Total AC loss characteristics of untwisted and twisted Bi-2223 multifilamentary tapes andinteraction between self and external magnetic fields

Abstract

The authors have electrically measured the total AC losses of untwisted and twistedBi-2223 multifilamentary tapes in AC parallel and perpendicular transverse magnetic fields.The magnetization and transport losses in the untwisted and twisted Bi-2223multifilamentary tapes carrying an AC transport current in AC parallel and perpendiculartransverse magnetic fields were measured independently to obtain the total AC loss. Thetotal AC losses of both the untwisted and twisted Bi-2223 multifilamentary tapes ina parallel transverse magnetic field are approximately equal to the sum of thetransport loss without the external magnetic field and the magnetization losswithout the transport current. In particular, the total AC loss of the twisted tapein a parallel transverse magnetic field is in good agreement with this sum. Onthe other hand, the total AC losses of both the untwisted and twisted Bi-2223multifilamentary tapes in a perpendicular transverse magnetic field are largerthan the sum of the transport loss without any external magnetic field and themagnetization loss without transport current. The total AC loss of the twistedtape in a parallel transverse magnetic field can be predicted by the sum of themagnetization loss using the slab model for an equivalent filament thickness and thetransport loss given by Norris for a superconductor with an elliptical cross section.