HMX and retarded RDX.

In this work, the structure of the steady‐state detonation waves, the critical diameter, detonation parameters and the dependence of detonation velocity on the charge diameter for pressed hydrazine nitrate (HN) charges in the density range of 1.40–1.68 g/cm3 were investigated by VISAR interferometer. It was found that the critical diameter drops with the initial density decrease. Under steady‐state detonation conditions at a maximum initial density of 1.68 g/cm3, a high detonation velocity of 8.92 km/s is realized in HN charges. The change of the detonation velocity with variation of the initial density is not monotonic, but has a characteristic s‐shape. Experiments on the determination of Hugoniot data and initiation of detonation under shock wave action for HN were carried out with samples of maximum density. The results of the conducted experiments show the low shock wave sensitivity, which is much lower than that of TNT. A noticeable reaction rate behind the front of the initiating shock wave in charges of maximum density is observed only at a pressure above 20 GPa.