Shock Initiation of the CL-20-Based Explosive C-1 Measured with Embedded Electromagnetic Particle Velocity Gauges

Abstract

Hexanitrohexaazaisowurtzitane (CL-20) is a high-energy material with high shock sensitivity. The evolution of shock into the detonation of CL-20 deserves academic attention and research. An embedded electromagnetic particle velocity gauge was used to study the shock initiation of detonation in a pressed solid explosive formulation, C-1, containing 94 wt-% epsilon phase CL-20 and 6 wt-% fluororubber (FPM). In conventional experiments, the magnetic field was generated using a pair of electromagnets with a complex structure and operation. A new device was designed to solve complex problems. This device comprised NdFeB magnets, pole shoes and magnetic yokes; using this technique, a uniform magnetic field could be created. A series of shock initiation experiments on high-explosive C-1 was performed, and the explosive samples were initiated at different intensity input shocks by an explosive driven flyer plate. In situ magnetic particle velocity gauges were utilized to detail the growth from an input shock to detonation, and the attenuation of particle velocity in unreacted C-1 was also obtained in low-intensity shock initiation experiments. Hugoniot data for C-1 in the form of shock velocity D vs. particle velocity Up were obtained. A simulation model for shock initiation of C-1 was established, and the particle velocity data from several experiments were used to determine the parameters required for the unreacted equation of state and ignition and growth reactive flow model for C-1. These coefficients were then applied in the calculation of the initial shock pressure−distance to detonation relationship (Pop-plot) for the explosive. Based on the results of experiments and simulations, the shock sensitivity characteristic of C-1 was described.