Stress relaxation in SSC collared coils and their component materials

Previous work, reported at last year's meeting, has been continued. One model section of an SSC outer coil has had it's stress relaxation measured for nearly two years. In addition, the stress relaxation of SSC cable without insulation has been measured. Kapton insulation alone has been studied both in creep and stress relaxation. Creep has been measured parallel to the plane of the film. These measurements are dependent on internal stresses that may be present in the film and on the moisture content of the film. They indicate that any measurements of coil relaxation are not likely to be repeatable if these factors are not controlled. The measurements on Kapton film alone are being done at different temperatures to obtain a time-temperature shift factor so that measurements at one temperature may be used to predict relaxation at any other temperature. 12 refs., 8 figs