Laboratory and Numerical Investigations of Surface Waves in Flowing Liquid Metal Plasma-Facing Components for Fusion Reactors*

Free-surface flow liquid metal plasma-facing components (LMPFCs) present significant advantages in fusion reactors by enabling enhanced heat removal, impurity extraction, and access to low-recycling regimes. Despite these benefits, the presence of surface wave instabilities in the liquid metal flow, driven by intense magnetic fields and plasma interactions, presents substantial challenges. These instabilities can cause abrupt increases in heat flux and evaporation, as well as the ejection of liquid metal from the reactor walls, thereby complicating plasma containment and stability. We conduct systematic combined laboratory experiments and numerical simulations on free-surface liquid metal flow in a conducting chute with a magnetic field perpendicular to the flow direction in the horizontal plane. The experiments are carried out at PPPL’s LMX-U device, which models a single-channel open-surface liquid metal flow in divertor plasma-facing components of a fusion reactor. A preliminary combined laboratory and numerical surface velocity-height measurements at interaction parameter (Lorentz/Inertia) in a range of 0 ≲ N ≲ 20 will be presented. Moreover, we are developing scaling laws to provide insightful implications for parameter constraints and operating regimes of flowing LMPFC concepts. This research aims to derisk the prototyping process by offering guidelines on enhancing the stabilities of the flowing LMPFCs.