Shock initiation sensitivity and Hugoniot-based equation of state of Composition-B obtained using \textit{in situ} electromagnetic gauging

Composition-B (Comp-B) is a solid cast explosive comprised of 59.5 wt {\%} cyclotrimethylene-trinitramine (RDX), 39.5 wt{\%} 2,4,6-trinitrotoluene (TNT), and 1 wt{\%} wax. Its initial density depends on formulation method and as a result, the detonation properties of Comp-B have generally been studied at densities of 1.69 g/cm$^{3}$ and 1.72 g/cm$^{3}$. The shock initiation sensitivity (Pop-plot) of Comp-B has been reported previously; obtained using both explosively-driven wedge tests and embedded manganin gauge techniques. We describe the results of a series of gas-gun-driven plate-impact initiation experiments on Comp-B ($\rho_{0} = $1.72 g/cm$^{3})$ using embedded electromagnetic gauges to obtain \textit{in situ} particle velocity wave profiles at 10 Lagrangian positions in each experiment. From the wave profiles, an unreacted Hugoniot locus, the run-distance-to-detonation, and initiation waveforms are obtained in each experiment. The results indicate that Comp-B at $\rho_{0} = $1.72 g/cm$^{3}$ is more sensitive than reported previously. Comparisons are made of the new Hugoniot states with an earlier Hugoniot-based EOS. Measurements of the detonation wave profile using photonic Doppler velocimetry are also presented and discussed in the context of ZND detonation theory.