Reversible fluxoid motion in a superconducting Bi-2223 tape with fine filaments

The energy loss density was measured for a Bi-2223 tape with superconductin g filaments of average thickness 3 mu m which were separated by about 40 mu m so as to eliminate bridging of filaments. The result was compared with t he prediction of the modified Kim model. Although it was lower than the pre diction owing to the reversible fluxoid motion at temperatures above 77.3 K , it slightly increased at around 1 mT. It is considered that an increase i n the pinning strength and a resultant shortening of the ac penetration dep th suppressed the effect of the reversible fluxoid motion at such low ac ma gnetic field amplitudes.