The influence of individual evaluation of electron‐impact ionization, attachment, and photoionization rates on positive streamer propagation

Wei, Zhenyu; Komuro, Atsushi; Ono, Ryo

doi:10.1002/ppap.202300113

Cited by 3 publications

(2 citation statements)

References 60 publications

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“…R pho significantly increases with decreasing p, but is only 10 −3 of R net . The ratio of R pho /R net is close to the results in the simplified streamer fluid model in [36]. The photoionization promotes the propagation of streamer, complementing electron collisional ionization, but its contribution to R net is minor and can be replaced by background ionization [37].…”

Section: Effect Of Pressure On Streamer Dischargesupporting

confidence: 77%

Study on the effects of medium-low pressure and oxygen concentration on positive streamer based on a two-dimensional fluid model

Chen,

Yang,

Wei

et al. 2024

J. Phys. D: Appl. Phys.

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We studied positive streamers with a 5 mm gap under 20–101 kPa pressure and 1%–31% O2 concentrations conditions using a 2D axisymmetric fluid model based on local field approximation. As the pressure decreases from 101 kPa to 20 kPa, the axial reduced electric field, the mean electron energy and the electron diffusion coefficient increase, which leads to the acceleration of the streamer propagation velocity and the increase of the streamer channel radius. The opposite change of ionization cross section and gas molecular density caused by the decrease of pressure leads to the non-monotonic change of the peak of net ionization rate. At medium-low pressure, there is a wider ionization region at the streamer head. As the O2 concentration decreases from 31% to 1% in N2/O2, the streamer propagation velocity decreases. When the O2 concentration drops to 1%, the streamer velocity decreases with a descent gradient of nearly 4 times, compared to 11% O2. Based on the space charge effect and chemical reaction rate, a possible mechanism is proposed to explain the abrupt change in the streamer velocity.

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Section: Effect Of Pressure On Streamer Dischargesupporting

confidence: 77%

Study on the effects of medium-low pressure and oxygen concentration on positive streamer based on a two-dimensional fluid model

Chen,

Yang,

Wei

et al. 2024

J. Phys. D: Appl. Phys.

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“…Streamer discharges comprise rapidly growing ionised channels [1][2][3][4], which are a type of atmospheric pressure plasma [5]. In air and air-like mixtures, a streamer discharge results in the production of OH, O, and N radicals in addition to excited species and ions such as O − 2 , O − , O + , O + 4 , and N + 4 [6][7][8][9][10] and is thus widely adopted in different types of industrial devices, such as ozone generation [10][11][12][13], water purification [14,15] and surface processing [16,17] devices.…”

Section: Introductionmentioning

confidence: 99%

Simulation on the effect of oxygen concentration on the positive secondary streamer generated in oxygen-rich nitrogen–oxygen mixtures under atmospheric pressure

Wei,

Ono,

Komuro

2024

Plasma Sources Sci. Technol.

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In this study, we investigated the effect of various O 2 concentrations, from 20% to 90%, in nitrogen–oxygen ( N 2 / O 2 ) mixtures on the characteristics of secondary streamers. As oxygen molecules have different molecular characteristics from nitrogen molecules in terms of ionisation threshold and electron attachment property, streamer discharges generated under various nitrogen–oxygen ratios may exhibit differing characteristics such as electron density, electric field, and radical formation. We focused on the changes in these parameters in secondary streamers using simulations. Simulations were first performed under the same conditions as those in previous experiments to compare the results of the ozone production, discharge current, and discharge emission characteristics. To compare the ozone production characteristics, simulated O radicals–the precursor of ozone–were used in the simulation for simplicity. This comparison showed that, although the absolute values of each parameter were different, the simulation exhibited a similar trend in the case of the experimentally obtained oxygen concentration dependence. After the validity of the simulation was verified to some extent via a comparison with the experiment, the results obtained from the simulation were analysed in detail. The results showed that, although the electric field strength in the secondary streamer did not change much as the oxygen concentration increased, the decrease rate of the electron density was greatly accelerated by the electron attachment reaction of oxygen. As a result, many of the electrons had already dissipate during the development of the primary streamer, and few electrons remained when the secondary streamer was formed. This effect suggests that the ratio of the amount of O radicals produced in the primary streamer to that produced in the secondary streamer changes as the oxygen concentration changes.

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Numerical study on positive streamer in parallel-rod dielectric barrier discharge in atmospheric air

Zhang,

Wu,

Zhao

et al. 2024

Physics of Plasmas

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In this work, a parallel-rod dielectric barrier discharge (DBD) operating in atmospheric air is investigated through the two-dimensional plasma fluid model. The effects of applied voltage (Vp), secondary electron emission coefficient (γ), and photoionization are examined. Photoionization can significantly influence streamer dynamics by accelerating and broadening both volumetric and surface streamers and enhance the impact of the applied voltage. Without photoionization, the propagation distance of the surface streamer along the curved dielectric surface is limited to 0.1–0.2 mm under applied voltages of 8–8.5 kV. In contrast, with photoionization, this distance can extend to 0.3–0.6 mm. Achieving the same distance requires much higher voltages (10–11 kV) if without photoionization. The “double-layer” structure of the surface streamer is investigated, revealing that γ predominantly affects the surface branch with little impact on the volumetric branch. The critical charge density for streamer onset is found to be about 1018 m−3, and the volume-to-surface streamer transition is attributed to the lateral electric field provided by the space charges. This work provides insights into the regulation strategies and underlying mechanisms of streamer dynamics in parallel-rod DBDs in atmospheric air.

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The influence of individual evaluation of electron‐impact ionization, attachment, and photoionization rates on positive streamer propagation

Cited by 3 publications

References 60 publications

Study on the effects of medium-low pressure and oxygen concentration on positive streamer based on a two-dimensional fluid model

Study on the effects of medium-low pressure and oxygen concentration on positive streamer based on a two-dimensional fluid model

Simulation on the effect of oxygen concentration on the positive secondary streamer generated in oxygen-rich nitrogen–oxygen mixtures under atmospheric pressure

Numerical study on positive streamer in parallel-rod dielectric barrier discharge in atmospheric air

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