Carbon deposition at the bottom of gaps in TEXTOR experiments
Matveev, D.
Kirschner, A. / Esser, H. G. / Freisinger, M. / Kreter, A. / Van Hoey, O. / Borodin, D. / Litnovsky, A. / Wienhold, P. / Coenen, J. W. (Corresponding author) / Stoschus, H. / Philipps, V. / Brezinsek, S. / Van Oost, G.
Plasmaphysik; IEK-4
Journal of nuclear materials, 438 (2013) S. S775 - S779
Amsterdam [u.a.] Elsevier Science 2013
Journal Article
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Results of a new dedicated experiment addressing the problem of impurity deposition at the bottom in gaps are presented along with modelling. A test limiter with an isolated gap was exposed to the scrape-off layer plasma in TEXTOR. The exposure was accompanied by injection of 13C-marked methane in the vicinity of the gap. Deposition at the bottom of the gap was monitored in situ with Quartz-Microbalance diagnostics. The 13C deposition efficiency of about 2.6 × 10−5 was measured. Post mortem analysis of resulting deposited layers performed with SIMS and EPMA techniques yields about a factor 2 smaller value corresponding to approximately 10% contribution of the gap bottom to the total 13C deposition in the gap. This measured contribution is effectively much smaller than observed earlier in TEXTOR, taking the difference in geometry into account, and is in reasonable agreement with modelling performed with ERO and 3D-GAPS codes.