AC losses in multifilamentary Bi(2223) tapes with an interfilamentary resistive carbonate barrier

For the most common AC application frequencies, the main component of the A C losses in multifilamentary Bi(2223) tapes are caused by hysteresis- and c oupling losses. These losses can be reduced enhancing the matrix resistivit y and applying a twist to the filaments. We report on the AC loss propertie s of 37-filament tapes with AgAu (8 wt.%) matrix, and novel 19-filament tap es with SrCO3 barriers between the filaments. We performed transport AC los s and magnetic AC loss measurements in parallel and perpendicular magnetic fields. Both kinds of tapes were also prepared with filament twists below a twist pitch of 20 mm. The influence of the different tape modifications on the AC loss behaviour is presented and compared with theoretical models to understand the effect of the resistive matrix. In the case of magnetic AC loss measurements, reduced AC losses due to decoupled filaments were observ ed for the twisted tapes with a resistive matrix in low parallel fields. (C ) 1998 Elsevier Science B.V. All rights reserved.