Reduction of Magnetization in Windings Composed of HTS Tapes

Methods to reduce the magnetization in windings composed of high temperature superconductor (HTS) tapes are presented on the basis of the abnormal transverse-field effect. The toroidal arrangement as well as the coaxial arrangement of additional coils wound with non-magnetic wires such as copper wires is effective to uniformize the distribution of sheet current in the HTS tapes constituting the windings carrying a direct transport current when the non-magnetic coils are energized with an alternating transport current for a short time. By using a layer-wound coil fabricated with a commercially available coated conductor and a pair of copper coils with the coaxial arrangement, the influences of reducing the magnetization in the windings on the central magnetic fields of the HTS coil are studied in detail experimentally.