Electromagnetic field and ac power loss enhancements at the edges of adjacent strips in a superconducting cable

In most flexible superconducting cables the current is carried by a series of strips laid along the length of the cable with small gaps between their edges to accommodate bending. One consequence of dividing the conductor into strips is an enhancement of the electromagnetic fields in the vicinity of the gaps. The ac losses in the superconductor are thereby also enhanced. Data are presented which enable the effects of these field and loss enhancements on cable performance to be assessed. In particular it is found that there is an optimum corner radius for the strips to achieve a minimum increase in loss compared to a smooth tube and that this increase need not be large for a suitably rounded corner. A non-uniform distribution of the strips around the cross-section of the cable can be deleterious while any radial displacements are likely to increase the losses considerably.