GUIDE LINES FOR THE DESIGN OF VERY LARGE-APERTURE QUADRUPOLE MAGNETS

Very large aperture quadrupole magnets have been recently considered a s possible spectrometers on high energy colliders. The interesting cha racteristics are zero field on beam axis, low fields at small angles, transverse field at large angles. Dimension range is 1 m to 5 m for cl ear bore and 2 m to 8 m for length; typical maximum field is 2.5 T. Su perconducting magnets with cosine 2 theta structure, coils with one or two layers and iron yoke have been modelised, Use of two types of con ductors have been investigated : Rutherford cable and aluminium stabil ized composite. The paper describes the optimization procedure and giv es diagrams of feasibility. Two alternative structures are mentioned : superferric and active shield magnets.