Passive Superconductor a Viable Method of Controlling Magnetization Multipoles in the SSC Dipole

  • Michael A. Green


At injection, the magnetization of the superconductor produces the dominant field error in the SSC dipole magnets. The field generated by magnetization currents in the superconductor is rich in higher symmetric multipoles (normal sextupole, normal decapole, and so on). Pieces of passive superconductor properly located within the bore of the dipole magnet can cancel the higher multipoles generated by the SSC dipole coils. The multipoles generated by the passive superconductor (predominantly sextupole and decapole) are controlled by the angular and radial location of the superconductor, the volume of superconductor, and the size of the superconducting filaments within the passive conductor. This paper will present the tolerances on each of these factors. The paper will show that multipole correction using passive superconductor is in general immune to the effects of temperature and magnetization decay due to flux creep, provided that dipole superconductor and the passive correction superconductor are properly specified. When combined with a lumped correction system, the passive superconductor can be a viable alternative to continuous correction coils within the SSC dipoles.


Dipole Magnet Critical Current Density Flux Line Lawrence Berkeley Laboratory Filament Diameter 
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  1. 1.
    M. A. Green , IEEE Transactions on Nuclear Science NS-18 (3), p. 664, June 1971.Google Scholar
  2. 2.
    H. C. Brown , et al, IEEE Transactions on Magnetics Z1 (2), p. 979, March 1985.Google Scholar
  3. 3.
    H. E. Fisk, et al, “Magnetic Errors in the SSC”, Report of the SSC Central Design Group SSC-7, April 1985.Google Scholar
  4. 4.
    A. Chao and M. Tigner, “Requirements for Dipole Field Uniformity and Beam Tube Correction Windings”, SSC-N-183, May 1986.Google Scholar
  5. 5.
    D. Neuffer, “A Novel Method for Correcting the SSC Multipole Problem”, SSC-172, April 1988.Google Scholar
  6. 6.
    M. A. Green, “Residual Fields in Superconducting Magnets”, published in the Proceedings of the MT-4 Conference at Brookhaven National Laboratory, p. 339,1972.Google Scholar
  7. 7.
    W. J. Carr, IEEE Transactions on Magnetics, MAG-21 (2), p. 335.Google Scholar
  8. 8.
    M. N. Wilson, Superconducting Magnets. Clarendon Oxford Press, Oxford, UK, pp. 174–181, 1983.Google Scholar
  9. 9.
    E. W. Collings, “Stabilizer Design Considerations in Ultrafin Filamentary Cu/Ti-Nb Composites”, Proceedings of the 6th Workshop on Niobium-Titanium Superconductors, University of Wisconsin, Madison, Wl, 1986.Google Scholar
  10. 10.
    M. A. Green, Advances in Cryogenic Engineering 32, Plenum Press, New York, 1987.Google Scholar
  11. 11.
    D. A. Herrup et al., “Time Variations of Fields in Superconducting Magnets and their Effects on Accelerators”, IEEE Transactions on Magnetics, MAQ-25, No. 2,1989.Google Scholar
  12. 12.
    M. R. Beasley et al., Physical Review 181, pp. 682–700, May 1969.Google Scholar
  13. 13.
    W. S. Gilbert et al., “Magnetic Field Decay in Model SSC Dipoles”, IEEE Transactions on Magnetics, MAG-25. No. 2,1989.Google Scholar
  14. 14.
    M. A. Green, “Field Generated Within the SSC Magnets Due to Persistent Currents in the Superconductor”, Proceedings of the Ann Arbor Workshop on SSC Issues, LBL-17249, December 1983.Google Scholar
  15. 15.
    M. A. Green, “Aberrations Due to Asymmetries in Current, Filaments and Critical Current”, LBL Engineering Note M6670’,August 1987.Google Scholar
  16. 16.
    H.E. Fisk and A. D. Mclnturff, private communication on the use of a passive superconductor to correct the residual field higher multipoles.Google Scholar
  17. 17.
    M. A. Green, IEEE Transactions on Magnetics, Mag-23. No. 2, p. 506,1987.Google Scholar
  18. 18.
    M. A. Green, “Calculating the Jc, B, T Surface for Niobium Titanium Using Reduced State Model”, IEEE Transactions on Magnetics, MAG-25. No. 2, 1989.Google Scholar
  19. 19.
    A. K. Ghosh, National Laboratory, private communication on the decay of proximity coupled currents, January 1989.Google Scholar
  20. 20.
    W. S. Gilbert, Lawrence Berkeley Laboratory, private communication on LBL measurements of magnetization field decay, January 1989.Google Scholar

Copyright information

© Plenum Press, New York 1989

Authors and Affiliations

  • Michael A. Green
    • 1
  1. 1.Lawrence Berkeley LaboratoryBerkeleyUSA

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