Features of the secondary runaway electron flow formed in an elongated, atmospheric pressure air gap

Yalandin, M. I.; Sadykova, A. G.; Sharypov, K. A.; Shpak, V. G.; Shunaĭlov, S. A.; Zubareva, O. V.; Зубарев, Н. М.

doi:10.1063/5.0024785

Cited by 10 publications

(5 citation statements)

References 39 publications

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“…This indicates that even after filling the discharge gap with plasma, the reduced electric field strength can locally exceed the critical value required for electron runaway. The secondary generation of REs was also observed in [37] at an order of magnitude higher voltage across a gap filled with air at atmospheric pressure. To date, there is no clear understanding of the mechanism of the secondary generation of REs.…”

Section: Introductionmentioning

confidence: 80%

Generation of runaway electrons in plasma after a breakdown of a gap with a sharply non-uniform electric field strength distribution

Белоплотов¹,

Тарасенко²,

Shklyaev³

et al. 2021

J. Phys. D: Appl. Phys.

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The paper is devoted to the study of the initiation and formation of a negative streamer in a sharply inhomogeneous electric field and the generation of runaway electrons (REs) in air and helium at atmospheric pressure and below, as well as in sulfur hexafluoride at low pressure. Nanosecond voltage pulses of negative polarity with an amplitude of 18 kV were applied across a point-to-plane gap 8.5 mm long. The studies were carried out using broadband measuring sensors and equipment with picosecond time resolution, as well as using a four-channel ICCD camera. Using a special method for measuring the dynamic displacement current caused by the redistribution of the electric field during streamer formation, the waveforms of voltage, discharge current, RE current, and dynamic displacement current were synchronized to each other, as well as to ICCD images. Data on the generation of REs with respect to the dynamics of streamer formation were obtained. It was found that REs are generated not only during the breakdown of the gap, but also after that. It has been found that the formation time of explosive emission centers affects the generation of REs after breakdown. Based on the measurement data of the voltage, discharge current, and dynamic displacement current, the electron concentration in the plasma channel after breakdown and the electric field strength near the surface of the grounded electrode were calculated.

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Section: Introductionmentioning

confidence: 80%

Generation of runaway electrons in plasma after a breakdown of a gap with a sharply non-uniform electric field strength distribution

Белоплотов¹,

Тарасенко²,

Shklyaev³

et al. 2021

J. Phys. D: Appl. Phys.

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“…This note has been motivated by recent extensive studies of the runaway electron beams (REBs) generated in pulsed discharges [1][2][3]. It is widely accepted that REBs may drastically change the properties of pulsed discharges, providing a tool for pulsed power research and development [4,5].…”

mentioning

confidence: 99%

On the consistency between ionization and trapped runaway electron acceleration in a pulsed discharge

Tsventoukh¹

2021

Plasma Sources Sci. Technol.

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Runaway electrons accelerated in the electric field of a pulsed discharge may substantially change the discharge properties. The existence of this acceleration mechanism is indicated by the x-rays emitted from the discharge and by the increasing propagation velocity of the ionization front. An enhanced non-uniform electric field arises naturally due to the field distortion by the high-density plasma. A simple model is proposed to describe consistently the electron impact ionization, the electric field enhancement by the space charge of the discharge plasma, and the acceleration of runaway electrons to about 100 eV in the enhanced field. Optimal conditions for acceleration, ionization and field enhancement have been found at the plasma density level ∼10 15 -10 16 cm −3 and the energy of hundreds of eV. This energy corresponds to trapped runaway mode of acceleration then the electrons produce maximal ionization instead of continuous acceleration to the anode and x-rays production. Obtained estimations count towards revisiting the role of the runaway electrons in pulsed gas discharge.

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“…Runaway electrons (REs) were originally detected in high-pressure gas discharges due to the presence of X-rays [3][4][5]. Since that time, REs have been intensively studied both experimentally in laboratory gas discharges [6][7][8][9][10][11][12][13][14] and theoretically [15][16][17]. Subsequently, REs were also found to exist in lightning discharges [18][19][20].…”

mentioning

confidence: 99%

“…Expression (11) implies that, at small impact parameters, a fast electron interacts with a neutral atom as with a completely "stripped" nucleus, "missing" the orbital electrons.…”

mentioning

confidence: 99%

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Effect of bremsstrahlung on the characteristic growth length of an avalanche of runaway electrons

Oreshkin¹

2021

EPL

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In avalanches of runaway electrons, which are formed in high-altitude atmospheric discharges, the average electron energy is several megaelectronvolts. For such high-energy electrons, the loss of energy by bremsstrahlung is significant when they collide with gas atoms. The aim of this study was to evaluate the effect of bremsstrahlung on the exponential growth length of a runaway electron avalanche. It has been shown that taking account of the bremsstrahlung produced by the electrons of an avalanche gives corrections of no more than a few percent to the avalanche exponential growth length. The corrections are maximum for electric field strengths close to the threshold below which the avalanche electrons fail to become continuously accelerated. The effect of bremsstrahlung decreases with increasing electric field strength. The higher the atomic number of the gas in which an avalanche of runaway electrons propagates, the greater the corrections.

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Features of the secondary runaway electron flow formed in an elongated, atmospheric pressure air gap

Cited by 10 publications

References 39 publications

Generation of runaway electrons in plasma after a breakdown of a gap with a sharply non-uniform electric field strength distribution

Generation of runaway electrons in plasma after a breakdown of a gap with a sharply non-uniform electric field strength distribution

On the consistency between ionization and trapped runaway electron acceleration in a pulsed discharge

Effect of bremsstrahlung on the characteristic growth length of an avalanche of runaway electrons

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