A novel idea for coil collar structures in accelerator superconducting magnets

The dipoles for several different machines (LHC, SSC, HERA) were designed using nonmagnetic metallic collars to contain the superconducting coils. The coils are of two types, main and floating. This paper describes a structure with combined steel and plastic collars. Since the floating collars do not give an important contribution to the global rigidity of the dipole we propose to suppress them. The plastic collars are just fillers to limit the helium contained in the cold mass. Some data about thermoplastic materials to be possibly used for the collars are given and some estimations of mass and cost of this configuration are made. Finally the results of the tests of a 1-m-long twin aperture dipole with mixed steel-plastic collars are shortly described. The replacement of expensive alloys by high performance plastic in nonstructural components can be a cost-effective solution in view of future projects where superconducting magnets are involved and contained costs are a key issue.