Characterization of mass transfer in capillary porous systems for liquid metal plasma-facing components

In the context of enhancing endurance, liquid metal (LM) plasma-facing components (PFC) offer significant benefits, with a renewable protective layer of LM covering underlying solid components. A proposed configuration for LMPFC includes a solid porous sheet filled with LM facing the plasma, with a stream of LM flowing beneath to replenish the porous layer. This design effectively manages liquid layer surface instabilities by counteracting forces that cause droplet ejection through surface tension between the LM and porous substrate. Maintaining a complete fill of a porous layer is crucial for its functionality, as overfill causes liquid buildup and underfill exposes the solid substrate, leading to material meltdown. The porous layer's ability to absorb liquid metal from bulk flow is crucial for assessing its viability, as it must balance outflow and inflow under fusion-relevant conditions. Mass and heat transfer models in capillary porous systems require determining transport coefficients. However, mass transport of liquid across porous structures lacks experimental data. To fill that knowledge gap, the Liquid Metal In-Vacuo Injection (LIVIn) system is designed to inject lithium through porous material samples under UHV conditions, determining the hydraulic conductivity of the sample. The system is benchmarked using 316L stainless steel porous samples with 40µm pores. Recent test results and verified system capabilities will be presented.