Ferromagnetic Coating for Decreasingof Self-Magnetic Field Acting on HTS Tapes

The decreasing of critical current in the high-temperature tape superconductor (HTS) can be prevented by decreasing of the perpendicular component of self-magnetic field. The coating of this tape by the ferromagnetic material can deform the magnetic field around the HTS tape with flowing transport current. The present report contains the finite-element analysis of the effect of ferromagnetic coating near the HTS tape. The optimal configuration of the ferromagnetic coating for minimizing the perpendicular component of magnetic field was found. In present case, it reduces from 0.04 T to less than 0.01 T. The optimal shape of the coating contains the gap along the lateral side of the HTS tape. The influence of the twisting of the tape coated by ferromagnetic was also investigated. It was found that the difference between twisted and nontwisted cables was not large. The study was also performed for the stack of HTS tapes where neighbor tapes have the opposite direction of the transport current. It was found that the ferromagnetic coating and ribs make the magnetic field near edges smooth.