Reduction in AC Loss of REBCO Coils with Optimum Multi-Width Tape Induced by Part Slitting Method

The width of REBCO (REBa 2 Cu 3 O 7-x , RE: rare earths)-coated conductor is an important factor associated with AC (alternating current) loss of the tape. In the same electromagnetic environment, coils winding with narrow REBCO tapes generate less AC loss than the wide one. For a single coil, the critical current density of outer turns is higher than that of inner turns, due to the inhomogeneous distribution of magnetic field. This paper presents a multi-width technique which is applicable for single REBCO coil by partly slitting single tape in place, which can effectively reduce AC loss, while maintaining current-carrying capacity in high field. The AC loss of coils with slitting in different turns is calculated by the software of finite element modeling (FEM). The results indicate that the appropriate slitting in radially outer turns of coil appears effective to reduce AC loss, especially in the case of the coils running with high current.