Determination of the Thermal and Mechanical Strain Behavior of NbTi/Cu Cable Embedded in an Aluminum Stabilizer
Coextrusion processing of NbTi/Cu flat cable inside of high purity aluminum is a common method of conductor fabrication. Although this processing scheme has numerous advantages it produces a composite material with unknown and often unpredictable physical properties. Two such properties of interest to magnet designers are the composite’s elastic modulus and thermal expansion. Typically the properties of a composite can be predicted with models that use the constituent properties. Of course the properties of aluminum are well known but the NbTi/Cu flat cable properties should be measured. The cabled geometry and the effect that coextrusion processing may have on the cable, complicates estimating or measuring this components properties. Here an in-situ measurement method is used that provides data on the composite conductor and the components. The thermal expansion from 293 K to 4 K and the 4 K elastic modulus are measured as a function of the volume fraction of superconductor cable within the composite conductor. The data are compared to properties that are estimated from simple models and evaluated with regard to assumptions that are used for the models.
KeywordsThermal Contraction Composite Conductor Thermal Expansion Property Constituent Property Magnet Designer
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