Design and construction of a 20W/1000A cryogenic power supply

In order to meet the requirements for accurate and low power supplies for superconducting applications, a 20W/1kA cryogenic power supply was designed and constructed. It is a full-wave superconducting rectifier, and is taken as a starting point for further developments. The superconducting part consists of an air core transformer and thermally controlled superconducting switches. To operate the system Holec constructed an electronic control unit. The rectifier was tested by using a small 17.5mH coil and an 0.5T NMR magnet. The small coil was loaded to 750A; the current was limited by quenches in the load coil. The average power of the rectifier was measured at several currents . Experiments show that the efficiency is higher than 97%. From the experiments it was concluded that in general the performance of the rectifier is according the design specifications.