New results are shown on carbon deposition and mixed layer formation on tungsten surfaces in TEXTOR test limiter experiments by varying surface conditions such as surface roughness (Ra: 10nm–1μm), temperature (300–900°C), and initial surface carbon concentration (0–60%). It is found that surface roughness significantly affected C deposition for both W and graphite substrates such as increase in the C deposition and extension of the C deposition area. Not only the surface roughness parameter Ra but also detailed surface morphology closely relate to C deposition on tungsten. Carbon deposition hardly occurred at least above ∼520°C on tungsten under TEXTOR edge plasma conditions. Carbon behavior on tungsten at 770–930°C depends on the incident carbon ion energy. Although tungsten and carbon mixing layers affected C deposition, their effect is less than the roughness effect.
Journal of Nuclear Materials 06/2009; 390-391. DOI:10.1016/j.jnucmat.2009.01.042 · 2.02 Impact Factor