Numerical simulation of positive streamer propagation in cyclohexane

Hestad, O.L.; Grav, Torstein; Lundgaard, L.E.; Ingebrigtsen, S.; Unge, Mikael; Hjortstam, Olof

doi:10.1109/icdl.2014.6893124

Cited by 5 publications

(11 citation statements)

References 20 publications

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“…4) is too high for slow streamers [1], as expected [2]. Given a lower propagation voltage, the simulations could have shown streamers initiating in fast mode, slowing down, and closing the gap.…”

Section: Resultsmentioning

confidence: 78%

“…Our streamer model has been developed with the aim to capture the most important aspects of streamer inception and streamer propagation, while keeping it simple [2]. The model is built on the Townsend-Meek criterion, following the assumption that electron avalanches occur in the liquid phase [4].…”

Section: Streamer Modelmentioning

confidence: 99%

“…The seeds are considered to be anions in low-field conditions, electrons in intermediate fields, and electron avalanches in highfield conditions. Seeds are moved according to their mobility, and avalanches grow according to (2). A electron avalanche reaching the Townsend-Meek criterion is considered as a part of the streamer.…”

Section: Seedsmentioning

confidence: 99%

“…The main parameters are summarized in Tab. I and are similar to those used before [2]. Here, however, the gap is larger, and parameters for photoionization are added.…”

Section: E Model Parametersmentioning

confidence: 99%

“…The present work concerns modeling positive streamers in liquid cyclohexane, propagating in a tube, in a needle-plane gap. Streamer propagation is investigated by combining models based on electron avalanches [2] and on photoionization [3].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Modeling the transition to fast mode streamers in dielectric liquids

Madshaven

Åstrand

Hestad

et al. 2017

2017 IEEE 19th International Conference on Dielectric Liquids (ICDL)

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Section: Resultsmentioning

confidence: 78%

Section: Streamer Modelmentioning

confidence: 99%

Section: Seedsmentioning

confidence: 99%

“…The main parameters are summarized in Tab. I and are similar to those used before [2]. Here, however, the gap is larger, and parameters for photoionization are added.…”

Section: E Model Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Modeling the transition to fast mode streamers in dielectric liquids

Madshaven

Åstrand

Hestad

et al. 2017

2017 IEEE 19th International Conference on Dielectric Liquids (ICDL)

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Simulation model for the propagation of second mode streamers in dielectric liquids using the Townsend-Meek criterion

et al. 2018

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A simulation model for second mode positive streamers in dielectric liquids is presented. Initiation and propagation is modeled by an electron-avalanche mechanism and the Townsend-Meek criterion. The electric breakdown is simulated in a point-plane gap, using cyclohexane as a model liquid. Electrons move in a Laplacian electric field arising from the electrodes and streamer structure, and turn into electron avalanches in high-field regions. The Townsend-Meek criterion determines when an avalanche is regarded as a part of the streamer structure. The results show that an avalanche-driven breakdown is possible, however, the inception voltage is relatively high. Parameter variations are included to investigate how the parameter values affect the model. visible light [3], re-illuminations, from one or more of its branches. Above the breakdown voltage, streamers may change between the 2nd, the 3rd, and the 4th mode during propagation. There are usually more reilluminations in the 3rd mode than the 2nd mode. The inception of the 4th mode is associated with a drastic increase in speed and fewer, more luminous, branches [2].There are numerous mechanisms that can be involved in the streamer phenomena, the challenge is identifying their importance during initiation and propagation. Applying a potential to a needle can cause charge injection, giving a space-charge limited current [16] causing Joule heating [16], which in turn can cause bubble nucleation [17]. A breakdown in the gas bubble can then propagate the needle potential, and the process may repeat. This is one way to explain 1st mode propagation. Electric fields can also cause electrohydrodynamic flow, which could cause streamer formation through cavitation [18]. Electrostatic cracking has also been proposed as a cavitation mechanism [19]. A main topic of discussion is whether a lowering of the liquid density is needed before charge generation can occur. Electron avalanches are important in gas discharge, but their importance in liquid breakdown is still disputed. In water, strong scattering could prevent electrons from forming avalanches in the liquid phase [20]. Therefore, discharges in micro-bubbles can be important for charge generation [10,14,20]. The same mechanism was also proposed for non-polar liquids [19], however, the relative permittivity is about 80 in water and about 2 in a typical oil, and this difference can prove important since the field enhancement within a bubble in oil is much lower than in water. Contrary to water, there are indications of electron avalanches in non-polar liquids [16,21,22], furthermore, while the initiation and the propagation length of 2nd mode streamers are dependent on the pressure, their propagation velocity is not pressure dependent [16,23]. This implies that the mechanism responsible for propagation occurs in the liquid phase and that the gaseous channel follows as a consequence. In very high electric fields, field-ionization can occur [24,25], and this mechanism has been proposed for the fast 3rd and 4th propagation mode...

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Conductivity and capacitance of streamers in avalanche model for streamer propagation in dielectric liquids

Madshaven¹,

Hestad²,

Unge³

et al. 2019

Plasma Res. Express

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Propagation of positive streamers in dielectric liquids, modeled by the electron avalanche mechanism, is simulated in a needle–plane gap. The streamer is modeled as an RC-circuit where the channel is a resistor and the extremities of the streamer have a capacitance towards the plane. The addition of the RC-model introduces a time constant to the propagation model. Increase in capacitance as a streamer branch propagates reduces its potential, while conduction through the streamer channel increases its potential, as a function of the time constant of the RC-system. Streamer branching also increases the capacitance and decreases the potential of the branches. If the electric field within the streamer channel exceeds a threshold, a breakdown occurs in the channel, and the potential of the streamer is equalized with the needle electrode. This is interpreted as a re-illumination. According to this model, a low conductive streamer branch can propagate some distance before its potential is reduced to below the propagation threshold, and then the RC time constant controls the streamer propagation speed. Channel breakdowns, or re-illuminations, are less frequent when the channels are conductive and more frequent for more branched streamers.

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Numerical simulation of positive streamer propagation in cyclohexane

Cited by 5 publications

References 20 publications

Modeling the transition to fast mode streamers in dielectric liquids

Modeling the transition to fast mode streamers in dielectric liquids

Simulation model for the propagation of second mode streamers in dielectric liquids using the Townsend-Meek criterion

Conductivity and capacitance of streamers in avalanche model for streamer propagation in dielectric liquids

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