Tests of full scale SSC R&D dipole magnets

Four full-scale SSC (Superconducting Super Collider) research and development dipole magnets, incorporating successive mechanical design improvements, have been quench-tested. Three of the magnets are heavily instrumented with sensors to measure their mechanical behavior and verify the effectiveness of the mechanical improvements and with multiple voltage taps to locate the origin of quenches. The last two magnets of this series reach the SSC design operating field of 6.6 T in two or fewer quenches. Load cells and motion sensors show that in these two magnets the azimuthal clamping stress is higher at zero current and drops more slowly with excitation that in previous long magnets, and that the axial motion of the coil upon excitation has been greatly reduced. Quenches are found to originate preferentially in several locations, suggesting other design improvements. >