Plasma-facing material alternatives to tungsten

Tungsten is the leading high-Z candidate surface material for magnetic fusion reactor plasma-facing components, however, there are specific performance concerns for tungsten, and a general major concern about relying on one material. To broaden the options for fusion development we identified and examined five potential alternative high-Z plasma-facing materials: zirconium, niobium, molybdenum, hafnium and tantalum. We assess these materials from three standpoints: neutron-induced activation, sputter erosion/redeposition and plasma transient response. This initial analysis is encouraging showing (1) environmentally attractive activation properties with minimum waste disposal, for a tokamak reactor divertor, using advanced recycling techniques, (2) acceptable sputtering erosion/redeposition performance, similar to a tungsten divertor, and (3) concerns about the transient response of the alternative materials, but not fundamentally different than concerns for tungsten. We identify work needed to advance the qualification of these materials.