Enhanced Proximity Effect Coupling Due to the Presence of a Nb Barrier in Fine NbTi Multifilamentary Composites

  • M. D. Sumption
  • H. Liu
  • E. Gregory
  • E. W. Collings
Part of the Advances in Cryogenic Engineering Materials book series (ACRE, volume 42)


Recent measurements have shown that hydro-extruded fine-filament multifilamentary NbTi/Cu composite (MF) strands in which the NbTi filaments were not protected by Nb barriers exhibited extremely low proximity effect (PE) coupling. To examine this anomaly two series of MF strands were fabricated, one with and the other without the Nb barrier. Magnetization measurements performed on these strands confirmed that the presence of the Nb barrier was associated with an enhancement of the PE coupling. It is concluded that any additions to the matrix of a MF strand that would provide the needed protection against Cu/NbTi interface compound formation, without requiring the use of Nb as a barrier, can be expected to lower the tendency for PE coupling.


Proximity Effect Filament Diameter Hydrostatic Extrusion Twist Pitch Strand Type 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    A.K. Ghosh, W.B. Sampson, E. Gregory, and T.S. Kreilick, Anomalous low field magnetization in fine filament NbTi conductors, IEEE Trans. Magn. MAG-23, 1724–1727 (1987).CrossRefGoogle Scholar
  2. 2.
    D.K. Finnemore, H.C. Yang, V.G. Kogan, and S.L. Miller, Magnetic impurity scattering m-situ superconductors, Adv. Cryo. Eng. (Materials) 30, 909–915 (1984).Google Scholar
  3. 3.
    E.W. Collings, Stabilizer design considerations in ultrafine filamentary Cu/NbTi composites, Sixth NbTi Workshop, Madison, WI, Nov. 12–13, 1986;Google Scholar
  4. 3a.
    E.W. Collings, Stabilizer design considerations in ultrafine filamentary Cu/NbTi composites, Adv. Cryo. Eng. (Materials) 34, 867–878 (1988).Google Scholar
  5. 4.
    E.W. Collings, K.R. Marken, Jr., and M.D. Sumption, Interfilament and intrafilament magnetizations in fine-filament composite strands for precision-dipole magnet applications, Cryogenics 30, 48–55 (1990).Google Scholar
  6. 5.
    E.W. Collings, K.R. Marken, Jr., and M.D. Sumption, Design of multifilamentary strands for SSC dipole magnets, in Supercollider 2, ed. by M. McAshan (Plenum Press NY, 1990) pp.581–592.CrossRefGoogle Scholar
  7. 6.
    K. Yamafuji, Y. Mawatari, N. Harada, et al, Effect of flux creep on the SSC dipole magnets, Cryogenics 30 (Suppl.), 615–619 (1990).Google Scholar
  8. 7.
    N. Harada, Y. Mawatari, O. Miura, et al, Excess magnetization due to interfilamentary proximity coupling in NbTi multifilamentary wires, Cryogenics 31, 183–191 (1991).CrossRefGoogle Scholar
  9. 8.
    M.D. Sumptionand E.W. Collings, Effect of twist pitch, sample length, and field orientation on the proximity effect enhanced magnetization in fine filamentary multifilamentary strands, Adv. Cryo. Eng. (Materials) 38, 783–790 (1992).Google Scholar
  10. 9.
    M.D. Sumption and E.W. Collings, Influence of twist pitch and sample length on proximity effect coupling in multifilamentary composites described in terms of a field-independent, two-current-region model, Cryogenics 34, 491–505 (1994).CrossRefGoogle Scholar
  11. 10.
    M.D. Sumption and E.W. Collings, Innovative strand design for accelerator magnets, Int. J. Mod. Phys. A (Proc. Suppl.) 2B, 662–664 (1993).Google Scholar
  12. 11.
    K. Itoh and H. Wada, Magnetization of VAMAS NbTi AC loss test wires, Proc. ICFA Workshop on AC Superconductivity, KEK Proc. 92–14, 149–151 (1992);Google Scholar
  13. 11b.
    also K. Itoh, H. Wada, and K. Tachikawa, 2nd VAMAS AC loss intercomparison on NbTi wires, Proc. 8th US-Japan Workshop on High-Field Superconductor Materials, University of Wisconsin-Madison, March 17–19 (1993), pp. 73–77.Google Scholar
  14. 12.
    R.W. Heussner, P.J. Lee, P.D. Jablonski, and D.C. Larbalestier, The influence of niobium and niobium-titanium grain size on the drawing instability of niobium diffusion barriers in niobium-titanium wire, Adv. Cryo. Eng. (Materials) 40, 755–762 (1994).Google Scholar
  15. 13.
    E.W. Collings, Applied Superconductivity, Metallurgy and Physics of Titanium Alloys, Vol. 2, (Plenum Press, NY 1986) p.444.CrossRefGoogle Scholar
  16. 14.
    H.C. Kanithi, P. Valaris, and B.A. Zeitlin, Superconductors with 2.5 micron NbTi filaments, in Supercollider 3, ed. by J. Nonte (Plenum Press, NY, 1991) pp.689–693.CrossRefGoogle Scholar
  17. 15.
    M.D. Sumption and E.W. Collings, Bridging in superconductors, Proc. ICMC Symposium Critical State in Superconductors, Honolulu, HI, Oct. 24–26, 1994 — to be published.Google Scholar
  18. 16.
    H. Liu, K.J. Faase, E. Gregory, et al., The effect of silicon addition to the interfilamentary copper on Jc , compound formation and interdiffusion, in Supercollider 5, ed. by P. Hale (Plenum Press NY, 1994)pp.591–594.CrossRefGoogle Scholar
  19. 17.
    F.R. Fickett, in Materials at Low Temperatures, ed. by R.P. Reed and A.F. Clark (Amer. Soc. Metals, Metals park, OH, 1983) p. 173.Google Scholar
  20. 18.
    S. Akita, S. Torii, H. Kasahara, et al., Ultrafine multifilamentary Nb-Ti wires with Cu-Si alloy matrix, Cryogenics 33, 199–204 (1993).CrossRefGoogle Scholar
  21. 19.
    M.D. Sumption, Proximity effect magnetization and energy loss in multifilamentary composites: influence of strand design and sample geometry, Ph.D. Thesis, Ohio University, Athens, OH, 1992.Google Scholar
  22. 20.
    M.D. Sumption, D.S. Pyun, and E.W. Collings, Transverse and longitudinal resistivities in NbTi multifilamentary strands with Cu and CuMn matrices, IEEE Trans. Appl. Superconductivity 3, 859–862 (1993).CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1996

Authors and Affiliations

  • M. D. Sumption
    • 1
  • H. Liu
    • 2
  • E. Gregory
    • 2
  • E. W. Collings
    • 1
  1. 1.Department of Materials Science and EngineeringThe Ohio State UniversityColumbusUSA
  2. 2.IGC Advanced Superconductors Inc.WaterburyUSA

Personalised recommendations