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The growth of codeposited layers has been studied with long-term samples below the divertor IIb and in a pump duct of ASDEX Upgrade from March to August 2001. The composition of re-deposited layers and their optical properties were analysed with ion beam techniques and ellipsometry. The deposition in the sub-divertor area showed a complicated deposition pattern with a maximum deposition of about 1.3 µm. All deposits form soft hydrocarbon layers that consist mainly of deuterium and carbon with D/C from 0.7 to 1.4. Only a small deposition was observed in the pump duct, with a maximum of about 2.5×10{15} D-atoms/cm{2} at the duct entrance. The observed deposition pattern in the duct is compared with simulation calculations assuming neutral hydrocarbon radicals as precursors for film deposition. The deposition pattern can be explained by two different radical species with surface loss probabilities Beta<10{-3} and 0.1=Beta=0.9. The most likely species are CD(3), C(2)D(5) and C(2)D(3) radicals.

Additional information

Authors: MAYER M, Max-Planck-Institut für Plasmaphysik, IPP-EURATOM Association, Garching (DE);ROHDE V, Max-Planck-Institut für Plasmaphysik, IPP-EURATOM Association, Garching (DE);VON KEUDELL A, Max-Planck-Institut für Plasmaphysik, IPP-EURATOM Association, Garching (DE)
Bibliographic Reference: An article published in: Journal of Nuclear Materials, Volumes 313-316, March 2003, Pages 429-433
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Record Number: 200316338 / Last updated on: 2003-06-09
Original language: en
Available languages: en