Characterisation of a PE8 ring initiation system

To investigate Mach Stem and converging shock wave phenomena in explosives, a specialised initiation system, called the ring initiator, was developed. It is designed to produce a simultaneous output of a detonation ring from the end face. The initiator consists of plastic explosive held in a revolved Y-shape by an inner and outer nested polycarbonate shell. A non-precision detonator is used to initiate the plastic explosive at the cylindrical end and the explosive path is designed to produce a detonation ring at the opposite end. The neck region is designed to allow the detonation wave to reach steady state before the conical region is reached.

The ring initiator design has been validated using a PE4 fill that had a temporal planarity of < 160 ns around the 76 mm inner diameter output ring. However, as PE4 is no longer readily available, a PE8-filled ring initiator design has been characterized via a series of explosive shots. The output of the initiator was characterised by a ring of 32 radially equi-spaced ionisation probes in contact with the PE8 and the results are compared to the PE4 ring initiator data.

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