Radiation resistance of fusion magnet materials

The ability of magnet materials to absorb neutrons and gamma rays without unacceptable damage determines the lifetime of burning plasma experiments and the shield thickness and size of fusion reactors. The insulation system is usually the component with the shortest lifetime in both superconducting and normal copper magnets. The International Thermonuclear Experimental Reactor (ITER) requires insulation that can withstand 10⁹ rads, while the unshielded insulation of the fusion ignition research experiment (FIRE) must absorb 10¹⁰ rads. Recent advances have been made in the development of high radiation resistant organics with good potting properties, wrappable ceramics, and ceramic-organic hybrids. Little progress has been made in hardening superconducting materials. Recent research focuses on characterizing the response to nuclear radiation of recently developed superconducting materials, including the high-temperature superconductors BSSCO and YBCO, and the medium temperature superconductor MgB₂.