Shock initiation of PBX-9502 at elevated temperatures

The shock sensitivity of PBX-9502 is known to change with temperature. Both volume expansion and increased internal energy may contribute to theis phenomenon. PBX-9502 was heated and its initiation and detonation behavior was examined, using MI and shock tracker gauging on a light gas gun. Sensitivity and reactive wave profiles were measured. Complementary experiments were done on PBX-9502 made to undergo ``ratchet growth``, or non-reversible anisotropic thermal expansion, under carefully controlled thermal cycling. This process causes noticeable size changes and significant changes in sensitivity. Sensitivity and reactive wave profiles are discussed in terms of density and microscopic material morphology.