Future fusion reactors based on high temperature superconductors (HTS), which allow for higher magnetic fields and more compact reactor profiles will present additional challenges for the electrical insulation systems used in magnet construction. In addition to higher shear stresses brought about by the higher magnetic fields in these devices, fusion magnets are subjected to thousands of mechanical cycles as the fusion device is operated. The primary objective of the Phase I work is to develop low viscosity insulation systems with high bond and shear strength and excellent shear fatigue performance. These systems will utilize a novel toughening system that, in contrast to conventional tougheners, offers a significant reduction in resin viscosity in addition to offering comparable or improved toughening and improved shear strength. These resin systems will be demonstrated in subscale conductor assemblies designed to represent structures typical of those used in magnets for fusion energy systems. The overall goal of this proposed Phase I program is to address the need for low viscosity electrical insulation resins that enable insulations with high shear strength and excellent shear fatigue performance. In Phase I, we will incorporate a novel toughening additive that has been shown to improve resin bonding and shear performance while simultaneously improving the processability of the resin by significantly lowering the viscosity. Electrical and mechanical performance of the resulting systems at both the coupon scale and in subscale conductor assemblies will be demonstrated. Radiation stability will also be evaluated. In addition to benefitting fusion energy and high energy physics applications, the proposed work will benefit several segments of the U.S. economy. These include medical imaging, scientific instruments, transportation, and defense. Specific examples include superconducting magnets for Magnetic Resonance Imaging and Nuclear Magnetic Resonance systems.
