Use of carbon in tokamaks leads to a serious tritium retention issue due to co-deposition. To further investigate the processes involved, a detached ELMy H-mode (6.5 MW NBI) experiment was performed on DIII-D in which (CH4)-C-13 was puffed into the main vessel through the toroidaly symmetric pumping plenum at the top of lower single-null discharges. Subsequently, the C-13 content of tiles taken from the vessel wall was measured. The interpretive OEDGE code was used to model the results. The C-13 deposition pattern could be reproduced, in general shape and magnitude, by assuming in the code the existence of a parallel flow and a radial pinch in the scrape-off layer. Parallel flows of Mach similar to 0.3 toward the inner divertor and a radial pinch similar to 10-20 m/s (+R-direction) were found to yield C-13 deposition comparable to the experiment. (c) 2007 Elsevier B.V. All rights reserved.
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