A thermally switched 9 kA superconducting rectifier fluxpump

The feasibility of superconducting rectifier-fluxpumps has to be demonstrated at current levels of 10 - 100 kA, where is asked for in the superconducting devices now being planned. An intensive program has been started at the low temperature division of the University of Twente to construct such high current rectifiers. A thermally switched 9 kA full wave rectifier-fluxpump will be presented. The s.c. rectifier consists of a current step up transformer, two reliable thermally activated switches and a dummy load inductor. Both, load coil and rectifier are fully protected against failure modes. The rectifier is now (March, 1981) under test and has energized yet the load coil to a level of 4.5 kJ at 9 kA within 150 seconds, frequency 0.11 Hz, mean power 30 W, the efficiency of the energy conversion is 99,1%.