A radical alternative to solid plasma-facing materials — using flowing liquid lithium, tin, or gallium surfaces that continuously self-heal from plasma erosion and could solve the divertor heat exhaust problem.
ReviewedLast reviewed: 9 Aug 2026·Category: Fuels & Materials
Concept
Instead of using solid materials (tungsten, beryllium) to face the plasma, liquid metal plasma-facing components (PFCs) use a continuously flowing film of liquid metal on the surface. The liquid is circulated, so erosion damage is continuously repaired and heat is efficiently removed by the flowing liquid itself.[1]
Key advantage: Liquid surfaces cannot crack, embrittle, or accumulate radiation damage — the three failure modes that limit the lifetime of solid PFCs. A flowing liquid metal divertor could potentially handle heat fluxes far exceeding the 10–20 MW/m² limit of solid tungsten.
Candidate Metals
Lithium: Low atomic number (reduces core plasma contamination), low melting point (180°C), breeds tritium. Demonstrated to dramatically improve plasma performance in NSTX and CDX-U experiments at Princeton. Tin: Higher atomic number but much lower vapour pressure than lithium at elevated temperatures, reducing contamination risk. Gallium: Very low melting point (30°C) and low vapour pressure.[2]
Challenges
Key challenges include: MHD effects (liquid metals in strong magnetic fields experience forces that can disrupt flow patterns); evaporation and plasma contamination at high temperatures; tritium inventory management in lithium systems; and engineering complexity of maintaining a uniform liquid film in a reactor environment.[3]
Sources
Majeski, R. et al. "Compatibility of lithium plasma-facing surfaces with high edge temperatures in the CDX-U spherical torus." Physical Review Letters, 97, 075002, 2006.
Ono, M. et al. "Liquid lithium loop system to solve challenging technology issues for fusion power plant." Nuclear Fusion, 57, 116056, 2017.
Shimada, M. et al. "Liquid metal and liquid lithium applications for fusion reactor divertor concepts." Fusion Engineering and Design, 117, 198–207, 2017.