Study of helium effects in SiC/SiC composites under fusion reactor environment

Helium release behavior from He-ion implanted SiC/SiC, monolithic β-SiC, and SiC fiber (Hi-Nicalon) was studied using the thermal desorption method with annealing temperatures between 500°C and 1600°C in 100°C increments. Helium release from SiC/SiC composites began below 500°C, while from monolithic β-SiC, helium release was observed above 1000°C. The magnitude of the helium released from β-SiC was 1/10 to 1/50 of the helium released from the composites. Helium release from the fiber became apparent above 1300°C. Helium release from composites at low temperature might be attributed to helium release from the carbon interphase. Behavior of transmuted helium in the SiC/SiC composites under fusion reactor conditions is discussed.