Reversible Motion of Flux Lines and AC Losses in High-temperature Superconducting Tapes

The possibility of reducing AC losses in superconducting Bi-2223 tapes with the aid of the reversible motion of flux lines is investigated. It was found that the AC loss was reduced by reducing the size of superconducting filaments, and the behavior was explained by the theoretical model of Campbell. To get a sufficient reduction of AC losses at 77.3K from the prediction using the critical state model, it is necessary to reduce the filament thickness below 2.5μm.