Effects of trace of nitrogen on the helium atmospheric pressure plasma jet interacting with a dielectric substrate

Abstract

Experimental observations and simulation results regarding a pure He atmospheric pressure plasma jet (APPJ) and He + N 2 APPJs interacting with a downstream dielectric substrate are presented in this paper. Experiments utilizing spatialtemporal imaging show that, in the case of the pure He APPJ, an annular plasmasubstrate interaction pattern is formed. With the introduction of N 2 , the plasma is more uniformly distributed on the substrate surface, appearing a solid interaction pattern. The experimental measurements indicate 0.5% N 2 mixture is the optimal condition to achieve the most intense discharge, while the plasma substrate contact area is slightly reduced by 6.1% in comparison to that of the pure He APPJ. A 2D selfconsistent fluid model is constructed to provide insights into the role of the addition of trace of N 2 on the discharge dynamics. The discharge morphologies predicated by the model is in principle consistent with the experimental observations. The simulation reveals that the conversion from the annular plasmasubstrate interaction pattern to the solid one is attributed to the synthetic effect of the addition of N 2 and the presentence of the substrate acting as the cathode to enhance the local electric field. In the solid interaction pattern, the Penning ionization makes a significant contribution to the surface discharge, especially in the afterglow region. The dominant positive ions (N + 2 and N + 4 ) and the reactive oxygen and nitrogen species including O and N gain remarkable increment in the flux intensity to the central surface, which merits great application potential.

Spatial‐temporal evolutions of surface discharge patterns generated on dielectric target interacted with a plasma jet

“…A crescent pattern appears on a dielectric colliding obliquely with a helium plasma plume, which transits to a solid‐disk pattern for vertical incidence of the plume . Moreover, the solid disk can transit to a single ring by varying the gas flow rate, changing the gap distance, or adding trace of nitrogen into helium . Besides these patterns related to helium jet, Lichtenberg figures have been formed on a dielectric interacting with argon jets …”

“…[29,30] Moreover, the solid disk can transit to a single ring by varying the gas flow rate, [29,30] changing the gap distance, [31] or adding trace of nitrogen into helium. [32] Besides these patterns related to helium jet, Lichtenberg figures have been formed on a dielectric interacting with argon jets. [33] In this paper, some patterns composed of interacting streamers are reported on a dielectric impinged vertically by an argon plume, which includes diffuse spot, single ring, and concentric triple rings.…”

Investigation of mode interconversion for interfacial pattern formation through plasma–surface interaction

“…Obviously, an interfacial pattern by plasma–surface interaction would be formed on the substrate. This pattern of interaction can change dramatically for different experimental conditions, so that this causes different feedback effects . For example, when the APPJ is interacting with the substrate, controlling the experimental parameters (including gas flow rate, substrate material, pulse polarity, and treatment distance) would lead to a remarkable shrinkage or enlargement of the effective treatment area, in particular affecting the pattern mode transformation and the distribution of radical species on the substrate, which are significant factors to be considered for the design and optimization in applications.…”

“…This pattern of interaction can change dramatically for different experimental conditions, so that this causes different feedback effects . For example, when the APPJ is interacting with the substrate, controlling the experimental parameters (including gas flow rate, substrate material, pulse polarity, and treatment distance) would lead to a remarkable shrinkage or enlargement of the effective treatment area, in particular affecting the pattern mode transformation and the distribution of radical species on the substrate, which are significant factors to be considered for the design and optimization in applications. As per the recent editorial article from the PSST Editorial Board reported on by Lafleur et al, the plasma–surface interaction is a complex process and plays a prominent and fundamental role in practical applications, but knowledge about this is severely deprived compared with that of the free APPJ.…”

How does the moderate wavy surface affect the discharge behavior in an atmospheric helium dielectric barrier discharge model?

“…Based on the argument above, it is of great importance to carry out some research concerning the plasma–surface interaction under the circumstance of surface fluctuation. In this regard, we have executed one numerical modeling to investigate the plasma jet impinging on a wavy dielectric surface under one validated chemical scheme . But in this paper, we pay specific attention to the role of the moderate wavy surface on the DBD‐based implementation.…”