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Characterization of insulating coatings for wind-and-react coil fabrication

  • Author(s): Cheng, DW
  • Dietderich, DR
  • Godeke, A
  • Hafalia, AR
  • Marchevsky, M
  • Prestemon, SO
  • Roy, PK
  • Sabbi, G
  • Swenson, CA
  • et al.

Published Web Location

https://doi.org/10.1063/1.4860621
Abstract

Electrical insulation breakdown between conductor and coil parts and structures is a limiting factor in the performance of high-field magnets. We have evaluated various insulation coatings for possible application in both Nb3Sn and Bi-2212 coil fabrication. Such coatings must be robust to maintain structural integrity and provide adequate voltage standoff after the wind-and-react coil fabrication process. Such processes are characterized by reaction temperatures of 650°C in an inert atmosphere for Nb3Sn and 890°C in a pure oxygen atmosphere for Bi-2212, and down to cryogenic temperatures when coils are in service. We present a method of testing standardized samples and report the performance characteristics of oxide layers produced (or applied) by plasma-spray, surface conversion, and "paintable" coatings in common areas of voltage breakdown in coil parts. We also address material compatibility and durability during high-temperature heat treatment and cryogenic shock. Suitable coatings selected in the testing process will be instrumental in improving the performance of future wind-and-react coils. © 2014 AIP Publishing LLC.

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