Advanced Technologies and Materials for Fusion Energy Systems/Superconducting Magnets and Materials

The U.S. Department of Energy is currently developing a series of fusion devices that will further advance the nation¿s fusion energy program. Magnet designers are presented with the challenge of ensuring the long-term reliability of these new systems. One challenge in particular is in developing an electrical insulation that can withstand the combined loads of extreme temperatures, both cryogenic and elevated, large shear and compressive stresses, high operating voltages, and high levels of incident irradiation. This project seeks to extend the performance capabilities of future fusion magnets by improving insulation to enable operation at either cryogenic or elevated temperatures, and in high-radiation environments. In previous work, CTD demonstrated the mechanical performance and radiation resistance of a new family of cyanate ester-based insulations, but to date no large devices have been produced using these materials. Therefore, the project includes developing and demonstrating large-scale processing techniques for use with these insulations, fabricating and testing of conductor assemblies, and modeling of insulation performance in fusion-specific configurations. The Phase I work included the fabrication and testing of composite insulation specimens based on cyanate ester resin chemistries. The mechanical, electrical, and thermal properties, as well as the moisture resistance of these systems were evaluated. The requirements of the Quasi-Poloidal Stellarator at Oak Ridge National Lab were used as the basis of this testing, although the results are directly applicable to several other fusion programs currently under development. In Phase II, CTD and the University of Tennessee will continue to collaborate on the development of magnets using cyanate ester insulations. The work will optimize materials and process for use in large-scale applications, test the electro­mechanical performance of cyanate ester-insulated cable assemblies, and develop models that predict insulation performance based on various parameters and magnet configurations. Commercial Applications and other Benefits as described by the awardee: The insulation materials developed in this program will be directly applicable to the high-field magnets being produced in support of the nation¿s High-Energy Physics programs, as well as commercial magnet systems under development for medical applications. These magnets will require insulation materials that can withstand high levels of radiation during their operation, while maintaining their mechanical, electrical, and thermal properties.