Shock initiation of the TATB-based explosive PBX 9502 cooled to 77 Kelvin

We present gas-gun driven plate impact shock initiation experiments on the explosive PBX 9502 (95 weight percent triaminotrinitrobenzene, 5 weight percent Kel-F 800 binder) cooled to liquid nitrogen temperature, 77K. PBX 9502 samples were cooled by flowing liquid nitrogen through a sample mounting plate and surrounding coil. Temperatures were monitored using embedded and surface mounted thermocouples. Reactive flow was measured with embedded electromagnetic particle velocity gauges. Wave profiles from the particle velocity gauges show that, even at 77K, shock initiation in PBX 9502 retains a heterogeneous or "hot-spot" character. The "Pop-plot," or distance to detonation, x(D), vs. impact pressure, P, is log(10)(x(D)) = 4.9 - 3.3log(10)(P).