Effect of Initial Temperature on the Detonation Performance of the TATB-Based Explosive PBX 9502

When heated, common high explosives expand and decrease in density, with possible implications for the detonation timing and acceleration of confining materials. Here, we report on the effect of elevated initial temperatures on detonation performance as measured in a series of new and previously reported rate-stick and cylinder expansion (CYLEX) test experiments for the 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) based insensitive high explosive PBX 9502. Specifically, PBX 9502 rate stick and CYLEX tests at both ambient (25 °C) and elevated (75 °C) initial temperatures are examined. Detonation velocities, front shapes, and confiner motion are compared. At 75 °C, the density of PBX 9502 is in the range of 1.860-1.870 g/cc as compared to 1.885-1.895 g/cc, which, in the absence of other effects, would tend to decrease detonation velocity and product energy. However, we find that except for very large charges, the performance of the thermally elevated PBX 9502 charges is very similar to that of the higher density ambient charges. Furthermore, the 75 °C PBX 9502 outperforms low density ambient PBX 9502, despite having an even lower density when heated. We show that this higher-than-expected performance of low-density heated explosive is not solely attributable to the increase in charge diameter as it is heated, and the detonation front shapes suggest that faster reaction kinetics of the elevated temperature explosive plays an important role.