Experimental velocity-diameter D(d) and velocity-density D ( p 1 ) curves are presented for 80/20 TNT-Aluminum (AI), 45/30/25 RDX-TNT-Aluminum (AI), 75/25 Composition B-AI (HBX), and various mixtures of ammonium nitrate and aluminum ranging from pure ammonium nitrate to 6OY0 AN. Also presented are some results with AN-DNT mixtures. Results show that aluminum reacts too rapidly for the energy release as a function of time to be a limiting factor in TNT-AI and RDX-TNT-AI mixtures at diameters above 5 cm., but it reacts relatively slowly in the AN-AI mixtures and the rate of reaction of aluminum (and AN), or the rate of energy release is a limiting factor in this case. The familiar pro erties of the high temperature Al-explosives are here attributed to the thermodynamics of AI-reactions in which the A128(g) /Al~Os(c) ratio is appreciable in the detonation wave but becomes negligible later on during adiabatic expansion. The change of this ratio from a high value in the detonation wave to an ultimate low value gives aluminized explosives low "brisance" but high blast potential. The AN-A1 mixtures were shown to be "non-ideal" (D < D*) over the entire range of conditions studied.Reaction rates in these mixtures are shown to depend on the particle size of both the AN atid the Al. They seem to be controlled by mass transfer which leads to anomalous D(p1) curves each showing a maximum at a relatively low density (1.0 to 1.2 g./cc.). IntroductionAluminized explosives are chayacterized in general by relatively low "brisance" but high (underwater, open air and underground) blast potential. The low relative I' brisance" of aluminized explosives has been attributed in the past to incomplete reaction of A1 a t the " Chapment-Jouguet plane," and the high blast-potential to after-burning of aluminum. Thus early unpublished shaped charge studies with aluminized explosives, interpreted in light of the observed linear variation with detonation pressure of hole depth and volume from jets in uniform targets indicated that aluminum acts effectively as a diluent as far as the end effect, e.g., shaped charge action, is concerned. More careful study showed, however, that aluminum lowers the "detonation" pressure and velocity even more, sometimes quite considerably more, than an ideal diluent. The effectively endothermic reaction of A1 in the detonation wave may be seen, for example, in the results of detonation pressure measuresummarized in Table I, by the shaped charge method (using calibration curves established with known ideal explosives). These data show that

Studies are presented showing the electrical properties of the highly ionized, detonation-generated plasmas ejected into various gaseous media at the bare surfaces of high explosives. These external plasmas are shown to originate from chemionization in the reactions of high explosive at free surfaces and are not produced by thermal ionization in the shock wave propagated in the surrounding gaseous medium. The initial external-plasma length Lp* was found to be directly proportional to the length a0 of the reaction zone of the high explosive-generating source. Conduction measurements in plasmas propagating in chlorine, oxygen, argon, nitrogen, helium, and air showed that the electron affinity of the gaseous medium is important in determining the rate of decay of the plasma and its ultimate disintegration. The lifetime of external plasmas are substantial in media of low electron affinity, exceeding appreciably 250 μsec in such media as argon, helium, and nitrogen. Free electrons contribute practically the entire conductivity of these plasmas. Interesting pulsations occur when the external plasmas are generated by a charge of diameter smaller than the constraining tube and upon passing from a smaller into a larger constraining tube. A striking confirmation of the quasi-lattice or metallic-like model of plasmas is the observation that the plasma finally ``explodes'' into a gas cloud many times larger when its ion density decays to a critical low level.

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Overdrivendetonation and soundspeed measurements in PBX9501 and the ''thermodynamic (110ft (Received Fehruary 26, lCJ(2) The "aquarium technique" is applied in the experimental determination of the equation of state for water and Lucite. Results for water are compared with similar results obtained by other methods. Measurements of the peak pressures in the detonation waves are presented for explosives of various types and rates of reaction. The peak pressures were found to be the Chapman-Jouguet or "detonation" pressures of the thermohydrodynamic theory. There was no evidence whatever for the "spike" of the Zeldovich-von Neumann model even though conditions were such that this spike would have been detected by the meth(xl employed if it were actually present, at least in the large diameter, nonideal explosives of maxi~1Um reaction zone length.

Extensive wave shape data are presented for various (effectively) unconfined explosives over wide ranges of diameter d, length L, density PI, and physical conditions. Observed wave fronts were invariably spherical segments with radii of curvature R increasing at first directly with L(R = L), but eventually becoming steady at a constant value Rm/d between 0.5 and 4 depending on the charge diameter primarily through the ratio ao/d (ao=reaction zone length). At the critical diameter of propagation (large ao/d) Rm/d approached 0.5, and at large diameter (small ao/d) it approached or leveled off at the upper limit of about four. The upper limit (R m /d, ... 4) is apparently a restriction imposed by the fundamental nature of detonation of solid explosives with free boundaries.[This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 130.70.241.163 On: Mon, 22 Dec 2014 11:56:41