Electron energy distribution functions in weakly ionized argon

Vrhovac, S. B.; Radovanov, Svetlana; Petrović, Z.Lj.; Jelenković, B. M.

doi:10.1088/0022-3727/25/2/014

Cited by 16 publications

(9 citation statements)

References 35 publications

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“…The development of run-away electrons has been studied in a range of constant uniform electric fields with particle swarm experiments [76,24,111,70,14,15], in agreement with [112,10], where it was shown that thermal electrons run away when electric field exceeds a critical strength of E≈ 260 kV/cm at standard temperature and pressure, and the runaway rate increases as the field increases. This is quite reasonable if one considers that in such a field an electron gains 200 eV within less than 8µm, which is the range of the mean free ionization length.…”

Section: Physical Predictionsmentioning

confidence: 59%

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Spatially hybrid computations for streamer discharges : II. Fully 3D simulations

Ebert

Hundsdorfer

2012

Journal of Computational Physics

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We recently have presented first physical predictions of a spatially hybrid model that follows the evolution of a negative streamer discharge in full three spatial dimensions; our spatially hybrid model couples a particle model in the high field region ahead of the streamer with a fluid model in the streamer interior where electron densities are high and fields are low. Therefore the model is computationally efficient, while it also follows the dynamics of single electrons including their possible run-away. Here we describe the technical details of our computations, and present the next step in a systematic development of the simulation code. First, new sets of transport coefficients and reaction rates are obtained from particle swarm simulations in air, nitrogen, oxygen and argon. These coefficients are implemented in an extended fluid model to make the fluid approximation as consistent as possible with the particle model, and to avoid discontinuities at the interface between fluid and particle regions. Then two splitting methods are introduced and compared for the location and motion of the fluid-particle-interface in three spatial dimensions. Finally, we present first results of the 3D spatially hybrid model for a negative streamer in air.

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Section: Physical Predictionsmentioning

confidence: 59%

“…In particular, individual electrons can run away [10,11,12]. And when the electric field exceeds a threshold, the majority of electrons will run away and the density or fluid model will break down completely [13,14,15].…”

Section: High Electron Energies and Electron Run-awaymentioning

confidence: 99%

Spatially hybrid computations for streamer discharges : II. Fully 3D simulations

Ebert

Hundsdorfer

2012

Journal of Computational Physics

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“…2. The configuration of the discharge cell is similar to that used in earlier work [50]. It consisted of two parallel circular stainless-steel electrodes 4.2 cm in diameter separated by a distance of 1.4 cm.…”

Section: Methodsmentioning

confidence: 99%

Ion kinetics and symmetric charge-transfer collisions in low-current, diffuse (Townsend) discharges in argon and nitrogen

et al. 1995

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Tcanslational kinetic-energy distributions of mass-selected ions have been measured in diffuse, low-current Townsend-type discharges at high electric field-togas density ratios (EjN) in the range of 1 x 10-18_2 X 10-11 Vm2 (1-20 kTd). The discharges were generaied in Ar and N2 under uniform-field conditions and ion energies were measured using a cylindrical-mirror energy analyzer coupled to a quadrupole mass spectrometer. The mean ion energies determined from measured energy distributions of Ar+ in Ar and N2+ in N2 are compared with the mean energies predicted from solutions of the Boltzmann transport equation based on the assumption that symmetric resonant charge transfer is the predominant ion-neutral interaction. The results for Ar+ and N2+ are consistent with predictions made using a constant (energy independent) cross section for which an effective ion temperature can be defined. However, for both ions, the measured mean energies tend to fall increasingly below the predicted values as E j N increases. The possible causes and significance of the differences between the measured and calculated mean ion energies are examined by considering collisions other than charge-transfer that can affect ion energies as well as uncertainties in the charge-transfer cross sections used in the calculations. Measurements were also made of the relative contributions from N+ and Ar2+ to the ion ftux. Over the E j N range of interest, N+ accounts for less than 15% ofthe ion ftux in nitrogen and Ar2+ accounts for less than 5% of the ion ftux in argon.

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“…For conventional breakdown, E thr is proportional to the number density of molecules. This kind of electric discharge, or breakdown, has been extensively studied and well documented [2][3][4][5]. In air at atmospheric pressure, E thr ∼ 2 MV m −1 .…”

Section: Introductionmentioning

confidence: 99%

Revisiting the momentum-space study of runaway electrons during lightning initiation

Bakhtiari¹

2008

J. Phys. D: Appl. Phys.

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Electron energy distribution functions in weakly ionized argon

Cited by 16 publications

References 35 publications

Spatially hybrid computations for streamer discharges : II. Fully 3D simulations

Spatially hybrid computations for streamer discharges : II. Fully 3D simulations

Ion kinetics and symmetric charge-transfer collisions in low-current, diffuse (Townsend) discharges in argon and nitrogen

Revisiting the momentum-space study of runaway electrons during lightning initiation

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