Abstract
The authors have studied A.C. losses in an ultra-fine multifilamentary superconducting 42-strand cable using two A.C. coils. To reduce A.C. losses, the conductor consists of 15, 367 NbTi filaments (0.42μm in diameter with 1.1mm twist pitches) and CuNi matrix. The critical current density Jc in this superconductor was unexpectedly small but the hysteresis loss was larger than that calculated on the basis of the Jc result. The measured A.C. losses were very small, i.e. 2.2W/coil at 1.5T. From comparison between two coils A.C. losses inter-strand coupling loss was estimated very small, compared with the total A.C. losses. These results suggest the potential use of a bare strand cable in constructing A.C. coils.
