DEVELOPMENT OF THE SSC TRIM COIL BEAM TUBE ASSEMBLY

sextupole corrector which is distributed along the outside of the beam tube. The number of turns is maximized to decrease the reqmred current in the trim coil. The absolute position of each conductor is controlled to kO.05 mm along the length of the -17 m beam tube. This positioning tolerance was especially challenging because there was no conventional way to mass produce long complex multiturn coils using wire only =.2 mm in diameter to such precision. The variations due IO accumulated tolcranccs of the wire position produce coil blocks of unequal conductor density and the required symmetry of the coil is lost. To obtain the required precision with a method suitable for production, a technique developed by the Kolmorgan Corporation was adopted. In that technique, copper wires are placed directly onto an adhesive coated G-10 circuit board by an accurate, fast, fully automated process. We felt that we could exploit this established technology to produce complex coil patterns for the SSC. This technique was adapted to produce a flat coil pattern on a flexihlc substrate that could be bent around the outside of the beam tube. The edges of the pattern must meet precisely because a varying gap or coil asymmetry would produce unwanted field harmonics. The coil is secured to the beam tube; the substrate must be slit to a precise siLe to fit the beam tube, which has an outside diameter tolerance of f.02 mm over the entire 17 meter length. The trim coil’s substrate must withstand cryogenic temperatures and tolerate high radiation levels. The beam tube must be made from a high strength material of the required size which would not exhibii high eddy current loading during magnet quenches and which has an extremely low and uniform permeability. It must have an extremely pure layer of copper on its inside surface. The copper coaling must have excellent adhesion IO lhe beam tube without contaminates to poison the UHV. The copper must be uniformly applied over the full 17 meters.