Premium
Surface effects on the diagnostic of carbon/nitrogen low‐pressure plasmas studied by differentially pumped mass spectrometry
Author(s) -
Alegre Daniel,
Ferreira Jose A.,
Tabarés Francisco L.
Publication year - 2014
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.3346
Subject(s) - chemistry , glow discharge , mass spectrometry , amorphous solid , analytical chemistry (journal) , carbon fibers , amorphous carbon , layer (electronics) , plasma , oxide , chemical engineering , environmental chemistry , chromatography , organic chemistry , composite number , composite material , materials science , physics , quantum mechanics , engineering
In this work, the characterization of the species produced in reactive plasmas by differentially pumped mass spectrometry is addressed. A H 2 /CH 4 /N 2 mixture (90 : 5 : 5) was fed into a direct current glow discharge and analysed by conventional and cryo‐trap assisted mass spectrometry. The gaseous mixture was chosen because of its particular relevance in the inhibition of tritium‐rich carbon film deposition in fusion plasmas (scavenger technique) and in the deposition of amorphous hydrogenated carbon films by plasma‐assisted chemical vapour deposition. Important changes in the composition of the detected species upon surface modification of the reactor walls (stainless steel or covered by an amorphous hydrogenated carbon layer) or in the way they are sampled (length and spatial configuration of the stainless steel duct) were detected. They are analysed in terms of radical formation and recombination on the reactor walls or into the sampling duct, thus providing some insight into the underlying chemistry. In general, when the reactor walls are covered by an amorphous hydrogenated carbon layer, more hydrocarbons are produced, but the radical production is lower and seem to be less reactive than in stainless steel. Also, two sources of oxygen contamination in the plasma have been identified, from the native oxide layer in stainless steel and from unintended water contamination in the chamber, which modify considerably the detected species. Copyright © 2014 John Wiley & Sons, Ltd.