Double-Helix Coil Technology for Bent Accelerator Magnets

High-field (~5 T) bent-dipole (0.7 m radius) magnets are required as part of a 180-degree-bend beam-transport region in the high radiation areas of a planned Rare Isotope Accelerator (RIA). The requirements for these magnets can be met by using a novel coil design called the double-helix dipole (DHD). The double-helix approach offers a solution to the design of these curved magnets that is much more cost effective and reliable than can be obtained using conventional cosine-theta accelerator magnet designs. This project will demonstrate a bent dipole with double-helix coils, designed not only to meet the operating specifications but also to be suitable for use in the high radiation areas of the RIA. The method employs helical windings on composite or moldable ceramic coil forms, followed by an epoxy vacuum-impregnation process that creates the strong coil structure necessary for high field magnet applications. In Phase I, the magnetic and mechanical design concept for a radiation-hard bent dipole will be developed. The method of coil manufacture, involving composite or moldable ceramic tubes with vacuum-impregnation of epoxy, will be demonstrated by fabricating test coil sections that have the approximate cross section of the final magnet. The impregnation adhesive will be tested by thermally shocking the test coils and then examininng the interior to show that the adhesive does not crack or otherwise degrade. A demonstration dipole using this technology will be built and tested in Phase II. Commercial Applications And Other Benefits as described by the Applicant: The bent double-helix magnets should provide an important contribution to accelerator magnet design for the RIA and other applications having similar requirements. For example, a bent solenoid magnet with superimposed dipole field is required in the cooling channel of a future Muon Collider. Another application of double-helix dipole windings, especially with the use of high temperature superconducting materials, is in the stators and rotors of superconducting electrical machines used to produce high power density motors and generators. Such devices would be of interest to government agencies such as DOD and NASA.