Temporal characteristics of runaway electrons in electron-neutral collision-dominated plasma of dense gases. Monte Carlo calculations

Bakhov, K. I.; Babich, L. P.; Kutsyk, I. M.

doi:10.1109/27.893314

Cited by 56 publications

(82 citation statements)

References 21 publications

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“…An initial assembly of 1 eV electrons ( N 0 = 5000) with velocities unidirectional with the electric force was placed in N 2 gas at ground pressure with applied electric fields of 400 kV/cm, 350 kV/cm, and 325 kV/cm, and simulated for times of t = 1 ns, t = 6 ns, and t = 25 ns, respectively. In accordance with Bakhov et al [2000], the following nitrogen electronic states were considered (see Table 1): A 3 Σ u + (v = 5–9 and v = 10+), B 3 Π g , W 3 Δ u , B ′ 3 Σ u − , C 3 Π u , w 1 Δ u , a 1 Π g , and the sum of the remaining singlet states (threshold ɛ = 13 eV). Elastic and ionization collisions were also considered; however, while ionization was considered as an energy loss mechanism, secondary electrons were not added to the particle assembly.…”

Section: Zero‐dimensional Calculations and Model Validationmentioning

confidence: 99%

“…Results for zero‐dimensional modeling of the electron distribution under the influence of a uniform electric field are first presented and compared with existing data. At high electric fields the model is validated by comparisons with studies conducted for N 2 by Tzeng and Kunhardt [1986] and more recently by Bakhov et al [2000]. At low electric fields, model results are compared to available data from swarm experiments in air [ Davies , 1983], numerical solutions of the Boltzmann equation based on the two‐term spherical harmonic expansion of the electron distribution function [ Morgan and Penetrante , 1990], and analytical models proposed by Aleksandrov et al [1995] and Morrow and Lowke [1997].…”

Section: Introductionmentioning

confidence: 96%

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Monte Carlo model for analysis of thermal runaway electrons in streamer tips in transient luminous events and streamer zones of lightning leaders

et al. 2006

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[1] Streamers are thin filamentary plasmas that can initiate spark discharges in relatively short (several centimeters) gaps at near ground pressures and are also known to act as the building blocks of streamer zones of lightning leaders. These streamers at ground pressure, after 1/N scaling with atmospheric air density N, appear to be fully analogous to those documented using telescopic imagers in transient luminous events (TLEs) termed sprites, which occur in the altitude range 40-90 km in the Earth's atmosphere above thunderstorms. It is also believed that the filamentary plasma structures observed in some other types of TLEs, which emanate from the tops of thunderclouds and are termed blue jets and gigantic jets, are directly linked to the processes in streamer zones of lightning leaders. Acceleration, expansion, and branching of streamers are commonly observed for a wide range of applied electric fields. Recent analysis of photoionization effects on the propagation of streamers indicates that very high electric field magnitudes $10 E k , where E k is the conventional breakdown threshold field defined by the equality of the ionization and dissociative attachment coefficients in air, are generated around the tips of streamers at the stage immediately preceding their branching. This paper describes the formulation of a Monte Carlo model, which is capable of describing electron dynamics in air, including the thermal runaway phenomena, under the influence of an external electric field of an arbitrary strength. Monte Carlo modeling results indicate that the $10 E k fields are able to accelerate a fraction of low-energy (several eV) streamer tip electrons to energies of $2-8 keV. With total potential differences on the order of tens of MV available in streamer zones of lightning leaders, it is proposed that during a highly transient negative corona flash stage of the development of negative stepped leader, electrons with energies 2-8 keV ejected from streamer tips near the leader head can be further accelerated to energies of hundreds of keV and possibly to several tens of MeV, depending on the particular magnitude of the leader head potential. It is proposed that these energetic electrons may be responsible (through the ''bremsstrahlung'' process) for the generation of hard X rays observed from ground and satellites preceding lightning discharges or with no association with lightning discharges in cases when the leader process does not culminate in a return stroke. For a lightning leader carrying a current of 100 A, an initial flux of $2-8 keV thermal runaway electrons integrated over the cross-sectional area of the leader is estimated to be $10 18 s À1 , with the number of electrons accelerated to relativistic energies depending on the particular field magnitude and configuration in the leader streamer zone during the negative corona flash stage of the leader development. These thermal runaway electrons could provide an alternate source of relativistic seed electrons which were previously thought to require gala...

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Section: Zero‐dimensional Calculations and Model Validationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Monte Carlo model for analysis of thermal runaway electrons in streamer tips in transient luminous events and streamer zones of lightning leaders

et al. 2006

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“…Because the critical field, E c , is about 10 times larger than the conventional breakdown field (E k = 3 × 10 6 V/m × n) (Moss et al 2006), until relatively recently in 2004, it was not clear whether or not conditions exist in the atmosphere that allow thermal runaway to occur, since such high fields should discharge on very short timescales (Babich 2003;Bakhov et al 2000). When it was established that lightning emits x-rays (Moore et al 2001;, many researchers assumed that this energetic emission was produced by the RREA mechanism acting on cosmic-rays.…”

Section: Thermal Runaway Electronsmentioning

confidence: 99%

High-Energy Atmospheric Physics: Terrestrial Gamma-Ray Flashes and Related Phenomena

2012

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It is now well established that both thunderclouds and lightning routinely emit x-rays and gamma-rays. These emissions appear over wide timescales, ranging from submicrosecond bursts of x-rays associated with lightning leaders, to sub-millisecond bursts of gamma-rays seen in space called terrestrial gamma-ray flashes, to minute long glows from thunderclouds seen on the ground and in or near the cloud by aircraft and balloons. In particular, terrestrial gamma-ray flashes (TGFs), which are thought to be emitted by thunderclouds, are so bright that they sometimes saturate detectors on spacecraft hundreds of kilometers away. These TGFs also generate energetic secondary electrons and positrons that are detected by spacecraft in the inner magnetosphere. It is generally believed that these x-ray and gamma-ray emissions are generated, via bremsstrahlung, by energetic runaway electrons that are accelerated by electric fields in the atmosphere. In this paper, we review this newly emerging field of High-Energy Atmospheric Physics, including the production of runaway electrons, the production and propagation of energetic radiation, and the effects of both on atmospheric electrodynamics.

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“…The number of thermal runaway electrons is estimated based on the equation (4) (e.g., Babich et al, 2015;Bakhov et al, 2000).…”

Section: Estimation Of the Energy And The Number Of Thermal Runaway Ementioning

confidence: 99%

“…where run (E) = 3.5 × 10 −24 exp ( −(2.166 × 10 −7 × E) 2 + 3.77 × 10 −6 × E ) is the runaway electron frequency calculated by a Monte Carlo simulation (Bakhov et al, 2000).…”

Section: Estimation Of the Energy And The Number Of Thermal Runaway Ementioning

confidence: 99%

Modeling of a New Electron Acceleration Mechanism Ahead of Streamers

et al. 2019

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Head‐on collisions between negative and positive streamers have been proposed as a mechanism behind X‐ray emissions by laboratory spark discharges. Recent simulations using plasma fluid and particle in cell models of a single head‐on collision of two streamers of opposite polarities in ground pressure air predicted an insignificant number of thermal runaway electrons >1 keV and hence weak undetectable X‐ray emissions. Because the current available models of a single streamer collision failed to explain the observations, we first use a Monte Carlo model coupled with multiple static dielectric ellipsoids immersed in a subbreakdown ambient electric field as a description of multiple streamer environment and we investigate the ability of multiple streamer‐streamer head‐on collisions to accelerate runaway electrons >1 keV up to energies ∼200–300 keV instead of just one single head‐on collision. The results of simulations show that the streamer head‐on collision mechanism fails to accelerate electrons; instead, they decelerate in the positive streamer channel. In a second part, we use a streamer plasma fluid model to simulate a new streamer‐electron acceleration mechanism based on a collision of a large negative streamer with a small neutral plasma patch in different Laplacian electric fields |E0|= (35, 40, 45) kV/cm, respectively. We observe the formation of a secondary short propagating negative streamer with a strong peak electric field >250 up to 378 kV/cm over a time duration of ∼0.16 ns at the moment of the collision. The mechanism produces up to 106 runaway electrons with an upper energy limit of 24 keV.

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Temporal characteristics of runaway electrons in electron-neutral collision-dominated plasma of dense gases. Monte Carlo calculations

Cited by 56 publications

References 21 publications

Monte Carlo model for analysis of thermal runaway electrons in streamer tips in transient luminous events and streamer zones of lightning leaders

Monte Carlo model for analysis of thermal runaway electrons in streamer tips in transient luminous events and streamer zones of lightning leaders

High-Energy Atmospheric Physics: Terrestrial Gamma-Ray Flashes and Related Phenomena

Modeling of a New Electron Acceleration Mechanism Ahead of Streamers

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