Wall fluxes of reactive oxygen species of an rf atmospheric-pressure plasma and their dependence on sheath dynamics
Ding-Xin Liu
Aijun Yang
Xiao-Hua Wang
Ming-Zhe Rong
Felipe Iza
Michael G. Kong
2134/16405
https://repository.lboro.ac.uk/articles/journal_contribution/Wall_fluxes_of_reactive_oxygen_species_of_an_rf_atmospheric-pressure_plasma_and_their_dependence_on_sheath_dynamics/9572195
A radio-frequency (rf) atmospheric-pressure discharge in He–O2 mixture is studied using a
fluid model for its wall fluxes and their dependence on electron and chemical kinetics in the
sheath region. It is shown that ground-state O, O+2 and O− are the dominant wall fluxes of
neutral species, cations and anions, respectively. Detailed analysis of particle transport shows
that wall fluxes are supplied from a boundary layer of 3–300μm immediately next to an
electrode, a fraction of the thickness of the sheath region. The width of the boundary layer
mirrors the effective excursion distance during lifetime of plasma species, and is a result of
much reduced length scale of particle transport at elevated gas pressures. As a result, plasma
species supplying their wall fluxes are produced locally within the boundary layer and the
chemical composition of the overall wall flux depends critically on spatio-temporal
characteristics of electron temperature and density within the sheath. Wall fluxes of cations
and ions are found to consist of a train of nanosecond pulses, whereas wall fluxes of neutral
species are largely time-invariant.
2014-12-01 14:56:17
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Mechanical Engineering not elsewhere classified