2D spatially resolved O atom density profiles in an atmospheric pressure plasma jet: from the active plasma volume to the effluent

Abstract

Two-dimensional spatially resolved absolute atomic oxygen densities are measured within an atmospheric pressure micro plasma jet and in its effluent. The plasma is operated in helium with an admixture of 0.5% of oxygen at 13.56 MHz and with a power of 1 W. Absolute atomic oxygen densities are obtained using two photon absorption laser induced fluorescence spectroscopy. The results are interpreted based on measurements of the electron dynamics by phase resolved optical emission spectroscopy in combination with a simple model that balances the production of atomic oxygen with its losses due to chemical reactions and diffusion. Within the discharge, the atomic oxygen density builds up with a rise time of 600 µs along the gas flow and reaches a plateau of 8 × 1015 cm−3. In the effluent, the density decays exponentially with a decay time of 180 µs (corresponding to a decay length of 3 mm at a gas flow of 1.0 slm). It is found that both, the species formation behavior and the maximum distance between the jet nozzle and substrates for possible oxygen treatments of surfaces can be controlled by adjusting the gas flow.

Zero-dimensional and pseudo-one-dimensional models of atmospheric-pressure plasma jets in binary and ternary mixtures of oxygen and nitrogen with helium background

“…The experimental details to obtain these measurements are summarized in an investigation of a helium oxygen mixture by Steuer et al [116]. The zero-dimensional and the pseudoone-dimensional O( 3 P) simulation results of the aforementioned distinct sets of NO formation mechanisms are presented, accordingly.…”

Validation of in situ diagnostics for the detection of OH and H2O2 in liquids treated by a humid atmospheric pressure plasma jet

“…[10,11] In plasma-liquid arrangements where the plasma is not ignited in the liquid but its effluent is in contact with the liquid, as is often the case with plasma jets, reactive oxygen and nitrogen species generated in the plasma and transported into the liquid are the main driver for the desired reactions. [12] Besides the detection of reactive species in the plasma or in the effluent, [13][14][15][16] the knowledge of concentrations of reactive species measured in the plasma-treated liquid is of major interest for the applications. There are various methods and approaches for the detection of reactive species in plasma-treated liquids: UV-broadband absorption spectroscopy, [17] electron paramagnetic resonance, [18,19] fluorescence assays, [19][20][21] colorimetric assays, [21][22][23] and electrochemical sensors.…”

Optical diagnosis of a kHz-driven helium atmospheric pressure plasma jet

“…It is now well known that any object in close vicinity of the plasma plume will change the dynamics of the plasma (Akishev et al 2017;Kovačević et al 2018;. The addition of a target has already been shown to increase helium metastable densities (Urabe et al 2010;Zaplotnik et al 2016) and electron densities in close proximity to the target (Klarenaar et al 2018;Hofmans et al 2020;. It is therefore essential to study the plasma under different target conditions similar to those of their particular application to get a better understanding of the typical plasma behaviour and properties.…”

“…One of the primary goals for APPJs within this decade has been to develop diagnostic methods capable of measuring densities of excited species, metastable states and reactive species (Lu et al 2014). Concentrations of reactive species such as O, OH and NO can be determined experimentally through the use of one-or two-photon laser-induced fluorescence spectroscopy and optical absorption spectroscopy (van Gessel, Alards & Bruggeman 2013;Pei et al 2014;Yonemori & Ono 2014;Xiong, Yang & Bruggeman 2015;Schröter et al 2020;Steuer et al 2021). However, few experimental studies have focused on measuring the density of excited species.…”

“…2020; Steuer et al. 2021). However, few experimental studies have focused on measuring the density of excited species.…”