Materials research under ITER-like divertor conditions at FOM Rijnhuizen

Abstract

At FOM Rijnhuizen, linear plasma generators are used to investigate plasma-material interactions under high-density (⩽1021m−3), low-temperature (⩽5eV) plasma bombardment. Research into carbon-based materials has been focused on chemical erosion by hydrogen plasmas. Results from plasma exposure to high-flux (>1023H+/m2s) and low-temperature hydrogen plasma indicate silicon carbide has a lower relative rate of gross erosion than other carbon-based materials (e.g. graphite, diamond, carbon-fiber composites) by a factor of 7–10. Hydrogenic retention is the focus of research on tungsten and molybdenum. For target temperatures of 700–1600K, the temperature dependence of hydrogenic retention is the dominant factor. Damage to the surface by heavy ion irradiation has shown to enhance retention by a factor of 2.5–4.1. Thermal stressing of W via. e-beam thermal cycling also enhances hydrogenic retention by a factor of 2.1±0.2, likely due to the introduction of thermal defects, which act as trapping sites for implanted hydrogenic isotopes.