Combined Electromagnetic Particle Velocity Gauge And Explosives Shock Initiation Process Research

The main works of this dissertation are as follows:1. A multiple electromagnetic particle velocity gauge method was established, which was applied to study the shock initiation process of explosives. The gauge consists of a "shock tracker" and six separate particle velocity gauges, which is made from a 5μm thick copper foil by laser etching, and then, the gauge is coated by two Polytetrafluoroethylene film. The magnetic field is provided by a helmholtz loop with constant DC, and the initial shock loading is provided by planar wave lens. The response time of the whole measurement is no more than 23ns, and its relative measuring error is no more than 2.4%.2. The shock initiation process of the JOB-9003 explosive under different initial shock loading was recorded by using the multiple electromagnetic particle velocity gauge method. The measured reactive particle velocity profiles of the JOB-9003 explosive show that most of reactive wave develops well behind the shock front, which indicates that the JOB-9003 explosive shows more homogeneous behavior. The run distance and the time to detonation of the JOB-9003 explosive (ρ₀=1.850g/cm³) were obtained under 4.9GPa and 5.8GPa initial shock loading. For 4.9GPa, the run distance and the time to detonation are 6.06mm and 1.13μs, and for 5.8GPa, the results are 5.66mm and 1.01μs respectively.3. The influence of thermal damage on the shock initiation character of the JB-9014 explosive was studied. Thermal damage experiment of the JB-9014 explosive was carried out by keeping it under 200℃ for two hours. The damage degree was analyzed by optic microscopy, scanning electron microscopy (SEM) and damage ultrasonic testing respectively. The results show that the ultrasonic velocity in the JB-9014 explosive decreased, the ultrasonic plus value increased at the same time, and the volume expanded by about 2.2% in average, correspondingly, the density of explosive decreased by 2.3% in average, and some cracks and holes appeared on the surface and inside of the explosive after thermal damage. The shock initiation processes of the JB-9014 explosive before and after thermal damage were investigated by using multiple electromagnetic particle velocity gauge method, the results show that thermal damage increased the shock sensitivity of the JB-9014 explosive.4. The particle velocity profiles of the JOB-9003 explosive during the shock initiation process were calculated by using the one-dimensional hydrodynamic code SSS. In calculating, the "Forest Fire" reaction rate model was applied. The calculation results are in good agreement with the experiment.