Plasma-Facing Materials Research for Fusion Reactors at FOM Rijnhuizen

Full text: 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 (≤ 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 2010. 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. An overview of the results obtained on Pilot-PSI with respect to carbon erosion, hydrogen retention in refractory metals and transient heat loads are presented. (author)