Study of local carbon transport on graphite, tungsten and molybdenum test limiters in TEXTOR by 13CH4 tracer injection

Abstract 13 CH 4 was injected through an aperture in a roof-like test limiter covered by a graphite, tungsten or molybdenum plate during Ohmic discharges. The evolution of the deposition pattern was studied by in situ reflectometry during each plasma pulse. Amounts of locally deposited 13 C and co-deposited background 12 C in each shot were determined post-mortem . The 13 C deposition efficiency is in a range of 0.05–0.2% and grows with the increasing amount of 12 C. For the same 12 C content the efficiency is of 0.11% for tungsten, 0.14% for molybdenum and 0.17% for graphite.