Study on AN/AP/AL Mixture Powders Ignited by Microsecond Exploding Tungsten Wire

Abstract

Based on high pulsed power technology, electrical explosion has been utilized to generate controllable underwater shock waves with high pressure. To further magnify the amplitude, a developing technique that using energetic materials ignited by the plasma of microsecond wire explosion has been put forward. To study the plasma material interaction, we investigated the mixture powders of ammonium nitrate, ammonium perchlorate and aluminum in two mass formulas (A: 45%AN/40%AP/15%Al, B: 65%An/25%Ap/15%Al) which were ignited by exploding tungsten wire (diameter 0.3 mm and length 60 mm). Results showed that the shock wave pressure waveforms of different formulas were quite similar. When the charge mass was 30 g, the area impulse of the shock wave generated by the B load was <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$15.7 \text{MPa}\cdot \mu \mathrm{s}$</tex> larger than that of the A load, while the peak pressure was only 0.35 MPa lower than that of the A load. Since the explosion heat of AN was −365.5 kJ/mol, and that of AP was −293.72 kJ/mol, assuming that the reactants react completely, the volume of gas produced per unit mass of AN would be 1.19 times that of AP, and the explosion heat would be 1.83 times that of the latter. Therefore, the B formula with higher AN mass fraction was more powerful. Moreover, as the mass of the charge increases, the area impulse showed a certain increase but gradually saturated. This is probably because with the mixture powders gradually compacting, the internal air gap was reduced, and the reaction tended to a negative oxygen balance. Therefore, the reaction failed to proceed to the final decomposition product. Finally, a simple AN/AP/Al load mass and formula scheme suitable for microsecond exploding wire plasma was proposed.