Test results from two 5m two-in-one superconducting magnets for the SSC

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Two 5m long superconducting dipole magnets with specifications similar to the reference design for the proposed Superconducting Super Collider have been successfully tested. The " <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\cos \theta</tex> " coils of the magnets were made from two layers of "standard" CBA/Tevatron NbTi superconductor, keystoned to an angle of 2.8 degrees. The inner diameter of the inner layer was 3.2 cm. The ends of the coils were flared to increase the minimum bending radius so that future magnets can be wound from prereacted Nb <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Sn. The windings of the two-aperture magnets were clamped in a "two-in-one" iron yoke with a tensioned stainless steel shell. The fields of the two apertures were closely coupled, since the flux in one aperture returned through the other. The inner and outer layers of the coil were powered separately so that their short-sample limits would be reached simultaneously. With minimal training the magnets reached a central field of 6 T, the short sample limit of the conductor at the 4.5 K temperature of the liquid helium bath. At 2.6 K, a central field in excess of 7 T was reached, again with minimal training. The measured values of the allowed sextupole and decapole harmonics are within 10% of the calculated values and the non-allowed harmonics are all small or zero, as predicted.