Radiation Resistant Insulation with Improved Shear Strength for Fusion Magnets

70312S02-II Magnet insulation materials, used in many Next-Step Option fusion research devices, will be subjected to high stresses at both cryogenic and elevated temperatures. Unfortunately, at high stress levels, their low shear strength and their inability to adhere to the copper conductors can result in significant design compromises, such as increasing the overall compressive stress. This project will develop, evaluate, and characterize new materials and methods to provide improved shear and adhesive strength of organic and inorganic insulation systems for copper and superconducting conductors used in fusion magnets. Phase I identified and tested several adhesion promoters and processes, including silanes, triazoles, and black and brown oxide coatings. Several surface preparation methods were screened, and the effect of superconductor heat treatment on these materials was evaluated. Properties of the best systems were measured at 76 K, 296 K, and 373 K, and after thermal cycling among these temperatures. Phase II will develop, optimize, and screen adhesion enhancement materials, including the further development of cyanate ester primer systems, oxide coatings, and resin additives. Comprehensive adhesive/insulation testing will be conducted at cryogenic, room, and elevated temperatures. The materials will be exposed to neutron and gamma radiation to determine the effect on performance. Commercial Applications and Other Benefits as described by awardee: Many different components within fusion devices and experiments could benefit from radiation-resistant insulation with improved high temperature and adhesive shear performance. Electrical feedthroughs, ground planes, and support structures could be more efficiently designed with materials of this nature.