Any material surface directly exposed to the fusion plasma — including the first wall, divertor tiles, and limiters — subjected to the most extreme thermal, particle, and neutron loads in a reactor.
ReviewedLast reviewed: 9 Aug 2026·Category: Glossary
Definition
Plasma-facing components (PFCs) are the material surfaces inside a fusion device that are directly exposed to the plasma or its exhaust. They include the first wall, divertor target plates, baffles, and limiters. PFCs must withstand extraordinary conditions: heat fluxes from 0.1 to over 20 MW/m², particle bombardment causing erosion, and intense neutron irradiation in D–T devices.[1]
Material choices: Tungsten is the leading PFC material for future reactors due to its high melting point (3422°C), low sputtering yield, and low tritium retention. Carbon fibre composite (CFC) was used in JET originally but redeposits tritium unacceptably. Beryllium was used for JET’s ITER-Like Wall. ITER uses both tungsten (divertor) and beryllium (main wall).
Challenges
Erosion: Physical sputtering by plasma ions removes surface material, limiting lifetime. Redeposition: Eroded material redeposits elsewhere, potentially trapping tritium. Neutron damage: In D–T reactors, 14.1 MeV neutrons cause lattice displacement damage (50–150 dpa over component lifetime), embrittling metals and creating transmutation products.[2]
PFC Lifetime
In a fusion power plant, divertor PFCs may need replacement every 1–2 years and first-wall PFCs every 3–5 years due to erosion and neutron damage. All replacements must be performed by remote handling systems.[3]
Sources
Rieth, M. et al. "Recent progress in research on tungsten materials for nuclear fusion applications in Europe." Journal of Nuclear Materials, 432, 482–500, 2013.
Zinkle, S.J. and Was, G.S. "Materials challenges in nuclear energy." Acta Materialia, 61, 735–758, 2013.
Pitts, R.A. et al. "A full tungsten divertor for ITER." Journal of Nuclear Materials, 438, S48–S56, 2013.