A new method for decreasing transport ac losses in multifilamentary coated superconductors

Numerical modelling was used to investigate the effect on transport ac losses of decoupling the filaments in superconducting YBCO coated conductors by magnetic screening. The different configurations of multifilament geometry with filaments covered with layers of a soft iron with non-linear B(H) characteristic considered were modelled. Calculations of contribution of the individual filaments to ac loss were conducted for selected configurations. A comparison of the calculated ac loss results in the multifilamentary conductors with a perfect inter-filamentary decoupling was provided. Since the multifilamentary coated conductors appear to be a favourable solution for low ac losses applications, the factors which affect the percolative nature of current flow in superconducting coated conductors, such as grain size and sample dimensions, have also been presented. (C) 2001 Elsevier Science B.V. All rights reserved.