KINETICS OF HO₂ RADICAL IN NS PULSE O₂-He PLASMAS OVER A LIQUID WATER SURFACE AND UNDER ATMOSPHERIC PLASMA JET USING CAVITY RING DOWN SPECTROSCOPY

Telfah, Hamzeh

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https://hdl.handle.net/2142/122716 Copy

Description

Title

KINETICS OF HO₂ RADICAL IN NS PULSE O₂-He PLASMAS OVER A LIQUID WATER SURFACE AND UNDER ATMOSPHERIC PLASMA JET USING CAVITY RING DOWN SPECTROSCOPY

Author(s)

Telfah, Hamzeh

Contributor(s)

• Adamovich, Igor V.
• Jans, Elijah R
• Raskar, Sai

Issue Date

2023-06-23

Keyword(s)

Instrument/Technique Demonstration

Abstract

Time-resolved, absolute HO₂ number density in O₂-He mixtures excited by a repetitive ns pulse discharge over a pool of distilled water and in atmospheric pressure plasma jets is measured in situ by Cavity Ringdown Spectroscopy (CRDS). The discharge cell with external electrodes to generate the plasma and a water reservoir are integrated into the CRDS cavity. The experimental results are obtained at near room temperature, both during the discharge pulse burst and in the afterglow. The HO₂ number density is inferred from the CRDS data using a spectral model exhibiting good agreement with previous measurements of absolute HO₂ absorption cross sections. HO₂ is generated during the discharge burst and decays in the afterglow between the bursts, on a ms time scale. Comparison with the kinetic modeling predictions demonstrates good agreement with the data and identifies the dominant HO₂ generation and decay processes. HO₂ in the plasma is formed predominantly by the recombination of H atoms, generated by the electron impact of water vapor, with O₂ molecules. Reactions with O atoms and OH radicals are among the main HO₂ decay processes in the afterglow. CRDS was also be used for HO₂ measurements in atmospheric pressure plasma jets, where the jet is integrated in the Open-air Cavity, the mirrors were protected with purge. The HO₂ number density is inferred from the CRDS data using a spectral model exhibiting good agreement with previous measurements of absolute HO₂ absorption cross sections.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122716

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