Performance of a 16.7 m air rod-plane gap under a negative switching impulse

Ortéga, Pascal; Domens, P.; Gibert, A.; Hutzler, B.; Riquel, G.

doi:10.1088/0022-3727/27/11/019

Cited by 49 publications

(64 citation statements)

References 3 publications

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“…It may be concluded from the figure that, for the range of characteristics tested, longer insulator lengths result in a higher current during propagation. This tendency was also observed for electrical breakdown in air gaps [114].…”

Section: Propagating Arcsupporting

confidence: 68%

“…Figure 6.22 indicates the effects of the above-mentioned parameters on arc velocity, from which it may be concluded that, for the range of characteristics tested, longer insulator lengths result in higher maximum velocities during arc propagation. This tendency was also observed for electrical breakdown in air gaps [114]. Wider ice bands and higher applied water conductivities will also result in higher maximum velocities.…”

Section: Arc Currentsupporting

confidence: 54%

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Dynamic modeling of AC arc development on ice surfaces

Zaniani¹

2004

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Section: Propagating Arcsupporting

confidence: 68%

Section: Arc Currentsupporting

confidence: 54%

Dynamic modeling of AC arc development on ice surfaces

Zaniani¹

2004

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“…The average stepping period results between 15 and 20 µs. The calculated current is composed by a series of pulses which are consistent with current measurements [33].…”

Section: Negative Dischargementioning

confidence: 53%

Fundamental processes in long air gap discharges

Gallimberti¹,

Bacchiega²,

Bondiou-Clergerie

et al. 2002

Comptes Rendus. Physique

249

196

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The development of atmospheric lightning is initiated and sustained by the formation in virgin air of 'streamer corona' and 'leader' discharges, very similar to those observed in laboratory long sparks. Therefore, the experimental and theoretical investigations of these laboratory discharges have become of large interest to improve the physical knowledge of the lightning process and to develop self-consistent models that could be applied to new protection concepts.In the present paper the fundamental processes of the subsequent phases of long air gap discharges are analyzed, from the first corona inception and development to the leader channel formation and propagation. For all these processes simulations models are discussed that have been essentially derived and simplified by the authors, in order to develop sequential time-dependent simulation of the laboratory breakdown, with both positive and negative voltages. The possibility of extending these models to the case of natural lightning is discussed in the companion paper, presented in this same volume.

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“…The negative space leader extremity becomes the new leader head and the process is repeated [Bazelyan and Raizer, 1998, p. 255]. The formation of a space leader ahead of the negative leader is a fundamental stage in the leader progression, as evidenced in laboratory [e.g., Ortega et al, 1994;Reess et al, 1995;Bazelyan and Raizer, 1998;Gallimberti et al, 2002] and lightning [e.g., Biagi et al, 2009Biagi et al, , 2010Hill et al, 2011] observations. Although positive and negative leaders exhibit different dynamical features, it can be seen, from the above discussion, that the streamer-to-leader transition (or in other words, the air heating) is a fundamental process that defines leader propagation in both cases.…”

Section: Phenomenology Of Positive and Negative Leadersmentioning

confidence: 99%

Dynamics of streamer‐to‐leader transition at reduced air densities and its implications for propagation of lightning leaders and gigantic jets

2013

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[1] In this paper we present modeling studies of air heating by electrical discharges in a wide range of pressures. The developed model is capable of quantifying the different contributions for heating of air at the particle level and rigorously accounts for the vibration-dissociation-vibration coupling. The model is validated by calculating the breakdown times of short air gaps and comparing to available experimental data. Detailed discussion on the role of electron detachment in the development of the thermal-ionizational instability that triggers the spark development in short air gaps is presented. The dynamics of fast heating by quenching of excited electronic states is discussed and the scaling of its main channels with ambient air density is quantified. The developed model is employed to study the streamer-to-leader transition process and to obtain its scaling with ambient air density. Streamer-to-leader transition is the name given to a sequence of events occurring in a thin plasma channel through which a relatively strong current is forced through, culminating in heating of ambient gas and increase of the electrical conductivity of the channel. This process occurs during the inception of leaders (from sharp metallic structures, from hydrometeors inside the thundercloud, or in virgin air) and during their propagation (at the leader head or during the growth of a space leader). The development of a thermal-ionizational instability that culminates in the leader formation and propagation is characterized by a change in air ionization mechanism from electron impact to associative ionization and by contraction of the plasma channel. The introduced methodology for estimation of leader speeds shows that the propagation of a leader is limited by the air heating of every newly formed leader section. It is demonstrated that the streamer-to-leader transition time has an inverse-squared dependence on the ambient air density at near-ground pressures, in agreement with similarity laws for Joule heating in a streamer channel. Model results indicate that a deviation from this similarity scaling occurs at very low air densities, where the rate of electronic power deposition is balanced by the channel expansion, and air heating from quenching of excited electronic states is very inefficient. These findings place a limit on the maximum altitude at which a hot and highly conducting lightning leader channel can be formed in the Earth's atmosphere, result which is important for understating of the gigantic jet (GJ) discharges between thundercloud tops and the lower ionosphere. Simulations of leader speeds at GJ altitudes demonstrate that initial speeds of GJs are consistent with the leader propagation mechanism. The simulation of a GJ, escaping upward from a thundercloud top, shows that the lengthening of the leader streamer zone, in a medium of exponentially decreasing air density, determines the existence of an altitude at which the streamer zones of GJs become so long that they dynamically extend (jump) all the way to th...

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Performance of a 16.7 m air rod-plane gap under a negative switching impulse

Cited by 49 publications

References 3 publications

Dynamic modeling of AC arc development on ice surfaces

Dynamic modeling of AC arc development on ice surfaces

Fundamental processes in long air gap discharges

Dynamics of streamer‐to‐leader transition at reduced air densities and its implications for propagation of lightning leaders and gigantic jets

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