Photoionization capable, extreme and vacuum ultraviolet emission in developing low temperature plasmas in air

Stephens, J.; Fierro, Andrew; Beeson, Sterling; Laity, George; Trienekens, Djm Dirk; Joshi, Ravi; Dickens, J.; Neuber, A.

doi:10.1088/0963-0252/25/2/025024

Cited by 26 publications

(28 citation statements)

References 80 publications

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“…The proportionality factor ξ is in principle field-dependent [15], but for simplicity we here set it to ξ = 0.075 (except for section 4.3, where it is varied). As stated in the introduction, there have recently been several efforts to improve upon Zheleznyak's model, for example by taking different excited states and their lifetime into account [17] or by considering different gas mixtures [16]. Since in this paper we focus on the effect of stochastic fluctuations, we use Zheleznyak's model in its standard formulation.…”

Section: Photoionization Modelsmentioning

confidence: 99%

The effect of the stochasticity of photoionization on 3D streamer simulations

Bagheri

Teunissen

2019

Plasma Sources Sci. Technol.

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Positive streamer discharges require a source of free electrons ahead of them for their growth. In air, these electrons are typically provided by photoionization. Here we investigate how stochastic fluctuations due to the discreteness of ionizing photons affect positive streamers in air. We simulate positive streamers between two planar electrodes with a 3D plasma fluid model, using both a stochastic and a continuum method for photoionization. With stochastic photoionization, fluctuations are visible in the streamer's direction, maximal electric field, velocity, and electron density. The streamers do not branch, and we find good agreement between the averaged stochastic results and the results with continuum photoionization. The streamers stay roughly axisymmetric, and we show that results obtained with an axisymmetric model indeed agree well with the 3D results. However, we find that positive streamers are sensitive to the amount of photoionization. When the amount of photoionization is doubled, there is even better agreement between the stochastic and continuum results, but with half the amount of photoionization, stochastic fluctuations become more important and streamer branching starts to occur.

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Section: Photoionization Modelsmentioning

confidence: 99%

The effect of the stochasticity of photoionization on 3D streamer simulations

Bagheri

Teunissen

2019

Plasma Sources Sci. Technol.

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“…Even though there have been many studies on the physics of photoionization in air as well as on its numerical implementation in discharge models [31,33,34,37,38], to the best of our knowledge there are no quantitative photoionization models for discharges in CO 2 and CO 2 containing gas mixtures.…”

Section: Model Equationsmentioning

confidence: 99%

Simulation of positive streamers in CO₂ and in air: the role of photoionization or other electron sources

Bagheri

Teunissen

Ebert

2020

Plasma Sources Sci. Technol.

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Positive streamer discharges have been studied and modelled extensively in air. Here we study positive streamers in CO 2 with and without oxygen admixtures; they are relevant for current high voltage technology as well as for discharges in the atmosphere of Venus. We discuss that no ef cient photoionization mechanism is known for gases with a large CO 2 fraction, as photons in the relevant energy range are rapidly absorbed. Hence positive streamers can propagate only due to some other source of free electrons ahead of the ionization front. Therefore we study positive streamer propagation in CO 2 with different levels of background ionization to provide these free electrons. The effect of replacing photoionization by background ionization is studied with simulations in air. Simulating streamers in background elds of 16 to 20 kV cm −1 at standard temperature and pressure within a gap of 6.4 cm, we nd that streamer propagation is rather insensitive to the level of photoionization or background ionization. We also discuss that the results depend not only on the value of breakdown eld and applied electric eld, and on preionization or photoionization, but also on the electron mobility µ(E) and the effective ionization coef cient α eff (E), that are gas-dependent functions of the electron energy or the electric eld.

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“…Photo-ionization in air occurs, when an energetic electron in the ionization front excites a nitrogen molecule to the b 1 [136,137,138,139]. The molecule can then emit a photon with a wavelength in the range of 98 -102.5 nm that can ionize an oxygen molecule at some (isotropically distributed) distance.…”

Section: Streamers In Different Gasesmentioning

confidence: 99%

The physics of streamer discharge phenomena

Nijdam,

Teunissen,

Ebert

2020

Preprint

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In this review we describe a transient type of gas discharge which is commonly called a streamer discharge, as well as a few related phenomena in pulsed discharges. Streamers are propagating ionization fronts with self-organized field enhancement at their tips that can appear in gases at (or close to) atmospheric pressure. They are the precursors of other discharges like sparks and lightning, but they also occur in for example corona reactors or plasma jets which are used for a variety of plasma chemical purposes. When enough space is available, streamers can also form at much lower pressures, like in the case of sprite discharges high up in the atmosphere.We explain the structure and basic underlying physics of streamer discharges, and how they scale with gas density. We discuss the chemistry and applications of streamers, and describe their two main stages in detail: inception and propagation. We also look at some other topics, like interaction with flow and heat, related pulsed discharges, and electron runaway and high energy radiation. Finally, we discuss streamer simulations and diagnostics in quite some detail.This review is written with two purposes in mind: First, we describe recent results on the physics of streamer discharges, with a focus on the work performed in our groups. We also describe recent developments in diagnostics and simulations of streamers. Second, we provide background information on the above-mentioned aspects of streamers. This review can therefore be used as a tutorial by researchers starting to work in the field of streamer physics.

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Photoionization capable, extreme and vacuum ultraviolet emission in developing low temperature plasmas in air

Cited by 26 publications

References 80 publications

The effect of the stochasticity of photoionization on 3D streamer simulations

The effect of the stochasticity of photoionization on 3D streamer simulations

Simulation of positive streamers in CO₂ and in air: the role of photoionization or other electron sources

The physics of streamer discharge phenomena

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Photoionization capable, extreme and vacuum ultraviolet emission in developing low temperature plasmas in air

Cited by 26 publications

References 80 publications

The effect of the stochasticity of photoionization on 3D streamer simulations

The effect of the stochasticity of photoionization on 3D streamer simulations

Simulation of positive streamers in CO2 and in air: the role of photoionization or other electron sources

The physics of streamer discharge phenomena

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Product

Resources

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Simulation of positive streamers in CO₂ and in air: the role of photoionization or other electron sources