Measurement of gas-density variation in pulsed streamer discharge at atmospheric pressure by Mach–Zehnder interferometry

Komuro, Atsushi; Natsume, China; Andõ, Akira

doi:10.1088/1361-6595/ac1def

Cited by 3 publications

(2 citation statements)

References 39 publications

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“…An early simulation conducted by Marode et al [15] showed that discharge channels could heat air and initiate a radial flow of neutral air molecules, reducing the air density in the path by up to 50%. Such air perturbations have been further studied computationally in [16][17][18], and measured experimentally in [18][19][20][21][22][23][24][25]. These studies confirm the presence of spherical or plane shock waves and gas thermal expansion in association with spark and leader discharges.…”

Section: Gas Density Inhomogeneitiesmentioning

confidence: 61%

3D modeling of positive streamers in air with inhomogeneous density

Guo,

Ebert,

Teunissen

2023

Plasma Sources Sci. Technol.

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We study the effect of an inhomogeneous gas density on positive streamer discharges in air using a 3D fluid model with stochastic photoionization, generalizing earlier work with a 2D axisymmetric model by Starikovskiy and Aleksandrov (2019 Plasma Sources Sci. Technol. 28 095022). We consider various types of planar and (hemi)spherical gas density gradients. Streamers propagate from a region of density n 0 towards a region of higher or lower gas density n 1 , where n 0 corresponds to 300 K and 1 b a r . We observe that streamers can always propagate into a region with a lower gas density. When streamers enter a region with a higher gas density, branching can occur at the density gradient, with branches growing in a flower-like pattern over the gradient surface. Depending on the gas density ratio, the gradient width and other factors, narrow branches are able to propagate into the higher-density gas. In a planar geometry, we find that such propagation is possible up to a gas density slope of 3.5 n 0 / m m , although this value depends on a number of conditions, such as the gradient angle. Surprisingly, a higher applied voltage makes it more difficult for streamers to penetrate into the high-density region, due to an increase of the primary streamer’s radius.

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Section: Gas Density Inhomogeneitiesmentioning

confidence: 61%

3D modeling of positive streamers in air with inhomogeneous density

Guo,

Ebert,

Teunissen

2023

Plasma Sources Sci. Technol.

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“…It does not depend on the self-illumination of the flow field to be measured. Considering the cost and complexity of experiment, the refractive index of plasma is mostly measured at a single wavelength, and the plasma temperature and particle density are obtained based on LTE [23][24][25]. For MV AC air arcs, it is difficult to apply the above plasma diagnostic techniques.…”

Section: Introductionmentioning

confidence: 99%

Measurement of medium-voltage AC air arc temperature and particle number density based on dual-wavelength Moiré deflection technology

Zhou,

Yang,

Yuan

et al. 2024

J. Phys. D: Appl. Phys.

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AC air arcs are generated in medium-voltage (MV) power systems under the effect of harsh weather conditions, equipment aging, and high penetration of distributed generation, threatening equipment and public safety. The arc current and temperature are low due to the wide application of arc suppression devices. In this scenario, the MV AC air arc does not satisfy the local thermodynamic equilibrium (LTE) condition. In addition, the repeated arcing and extinguishing processes further complicate the arc discharge mechanism, which bring challenges in the modeling and detection of MV AC air arcs. Experimental methods are a direct and efficient approach to determine the properties of arc plasmas. In this study, a dual-wavelength moiré deflection diagnostic system was established to determine the time evolution of the particle density and radial distribution of the temperature in an MV AC air arc without relying on the LTE assumption. The electron number density and heavy particle number density change transiently during the arc discharge process and change gradient along the radial direction. The heavy particle temperature and electron temperature were then calculated based on the measured particle number density. During the arcing stage, the temperature of the electrons exceeded that of the heavy particles significantly, and the arc deviated from LTE. Finally, the limitations of the traditional single-wavelength moiré deflection method are analyzed. The classic single-wavelength moiré deflection method, while capable of estimating heavy particle temperature in plasma, exhibits a significant error in electron density estimation compared to the dual-wavelength moiré deflection method.

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Experimental study on the axial growth characteristics of streamer stem during dark period in long spark discharge

Cheng,

He,

Huang

et al. 2023

Physics of Plasmas

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This paper presents an original investigation into the axial evolution of streamer stem during a dark period in long spark discharge. To obtain thermodynamic morphology and temperature distribution of stems, we set up a quantitative schlieren system with the temporal and spatial resolutions of 0.37 μs and 31 μm/pixel, respectively. The quantitative schlieren observation experiments of positive leader discharge with a 1.0 m rod-plate gap were carried out, and the time-resolved quantitative schlieren images were captured. Furthermore, the temperature distribution of stems and its morphology evolution in the axial direction during a dark period were obtained. Due to the dispersion of first streamer discharge, the gas temperature in stem roots shows two evolutionary trends, namely, rising and falling. It was found that the gas temperature in stem decreased along the axis with the increase in the distance from stem root, and the gas temperature of a thermal thin channel was between 400 and 800 K. There is a significant dependency between axial development parameters of thermal thin channels and the first streamer discharge parameters. The phenomenon of channel abrupt elongation triggered by secondary streamer discharge was observed by the schlieren system, and the influence of characteristic parameters on the inception of secondary streamer was statistically analyzed. The ion current waveform in leader relaxation phase was measured, and it is clarified that the generation mechanism of thermal thin channels is due to the energy transfer between positive ions and neutral particles, which finally leads to the increase in gas temperature in the channels.

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Measurement of gas-density variation in pulsed streamer discharge at atmospheric pressure by Mach–Zehnder interferometry

Cited by 3 publications

References 39 publications

3D modeling of positive streamers in air with inhomogeneous density

3D modeling of positive streamers in air with inhomogeneous density

Measurement of medium-voltage AC air arc temperature and particle number density based on dual-wavelength Moiré deflection technology

Experimental study on the axial growth characteristics of streamer stem during dark period in long spark discharge

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