The polarity effect of nanosecond voltage pulses on the propagation of streamers in a point-to-plane gap filled with air

Белоплотов, Д. В.; Genin, D. E.; Pechenitsin, Dmitry S.

doi:10.35848/1347-4065/ab70a9

Cited by 5 publications

(5 citation statements)

References 29 publications

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“…Both the conduction current and the deposited energy remain at noise levels. The nanosecond pulsed corona discharge illustrates a fairly uniform appearance (ball-like [36]) without visible filamentary channels from the first image in figure 4(d), different from branching features under repetitive sub-microsecond pulses [28]. The ultrashort pulse width probably renders the breakup of the initial cloud [37].…”

Section: Needle-needle Structurementioning

confidence: 94%

Periodical discharge regime transitions under long-term repetitive nanosecond pulses

Zhao

Zheng

et al. 2022

Plasma Sources Sci. Technol.

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Intuitively, the nanosecond repetitively pulsed (NRP) corona and spark regimes are sustained successively after onsets due to the high background electron density and/or the surplus heat. In this paper, the NRP discharge unexpectedly swings among different regimes (corona→glow→spark→corona→…) in one pulse train, which is characterized by the periodical spark quench and reestablishment. We have investigated discharge regime instabilities by applying long-term repetitive high-voltage nanosecond pulses of ~15 ns duration to needle-needle and needle-plane gaps in atmospheric-pressure N2 and N2-O2 mixtures. Pulse-sequence resolved electrical and optical diagnostics have been implemented to capture transition processes. The initial corona gradually grows into glow and then spark “pulse-by-pulse”, however, the spark regime was interrupted after a certain number of voltage pulses until the next reestablishment. Narrow pulse width impedes the discharge instability growth within one pulse, and a certain number of voltage pulses are required for the discharge regime transition. The addition of O2 dramatically boosts the duration length of spark regime. A lower output impedance of the power supply induces a higher deposited energy into a spark, however, not necessarily leads to a longer spark regime duration, although both the energy storage and the average electric field strength are approximate. Polarity effects, conventionally diminished in pulse-periodic discharges, are still evident during the discharge regime transition. The periodical discharge regime transition is qualitatively explained based on the plasma-source coupling and the evolution trajectory along the power transfer curve. Feedback mechanisms and residual-conductivity related screening effect in NRP spark discharges are analysed based on a simplified 0D simulation. The periodical feature is probably caused by the insufficient average deposited energy per unit distance per one pulse cycle. In-depth understandings of “non-binary” regimes (neither corona nor spark) and memory effect mechanisms of NRP discharges could be reached.

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Section: Needle-needle Structurementioning

confidence: 94%

Periodical discharge regime transitions under long-term repetitive nanosecond pulses

Zhao

Zheng

et al. 2022

Plasma Sources Sci. Technol.

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“…Wide negative streamers can propagate faster than positive (as is the case for diffuse discharges) [51]. For example, in [52] nanosecond voltage pulses were applied across a 0.85 cm point-to-plane gap filled with air. Negative streamer crossed the gap faster than positive.…”

Section: Wide Streamersmentioning

confidence: 99%

Formation of wide negative streamers in air and helium: the role of fast electrons

Babaeva¹,

Naidis²,

Терешонок³

et al. 2022

J. Phys. D: Appl. Phys.

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Available experimental data show that the use of voltage pulses with subnanosecond rise times and amplitudes that essentially exceed the breakdown voltage leads to the formation of wide spherical or conical streamers. In this paper, the structure and dynamics of atmospheric pressure wide negative streamers in air and helium by applying high overvoltages with a short rise time to a sharp needle electrode are investigated experimentally and computationally. In the simulations, the two-dimensional fluid and kinetic Electron Monte Carlo Simulation models are used. All the streamers were simulated with the conventional photoionization term Sph that was never turned off. By including an additional source SMC, responsible for the generation of fast electrons, wide and diffuse streamers are obtained. We compare the shapes, width and velocities of conventional streamers in air and helium with those for streamers driven by fast electrons. We show that a conventional streamer in air has a cylindrical form. The conventional streamer in helium is wider than that in air and has a shape of an expanding cone. While accounting for fast electrons, different streamer shapes were obtained. In air, the gap was closed by a spherical streamer. In helium, the shape of a streamer resembles that of a pumpkin. By the application of high (by a factor of four or greater) overvoltages to a sharp needle electrode, the formation of a discharge with several parallel streamers was observed. In this regime, the trajectories of fast electrons originated not only from the cathode, but also from the region of a streamer front where the electric field is high. As a result, the so-called diffuse discharge was formed with high intensity plasma channels surrounded by an aureole of smaller electron density.

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“…Studies of the diffuse discharge formation with the measurement of the runaway electron current and X-ray radiation (XR) were performed in many works; see, for example, [10,28,29]. In our previous studies [1,3,30] under similar experimental conditions, runaway electrons were recorded behind a flat foil anode with a collector having the picosecond temporal resolution.…”

Section: Measurement Of Voltage Discharge Current and X-ray Radiationmentioning

confidence: 99%

Thin Luminous Tracks of Particles Released from Electrodes with A Small Radius of Curvature in Pulsed Nanosecond Discharges in Air and Argon

et al. 2023

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Features of the nanosecond discharge development in a non-uniform electric field are studied experimentally. High spatial resolution imaging showed that thin luminous tracks of great length with a cross-section of a few microns are observed against the background of discharge glow in air and argon. It has been established that the detected tracks are adjacent to brightly luminous white spots on the electrodes or in the vicinity of these spots, and are associated with the flight of small particles. It is shown that the tracks have various shapes and change from pulse to pulse. The particle tracks may look like curvy or straight lines. In some photos, they can change their direction of movement to the opposite. It was found that the particle’s track abruptly breaks and a bright flash is visible at the break point. The color of the tracks differs from that of the spark leaders, while the bands of the second positive nitrogen system dominate in the plasma emission spectra during the existence of a diffuse discharge. Areas of blue light are visible near the electrodes as well. The development of glow and thin luminous tracks in the gap during its breakdown is revealed using an ICCD camera. Physical reasons for the observed phenomena are discussed.

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The polarity effect of nanosecond voltage pulses on the propagation of streamers in a point-to-plane gap filled with air

Cited by 5 publications

References 29 publications

Periodical discharge regime transitions under long-term repetitive nanosecond pulses

Periodical discharge regime transitions under long-term repetitive nanosecond pulses

Formation of wide negative streamers in air and helium: the role of fast electrons

Thin Luminous Tracks of Particles Released from Electrodes with A Small Radius of Curvature in Pulsed Nanosecond Discharges in Air and Argon

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