The influence of geometry on self-field AC losses of Ag sheathed PbBi2223 tapes

Abstract

We measured axial fields along an Ag sheltered PbBi2223 superconducting tape 3 mm wide and 0.03 mm thick carrying 47 Hz alternating currents. Tte critical current of the tape at 77 K was 1 5 A corresponding to a critical current density of 16 000 A/cm 2. The axial electric field was measured by pairs of voltage leads brought out in a plane perpendicular to the tape axis, turned axially to meet and so led out to a voltmeter. The spatial variation and the current dependence of the electric field, obtained from several pairs of taps closed at different radial positions, were consistent with the prediction for a uniform superconducting thin rectangle with a critical current I c rather than a superconductor of elliptical cross-section. Our results also showed that the hysteretic losses at currents below I c can be measured with an accuracy of about 5% using a pair of taps closed at a radial distance about three times the tape half-width.