Greifswald 2024 – scientific programme
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P: Fachverband Plasmaphysik
P 18: Atmospheric Pressure Plasmas and their Applications IV
P 18.5: Talk
Wednesday, February 28, 2024, 17:45–18:00, WW 1: HS
The ring-shaped spatial distribution of argon excimer, Ar2*, in the effluent of the kINPen-Sci — •Andy Nave, Jente Wubs, Philipp Mattern, and Jean-Pierre van Helden — Leibniz institute for Plasma Science and Technology (INP), Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany
The argon excimer (Ar2*) species is considered to play an important role in the chemistry of cold atmospheric plasma jets (CAPJs), notably in the formation of reactive oxygen and nitrogen species (RONS). In the present work, we demonstrate that cavity ring-down spectroscopy (CRDS) can be used to detect and quantitatively measure Ar2* in the effluent of a cold atmospheric plasma jet, the so-called kINPen-Sci. The spectroscopic features of the 5pπ3Πg ← a3Σu+ Δν = 0 and 7pσ3Σg+ ← a3Σu+ (ν′ - ν″) systems were clearly identified allowing unambiguous assignment to the Ar2* species.
Moreover, spatially resolved measurements allowed to distinguish two distinct Ar2* populations in the effluent of the kINPen-Sci: a Gaussian and a toroidally shaped distribution. The production mechanisms of these populations seem to differ. On the one hand, a strong correlation was found between the Gaussian Ar2* population and the spatial distribution of the filaments produced in the effluent of the kINPen-Sci. On the other hand, the mechanism of formation of the toroid Ar2* population remains unclear. However, further measurements were performed while varying the experimental conditions under which the kINPen-Sci was operated. It was found that gas flow velocity must play a major role in the formation of the toroid Ar2* population.
Keywords: argon excimer; cold atmospheric plasma jet; cavity ring-down spectroscopy; spatially resolved