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Description
Keywords: Magnetic confinement Fusion, liquid metal, capillary structures, lattice, tungsten, additive manufacturing
One of the main challenges in the development of a magnetic confinement fusion reactor is the durability and maintenance of internal components, particularly the divertor, which is exposed to the highest heat and particle fluxes. To withstand these extreme conditions, plasma facing components (PFCs) in ITER rely on actively cooled tungsten monoblocks. However, these monoblocks show several durability limitations notably, including localized melting, cracking and erosion caused by sputtering. These promote the exploration of alternative solutions that could improve maintainability & availability of future fusion power plants.
Liquid metals (LMs) represent a particularly promising solution for PFCs, as they help mitigate several limitations of solid materials. Their continuous renewal provides self-healing capabilities, while local evaporation contributes to heat removal. Moreover, because atoms in a liquid are already mobile and disordered, LMs are largely unaffected by displacement-damage mechanisms that degrade solid materials. Convective motion of the LMs also promotes efficient and uniform heat dissipation. Among the concepts developed so far, Capillary Porous Systems (CPS) infiltrated with low-melting-point metals such as lithium and tin have attracted significant attention. Capillary forces stabilize the liquid metal within the porous structure, reducing plasma contamination. Nevertheless, precise control of pore geometry and manufacturing constraints remain major challenges.
In this work, we investigate the fabrication of tungsten lattice structures via Laser Powder Bed Fusion (LPBF) to achieve an architectured porosity suitable for tin infiltration and retention. The first phase focuses on optimizing process parameters through the fabrication of bulk cubes. Performance comparison was based on measurement of relative density and cracks observation. This step is essential to ensure the manufacturability of future porous structures, which are particularly sensitive to sintering defects. The resulting samples were characterized in terms of density and microstructure. In a second step, the wettability of tin on tungsten was assessed. These results provide a solid foundation for the fabrication of fully architectured tungsten lattice structures able of being infiltrated by liquid metal and functioning as CPS.