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Conductors from Superconductors: Conventional Low-Temperature and New High-Temperature Superconducting Conductors

Published online by Cambridge University Press:  29 November 2013

David C. Larbalestier  and
Martin P. Maley
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A useful superconducting conductor must have several properties. Some of the key properties among these are illustrated by the cross section of a Nb-47wt%Ti/Cu composite (Figure 1) which was manufactured for the dipole magnets of the Superconducting Super Collider (SSC). It represents the state of the art for conventional conductor fabrication and is thus an excellent place to start in considering what is needed for any new conductor. First among the essential properties is a high critical current density (Jc); the lower limit of useful Jc is ~104 A/cm2, but really useful values lie between 105 and 106 A/cm2. The SSC conductor achieves this at fields up to 9 T at 4.2 K, the normal temperature used for magnets cooled by liquid helium.

A critical second requirement is that the superconductor be paralleled by an intimately connected good normal conductor, in this case high-conductivity Cu. One function of the Cu is to stabilize the superconductor against small temperature disturbances that lead to flux jumps that could result in local quenching of superconductivity. This requirement forces the subdivision of a given cross section of the superconductor into many filaments having a maximum diameter of no more than about 50 μm, since bigger filaments store more electromagnetic energy than can safely be deposited in the filament without locally heating it above its critical temperature (Tc). One advantage of high-temperature superconducting (HTS) materials is that they can operate at temperatures above ~10 K. Since the specific heat is a strongly increasing function at low temperatures, this permits the safe filament size to greatly increase too. The need to minimize hysteresis losses, however, often provides a separate drive to minimize the filament diameter, as in the conductor of Figure 1, where there are some 7,000 filaments which are only 6 μm in diameter. The overall Cu:Nb-Ti ratio is about 1.5:1. This represents a compromise between the need to minimize the dilution of the supercurrent density by Cu and the need to provide sufficient high-conductivity normal metal to pass the current when the magnet makes the transition from the superconducting to the normal state (a quench).

Type
Materials Science in High Magnetic Fields
Information
MRS Bulletin , Volume 18 , Issue 8 , August 1993 , pp. 50 - 56
Copyright
Copyright © Materials Research Society 1993

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References

1.Warnes, W.H., Metals Handbook 2, 10th ed. (ASM International, 1990) p. 1030.Google Scholar
2.Larbalestier, D., Fisk, G., Montgomery, B., and Hawksworth, D., Phys. Today 39 (3) (1986) p. 24.CrossRefGoogle Scholar
3.Larbalestier, D., Phenomenology and Applications of High-Temperature Superconductors, edited by Bedell, K.S.et. al. (Addison Wesley, 1992) p. 464.Google Scholar
4.Kes, P.H., Phenomenology and Applications of High-Temperature Superconductors, edited by Bedell, K.S.et. al. (Addison Wesley, 1992) Reference 3, p. 290.Google Scholar
5.Lee, P.J. and Larbalestier, D.C., in Concise Encyclopaedia of Magnetic and Superconducting Materials, edited by Evetts, J.E. (Pergamon Press, London, 1992).Google Scholar
6.Kreilick, S., Metals Handbook 2, 10th ed. (ASM International, 1990) p. 1043.Google Scholar
7.Smathers, D.B., Metals Handbook 2, 10th ed. (ASM International, 1990), p. 1060.Google Scholar
8. See Proceedings of the International Workshop on Chevrel Phase Superconductors, edited by Decroux, M. and Fischer, O. (University of Geneva, Switzerland, 1991).Google Scholar
9.Larbalestier, D.C., Phys. Today 44 (6) (1991) p. 74.CrossRefGoogle Scholar
10.Babcock, S.E., MRS Bulletin XVII (8) (1992) p. 20.CrossRefGoogle Scholar
11.Shaw, D., MRS Bulletin XVII (8) (1992) p. 39.CrossRefGoogle Scholar
12.Hellstrom, E.E., MRS Bulletin XVII (8) (1992) p. 45.CrossRefGoogle Scholar
13.Haldar, P., J. Met. 44 (10) p. 54.Google Scholar
14.Kato, T., Hikata, T., Ueyama, M., Sato, K., and Iwasa, Y., MRS Bulletin XVII (8) (1992) p. 52.CrossRefGoogle Scholar
15.Raveau, M., Phys. Today 45 (10) (1992) p. 53.CrossRefGoogle Scholar
16.Nelson, D.R., Phenomenology and Applications of High-Temperature Superconductors, edited by Bedell, K.S.et. al. (Addison Wesley, 1992) p. 464.Google Scholar
17.Maley, M.P., Kung, P.J., Coulter, J.Y., Carter, W.L., Riley, G.N., and McHenry, M.E., Phys. Rev. B 45 (1992), p. 7566.CrossRefGoogle Scholar
18.Thompson, J.R., Sun, Y.R., Kerchner, H.R., Christen, D.K., Sales, B.C., Chakoumakos, B.C., Marwick, A.D., Civale, L., and Thomson, J.O., Appl. Phys. Lett. 60 (1992) p. 2306.CrossRefGoogle Scholar
19.Kim, D.H., Gray, K.E., Kampwirth, R.T., Smith, J.C., Richeson, D.S., Marks, T.J., and Eddy, M., Physica C 177 (1991) p. 431.CrossRefGoogle Scholar
20.Roas, B., Schultz, L., and Saemann-Ischenko, G., Phys. Rev. Lett. 64 (1990) p. 479.CrossRefGoogle Scholar
21.Yamada, Y., Satou, M., Murase, S., Kitamura, T., and Kamisada, Y.. To appear in Proceedings of the International Symposium of Superconductivity (ISS92, Kobe, Japan), (Springer-Verlag, 1993).Google Scholar
22.Yamasaki, H., Endo, K., Kosaka, S., Umeda, M., Yoshida, S., and Kajimura, K., IEEE Transactions on Applied Superconductivity 3 (1993) p. 1536.CrossRefGoogle Scholar
23.Otte, A., Masur, L.J., Gannon, J., Podtburg, E., Daley, D., Yurek, G.J., and Malozemoff, A.P., IEEE Transactions on Applied Superconductivity 3 (1993) p. 915.CrossRefGoogle Scholar