Development and fabrication aspects regarding tungsten components for a He-cooled divertor

Under the EU framework of power plant conceptual study (PPCS), a modular He-cooled divertor concept is investigated, which is projected to remove high heat loads of up to 15 MW/m2. This design is based on a modular arrangement of cooling fingers consisting of a tile acting as sacrificial layer, a thimble through-flowed by high pressurized He and special micro-structured components for enhanced heat transfer. The success of this design is strongly correlated to the availability of special tungsten alloys and for the pin/slot option efficient micro-structuring of W or W–1% La2O3 arrays. An evaluation of shaping technologies for array manufacturing under consideration of applicability, degree of development status, expected effectiveness and economy was performed and the most promising methods were tested. Based on the todayʹs knowledge, electrical discharge machining (EDM) and laser etching (LE) allow the shaping of slot arrays; however, an impact on microstructure was detected. Technologies like powder injection moulding (PIM) or electro-chemically assisted machining processes (ECM) need further development and testing to be applied as reliable fabrication processes in structuring of W-alloys.