Düsseldorf 2007 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 16: Poster
P 16.29: Poster
Mittwoch, 21. März 2007, 16:30–18:30, Poster A
Online Analysis of Hydrocarbon Chemistry in Fusion Edge Plasmas — •Bettina Küppers and Detlev Reiter — Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, EURATOM-Association, Trilateral Euregio Cluster, D-52425, Jülich, Germany
Hydrocarbon catabolism and transport of fragments in fusion edge plasmas is important for determining chemical erosion yields and for quantifying carbon deposition (and hence tritium co-deposition) in fusion devices with carbon walls. A comprehensive cross section database for hydrocarbon brake-up, covering electron and proton impact collision processes from CH up to C3H8 molecules and their ions [1], has been made available online (www.eirene.de/eigen/). It has recently been validated by various groups using experimental results from TEXTOR, JET, DIII-D and JT-60U tokamaks. We show that a spectral analysis of the resulting master rate equation for homogeneous hydrogen plasma conditions allows separation of time-scales (and hence definition of reduced models) only at low divertor plasma temperatures (Tp ≤ 2 eV), whereas above those temperatures the full reaction kinetics has to be taken into account. However, at these low temperatures, the resulting reduced model happens to be consistent with the simple approach currently adopted in integrated edge plasma modelling (e.g., B2-EIRENE) to neglect hydrocarbons altogether and only to treat C atoms instead. The online analysis tool is presently being extended by implementing surface processes and a sensitivity analysis.
[1] Janev, R., Reiter, D., Physics Plasmas, 9, 4071 (2002); ibid., 11, 780 (2004)