Alternating current loss characteristics of a Roebel cable consisting of coated conductors and a three-dimensional structure

The three-dimensional structure of Roebel cables consisting of coated conductors influences their ac loss characteristics. Measurements of the ac loss and numerical electromagnetic field analyses were carried out using a six-strand Roebel cable as well as several reference conductors: a single straight coated conductor, a 3 x 1 stack, where three straight coated conductors were stacked, and a 3 x 2 stack, where two 3 x 1 stacks were placed side by side. The measured and calculated ac losses of the Roebel cable and those of the reference conductors were compared with one another. The ac loss characteristics were discussed on the basis of the electromagnetic phenomena inside the superconductors obtained from numerical electromagnetic field analyses. The influence of the three-dimensional structure of the Roebel cable on its ac loss characteristics was verified on the basis of the experimental and numerical results.