Increased recombination of CH3 radicals on stainless steel

By using a so-called ‘stream technique’, which consists of flowing gas in laminar regime along a quartz tube, we determine that CH3 radicals are completely removed from the pumped mixture (CH4/CXHY/H2/H/CH3) after several hundred collisions with the inner surface of a stainless steel insert (T=380–4...

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Veröffentlicht in:Journal of nuclear materials 2005-03, Vol.337-339, p.892-896
Hauptverfasser: Gorodetsky, A.E., Zalavutdinov, R.Kh, Zakharov, A.P., Vnukov, S.P., Varshavskaya, I.G., Makhankov, A.N., Mazul, I.V., Federici, G.
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Sprache:eng
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Zusammenfassung:By using a so-called ‘stream technique’, which consists of flowing gas in laminar regime along a quartz tube, we determine that CH3 radicals are completely removed from the pumped mixture (CH4/CXHY/H2/H/CH3) after several hundred collisions with the inner surface of a stainless steel insert (T=380–470K). The methyl sticking coefficient decreased to ∼10−6 and the recombination coefficient increased up to ∼0.01 at impingement with the metal surface. After passing through the heated zone no hydrocarbon deposition occurred at 300K. However, unsaturated hydrocarbons, which formed in discharge zone and appeared as a result of interaction of radicals with stainless steel, condensed in a liquid phase at a temperature of ∼130K and partial pressure of 0.01–0.1Pa. Liquid films underwent partial polymerization and formed island deposits, which were stable at 300K.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2004.10.133