Influence of Geometrical Configurations of HTS Roebel Cables on Their AC Losses

We calculated ac losses in the Roebel cables with various configurations considering their 3-D structures in order to clarify the effect of their geometrical configurations on their ac loss characteristics: the number of strands, the transposition length, and the width of the gap between the two rows of stacks of coated conductors were varied. We also calculated the ac losses in the coated-conductor stacks of which cross-sections were identical to the cross-sections of the straight section of the Roebel cables. Magnetization losses without transport current and transport current losses without externally applied magnetic field were calculated for each case. The difference in the ac loss characteristics of the Roebel cables and those of the coated-conductor stacks is significant for magnetization losses. We discussed this difference via a comparison of the longitudinal ac loss distribution.