Off-axis chemical crosstalk in an atmospheric pressure microplasma jet array

Effect of Additive Oxygen on the Reactive Species Profile and Microbicidal Property of a Helium Atmospheric Pressure Plasma Jet

“…This occurred largely through the three‐body reaction (RH014 in the SI: O + O 2 + M => O 3 + M) and also a two body collision with O 2 from ambient atmosphere (RH029: O 2 + O 2 ( 1 Δ) => O + O 3 ). This is consistent with the observations in, where a 0D numerical model showed that O 3 only appears after O and O 2 ( 1 Δ) have been lost.Formation of O 3 was a strongly preferential reaction, because the reactions leading to O 3 dissociation (e.g., RH028, RH090) were orders of magnitude slower with the exception of the reactions of O 3 with H (RH109: O 3 + H => O 2 + OH) and N (RH089: O 3 + N => O 2 + NO), which were the main reasons why O 3 number density was depleted near the axis of the jet, where the concentrations of atomic species was relatively high. By entering reaction (RH109), O 3 also contributed in part to the formation of the OH radical.…”

“…Several researchers have conducted comparison studies between experimental measurements and numerical simulations to understand the dynamics and chemistry in plasma jets. [39][40][41][42][43] Goree et al reported distinctive spatial inactivation patterns of Streptococcus mutans bacteria on agar surface treated with a helium radiofrequency (RF) plasma needle at atmospheric pressure, which varied from a solid circle to ring with an increase in gas flow rate. [39,40] In addition, they observed a ring-shaped pattern in the spatial distribution of energetic electrons corresponding to the ring-shaped inactivation pattern.…”

“…[41] Using a two-photon absorption laser-induced fluorescence (TALIF) spectroscopy, Sakiyama et al also measured the ground state atomic oxygen near the plasma treated surface, revealing a circular density distribution for a flow rate of 0.5 slm, while a ring for 1.0 slm, [42] similar in shape to the inactivation pattern observed by Goree et al [39,40] A recent study by Sun et al demonstrated evidence of off-axis chemistry in a microplasma jet array, and suggested the dominance of long living species such as O 3 and H 2 O 2 . [43] Moreover, their 1D fluid model simulation for describing the chemistry in a RF plasma ignited in a He/O 2 (0.5%) gas mixture generated with an electrode gap of 2 mm and having an effluent region of 3 cm in width calculated diffusion lengths of 1.3 and >30 mm for O and O 3 , respectively. [43] In this study, we examined the efficacy of an APPJ ignited either in helium (He) or a helium/oxygen (He/O 2 ) mixture in inactivating Escherichia coli bacteria on a Brain-Heart Infusion (BHI) agar surface.…”

“…[43] Moreover, their 1D fluid model simulation for describing the chemistry in a RF plasma ignited in a He/O 2 (0.5%) gas mixture generated with an electrode gap of 2 mm and having an effluent region of 3 cm in width calculated diffusion lengths of 1.3 and >30 mm for O and O 3 , respectively. [43] In this study, we examined the efficacy of an APPJ ignited either in helium (He) or a helium/oxygen (He/O 2 ) mixture in inactivating Escherichia coli bacteria on a Brain-Heart Infusion (BHI) agar surface. Moreover, we investigated the dependence of the He flow rate and sample distance on the inactivation shape and area induced by the APPJs.…”

Jet‐to‐jet interactions in atmospheric‐pressure plasma jet arrays for surface processing

“…[27] For jet arrays, there are strong jet-to-jet coupling interactions causing by gas flowing and electrical field from adjacent plasma plumes, which leads to plume divergence, [10,28] different discharge modes, [14,29] and thus affects the downstream plume uniformity and treatment effects. [18,30] To obtain economic, uniform, and large scale APPJ arrays for diverse applications, it is important to understand the mechanisms of the plasma jets interaction and jets propagation of the jet array in the surrounding air. However, most of the reported works on plasma arrays were about the realization of the uniform and large scale plasma area, and only a few of them conducted the experimental measurements and theoretical studies of the plasma jets interactions.…”