Development of Nb44wt%Ti 25wt%Ta based superconducting conductors for LHC magnets
ABSTRACT A trial cable for LHC dipole inner layers made up of the Nb ternary alloy Nb44wt%Ti 25wt%Ta has been manufactured by GEC Alstrom Intermagnetics within the framework of a CERN development program. This cable is composed of 28 strands of 1.065 mm in diameter. The purpose of the study is: (i) to improve the superconducting behaviour of LHC cables at 1.9 K, the operating temperature of the Large Hadron Collider (LHC), and (ii) to evaluate the cabling feasibility of wires made with this alloy. Ic tests performed on wire samples before and after cabling at 4.2 K and 1.8 K show that at 4.2 K NbTi25wt%Ta wires exhibit lower Jc than those of the conventional binary alloy Nb47wt%Ti or those of a ternary alloy with only 15wt%Ta. But they have a larger magnetic field shift when cooled down from 4.2 to 1.8 K (about 1 T). The cabling of NbTi25wt%Ta wires presented no particular problem. Jc degradations due to cabling and evaluated on extracted strands are comparable to those observed on NbTi material. The performances achieved are reported and discussed in this paper.
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ABSTRACT: The superconducting wire with approximately 10 μm diameter filaments of Nb-41 wt%Ti-28 wt%Ta alloy was fabricated from our standard production billet. Critical current densities and upper critical fields after various heat treatments were measured in the temperature range of 4.2 K to 1.6 K. Thermo-mechanical treatments for α-Ti precipitates were optimized to improve critical current densities. A 27-strand Rutherford type cable having a large keystone angle was trial-fabricated using the optimized-processed wires. The achieved J<sub>c</sub>s were 1383 A/mm<sup>2</sup> (10 T and 1.9 K) and 602 A/mm<sup>2</sup> (12 T and 1.9 K). The fabricated wire was proved to have high homogeneity and good workabilityIEEE Transactions on Applied Superconductivity 07/1999; · 1.20 Impact Factor
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ABSTRACT: The vacuum arc melting technique was used to obtain the ingots of Nb-Ti-Ta alloys with 12.3 and 20.4 wt.% Ta. The microhomogeneity of the alloys was investigated by electron probe method and T<sub>c</sub> of the alloys after homogenization was measured in comparison with that of the binary Nb-47.5wt%Ti alloy. Multifilamentary conductors with filament diameter ~60 μm have been fabricated. The characteristics of the wires which have been produced by the regime with 4 intermediate heat treatments are presentedIEEE Transactions on Applied Superconductivity 07/1997; · 1.20 Impact Factor