Performance of Four 4.5 M Two-in-One Superconducting R & D Dipoles for the SSC

Four 4.5 m long superconducting dipoles built to specifications similar to those for SSC Reference Design A have been successfully tested. They were wound with NbTi cable in two-layer cos¿ coils of 3.2 cm inner diameter. The coil ends were flared to increase thie minimum bending radius, anticipating coils wound from prereacted Nb3Sn. The coils were mounted in a reusable "two-in-one" iron yoke prestressed by means of a bolted stainless steel shell. The first two magnets as well as the fourth one, a special magnet designed to study cross-talk between the bores, used CBA/Tevatron cable. The third utilized cable with improved ("high homogeneity") NbTi conductor. All four reached central fields corresponding to their short sample limits at 4.5K without training, nearly 6. OT for the first two magnets, 6.5T for the third, and 5.4T for the fourth. At 2.5K modest training was required to reach short sample limits of 7.2T, 7.1T, 7.8T, and 6.6T respectively. The measured values of the allowed harmonics were within several × 10-4 of the calculated ones.