AC losses in circular arrangements of parallel superconducting tapes

The DC and AC properties of superconducting tapes connected in parallel and arranged in a single closed layer on two tubes (corresponding to power cab le conductor models with infinite pitch) with different diameters are compa red. We find that the DC properties, i.e., the critical currents of the two arrangements, scale with the number of tapes and hence appear to be indepe ndent of the diameter. However, the AC loss per tape (for a given current p er tape) appears to decrease with increasing diameter of the circular arran gement. Compared to a model for the AC loss in a continuous superconducting layer (Monoblock model) the measured values are about half an order of mag nitude higher than expected for the small diameter arrangement. When compar ed to the AC loss calculated for N individual superconducting tapes using a well known model (Norris elliptical) the difference is slightly smaller. ( C) 1998 Elsevier Science B.V. All rights reserved.