The magnetisation loss in multifilament HTS tape superconductors can be reduced by twisting the filaments and increasing the matrix resistivity. In this paper the influence of filament twist on the coupling current loss of the tape is studied. Magnetisation measurements on multifilament Bi2223 tape conductors with different twist pitches are performed at 77 K in magnetic field applied parallel and perpendicular to the wide face of the conductor. Both frequency and magnetic field amplitude are varied. In perpendicular magnetic field the filaments are fully coupled. In parallel magnetic field the twisted filaments are decoupled, even for twist pitches around 10 mm and a pure silver core. However, for increasing magnetic field >0.04 T, the influence of the coupling current loss increases. The transition to full coupling and the coupling current loss are analysed with an existing analytical model for a tape superconductor.
- AC loss