Alternating current loss in radially arranged superconducting strips
  Analytic expressions for alternating current (ac) loss in radially arranged superconducting strips are presented. We adopt the weight-function approach to obtain the field distributions in the critical state model, and we have developed an analytic method to calculate hysteretic ac loss in superconducting strips for small-current amplitude. We present the dependence of the ac loss in radial strips upon the configuration of the strips and upon the number of strips. The results show that behavior of the ac loss of radial strips carrying bidirectional currents differs significantly from that carrying unidirectional currents. 
Yasunori Mawatari and Kazuhiro Kajikawa