AC Losses in Multifilamentary Bi-2223/Ag Superconducting Tapes

In this study we examined ac losses in a multifilamentary Bi-2223/Ag superconducting tape carrying ae transport current. The tape consisting of 85 filaments was helically wound to a single-layer coil. The losses were measured at 77 K in the frequency range from 1 Hz up to 250 Hz. Current amplitudes Ip were ranging from i=Ip/Ic=0.6 to 1.5, critical current Ic=15.4 A determined by the standard 1 μV/cm static electric field criterion. The roles of special loss components were considered: hysteresis, flux-creep, coupling and eddy current losses. Hysteresis losses due to the self-field of the ac transport current were found to dominate when i≤1.1. Resistive losses dominated when i>1.2. In the hysteretic regime, the higher the frequency, the smaller the losses per cycle.