Improvement of I/sub c/ in Nb/sub 3/Sn conductors by reduction of axial prestrain

Author

Specking, W. ; Duchateau, J.L.

Author_Institution

Inst. fur Tech. Phys., Kernforschungszentrum Karlsruhe, Germany

Volume

5

Issue

2

fYear

1995

fDate

6/1/1995 12:00:00 AM

Firstpage

845

Lastpage

848

Abstract

Nb/sub 3/Sn conductors for large scale applications consisting of a high volume fraction of structural material which degrades I/sub c/ drastically because of the compressive prestrain on the Nb/sub 3/Sn filaments. This results from the higher thermal contraction of the structural components in comparison to that of Nb/sub 3/Sn during cooling from reaction to operation temperature. For example, in Nb/sub 3/Sn "Cable in Conduit" conductors using steel conduits I/sub c/ decreases by about 50% relative to the peak value at 12 T. Several alternatives for the reduction of the prestrain are possible leading to a remarkable improvement of I/sub c/: prestraining of the reacted conductor at room temperature; attaching the structural components onto the Nb/sub 3/Sn cable after reaction heat treatment of the cable; using reinforcing materials with lower thermal contraction coefficient comparable with that of Nb/sub 3/Sn.<>

Keywords

critical current density (superconductivity); heat treatment; niobium alloys; superconducting cables; tin alloys; Nb/sub 3/Sn; Nb/sub 3/Sn conductors; Nb/sub 3/Sn filaments; axial prestrain reduction; cable in conduit conductors; compressive prestrain; lower thermal contraction coefficient; reaction heat treatment; reinforcing materials; steel conduits; structural components; thermal contraction; Conducting materials; Conductors; Cooling; Joining processes; Large-scale systems; Niobium; Steel; Temperature; Thermal degradation; Tin;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.402680

Filename

402680