Development of New Nb-Ti Wires with a Cu-Si Alloy Matrix for AC Use
Nb-Ti ultrafine multifilamentary wires with Cu-Si alloy matrix have been fabricated for AC use. An AC coil of 100kVA-class capacity was wound by the stranded wire, and the coil has been operated in AC mode successfully. The stranded wire is composed of six elemental wires of 0.203mm in diameter and a central stainless steel wire for reinforcement. Each superconducting wire contains 164730 filaments of 0.14µm in diameter. We investigated the effects of Si concentration in the matrix and Nb barriers around filaments on the fabricability of wire. Also, critical current density, AC loss and the proximity effect of these wires were compared with those of conventional AC superconducting wires with Cu-Ni alloy matrix. Present new wires show almost no degradation in AC quenching current at low magnetic fields below 0.5T. As a consequence, these results demonstrate that the new wires can be applied to AC devices.
KeywordsAlloy Matrix Proximity Effect Hysteresis Loss Filament Diameter Stranded Wire
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