Measured mechanical properties of superconducting coil materials and their influence on coil prestress

Some measured thermal-mechanical characteristics of a film-insulated, superconducting, Rutherford-type flat cable are presented. Loads are applied, and strains measured, perpendicular to the wide face of the conductor, corresponding to the circumferential direction in a dipole magnet. Stress-strain-time behavior at room temperature, during cooldown, and at 77 K, with some data at 4 K, are presented. Properties were greatly improved by holding the insulated conductor at 100C for 4 hr. while under a compressive stress of 15 kpsi.