Operation of a 5-MJ Capacitor Bank for EML Materials Testing
NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV
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The U.S. Navy is considering the development of an electromagnetic launcher EML for surface-fire support and other missions. The EML system will need to have fire rates of 6-12 rounds per minute and barrel lifetimes approaching 10,000 rounds. The Naval Research Laboratory has initiated a program to develop and test materials to achieve these fire rates and lifetimes. A facility is being assembled to allow testing of rail and armature materials at the high current density, pressure and sliding velocity of the Navy EML. The test system needs to operate over a large range of charging voltages and test configurations. The system also needs to deliver high reliability and reproducibility to accommodate the testing requirements. The capacitor bank design previously proposed has been fabricated and tested. The module stores 500 kJ at 11 kV charge, using capacitors and fuses from General Atomics, ABB semiconductors and a custom 80 H inductor from Stangenes. A circuit model of the banks, using the no greater than values for internal resistance and inductance of the capacitors, predicted 100 kA output at 11 kV charge. The real devices deliver 100 kA at 10.4 kV charge, with 5 bank reversal. Reinforcements were added to prevent deformation at the inductor tabs, and limit the motion of the conductor plates at high current A 5-MJ system has been fabricated and installed, using 10 of these modules, stacked in set of two, and another 5- MJ of modules is in fabrication. All ten of the modules passed testing at 1 kV, and 4 random modules passed testing at 8 kV charge, with a 10 m load. 2 more, equivalent 500-kJ modules are being constructed using other 11-kV capacitors. Results of the testing and comparison with the initial circuit models will be presented. Results from initial firings into dummy loads at the breech and low power EML launches will also be presented.