Measurement of thermal contraction properties for NbTi and Nb/sub 3/Sn composites

Accurate knowledge of winding composite thermal contraction properties is critical to the design of large epoxy impregnated Nb/sub 3/Sn and NbTi coils. Measurement of thermal contraction properties allows the reliable design prediction of cold coil dimensions, the state of the coil form interface, resulting mechanical stresses from cool-down, and the correct locations of coils in an assembly. NbTi and Nb/sub 3/Sn epoxy glass winding composites have been built to precisely model the material, packing factors, and processing steps consistent with coil fabrication. Thermal contraction properties are measured using a strain gage measurement technique where gage signals are compared to known reference samples. Composites are inherently anisotropic. Gages are placed on each sample to measure the thermal contraction along each principal axis of the composite. This paper reports these measurement results.