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BIG-POWA Résumé de rapport

Project ID: G5RD-CT-2000-00219
Financé au titre de: FP5-GROWTH
Pays: Switzerland

Fabricating of square/round Bi-2223 wires

Square/round wires enable an easy assembly when fabricating high current capacity conductors compared with the existing flat tapes. By using a drawing machine and a two-axial rolling machine, we have succeeded in preparing round wires and square wires. However, it is still a challenge to obtain high textured and uniform Bi-2223 filaments in the wires.

A number of square/round wires have been fabricated by using two-axial rolling machine. Due to special deformation method, the properties of square/round wires are quite different to the standard flat tapes. We have experimentally showed that, for same filamentary configuration, the critical current of round wire always is lower than that in square wires.

Therefore, our studying in this project mainly focuses on the square wires, with respect to the deformation, heat treatment, AC losses and so on.

Long Ag-sheathed multifilamentary Bi(2223) square wires(more than 200 meters) fulfilling the specifications set out in the project have been successfully fabricated.

The 40-filament square wire has a 90o-rotation symmetrical filament arrangement and therefore exhibits an almost angle-insensitive behavior with respect to the applied magnetic field. A critical cuurent density of 18kA/cm2 at 77K, 0T has been obtained, which is very close to the planned value of 20kA/cm2. This represent a very high level, being only a factor ~2 below the highest values obtained for flat Bi,Pb(2223) tape.

Reported by

University of Geneva
24, quai Ernest-Ansermet
1211 Genève
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