Laser-induced fluorescence measurements of spatially resolved OH densities in a helium plasma jet interacting with three different targets in the open air

Autor: Cosimi, Julien, Marchal, Frederic, Merbahi, Nofel, Eichwald, Olivier, Gardou, Jean-Pierre, Yousfi, Mohammed
Přispěvatelé: Plasmas Réactifs Hors Equilibre (LAPLACE-PRHE), LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Plasma Sources Science and Technology
Plasma Sources Science and Technology, 2023, ⟨10.1088/1361-6595/acdbe6⟩
ISSN: 0963-0252
1361-6595
Popis: International audience; Abstract The presented research work is devoted to the measurements of the absolute densities of ground state OH radicals in an atmospheric pressure helium plasma jet launched in free air onto three different targets. The OH density is measured by using laser induced fluorescence (LIF). The plasma is generated inside a glass tube by a dielectric barrier discharge powered by a mono-polar pulsed high voltage. Estimation of the absolute density is based on a quantitative analysis of the spectral and temporal component of the LIF signal and does not require any assumption on the densities of colliding species. Based on this analysis, the spatially-resolved density distributions of OH radicals are determined in front of three different target (metallic, dielectric, and ultra-pure water) placed in the open air at 2 cm from the exit of the glass tube. In order to also investigate the temporal behaviour of the OH densities, and the influence of the gas flow rate and of the amplitude of the voltage-pulse, planar LIF (pLIF) has been performed investigating the fluorescence signal (i) during the intervals of the discharge pulses, (ii) for various gas flow rates, and (iii) as a function of the amplitude of the voltage pulse. In the free jet configuration without a target, the OH densities were determined to be in the order of 1019 m-3, whereas they increased up to a factor of 10 in contact with a target. The spatial distributions were also influenced by the dielectric properties of the target: in the case of the metallic target, the maximum of the OH density was found to be in the center between the exit of the glass tube and the target, whereas in the case of the dielectric target, the maximum was found to be close to the surface of the target. In the case of ultra-pure water, the densities were equally distributed between the exit of the glass tube and the target. With this work, the influence of a target on the production of OH radicals was demonstrated, which enables the optimisation of the plasma parameters for an efficient production of OH radicals in front of a target with various dielectric properties.
Databáze: OpenAIRE
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