A Composite Electrical Insulation in Superconducting Magnets

A composite electrical insulation tape has been developed for superconducting magnets in high-energy particle physics experiments. It is composed of glass-cloth(s)/polyimide-film (Upilex) laminations bonded with epoxy resin. The polyimide film provides optimum performance in electrical insulation and the glass-cloth contributes to reliable mechanical bonding of the superconductor to the other components. Reliable mechanical bonding is also essentially important to realize reliable conductive cooling in a superconducting magnet indirectly cooled by using forced two phase helium flow in cooling tube attached to the coil structure. The optimization has been made in the process of the lamination with some treatment on the polyimide surface and with optimized epoxy resin to realize the best mechanical bonding. This paper will describe development of the composite electrical insulation, including brief test results.