Investigation of the impact of fabrication methods on the microstructure features of W-components of a He-cooled divertor

Within the EU framework of the power plant conceptual study (PPCS), a He-cooled modular divertor concept to remove the expected heat loads of up to 15 MW/m2 is investigated at Forschungszentrum Karlsruhe. These high loads require sufficient cooling of the divertor components, which can only be obtained by an adapted design together with a close interaction with materials issues and development of manufacturing processes. Physical aspects favor tungsten as a functional and structural material. The design work performed indicates that sufficient heat removal by He requires microstructured W-surfaces in the shape of pin or slot arrays, or else a multi-jet cooling technology. In this work, manufacturing processes (e.g. EDM, laser etching, PIM, ECM) were analyzed for their applicability and cost effectiveness for shaping of microstructured W-arrays. In a second step, their impact on the microstructure and, thus, on stability and function of the parts were investigated. First test arrays were fabricated by EDM and brazed into the designed finger-like cooling structures. However, testing showed clearly that further development of the structuring processes (e.g. PIM, ECM) for W-components and of improved W-alloys are necessary.