Transient field losses in multifilamentary composite conductors carrying transport currents

Investigations of the losses in multifilamentary composite conductors which result from the simultaneous change of the external field Beand transport current I are presented. The total loss is best characterized by a maximum normalized transport current im= Im/Ic(Ic= critical current) and a dimensionless field-change rateβ = ̇ₑ/Bₚ, where τ is the relaxation time of the coupling current and Bpis the full-penetration field of a solid superconductor equivalent to the multifilamentary composite. Forβ 1, the composite conductor behaves like a solid and a saturation effect occurs in the loss. The characteristic feature of the composite appears only forβ 1. The increase in losses arising from the non-zero transport current theoretically, is not larger than about 30 percent. For practical calculations, the experimental results over a wide range of β and imagree well with the theory.