Losses in Superconducting Multifilament Composites under Alternating Changing Fields.

摘要

The first part of this report presents a brief review of the losses in superconducting composites in a changing external field. The losses are expressed for a single triangular shaped pulse and for a field varying exponentially with time. The losses are calculated as a function of two important time constants. The first is due to the coupling currents between the filaments,the second is due to the eddy currents induced in the matrix. In the second part of the report,the case of an oscillating sinusoidal field is considered. In particular,in a rapidly varying field,several layers of filaments can be saturated by returning currents. Complete expressions of the losses are provided together with simplified expressions which enable one to calculate the losses in most cases. In the third part, a comparison between several kinds of conductors shows that in some cases the losses are reduced by increasing the twist pitch of the conductor. (ERA citation 04:039270)