Experimental Verification of Screening Current-Induced Field Reduction Using a New HTS Coil Structure

Abstract

We propose a new structure for layer-wound coil manufactured using a high-temperature superconducting (HTS) wire in the form of a tape to reduce the central magnetic field produced by screening currents induced on the broad surfaces of HTS tapes. Reducing this screening current-induced field is based on the abnormal transverse-field effect observed generally in the mixed state of Type-II superconductors. The structure proposed enables the inner bore of special coil required nuclear magnetic resonance systems to be used effectively. However, it cannot eliminate the screening current-induced fields completely because the innermost and outermost parts of the HTS winding are always exposed to magnetic fields weaker than the full penetration fields. We carry out a series of experiments to confirm the effectiveness of reducing the screening current-induced fields in a HTS coil fabricated with a commercially available coated conductor.