Publication details

Concentration of atomic hydrogen in a dielectric barrier discharge measured by two-photon absorption fluorescence

Authors

DVOŘÁK Pavel TALÁBA Marek OBRUSNÍK Adam JAN Kratzer JIŘÍ Dědina

Type Article in Periodical
Magazine / Source Plasma Sources Science and Technology
MU Faculty or unit

Faculty of Science

Citation
Doi http://dx.doi.org/10.1088/1361-6595/aa76f7
Field Plasma physics
Keywords Laser induced fluorescence; TALIF; atomic hydrogen; H; dielectric barrier discharges
Description Two-photon absorption laser-induced fluorescence (TALIF) was utilized for measuring the concentration of atomic hydrogen in a volume dielectric barrier discharge (DBD) ignited in mixtures of Ar, H2 and O2 at the atmospheric pressure. The method was calibrated by TALIF of krypton diluted in argon at the atmospheric pressure, proving that three-body collisions had negligible effect on quenching of excited krypton atoms. The diagnostic study was complemented with a three-dimensional numerical model of the gas flow and a zero-dimensional model of chemistry in order to better understand the reaction kinetics and identify the key pathways leading to production and destruction of atomic hydrogen. It was determined that the density of atomic hydrogen in Ar - H2 mixtures was in the order of 10^{21} m^{-3} and decreased when oxygen was added into the gas mixture. Spatially resolved measurements and simulations revealed a sharply bordered region with low atomic hydrogen concentration when oxygen was added to the gas mixture. At substoichiometric oxygen/hydrogen ratios, this H-poor region is constricted to an area close to the gas inlet and it is shown that the size of this region is not only influenced by the chemistry but also by the gas flow patterns. Experimentally, it was observed that a decrease of H2 concentration in the feeding Ar - H2 mixture lead to an increase of H production in the DBD.
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