An Investigation of Cooldown Strain in Potted Superconductive Magnets
The David Taylor Naval Ship Research and Development Center is currently developing superconducting electrical machinery for ship propulsion. These machines employ superconducting magnets as field windings that require cooldown to 4.2 K before operation. The magnets are dry wound using superconducting wire with fiberglass cloth between each layer. An “overwrap” of fiberglass cloth is placed over the last layer of wire to provide additional mechanical support and a means to interface the coil with its support system. The coil assembly is then evacuated in a potting chamber and filled with epoxy resin. The anisotropic continuum that this construction yields presents a rather complex heat transfer problem. The wire is a good thermal conductor that exhibits low temperature gradients during cooling; on the other hand, epoxy and fiberglass are insulators that tend to exhibit high temperature gradients when cooled.
KeywordsThermal Contraction Magnet Composite Cooling Scheme Radial Temperature Gradient Test Magnet
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