Liquid metal flow characteristics in self-supplying capillary porous channels under strong magnetic field for fusion devices

Liquid metal CPS (capillary porous system) is a promising plasma facing component material, offering potential solutions to the safety challenges posed by the high heat flux and high-speed particle impacts on components such as the first wall and divertor in Tokamak nuclear fusion devices. In this paper, the flow behavior of liquid metal in CPS was reproduced using Galinstan and copper foam materials. The experiment investigated the flow characteristics of liquid metal in capillary porous channels under strong magnetic fields, including the variation in surface film flow with magnetic fields and the MHD (magnetohydrodynamic) flow within the porous channels. The results show that capillary porous channels effectively facilitate capillary wicking and surface spreading of liquid metal, forming a stable surface film flow. The special structure of the porous medium and the Forchheimer flow present in the entire baseplate mitigate the MHD drag effects and film thickness growth induced by magnetic fields. Experiments demonstrated that adjusting the parameters of the capillary porous channels and the liquid metal supply method significantly reduces the MHD drag effect on the film flow, improving the stability and uniformity of the liquid film. Based on experimental data, a dimensionless MHD Forchheimer flow correction equation for liquid metal in capillary porous channels and a dimensionless film thickness expression for surface flow under magnetic fields were derived. These provide valuable references for predicting the flow behavior of liquid metal in CPS capillary porous channels, and new insights for optimizing CPS structural designs.