Design Improvements to High-Explosive Pulsed-Power Isentropic-Compression Experiments

A series of 1-D isentropic-compression experiments (ICE) has been initiated using the high-explosive pulsed-power (HEPP) system. Accurate high-stress isentropic equation-of-state (EOS) data had been reported using the HEPP-ICE system. A number of important advantages of the system were demonstrated, including higher stresses, higher accuracy, and larger sample sizes than those of other methods. Several potential design improvements have since been identified and tested. The storage inductor was eliminated, and the experiment was performed before the output of the plate flux compression generator could short-circuit itself. This eliminated the loss of current that occurs when the generator plates bounce apart. A new design of explosively formed fuse opening switch was employed with a multipoint initiation system that reduced the explosive mass, significantly reduced the timing jitter by eliminating air gaps, and minimized flux losses. In addition, with this new switch, the resistance-versus-time profile may be adjusted by controlling the initiation times of its four quadrants. Anomalous results were obtained with the new switch. The results of using this switch in an EOS experiment on pure tantalum are reported.