Comparison of transport and magnetic AC losses in Bi-2223/Ag tapes — the role of superconducting core geometry |
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Authors: | Fedor G m ry, Laura Gherardi, Giovanni Crotti, Daniela Bettinelli, Luciano Martini, Luigi Bigoni,Sergio Zannella |
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Affiliation: | a Pirelli Cavi e Sistemi, c. 2140, Viale Sarca 222, 20126 Milan, Italy b Institute of Electrical Engineering, Slovak Academy of Sciences, Bratislava, Slovak Republic c CISE, Milan, Italy d Edison, Milan, Italy |
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Abstract: | AC losses were measured by 4-probe transport method and by external magnetization method in three samples of Bi-2223/Ag tape: a multifilamentary tape with separated filaments, another multifilamentary tape with ‘bridges' between filaments, and a two-shell tape. The transport losses agreed with those calculated using Ic from DC experiment. Magnetization experiments gave indications about the various paths of induced currents. For the tape with well separated filaments the main part of screening current closes inside individual filaments. Additional screening of the whole filamentary zone involves the normal metal matrix, leading to frequency dependent losses. In the case of tape with ‘bridged' filaments, supercurrents interconnect the filaments into bundles whose screening (and loss) is frequency-independent. Matching the experimental data indicates that a typical bundle was composed of 8 filaments. Magnetic losses of the two-shell tape were explained by a model for magnetization of superconducting wire with elliptical cross-section. |
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Keywords: | Transport AC loss Magnetic AC loss AC magnetic susceptibility Intergrowth Bi-2223 tape |
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