Development of fabrication technologies for the ITER divertor

The ITER divertor cassette consists of the cassette body and the high heat flux components (HHFCs), which include the vertical target, wing, dome and liner. In order to develop and fabricate these HHFCs, an improvement to the existing brazing of the surface materials to the cooling structures is necessary. Carbon fiber composites (CFCs) are one of the candidate surface materials, which are brazed to the cooling structures made of copper or copper alloys such as dispersion strengthened copper (DSCu). Available brazing materials were researched and some candidates were tested to assess their capability in this application. The fabrication technology of the cooling structure of HHFCs, which will have a complicated geometry, is also of concern. The wing must withstand the maximum heat flux of 5 MW/m2. Also, it has to satisfy connectivity to the neighboring HHFCs and the cassette body. For a wing concept, a CFC mono-block with copper alloy cooling tubes was proposed and some mock-ups using this concept were fabricated. Through the trial fabrication of the full-sized mock-up, the feasibility of the fabrication procedure for the CFC mono-block wing has been confirmed.