This title appears in the Scientific Report : 2005 

Dynamic transition between erosion and deposition on a tungsten surface exposed to edge plasmas containing carbon impurity
Ohya, K.
Tanabe, T. / Kirschner, A. / Hirai, T. / Philipps, V. / Wada, M. / Ohgo, T. / Noda, N.
Institut für Plasmaphysik; IPP
Werkstoffstruktur und Eigenschaften; IWV-2
Journal of nuclear materials, 337-339 (2005) S. 882 - 886
Amsterdam [u.a.] Elsevier Science 2005
882 - 886
Journal Article
Kernfusion und Plasmaforschung
Journal of Nuclear Materials 337-339
Please use the identifier: in citations.
By the exposure of high-fluence deuterium (D) plasmas (10(23)-10(26) m(-2)) containing a small amount (< 10%) of carbon (C), the dynamic transition from C deposition to the erosion of tungsten (W) with increasing plasma temperature from 10 eV to 100 eV is investigated using EDDY code. Above fluences of 10(23) m(-2), there appears to be a fluence-dependent change in the C deposition rate as a function of plasma temperature. At a fluence of more than 10(25) m(-2), a steady-state condition is reached where an abrupt transition is formed. This occurs due to temperature increases of only a few eV. The transition occurs as a result of small reflections in the incident C ions from a C-rich layer and the enhanced sputtering of the deposited C from a W-C mixed layer. This explains the very sharp boundary between the erosion and deposition zones observed on W test limiters exposed to TEXTOR edge plasmas. (c) 2004 Elsevier B.V. All rights reserved.