Characteristics of kilohertz-ignited, atmospheric-pressure dielectric barrier discharges plasma jet in argon

In this work, an atmospheric pressure plasma jet generated by AC voltage with 71 kHz frequency in Ar/water vapor has been investigated. It was shown the increase of water content in gas phase results to decrease of the input power and asymmetry of the voltage/current characteristic. Axial and spatially resolved optical emission spectroscopy has been done. Plasma with water content shows higher intensity of OH radicals emission than pure argon jet. Space resolved spectroscopy and ICCD technique have been applied for characterization of the afterglow. The gas temperatures were determined by two different methods: the simulation of OH radicals emission spectrums, and Boltzmann plot method. It was revealed that gas temperature is increased from 450 K (pure Ar) up to 850 K in Ar/H2O mixture (0.76%). Fast imaging results shows that the afterglow in argon discharge consists from filaments. During one current pulse only one formation of one filament is observed along whole afterglow. Plasma density has been estimated from current density measurement and is in order of 1013 cm-3. Electron temperature has been deduced from the ratio of intensity of argon emission lines. In case of pure Ar the electron temperature was 1.1 eV. Finally, DBD plasma jet was found to be a good source for OH radical production where yield of radicals can be control by variation of water vapor content in feed gas