Shock compression and sample recovery using cylindrical implosions

摘要

A one dimensional cylindrical implosion device has been developed which can compress materials into a terapascal pressure regime and at the same time makes sample recovery possible from such high dynamic pressures. Cylindrically imploding detonation wave was generated by a large area wire explosion system which physically explodes a copper—mesh array on a surface of 100 mm diameter and 150 mm length cylinder. This wire explosion initiates low density PETN. The main explosive is a hollow cylinder of an RDX based plastic—bonded explosive with 80 mm outer diameter and 40 mm inner diameter. For recovery experiments, several layers of inert materials (typically stainless steel) and one layer of explosive or similar material (active momentum trap, AMT) were inserted between the main explosive and the sample assembly. The thickness and the material for the AMT layer were determined using the hydrodynamic computations so that the sample capsule should not explode after the implosion. Recovery results showed that AMT idea works very well for recovery. When a steel was used as a sample, the central part disappeared due to melting or vaporization by high pressure compression. The lost area agreed well with hydrodynamic predictions. Analysis showed that approximately 2 mm diameter center area was compressed into sub TPa and higher pressure regions. It is also suggested that the AMT idea will also be effective in recucing the tensile stress in conventional recovery fixtures.