A Compact Pulser for Magnetically Driven Isentropic-Compression Experiments

The use of magnetic fields to isentropically compress materials for equation-of-state studies has been first demonstrated on the Z machine at SNL [1]. Sharing similarities with the GEPI pulser [2], a compact pulser has been designed and built, focusing on Isentropic Compression Experiments. In order to achieve high compacity and fast turn around, the design is built around a solid dielectric transmission line to couple current from eight low-inductance capacitors that are switched with ultra-low-inductance multi-channel gas switches operating in dry air at atmospheric pressure. A peaking stage made of 72 capacitors enhanced by a low inductance, multi-channel sharpening switch brings the fundamental rise time of the pulser down to 350 ns (10-90%). A set of inductances in parallel with the sharpening switch as well as using various gases into this switch allow us to modify the current wave shape. The pulser delivers a peak current of 4 MA at a charge voltage of 80 kV on a short circuit. The rise time can be lengthened to around 650 ns for a current of 4.2 MA. The use of post-holes convolutes in a solid dielectric insulation design makes that pulser unique as well as its compact size, ease of use and ease of access to the load.