Mode of magnetic flux penetration into high Tc superconductors with various cross-sectional shape and their AC loss characteristics

The current distribution in superconductors with various cross-sectional shapes is calculated numerically by the finite element method. The total loss in flat tapes carrying their transport current in the perpendicular magnetic field is increased by the interaction between the self and the perpendicular magnetic field. Though BSCCO round wires are often preferred to flat tapes, numerical results suggest that they are not always advantageous from the viewpoint of AC loss reduction. In YBCO coated conductors, the transport loss decreases with increasing aspect ratio of their cross-section. But, it remains much larger than the Norris's value for strip in small current region because of the finite aspect ratio of the region where magnetic flux penetrates. Importance of the critical current density near the tape edge is pointed out, because most of the loss is generated near the tape edge where the current density is large. (C) 2001 Elsevier Science B.V. All rights reserved.