Magnetohydrodynamic behavior of free-surface liquid metal plasma-facing components in fusion reactor environments

Next-generation fusion reactors pose challenges for plasma-facing components (PFCs) made from solid materials, primarily because of the intense heat and particle fluxes they encounter. To address these limitations, liquid metal (LM) PFC concepts have recently emerged as a promising alternative. However, the behavior of LM flows in the fusion reactor environment also presents significant challenges. A key issue is mitigating the pileup mechanism that arises from the interaction between the LM and the applied magnetic field. This study focuses on the characteristics of free-surface LM flow subjected to an external magnetic field created by a fusion reactor environment. Once the flow reaches a fully developed state, the imposed magnetic field generates Lorentz forces that interact and slow down the fluid flow, leading to an upstream pileup phenomenon. We quantify how magnetohydrodynamic effects govern LM transport in a fusion reactor environment. High-fidelity OpenFOAM simulations are employed to reveal the onset and growth of the pileup mechanism and the flow features under applied magnetic fields. These results inform the design of advanced PFCs and tritium-breeding walls.