Development and Analysis of YBCO Trapped Field Magnets in Electromechanical Devices

High-temperature superconducting trapped field magnets (TFMs) offer great potential as an alternative to second-generation YBCO wire, both in cost and performance. Attention is given to the calculation of current distribution within YBCO disks at partial and full activation and comparing this to experimental values. The best results are obtained by treating the current as a sequence of nested current rings. The fields are computed by integrating the elliptic integrals representing the fields from these rings and using variable metric optimization to choose the ring radii to best match the activation field over the unactivated material. A technique for treating the subregions of the TFM as voltage fed coils appears most expeditious for computing forces.