Large air-gap discharge and Schlieren techniques

Domens, P.; Dupuy, J.; Gibert, A.; Díaz, Rafael Gámez; Hutzler, B.; Riu, Jean-Pierre; Rühling, F.

doi:10.1088/0022-3727/21/11/011

Cited by 34 publications

(21 citation statements)

References 5 publications

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“…In this case, the streamer zone of the leader is probably similar to that of the leader of long spark, although the similarity may not be complete, if the formation of the leader and its streamer zone occurs after the streamers reach the opposite electrode, that is, during the breakthrough phase. Leader discharges in gaps of~1 m length were studied by Kurimoto et al (1978), Domens et al (1988), Reess et al (1995), Zhou et al (2015), and Ma et al (2019), but streamer zone parameters were not measured by those authors.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Streamer Zone of Long‐Spark Positive Leader Using High‐Speed Photography and Microwave Probing

et al. 2020

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The streamer zone of positive leader during the breakthrough phase of long sparks was experimentally investigated with two methods. One of the methods is the analysis of streamer‐zone images obtained with a high‐speed framing camera with image enhancement. This method allowed us to estimate the spatial distribution of streamer density and low‐frequency conductivity in the streamer zone. The other method is the microwave probing, which we applied for the first time to long sparks. The attenuation of microwave beam in the streamer zone in our experiments is proportional to the total number of free electrons inside the microwave beam. Experimental data on the microwave attenuation combined with the streamer density found using the first method allowed us to estimate the total number of free electrons in one streamer. The following parameters were obtained. The streamer density in the center of the streamer zone is (0.6–1) · 105 m−3, and the total number of streamers in the streamer zone is 4 · 105–106. The average total number of free electrons in one streamer is about 3 · 1010. Low‐frequency conductivity on the axis of streamer zone was estimated to be typically 2 · 10−5 S/m, which is similar to that estimated for corona sheath in lightning. Both methods are based on the assumption of constancy of electric field and similarity of all streamers inside the streamer zone. The overall results of this study are generally consistent with this assumption.

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Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Streamer Zone of Long‐Spark Positive Leader Using High‐Speed Photography and Microwave Probing

et al. 2020

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“…After the first streamer-corona burst, the discharge channel may experience a dark period during which the electric current vanishes and the light-emitting stops. Optical cameras cannot observe such lightless processes, and the Schlieren technique can serve as a powerful tool instead [62][63][64]. Domens [65] compared two types of relaxation phases of the discharge channel with the first type in the vicinity of the anode and the second type further into the gap.…”

Section: Stem Evolution During Dark Periodsmentioning

confidence: 99%

Schlieren techniques for observations of long positive sparks: Review and application

Wang

Zhao

et al. 2022

High Voltage

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Understanding the mechanism of positive leader discharge is important in lightning protection engineering and the external insulation design in high voltage power transmission systems. During the propagation of a positive leader, some processes without light-emitting, for example, the insulation recovery process after the breakdown, cannot be observed by optical photography techniques. With the combination of the digital high-speed imaging system, the conventional Schlieren techniques offer new vistas in the long air gap discharge observation. The important features of high spatial resolution, high sensitivity, and easy arrangement make Schlieren techniques powerful and effective tools for characterising the discharge processes without light-emitting. This work presents a brief review of current Schlieren techniques and discusses the design of the Schlieren optics system for long spark observations. Several interesting phenomena discovered at different phases of long sparks with high-speed Schlieren techniques are also presented.

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“…Therefore, it is impossible to determine the length of the initial leader according to time, or to consider the propagation of the initial leader. By reference to observation results for leader inception obtained employing schlieren techniques, 16 a new structure of the transition area, similar to a cone, is proposed in this paper, as shown in Fig. 9.…”

Section: Improved Inception Model Of Positive Upward Lssmentioning

confidence: 99%

An improved model to determine the inception of positive upward leader–streamer system considering the leader propagation during dark period

Xie

Chen

2013

Physics of Plasmas

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Stem-leader transition and front-streamer inception are two essential conditions for the inception of positive upward leader-streamer system (LSS). Previous models have not considered the initialleader propagation during dark period and have not been verified systematically. In this paper, a series of positive upward discharge simulation experiments was designed and carried out. Characteristic parameters of the discharge process related to the inception of positive upward LSS, namely, the first-corona inception voltage, the first-corona charge, the dark period, and the LSS inception voltage, were obtained. By comparing these experiment results with simulation results calculated using previous models, it was found that it is improper to assume that the length of the initial leader is a fixed value. Finally, an improved inception model of positive upward LSS considering the leader propagation during dark period was developed and verified with experiment results. V C 2013 AIP Publishing LLC. [http://dx.

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Large air-gap discharge and Schlieren techniques

Cited by 34 publications

References 5 publications

Experimental Investigation of the Streamer Zone of Long‐Spark Positive Leader Using High‐Speed Photography and Microwave Probing

Experimental Investigation of the Streamer Zone of Long‐Spark Positive Leader Using High‐Speed Photography and Microwave Probing

Schlieren techniques for observations of long positive sparks: Review and application

An improved model to determine the inception of positive upward leader–streamer system considering the leader propagation during dark period

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