Mechanical properties of organic insulators for superconducting magnets after low temperature irradiation

Organic insulators will be used as electric insulators and thermal insulators in superconducting magnets since ductile materials are required for coil windings. When superconducting magnets are used in fusion reactors, the magnet components will be exposed to fast neutron and gamma irradiation produced by fusion reactions. This paper describes the results on the mechanical properties of fiber reinforced organic insulators tested in liquid helium after irradiation at 5 about7 K in a fission reactor. Tensile, compressive and flexural strength and impact value, were measured at 4.2K without any warm-up. The mechanical strength of G-10CR was substantially degraded and that of G-11CR reduced by 10-30%. The mechanical strength of glass fiber reinforced polyimide increased. The compressive strength of G-10CR and G-11CR did not recover when specimen was warmed up to room temperature after irradiation