A semi-empirical expression for the first Townsend coefficient in strong electric fields

Radmilović-Radjenović, M.; Radjenović, Branislav; Klas, M.; Matejčík, Štefan

doi:10.1209/0295-5075/108/65001

Cited by 4 publications

(4 citation statements)

References 21 publications

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“…As can be seen from Fig. 8, the ionization coefficients in microgaps agree well with the values obtained for the standard size discharges indicating that the Townsend phenomenology does not need extension to describe microdischarges and that the ionization coefficients for such discharges obey the similarity law α /p=f (E/p) [42,43].…”

Section: E B /P [Kv/(cm X Atm)]supporting

confidence: 77%

Theoretical Studies of the Electrical Discharge Characteristics of Sulfur Hexafluoride

Radmilović-Radjenović¹,

Radjenović²

2017

Journal of Electrical Engineering and Technology

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-This paper contains results of the theoretical studies of the electrical breakdown properties in sulfur hexafluoride. Since the strong interaction of high-energy electrons with the polyatomic sulfur hexafluoride molecule causes their rapid deceleration to the lower energy of electron capture and dissociative attachment, the breakdown is only possible at relatively high field strengths. From the breakdown voltage curves, the effective yields that characterize secondary electron productions have been estimated. Values of the effective yields are found to be more consistent if they are derived from the experimentally determined values of the ionization coefficient and the breakdown voltages. In addition, simulations were performed using an one-dimensional Particle-in-cell/Monte Carlo collision code. The obtained simulation results agree well with the available experimental data with an error margin of less than 10% over a wide range of pressures and the gap sizes. The differences between measurements and calculations can be attributed to the differences between simulation and experimental conditions. Simulation results are also compared with the theoretical predictions obtained by using expression that describes linear dependence of the breakdown voltage in sulfur hexafluoride on the pressure and the gap size product.

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Section: E B /P [Kv/(cm X Atm)]supporting

confidence: 77%

Theoretical Studies of the Electrical Discharge Characteristics of Sulfur Hexafluoride

Radmilović-Radjenović¹,

Radjenović²

2017

Journal of Electrical Engineering and Technology

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“…The reduced ionization coefficient α /N in water vapor versus E/N has been obtained for the E/n range up to 10 4 Td [46,47], being at high E/N at the level around 3×10 −16 cm 2 . Typically, at E/N exceeding 10 4 Td the α/N values vary with the growth of E/N rather weakly [48], so that the estimate, for conditions of the breakdown of cavitation voids, α/N = 3×10 −16 cm 2 seems reasonable.…”

Section: Electrical Breakdown Of Cavitation Voidsmentioning

confidence: 96%

Pre-breakdown phenomena and discharges in a gas-liquid system

Терешонок¹,

Babaeva²,

Naidis³

et al. 2018

Plasma Sources Sci. Technol.

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In this paper, we investigate pre-breakdown and breakdown phenomena in gas-liquid systems. Cavitation void formation and breakdown in bubbles immersed in liquids are studied numerically, while complete breakdown of bubbled water is studied in experiments. It is shown that taking into account the dependence of water dielectric constant on electric field strength plays the same important role for cavitation void appearance under the action of electrostriction forces as the voltage rise time. It is also shown that the initial stage of breakdown in deformed bubbles immersed in liquid strongly depends on spatial orientation of the bubbles relative to the external electric field. The effect of immersed microbubbles, distributed in bulk water, on breakdown time and voltage is studied experimentally. At the breakdown voltage, the slow 'thermal' mechanism is changed by the fast 'streamer-leader' showing a decrease in breakdown time by two orders of magnitude by introducing microbubbles (0.1% of volumetric gas content) into the water. In addition, the plasma channel is found to pass between nearby microbubbles, exhibiting some 'guidance' effect.

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“…It is found that the ratio of the reduced electric field E/p is higher under the experimental conditions in this paper. The magnitude of its corrected ionization coefficient is close to the ionization coefficient obtained from the calculation of formula (2), so the exponentially resolved form of formula (2) is used in the study for the calculation and analysis of the ionization coefficient [29,30]. Therefore, in this study, an exponential analytical formula (2) was employed for ionization coefficient calculations and analysis.…”

Section: The Change In Discharge Path At the Electrode Edgementioning

confidence: 99%

“…The ratio of ionization coefficient α to gas pressure p is a function related to E/p, as expressed in α/p = f (E/p) [30]. Under similar discharge conditions, when comparing one set of gas discharge process parameters (d 1 , p 1 , α 1 ) and another set of gas discharge process parameters (d 2 , p 2 , α 2 ).…”

Section: The Discharge Path's Impact On the Theory Of Similaritymentioning

confidence: 99%

The effect of micro-gap discharge paths on ionization coefficients and similarity theory

Zhang,

Zhao,

Wang

et al. 2024

Phys. Scr.

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In order to investigate the impact of discharge paths at the micrometer scale on breakdown, two sets of different electrodes were arranged with electrode gaps ranging from 10μm to 100μm and gas pressures varying from 1kPa to 100kPa. The research has revealed that without an insulating layer at the edge of the electrode, when the product of gas pressure (p) and electrode gap (d) is less than 60Pa·cm, the number of positive ions cannot satisfy the conditions for self-sustaining discharge at the electrode gap (d). As a result, the discharge path varies along a longer path (s) to satisfy the conditions for self-sustained discharge, thereby maintaining the minimum breakdown voltage. This long-path discharge mechanism affects the ionization coefficient, resulting in an inconsistency between the ionization coefficient ratio at different distances and their respective scale factor (k) values. Therefore, on a micrometer scale, changes in the path make the application of similarity theory no longer applicable.

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A semi-empirical expression for the first Townsend coefficient in strong electric fields

Cited by 4 publications

References 21 publications

Theoretical Studies of the Electrical Discharge Characteristics of Sulfur Hexafluoride

Theoretical Studies of the Electrical Discharge Characteristics of Sulfur Hexafluoride

Pre-breakdown phenomena and discharges in a gas-liquid system

The effect of micro-gap discharge paths on ionization coefficients and similarity theory

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