The effect of working gas impurities on plasma jets

Liu, Xiaoyi; He, Mengbing; Liu, D. W.

doi:10.1063/1.4918693

Cited by 16 publications

(10 citation statements)

References 18 publications

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“…From the ionization rate plotted at 0.25 ns, two streamer heads have spread to 2 mm from the cathode. The electron density at this time in the plasma channel behind the streamer head is up to 2.01×10 19 /m 3 , which is not only consistent with the measured electron density of the negative air streamers [42], but is also almost 60 times higher than the density of the plasma jet in noble gas [22,39]. The voltage drop is in the sheath below the dielectric barrier, and the high conductivity in plasma channels result in 80% of the applied voltage in the streamer heads.…”

Section: Model Descriptionsupporting

confidence: 84%

“…The electron energy conservation equation computes the electron temperature. The three-term exponential Helmholtz model as referred in the literature [20,23,39] is solved for the photoionization source between N 2 and O 2 , due to photoionization playing an important role in the process producing radiation electrons in front of the plasma channels.…”

Section: Model Descriptionmentioning

confidence: 99%

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Interactions between multiple filaments and bacterial biofilms on the surface of an apple

Pan

et al. 2018

Plasma Sci. Technol.

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In this paper, the interactions between two dielectric barrier discharge (DBD) filaments and three bacterial biofilms are simulated. The modeling of a DBD streamer is studied by means of 2D finite element calculation. The model is described by the proper governing equations of air DBD at atmospheric pressure and room temperature. The electric field in the computing domain and the self-consistent transportation of reactive species between a cathode and biofilms on the surface of an apple are realized by solving a Poisson equation and continuity equations. The electron temperature is solved by the electron energy conservation equation. The conductivity and permittivity of bacterial biofilms are considered, and the shapes of the bacterial biofilms are irregular in the uncertainty and randomness of colony growth. The distribution of the electrons suggests that two plasma channels divide into three plasma channels when the streamer are 1 mm from the biofilms. The toe-shapes of the biofilms and the simultaneous effect of two streamer heads result in a high electric field around the biofilms, therefore the stronger ionization facilitates the major part of two streamers combined into one streamer and three streamers arise. The distribution of the reactive oxygen species and the reactive nitrogen species captured by time fluences are non-uniform due to the toe-shaped bacterial biofilms. However, the plasma can intrude into the cavities in the adjacent biofilms due to the μm-scale mean free path. The two streamers case has a larger treatment area and realizes the simultaneous treatment of three biofilms compared with one streamer case.

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Section: Model Descriptionsupporting

confidence: 84%

Section: Model Descriptionmentioning

confidence: 99%

Interactions between multiple filaments and bacterial biofilms on the surface of an apple

Pan

et al. 2018

Plasma Sci. Technol.

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“…2D simulations of the production of active species by a single pulse (single streamer) in HF N-APPJs are performed in [127][128][129][130][131][132]. Equations describing streamer propagation, with the account of mixing of the plasma forming gas with surrounding air, are solved together with kinetic equations (3).…”

Section: Brief Historical Perspectivementioning

confidence: 99%

Reactive species in non-equilibrium atmospheric-pressure plasmas: Generation, transport, and biological effects

et al. 2016

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Non-equilibrium atmospheric-pressure plasmas have recently become a topical area of research owing to their diverse applications in health care and medicine, environmental remediation and pollution control, materials processing, electrochemistry, nanotechnology and other fields. This review focuses on the reactive electrons and ionic, atomic, molecular, and radical species that are produced in these plasmas and then transported from the point of generation to the point of interaction with the material, medium, living cells or tissues being processed. The most important mechanisms of generation and transport of the key species in the plasmas of atmospheric-pressure plasma jets and other non-equilibrium atmosphericpressure plasmas are introduced and examined from the viewpoint of their applications in plasma hygiene and medicine and other relevant fields. Sophisticated high-precision, timeresolved plasma diagnostics approaches and techniques are presented and their applications to monitor the reactive species and plasma dynamics in the plasma jets and other discharges, both in the gas phase and during the plasma interaction with liquid media, are critically reviewed. The large amount of experimental data is supported by the theoretical models of reactive species generation and transport in the plasmas, surrounding gaseous environments, and plasma interaction with liquid media. These models are presented and their limitations are discussed. Special attention is paid to biological effects of the plasma-generated reactive oxygen and nitrogen (and some other) species in basic biological processes such as cell metabolism, proliferation, survival, etc. as well as plasma applications in bacterial inactivation, wound healing, cancer treatment and some others. Challenges and opportunities for theoretical and experimental research are discussed and the authors' vision for the emerging convergence trends across several disciplines and application domains are presented to stimulate critical discussions and collaborations in the future. 4 3.5 Optical absorption spectroscopy 3.5.1 Ozone 3.5.2 UV broadband absorption of OH density 3.5.3 Cavity ring-down spectroscopy 3.5 Selected non-optical techniques 3.5.1 Mass spectrometry 3.5.2 Flow visualization 3.5.3 Electron paramagnetic resonance spectroscopy 4. Temporal and spatial behaviour of key reactive species 4.1 Electron density (n e) 4.2 O atoms 4.2.1 Effect of admixture of O 2 /air on O concentration 4.2.2 Diffusion effect of shielding gas on O production 4.3 OH radical 4.3.1 Effect of H 2 O admixture on OH concentration 4.3.2 Effect of gas flow on OH concentration 4.3.3 Effect of O 2 on OH production 4.3.4 Effect of the treated samples on OH concentration 4.3.4.1 Effect of humidity of treatment sample on OH distribution 4.3.4.2 Effect of sample conductivity on OH distribution 4.3.4.3. Effect of the amplitude of the applied voltage on OH distribution 4.3.4.4. The effect of gas flow on OH distribution 4.3.4.5. The effect of the surface characteristics on OH distribution 4.3.5 Effe...

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“…The core solvers comprise a coupled set of governing equations for charged and neutral species continuity, electron energy transport, and self‐consistent electrostatic potential . In addition, the helium and air mole fraction along the dielectric tube are calculated by Navier‐Strokes and convection‐diffusion equations . The reactions between helium and air species are same as reported previously .…”

Section: Numerical Modelmentioning

confidence: 99%

“…In addition, the helium and air mole fraction along the dielectric tube are calculated by Navier‐Strokes and convection‐diffusion equations . The reactions between helium and air species are same as reported previously . Because it is difficult to quantify the possible role of photoionization on streamer propagation in helium, photoionization is not considered and a pre‐ionization electron density of 10 11 m −3 is used in this simulation.…”

Section: Numerical Modelmentioning

confidence: 99%

The Effect of Tube Diameter on an Atmospheric‐Pressure Micro‐Plasma Jet

Lü

Liu

2015

Plasma Processes & Polymers

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The micro-plasma jet is a unique way of transporting active species of plasma to small targets for applications such as a single cancer cell treatment, and endoscopic surgeries. In this letter, the authors present numerical studies on a single cylindrical electrode micro-plasma jet. The effect of tube diameter on sustaining voltage, electron density, and the density of reactive species are investigated. The diameter of the dielectric tube was varied in the range between 0.1 and 1mm. A pulsed direct current voltage with rising phase of 50 ns was used to ignite the plasma jet. The sustaining voltage monotonically increased with the decreasing diameter of the tube. More electrons wall losses happened due to the faster drift movement to the inner wall of smaller tube diameter, therefore, the decreasing pre-avalanche electron density need increasing ignition voltage to facilitate the avalanche-streamer transition as the tube diameter decreased. The increasing ignition voltage increased the chemical reactivity of plasma jet. The peak density of O 2 Ã and O increased more than 20 times as the tube diameter decreased from 1 to 0.1 mm.

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The effect of working gas impurities on plasma jets

Cited by 16 publications

References 18 publications

Interactions between multiple filaments and bacterial biofilms on the surface of an apple

Interactions between multiple filaments and bacterial biofilms on the surface of an apple

Reactive species in non-equilibrium atmospheric-pressure plasmas: Generation, transport, and biological effects

The Effect of Tube Diameter on an Atmospheric‐Pressure Micro‐Plasma Jet

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