Reactivity of water vapor in an atmospheric argon flowing post-discharge plasma torch

TL;DR

This study investigates how water vapor reacts within an atmospheric argon plasma torch's post-discharge, identifying key reactions and radicals produced, and analyzing the influence of ambient air on plasma chemistry.

Contribution

It provides a detailed analysis of water vapor reactivity in an RF atmospheric plasma torch, highlighting reaction pathways and the effects of ambient air on plasma chemistry.

Findings

Identification of main reactive species like H, OH, O radicals.

Reactions leading to H2O2 formation are characterized.

Ambient air influences plasma reactions and inhomogeneities.

Abstract

The reactivity of water vapor introduced in the flowing post-discharge of an RF atmospheric plasma torch is investigated through electrical characterization, optical emission spectroscopy and mass spectrometry measurements. Due to the technical features of the plasma torch, the post-discharge can be considered as divided into two regions: an inner region (inside the plasma torch device) where the water vapor is injected and an outer region which directly interacts with the ambient air. The main reactions induced by the injection of water vapor are identified as well as those indicative of the influence of the ambient air. Plausible pathways allowing the production of H, OH, O radicals and H2O2 are discussed as well as reactions potentially responsible for inhomogeneities and for a low DC current measured in the flowing post-discharge. Keywords: atmospheric post-discharge, H2O plasma reactivity, RF plasma torch