Magnet insulation with resistance to high levels of radiation

Large, capital intensive magnets, superconducting or resistive, are essential components of fusion devices and high energy physics (HEP) accelerators. Magnets built for these applications need to be reliable, possess long mean time between failures (MTBF), and be able to be manufactured using cost-effective materials and fabrication processes. Electrical insulation is often the weak-link in the design of magnets, due to its sensitivity to high radiation doses, embrittlement at cryogenic temperatures, and limitations in fabricability. Current magnet insulation materials provide sufficient electrical insulation, suitable mechanical properties at magnet operating temperatures, flexible processing for cost-effective coil fabrication and assembly, and reasonable cost. However, they degrade to unacceptable levels of performance when exposed to high levels of radiation. Recent work performed by CTD studied the hybridization of insulation chemistry. The goals of this work was to increase radiation resistance of the insulation while maintaining suitable properties and enable cost-effective processing techniques. Hybrids of different organic polymers including epoxies, polyimides, bismalimides (BMIs), and other aromatic based polymers were successfully demonstrated. Furthermore, hybridization of inorganic with organic materials was also demonstrated. The former materials are well suited for magnets manufactured from resistive conductors or NbTi, while the latter materials are well suited for Nb/sub 3/Sn and potentially HTS conductors because these materials enable a wind, insulate, and react fabrication scenario. A discussion of new hybridized radiation resistant insulation materials will be presented. Data will include anticipated end-of-life performance after exposure to high levels of radiation.