Beyond Phelix: Compact transformer drive For other high current applications

The approach called PHELIX, for Precision High Energy-density Liner Implosion eXperiment, provides a technique to allow research on high energy-density phenomena associated with liner implosions in a scaled-down system suitable for use with proton radiography. In the embodiment selected at Los Alamos National Laboratory, a static transformer arrangement is used to obtain currents in excess of 5MA from a compact, 486 kJ capacitor bank that provides 1.3 MA to the primary circuit. The cm-scale liner implosion on the secondary side successfully attains speeds in the km/s range. It has been noted that the ratio of load current to bank energy is almost an order of magnitude higher using this transformer technique than achievable with direct drive from high energy capacitor banks. This increase in current per stored-joule offers the opportunity for using similar transformer arrangements for other applications apart from imploding liners. These potential applications include rail-guns, and the dense plasma focus (DPF). In the latter case, the strong dependence of neutron yield on peak current (Y ~ J4, perhaps) places a premium on performing DPF research at higher currents. For systems comparable to the PHELIX apparatus at LANL, modest capacitor banks may thus allow progress on DPF studies without demanding large systems, such as Shiva Star or Atlas. Similar improvements in the current per joule may also apply to explosively-driven generator sources, thereby reducing the resources required for explosive operation. Larger devices to obtain operation at much higher currents (e.g., beyond Z) may also be possible. Results from the dimensionless analyses previously used successfully to design PHELIX will be described for these new applications and design limitations will be discussed. Such limitations may require a shift to dynamically-switched vs static transformer operation, which may be satisfactory for experiments that involve significant load and diagnostic refurbishment each shot.