Mechanical behavior of Fermilab-built 1.5 m model SSC collider dipoles

Several model SSC (Superconducting Super Collider) dipole magnets (50-mm aperture, 1.5-m magnetic length) have been built and tested at Fermilab. These magnets are instrumented with strain gauges to measure stresses in the coil, the cold mass shell, and the coil end clamp assembly. Measurements are made of these quantities during assembly, cooldown, excitation, and warmup. The collar vertical deflection with prestress and the shell azimuthal tension agree quantitatively with design expectations. Coil prestresses within the desired range have been achieved without pole shims. Prestress loss with cooldown compares favorably with 40-mm models. Most of the axial I×B force is transmitted to the shell via collar-yoke-shell friction, and not by compressive loading of the coil end. The yoke parting plane gap remains closed to well above the operating point, and end clamp deflections are ≲0.05 mm under excitation