超電導マグネット絶縁材料の低温照射効果

抄録

A review of the radiation damage problems in insulators expected to be used in a superconducting (SC) magnet of fusion reactors has been given. Organic insulators, when compared with inorganic ones, show great advantage in fabricability, but they suffer from larger sensitivity to irradiation.
In organic insulating materials electrical properties such as dielectric strength or dielectric loss and thermal properties such as thermal conductivity are less problematical than mechanical properties. In view of the possible pulse operation in the fusion reactor SC magnets, it should be stressed that the accumulation of the data on mechanical properties against time varying load at cryogenic temperatures, such as strain rate dependent fracture stress (and/or strain), impact strength or fatigue in necessary.
Radiation effects on organic insulator are again less problematical to electrical and thermal properties than to mechanical properties. Maximun allowable neutron fluence for the organic insulator has been considered at most 10¹⁸n·cm^-2. The design of the SC magnet for fusion reactors should take these results into consideration.