A Novel Rotating HTS Flux Pump Incorporating a Ferromagnetic Circuit

High-temperature superconductor (HTS) flux pumps enable large currents to be injected into a superconducting coil without requiring normal-conducting current leads. We present results from an experimental axial-type HTS rotating flux pump that employs a ferromagnetic circuit to focus incident flux upon a coated-conductor stator wire. We show that this device can inject currents of > 50 A into an HTS coil at 77 K and is capable of operating at flux gaps greater than 18 mm. Accommodating a cryostat wall within this flux gap will enable future flux pump designs, in which all moving parts are located outside the cryostat.