Runaway Electrons Emitted by Electron Avalanches in Nanosecond Discharges in Air

Mesyats, G. A.; Зубарев, Н. М.; Васенина, И.В.

doi:10.3103/s1068335620070052

Cited by 7 publications

(3 citation statements)

References 12 publications

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“…Therefore, the first electron that appears, initiating the discharge, begins the ionization of the gas with the formation of new electrons. In average fields, runaway electrons appear due to field amplification at the heads of electron avalanches [7]. Note that in the electric discharge in air we have considered, there are two types of runaway electrons.…”

Section: Discussionmentioning

confidence: 99%

“…However, when the discharge did occur upon initiation by single electrons [4,5], it turned out that the discharge formation time was orders of magnitude longer than that which should be in the case of a streamer breakdown [1,2]. We proposed to compare these three discharges with each other by the ratio of the gap length d to the length of the critical avalanche xk, which means an avalanche with an ion space charge field comparable to the external field [7,8]. If xk >> d, then the discharge will be Townsend; if xk ≥ d -the streamer one, and if xk << d, then the NDC discharge will occur.…”

Section: Nanosecond Diffuse-channel Dischargementioning

confidence: 99%

“…It can be seen from formula (7) for tungsten (φ = 4.5 eV) that when the field at the CMP tip is E = 1.5•10 8 V/cm, the FE current density is j = 10 10 A/cm 2 , and the time td = 2.4 10 -11 s.…”

Section: Explosive Electron Emission In Ndc-dischargementioning

confidence: 99%

See 2 more Smart Citations

Nanosecond discharge in atmospheric air in submillimeter gaps in a uniform electric field

Mesyats¹,

Васенина²

2022

8th International Congress on Energy Fluxes and Radiation Effects

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A nanosecond electric discharge in air in submillimeter gaps at the overvoltages up to 15-fold is under investigation. The initial electric field in such discharges is up to 106 V/cm. This field is sufficient for the electrons that initiate the discharge, as well as those obtained during the discharge, to go into the runaway mode. These electrons are called runaway electrons (RE). REs create plasma in the period 10-9 s. When the plasma density is reached of 104 cm-3, a glow discharge (GD) is initiated. The process of transition of the discharge to the GD mode lasts 10-11 s. During this time, about 5·1010 pieces of runaway electrons are formed, which, falling on the anode, lead to the formation of an X-ray beam. This beam is due to a rapid increase in the plasma density during the discharge. In the GD stage, the electric field between the cathode and the anode is divided into two parts: the cathode layer (CL) and the plasma column. The electric field in the CL exceeds 106 V/cm. At such a field, field emission (FE) from microprotrusions on the cathode surface takes place on the cathode. It leads to the explosive emission of electrons and the formation of a cathode spot and the transition of the discharge to the arc mode.

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Section: Discussionmentioning

confidence: 99%

Section: Nanosecond Diffuse-channel Dischargementioning

confidence: 99%

See 1 more Smart Citation

Nanosecond discharge in atmospheric air in submillimeter gaps in a uniform electric field

Mesyats¹,

Васенина²

2022

8th International Congress on Energy Fluxes and Radiation Effects

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Streak investigations of the dynamics of subnanosecond discharge developing in nitrogen at a pressure of 6 atm with the participation of runaway electrons

Ivanov¹,

Lisenkov²,

Mamontov³

2021

Plasma Sources Sci. Technol.

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The results of an investigation of a self-sustained subnanosecond discharge in nitrogen at a pressure of 6 atm are presented. A high voltage pulse with a front of approximately 770 ps at the level of 0.1-0.9 in amplitude was applied to the studied gas gap. In this case, the voltage rise rate in the discharge gap at the prebreakdown stage was 1.45 × 10 14 V s −1 . A breakdown occurs at the end of the front of the voltage pulse. The cathode geometry used provided a 3.3-fold enhancement of an electric field in the near-cathode spatial domain. It is shown that at the initial stage the discharge is of a volumetric form which turns into a spark form further. The discharge contraction starts from a cathode and an anode almost simultaneously. The propagation rate of ionization waves accompanying the spark channel development is 4.2 × 10 8 cm s −1 . The initial volumetric form of the discharge is provided by preliminary ionization of a gas medium by runaway electrons. The generation of runaway electrons takes place in the enhanced electric field area formed near a microprotrusion on the cathode surface, while the macro-geometry of the discharge gap does not ensure enhancing of the electric field up to the value which is sufficient to the implementation of the runaway electron generation criterion. Numerical simulation of a formation process of the electron avalanche initiated by an electron field-emitted from the top of the cathode microprotrusion was carried out taking into account the motion of each electron in the avalanche. To simulate electron motion through the discharge gap, the 3D Monte-Carlo technique was employed. The following runaway electron parameters were calculated: characteristic runaway electron trajectories; runaway electron energy gained during the motion through the discharge gap; and times required for runaway electrons to reach the anode.

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Study of Hard Ionizing Radiation Generation Regions in an Atmospheric Discharge

et al. 2022

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Runaway Electrons Emitted by Electron Avalanches in Nanosecond Discharges in Air

Cited by 7 publications

References 12 publications

Nanosecond discharge in atmospheric air in submillimeter gaps in a uniform electric field

Nanosecond discharge in atmospheric air in submillimeter gaps in a uniform electric field

Streak investigations of the dynamics of subnanosecond discharge developing in nitrogen at a pressure of 6 atm with the participation of runaway electrons

Study of Hard Ionizing Radiation Generation Regions in an Atmospheric Discharge

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