Abstract
Many applications involving atmospheric pressure plasma-substrate interactions are enabled by the large fluxes of short-lived reactive species such as OH radicals to the substrate, nonetheless, the accurate measurement of radical densities and fluxes at substrates at atmospheric pressure has received little attention to date, particularly for surface ionization waves. We report the measurement of the OH density distribution in a surface discharge on a fused silica (quartz) substrate generated by an impinging atmospheric pressure plasma jet in dry and humid helium. The OH density is measured by microscopic laser induced fluorescence with a spatial resolution of 10 µm in the direction perpendicular to the quartz substrate. The measured OH diffusive flux varied for the investigated experimental conditions by almost three orders of magnitude and had a maximum value of 1.7 × 1015 cm−2 s−1. The corresponding surface loss probability of OH on the quartz surface was determined to be ∼0.01. The high spatial resolution was required to accurately resolve the near surface gradient of OH radicals.
Original language | English (US) |
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Article number | 085016 |
Journal | Plasma Sources Science and Technology |
Volume | 32 |
Issue number | 8 |
DOIs | |
State | Published - Aug 2023 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2023 The Author(s). Published by IOP Publishing Ltd.
Keywords
- OH radicals
- laser induced fluorescence
- plasma-surface interactions
- radical flux
- surface loss probability