Formation and development of a leader channel in air

Popov, N. A.

doi:10.1134/1.1601648

Cited by 70 publications

(78 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Popov [2001,2011] and Flitti and Pancheshnyi [2009] presented calculations of the electron energy partition and they have demonstrated that the fraction of electronic power spent on excitation of electronic molecular states that is converted into gas heating is approximately independent of electric field (and is around 30 %), in agreement with previous assumptions by Aleksandrov et al [1998]. Popov [2003] employed a fully one-dimensional model to simulate the streamer-to-leader transition occurring in the head of a positive leader with an electrical current of 1 A. He discussed the effects of the current contraction and the role of associative ionization processes involving N 2 (A 3 † + u ) and N 2 (a 0 1 † -u ) excited species.…”

Section: Brief History Of Air Heating Modeling In the Context Of Elecsupporting

confidence: 63%

“…The channelcontrolled approach assumes a constant electric field in the gap and it is employed to describe streamer-to-spark transition after the streamer bridges a short gap [e.g., Marode et al, 1979;Bastien and Marode, 1985;Aleksandrov et al, 1998;Naidis, 1999Naidis, , 2005Riousset et al, 2010b]. The headcontrolled approach postulates either a time-dependent or a stationary current, and it is employed to study the streamerto-leader transition occurring in the leader inception and in leader heads propagating through long air gaps [e.g., Gallimberti, 1979;Aleksandrov et al, 2001a;Gallimberti et al, 2002;Bazelyan et al, 2007a;Popov, 2003Popov, , 2009. Some key contributions, from the above listed modeling works, are reviewed below.…”

Section: Brief History Of Air Heating Modeling In the Context Of Elecmentioning

confidence: 99%

“…The streamer-to-leader transition dictates the onset and propagation of leader discharges. In literature, the physical processes leading to the leader onset were theoretically studied in the context of laboratory discharges [e.g., Gallimberti, 1979;Bondiou and Gallimberti, 1994;Aleksandrov et al, 2001a;Vidal et al, 2002;Popov, 2003Popov, , 2009Bazelyan et al, 2007a], where experimental data are available. Similarly, in the context of lightning discharges, numerical models were employed to simulate the inception and propagation of upward lightning leaders from rocket-triggered lightning and tall structures [e.g., Aleksandrov et al, 2001b;Lalande et al, 2002;Becerra and Cooray, 2006;Becerra et al, 2007;Bazelyan et al, 2007bBazelyan et al, , 2008, where ambient conditions can be somewhat inferred.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

2013

View full text Add to dashboard Cite

[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...

show abstract

Section: Brief History Of Air Heating Modeling In the Context Of Elecsupporting

confidence: 63%

Section: Brief History Of Air Heating Modeling In the Context Of Elecmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

2013

View full text Add to dashboard Cite

show abstract

“…Actually, the inaccurate ionization level in the streamer interior in the first-order fluid model is a direct consequence of the inaccuracies of the electron energy distribution [18,19]. Inaccurate electron densities and energies also have direct consequences for the gas chemistry in the streamer interior [35][36][37][38][39][40]. In addition to the accuracy and comprehensiveness of our high-order fluid model, its firm theoretical foundation is certainly an additional favouring factor.…”

Section: Introductionmentioning

confidence: 99%

High-order fluid model for streamer discharges: II. Numerical solution and investigation of planar fronts

Markosyan¹,

Dujko²,

Ebert³

2013

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

The high-order fluid model developed in part I of this series is employed here to study the propagation of negative planar streamer fronts in pure nitrogen. The model consists of the balance equations for electron density, average electron velocity, average electron energy and average electron energy flux. These balance equations have been obtained as velocity moments of Boltzmann's equation and are here coupled to the Poisson equation for the space charge electric field. Here the results of simulations with the high-order model, with a particle-in-cell/Monte Carlo (PIC/MC) model and with the first-order fluid model based on the hydrodynamic drift-diffusion approximation are presented and compared. The comparison with the MC model clearly validates our high-order fluid model, thus supporting its correct theoretical derivation and numerical implementation. The results of the first-order fluid model with local field approximation, as usually used for streamer discharges, show considerable deviations. Furthermore, we study the inaccuracies of simulation results caused by an inconsistent implementation of transport data into our high-order fluid model. We also demonstrate the importance of the energy flux term in the high-order model by comparing with results where this term is neglected. Finally, results with an approximation for the high-order tensor in the energy flux equation is found to agree well with the PIC/MC results for reduced electric fields up to 1000 Townsend, as considered in this work.

show abstract

“…The electric current produced by the particle movement is calculated and the gas temperature is evaluated by means of the energy balance equations. If the gas temperature is equal or higher than 1500 K [7,9,26,27], then the streamer-to-leader transition occurs and a leader channel is considered as incepted. If the temperature does not surpass 1500 K, then the electric field is evaluated, again taking into account the background electric field and the effect of the densities of the charges on the electric field.…”

Section: Model Formulationmentioning

confidence: 99%

Unstable Leader Inception Criteria of Atmospheric Discharges

Arévalo

Cooray

2017

Atmosphere

View full text Add to dashboard Cite

In the literature, there are different criteria to represent the formation of a leader channel in short and long gap discharges. Due to the complexity of the physics of the heating phenomena, and the limitations of the computational resources, a simplified criterion for the minimum amount of electrical charge required to incept an unstable leader has recently been used for modeling long gap discharges and lightning attachments. The criterion is based on the assumption that the total energy of the streamer is used to heat up the gas, among other principles. However, from a physics point of view, energy can also be transferred to other molecular processes, such as rotation, translation, and vibrational excitation. In this paper, the leader inception mechanism was studied based on fundamental particle physics and the energy balance of the gas media. The heating process of the plasma is evaluated with a detailed two-dimensional self-consistent model. The model is able to represent the streamer propagation, dark period, and unsuccessful leaders that may occur prior to the heating of the channel. The main processes that participate in heating the gas are identified within the model, indicating that impact ionization and detachment are the leading sources of energy injection, and that recombination is responsible for loss of electrons and limiting the energy. The model was applied to a well-known experiment for long air gaps under positive switching impulses reported in the literature, and used to validate models for lightning attachments and long gap discharges. Results indicate that the streamer-leader transition depends on the amount of energy transferred to the heating process. The minimum electric charge required for leader inception varies with the gap geometry, the background electric field, the reduction of electric field due to the space charge, the energy expended on the vibrational relation, and the environmental conditions, among others.

show abstract

Formation and development of a leader channel in air

Cited by 70 publications

References 14 publications

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

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

High-order fluid model for streamer discharges: II. Numerical solution and investigation of planar fronts

Unstable Leader Inception Criteria of Atmospheric Discharges

Contact Info

Product

Resources

About