Flux Pumps for Use at 60 Hz

Many superconducting devices now being built require currents of a thousand or more amperes. When the currents needed are dc and large compared with the heat leakage into the cryostat from sources other than the electrical leads, it may be advantageous to use a flux pump or ac-to-dc converter within the dewar for powering the device. The flux pumps described convert low current-high voltage ac power into high current-low voltage dc power. Pumps designed to operate in the 500 to 1200 A range at 5 to 50 W will be discussed.