Mixed-materials development and characterization in PISCES

Auger Electron Spectrometer (AES) and an X ray Photoelectron Spectrometer (XPS) are used to investigate carbon-containing mixed-material layer formation during plasma bombardment of beryllium and tungsten samples. The concentration of impurities in the plasma (and therefore the arrival rate of these impurities at the surface) is influential in determining the resultant chemical bonding on the surface. If the arrival rate of carbon at the surface is large, then a surface rich in carbon-carbon bonding develops. If the arrival rate of carbon at the surface is reduced, then the carbon in the surface exhibits preferential carbidic bonding. At low carbon concentration, carbidic bonding is observed in the surface layer regardless of the temperature of the sample during the plasma exposure. (author)