Overdriven-detonation and sound-speed measurements in PBX-9501 and the ‘‘thermodynamic’’ Chapman–Jouguet pressure

Abstract

Sound speeds, at pressure, and the overdriven Hugoniot were measured for the plastic-bonded explosive PBX-9501. The two curves intersect at the Chapman–Jouguet (CJ) state because of the sonic condition D=c+u. This permitted a novel determination of the ‘‘thermodynamic’’ CJ pressure. A value of 34.8±0.3 GPa was obtained. The data permit a direct experimental determination of the isentropic gamma, γS=−(∂lnP/∂lnV)S, and the Grüneisen parameter, γ=V(∂P/∂E)V, in the overdriven pressure range.