Plasma-facing materials research for fusion reactors at Fom Rijnhuizen

In next generation magnetic fusion devices such as ITER, plasma-facing
materials are exposed to unprecedented high ion, power and neutron fluxes. Those
extreme conditions cannot be recreated in current fusion devices from the tokamak
type. The plasma-surface interaction is still an area of great uncertainty. At FOM
Rijnhuizen, linear plasma generators are used to investigate plasma-material
interactions under high hydrogen ion flux-densities up to 1025 m-2s-1 at low electron
temperatures (≤ 10 eV), similar to the conditions expected in the divertor of ITER. The
incident ion fluxes result in power fluxes of > 10 MW/m2. A new linear plasma device,
MAGNUM-PSI, is expected to begin regular plasma operations in the middle of 2011.
This device can operate in steady-state with the use of a 3 T super-conducting magnet,
and a plasma column diameter projected to 100 mm. In addition, experimental
conditions can be varied over a wide range, such as different target materials, plasma
temperatures, beam diameters, particle fluxes, inclination angles of target, background
pressures, magnetic fields, etc., making MAGNUM-PSI an excellent test bed for high
heat flux components of future fusion reactors. Current research is performed on a
smaller experiment, Pilot-PSI, which is limited to pulsed operation, a maximum
magnetic field of 1.6 T and a narrow (~ 20 mm) column width. The research is
primarily focused on carbon based materials and refractory metals. Erosion of
materials, surface morphology changes as well as hydrogen implantation, diffusion and
inventory in the materials are studied under fusion reactor conditions. The influence of
neutron damages is studied by irradiation of the materials with high energy ions. A
research programme addressing those before mentioned issues is presented