• K-doped tungsten as been identified as the prime candidate as plasma facing material for the divertor strike point area. • W 2 C and ZrC reinforced tungsten composites as well as W f W are potential alternatives as plasma facing materials with each representing individual challenges and drawbacks. • W-fiber reinforced CuCr and ODS-Cu using Y 2 O 3 particles have been identified as the most promising materials as heat sink materials with challenges in industrial fabrication and high temperature strength, respectively. • W-particle reinforced CuCr(Zr) is regarded as the back-up solution as heat sink material. • Additive manufacturing technologies are explored for fabricating plasma-facing materials, heat sink materials and hybrid concepts as well as using those as repair techniques which need to seek for the development of new design concepts not accessible by conventional manufacturing overcoming their main limitation bing their inability to produce the high-end microstructures identified above. Material development for future fusion devices has a decades-long history in Europe, initiated under EURATOM through the EFDA collaborative agreement and further developed in the framework of the EUROfusion Consortium. One particular topic thereby is the development of advanced plasma facing and heat sink materials, which should allow extending the operational regime and the lifetime of in-vessel components as well as tackle safety concerns in case of accidental scenarios with regard to the baseline materials tungsten and CuCrZr. While the primary focus in the European framework program FP8 was still on the optimization of the material concepts including chemical composition, manufacturing technology and material design, progressing into the conceptual design for DEMO the focus shifted towards industrial upscaling and technological implementation of the materials in the actual component design, which inevitably includes also qualification at operationally relevant neutron fluences. The progress thereby is, amongst others, monitored via assessment of the material technology readiness level of the individual materials, which also includes the identification of showstoppers leading to either modifications of the material / material concept or to discarding the material completely. In this down-selection process, on the one hand a multitude of materials and fabrication processes have been discarded. On the other hand, several materials and technologies are still part of the selection process for DEMO, among which are self-passivating tungsten alloys for First Wall applications and K-doped tungsten materials as plasma facing material and W-fiber and –particle reinforced Cu-alloys as well as ODS-Cu (Y 2 O 3 ) as heatsink. On top, material concepts on a low maturity level including additive manufacturing technologies for in-situ repair and for alternative and complex shaped design concepts are discussed.
Pintsuk et al. (Sun,) studied this question.