A tungsten-copper duplex structure has received consideration for use as a divertor plate in a conceptual design of the Fusion Experimental Reactor (FER). Thermal fatigue tests were performed on tungsten-copper brazed specimens using an argon-plasma jet as an energy source to heat the specimens. Two types of specimens were prepared: smooth and slit specimens at the braze region. The specimens were examined in detail through visual and non-destructive inspections after 100 cycles were carried out. Detectable change was not observed at the braze region of the specimens. From numerical analyses, a high shearing stress is expected to occur at the root of the slit, which is more than twice that for a smooth specimen. The results indicate that detailed techniques for detecting flaws lying especially in the edge region of the joining interface should be incorporated into the failure assessment of a duplex structure.
High heat flux tests of mock-ups for ITER divertor application