A Noninductive Bifilar Coil to Design Compact Flux Pumps for HTS Magnets

High-temperature superconducting (HTS) flux pump is a promising way of energizing superconducting magnets without direct electrical contacts. It can remove the resistive heating and heat leakage from the current leads at room temperature. It is well known that applying the current over the critical current of the superconductor will force the superconducting layer to enter into the flux flow regime. This flux flow resistivity generates a dc voltage across the length of the HTS tape. This phenomenon is well understood; however, it is difficult to generate a high dc charging voltage without a high current. In this article, we demonstrate a novel flux pumping technique by using a noninductive bifilar bridge wound in parallel to the HTS coil. This configuration can generate large dc voltages using relatively small currents. It results in effectively pumping dc currents equal to the critical current for large HTS magnets.