AbstractLarge, capital-intensive, superconducting or resistive magnets are essential components of most current and planned fusion devices. Magnets for these applications must be reliable, have a long mean-time-between-failure, and be able to be manufactured using cost-effective materials and fabrication processes. Electrical insulation is often the weak link in magnet design, due to insulation sensitivity to high radiation doses, embrittlement at cryogenic temperatures, and fabrication limitations. Improvements in electrical insulation can contribute to enhanced magnet system performance and achieve considerable cost reduction. For example, an insulator with improved radiation resistance would require less shielding, thus enabling the coil to be located closer to the radiation source, resulting in a lower field requirement for the coil, and thus reducing the conductor and structural needs for the magnet systems. In this manner, improvements in magnet insulator performance and processing can have a cascading effect on overall magnet system cost reductions. Composite Technology Development, Inc. has developed two new classes of insulation materials, an organic insulation system based on cyanate ester chemistry, and a ceramic insulation system that can be co-processed with the magnet. Both types of systems are suitable for the high radiation doses anticipated in Next-Step Option devices and future fusion reactors. This paper will describe the different material systems under current development, mechanical and electrical properties at cryogenic temperatures, and results of radiation exposure tests for these materials.
Magnetosolid mechanics in fusion reactor technology