Mechanical properties of superconducting coils

Experience with the present generation of Tevatron superconducting magnet coils has made apparent several areas of possible improvement of coil structure. Implementation of the structural changes; i.e., cabling, insulation, adhesive, etc., requires a new determination of coil mechanical properties. In particular, measurements to enable prediction of coil stresses from the dimensions of coil substructures and prediction of residual stresses as a result of magnet storage and operational conditions. Theoretical uncertainties, because of the complex geometries, make empirical measurements desirable. We will measure the relationship between assembly stress and the component dimensions for several coil structures. From this data and the allowable design stress levels, component dimensions can be set. We have also measured the effect on stress levels of storage for protracted periods at high ambient temperatures and of operational occurrences such as a forced warm up which will substantially elevate temperatures for short periods. This data makes it possible to predict the number and severity of such occurrences that can be tolerated.