AC Loss Reduction in HTS Coil Windings Coupled With an Iron Core

Rapid-cycling synchrotron (RCS) magnets based on a superferric design consist of high temperature superconducting (HTS) coil windings coupled with iron cores. However, the presence of iron cores significantly increases AC loss in HTS coil windings, making AC loss reduction a critical issue for applying HTS technology in RCSs. Enlarging the distance between iron cores and coil windings may reduce AC loss. In addition, magnetic materials with different saturation magnetic fields also may influence AC loss in HTS coil windings coupled with iron cores. To investigate the distance dependence, AC losses of 1DPC (double pancake coil)-, 2DPC-, 4DPC-, and 8DPC assemblies with various distances are simulated using the 3D T-A homogenization method with/without an iron core. Two magnetic materials with different saturation magnetic fields are chosen as the iron core to evaluate AC loss in HTS coil assemblies. The results show that the AC loss values in HTS coil assemblies coupled with the iron core decrease significantly with growing distance. For a given distance and current, when the iron core has a lower saturation field, the AC loss values of the 4DPC assembly are smaller than those with a higher saturation field.