  Although a superconductor has no DC losses, a superconducting system does
have significant losses, especially when it comes to power supply. Here, we
study two different power supply systems. The first, a conventional one,
consists of a transformer and a diode bridge operating at room temperature,
plus current leads that allow the current to flow from the room-temperature
medium to the cryogenic medium. The second consists of a transformer with a
superconducting secondary winding, combined with a diode bridge operating at
cryogenic temperature, thus dispensing with the need for current leads. We are
experimentally comparing the performance of conventional and superconducting
transformers, as well as the performance of a diode bridge at ambient and
cryogenic temperatures. Our results indicate that the prototype superconducting
transformer developed has lower winding resistance and secondary leakage
inductance than the conventional transformer. In addition, we found that only
certain diodes are suitable for operation at cryogenic temperatures. Finally,
the diode bridge made from adapted diodes shows reduced losses at cryogenic
temperature. This experimental work is the first step towards the realization
of a complete power supply system for a superconducting device.
