AC LOSSES OF AC SUPERCONDUCTING CABLE DUE TO TRANSPORT CURRENT IN EXTERNAL AC MAGNETIC-FIELD

Transport current AC losses of superconducting cables of the (6+1) con figuration (6 AC superconducting multifilamentary strands bundled arou nd a CuNi center wire) and the single strand composing the cable were measured in an AC external magnetic field. The measured AC loss data o f the cables of different twist pitches and directions were compared w ith those of the strand. It was shown that the transport current AC lo sses of the cables were affected by the twist directions and pitches o f the cables. A theoretical model to evaluate the AC loss due to trans port current was derived. In the model, the effect of the longitudinal magnetic field subjected to the strands and the current density vs. e lectric field characteristics of the strand were taken into considerat ion. Our theorectical model well explains the measured characteristics of the cable.