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Dissipative Energies of Epoxy Cracking in Superconducting Magnets

  • H. Yamajo
  • H. Fujita
  • E. S. Bobrov
  • Y. Iwasa
Part of the Advances in Cryogenic Engineering book series (ACRE, volume 31)

Abstract

Epoxy cracking in epoxy-impregnated superconducting magnets is caused by transverse shear stresses created by Lorentz forces. The dissipative energy of cracking can induce premature quenches in these magnets. Dissipative crack energies have been measured in a test coil; the maximum energy measured in the test coil was ~2 mJ.

Keywords

Dissipative Energy Acoustic Emission Epoxy Matrix Energy Transducer Mechanical Disturbance 
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.

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References

  1. 1.
    Y. Iwasa, Experimental and theoretical investigation of mechanical disturbances in epoxy-impregnated superconducting coils. Part 1: General introduction, Cryogenics 25; 304 (1985).CrossRefGoogle Scholar
  2. 2.
    E.S. Bobrov, J.E.C. Williams, and Y. Iwasa, Experimental and theoretical investigation of mechanical disturbances in epoxy-impregnated superrconducting coils. Part 2: Shear-stress-induced epoxy fracture as the principal source of premature quenches and training-Theoretical analysis, Cryogenics 25; 307 (1985).CrossRefGoogle Scholar
  3. 3.
    Y. Iwasa, E.S. Bobrov, O. Tsukamoto, T. Takaghi, and H. Fujita, Experimental and theoretical investigation of mechanical disturbances in epoxy-impregnated superconducting coils. Part 3: Fracture-induced premature quenchs, Cryogeneics 25; 317 (1985).CrossRefGoogle Scholar
  4. 4.
    H. Fujita, T. Takaghi, and Y. Iwasa, Experimental and theoretical investigation of mechanical disturbances in epoxy-impregnated superconducting coils. Part 4: Prequench cracks and frictional motion, Cryogencis 25; 323 (1985).CrossRefGoogle Scholar
  5. 5.
    H. Fujita, E.S. Bobrov, and Y. Iwasa, Simultaneous measurements of energy release and acoustic emission due to cracking and frictional movement, in this volume. Also see Hiroyuki Fujita and Yukikazu Iwasa, High-resolution experimental techniques for cryomechanics—a study of mechanical behavior of materials at 4.2 K (to appear in Experimental Mechanics 1986.)Google Scholar
  6. 6.
    O. Tsukamoto, J.F. Maguire, E.S. Bobrov, and Y. Iwasa, Identification of quench origins in a superconcuctor with acoustic emission and voltage measurements, Appl. Phys. Lett. 39; 172 (1981).CrossRefGoogle Scholar
  7. 7.
    H.A. Duncan, Energy Processing Techniques for Stress Wave Emission Sigals. J. Acoust. Soc. Am. 65; 6 (1979).CrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1986

Authors and Affiliations

  • H. Yamajo
    • 1
    • 2
  • H. Fujita
    • 1
    • 2
    • 3
  • E. S. Bobrov
    • 1
    • 2
  • Y. Iwasa
    • 1
    • 2
  1. 1.Francis Bitter National Magnet LaboratoryMassachusetts Institute of TechnologyCambridgeUSA
  2. 2.Plasma Fusion CenterMassachusetts Institute of TechnologyCambridgeUSA
  3. 3.Institute of Industrial ScienceUniversity of TokyoTokyoJapan

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