Reduction of Screening-Current-Induced Fields in an HTS Tape Winding Using Toroidal Arrangement of Shaking Coil

Screening-current-induced fields (SCFs) in an HTS main coil are experimentally reduced by using a copper shaking coil. The HTS main coil is wound using a Gd-based coated conductor into four double pancakes without a joint between them. The shaking coil is also toroidally wound around the HTS main coil using a round copper wire. Both the HTS and copper coils are immersed in liquid nitrogen, and axial magnetic fields at the center of the HTS main coil are observed using a Hall probe. By applying alternating currents to the copper shaking coil and, therefore, azimuthal AC magnetic fields to the HTS main coil, the SCFs at the center of the HTS coil are reduced successfully.