High Resolution Shock Sensor to Study the Effect of the Microstructure on the Detonation Front

A sensor based on direct imaging with a streak camera of the ionization of gas trapped in microcavities is proposed. Very high temporal and spatial resolutions of 0.7 ns and 20 µm per pixel, respectively, were achieved, enabling to study the impact of the explosive microstructure on the shape of the detonation front. The analysis of the shock velocity fluctuations in the sensor for three granulometries of RDX evidenced an effect of the material heterogeneities, both at the grain surface and inside the larger grains. Furthermore, when studying the addition of an energetic binder composed of small RDX grains in hexowax, it seems that in spite of the reduced reaction zone thickness, both grain populations are ruled by their own decomposition kinetics. This leads to interferences that can be destructive, resulting in local disturbances on the detonation front.