Abstract
JAERI has carried out design and R&Ds activities on divertors for the future DEMO plant, which needs to handle high heat load more than 10MW/m^2. In DEMO designs, F82H, one of Reduced Activation Ferritic Martensitic (RAFM) steels, is applied to cooling structure of Plasma-Facing Components (PFCs) and is covered with tungsten material as armor against ions and neutral particle fluxes. Thermal analyses show that divertor structure of a F82H cooling tube with monoblock tungsten armors meet a design requirement to remove 10MW/m^2 without an excess of temperature in F82H over the upper limit of its service temperature. Thermal and mechanical tests of F82H cooling tube such as Critical Heat Flux and thermal fatigue have been performed to assess the applicability of F82H to high heat flux components. The results of joining tests between tungsten and F82H with brazing and direct diffusion bonding processes are also reported.
