Effect of the initial density on the structure of detonation waves in heterogeneous explosives

Reaction zones in steady detonation waves in RDX, HMX, TNEB, and ZOX with different initial densities are studied with the use of a VISAR interferometer. The critical initial density which causes the qualitative change in the reaction-zone structure is determined: below the critical density, a chemical spike is registered, whereas above this density, the chemical spike disappears and an increase in pressure is observed. It is shown that the critical density for a given dispersion of high explosives depends on the method of charge pressing and equals 1.73, 1.84, 1.56, and 1.71 g/cm$^3$ for RDX, HMX, TNETB, and ZOX, respectively. It is concluded that the unusual structure of the detonation wave is caused by the reaction of the high explosive directly in the shock-wave front.