DocumentCode :
843262
Title :
Compressive pre-strain in high-niobium-fraction Nb3Sn superconductors
Author :
Ekin, Jack W. ; Cheggour, Najib ; Abrecht, Mike ; Clickner, Cameron ; Field, Mike ; Hong, Seung ; Parrell, Jeff ; Zhang, Youzhu
Author_Institution :
Electromagn. Div., Nat. Inst. of Stand. & Technol., Boulder, CO, USA
Volume :
15
Issue :
2
fYear :
2005
fDate :
6/1/2005 12:00:00 AM
Firstpage :
3560
Lastpage :
3563
Abstract :
Multifilamentary Nb3Sn superconducting strands fabricated with high niobium fractions have exceptionally high critical-current densities but are sometimes marginally stable during testing. We report a technique for determining the pre-strain in such conductors, in which additional stabilizing copper is electroplated onto the conductor and the pre-strain is determined by extrapolation to the as-fabricated niobium fraction. This technique is used to measure the pre-strain in conductors with high niobium fractions of 20% to 30%. Values of the pre-strain εmax in these conductors are reduced to the range 0.1% to 0.2%, which is significantly less than the εmax values of 0.2% to 0.4% in traditional bronze-process Nb3Sn conductors (where niobium fractions are typically about 10% to 15%). However, including about 20% dispersion-strengthened copper into the conductor matrix restores εmax to the range 0.25% to 0.35%, thus providing practical levels of εmax for magnet design in high-niobium-fraction strands.
Keywords :
critical currents; electroplating; extrapolation; internal stresses; multifilamentary superconductors; niobium alloys; tin alloys; type II superconductors; Nb3Sn; compressive prestrain; conductor matrix; electroplating; extrapolation; high niobium fractions; multifilamentary superconducting strands; stabilizing copper; Conductors; Copper; Critical current; Multifilamentary superconductors; Niobium; Strain measurement; Superconducting magnets; Superconductivity; Tin; Wires; Axial strain; critical current; electromechanical properties; niobium-tin; pre-strain; thermal contraction;
fLanguage :
English
Journal_Title :
Applied Superconductivity, IEEE Transactions on
Publisher :
ieee
ISSN :
1051-8223
Type :
jour
DOI :
10.1109/TASC.2005.849360
Filename :
1440441
Link To Document :
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