Numerical Analysis of Electron Runaway in the Presence of Enhanced Field in the Vicinity of a Microtip

Lisenkov, V. V.; Ivanov, S. N.; Mamontov, Yu. I.; Tikhonov, I. N.

doi:10.1134/s1063784218120095

Cited by 16 publications

(8 citation statements)

References 25 publications

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“…It was also analytically shown [79] that, at pressures up to 10 atm in a discharge gap with a uniform electric field distribution, running away of electrons is possible in the region of an enhanced electric field near a microprotrusion on the cathode surface. Later, we approved the method of numerical calculations in the enhanced electric field domain near the microprotrusion using the Monte-Carlo approach [80][81][82][83].…”

Section: Resultsmentioning

confidence: 99%

“…It should be noted that the runaway of an electron begins precisely in the region of the enhanced field of the microprotrusion, which has small spatial dimensions. But, the potential drop in this region is not enough, and the RAE, having passed this region, cannot gain the necessary energy to continue to run away in the weak average field of the discharge gap [79][80][81]. Further energy gain to this required level occurs in a more extended region of the amplified field determined by the geometry of the cathode.…”

Section: Numerical Simulationmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

Section: Numerical Simulationmentioning

confidence: 99%

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 research results were summarized in monographs and reviews [30,31,46,47]. Subsequently, self-consistent numerical calculations were performed for the kinetics of electrons (including runaway ones) taking into account the dynamics of the electromagnetic field in the gas discharge gap [48,49]. According to these calculations, single RAEs in air begin to appear at E/p equal to 260 [49] ÷ 315 [48] V (cm Torr) −1 .…”

Section: Introductionmentioning

confidence: 99%

“…Subsequently, self-consistent numerical calculations were performed for the kinetics of electrons (including runaway ones) taking into account the dynamics of the electromagnetic field in the gas discharge gap [48,49]. According to these calculations, single RAEs in air begin to appear at E/p equal to 260 [49] ÷ 315 [48] V (cm Torr) −1 . Mass runaway of electrons, according to the simulation of their motion by the Monte Carlo method, was observed at field strengths close to the field strengths obtained by the runaway criterion [30,31,46,47] (at E/p > 500 V (cm Torr) −1 ).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the switching characteristics of high-pressure subnanosecond gas dischargers with the purpose of a sharp increasing of the breakdown voltages and the switching speed

Ivanov¹

2022

Plasma Sources Sci. Technol.

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The paper analyzes the data obtained in the subnanosecond time range on the times (t br) and speeds (V br) of switching of hydrogen diode dischargers. These data were obtained in a wide range of hydrogen pressures (p) and the degree of the discharge gap overvoltage (the length of the cathode-anode gap d) in a uniform electric field. It is shown that the reduced strength of the average electric field E br/p in the discharge gap at the moment of the beginning of the breakdown significantly decreases when the gas pressure increases from 5 atm to 50 atm. An increase in pressure from 50 atm to 60 atm leads to a sharp (by 40–135%, depending on the d) increase in the pulse breakdown voltage (U br) and an increase in E br/p. In proportion to the growth of E br/p the switching speed V br of the discharge gas gap increases. The observed effect is explained by the change in the discharge initiation mechanisms. The limitation of U br and V br in the hydrogen pressure range from 5 atm to 50 atm occurs as a result of gas ionization by runaway electrons and the subsequent development of a multi-avalanche discharge in the volume of the discharge gap. With a further increase in pressure, the discharge develops according to the streamer type. To design ultrafast gas dischargers of the subnanosecond range intended for switching high voltages, it is necessary to select an appropriate range of working gas pressures in order to ensure the development of a streamer-type discharge.

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“…Однако для микроострия высотой 10 µm ситуация меняется. В работе [32] показано, что при давлениях выше 10 atm электроны могут уходить в режим убегания непосредственно с вершины микроострия при напряженности электрического поля в межэлектродном промежутке, равной 820 kV/cm. В работе [31] показано, что такая напряженность поля может реализовываться в самом начале формирования катодного слоя, что может дать старт анодонаправленому стримерному каналу, приводящему к контракции объемного разряда.…”

Section: Introductionunclassified

Численное Исследование Возможности Генерации Убегающих Электронов В Формирующемся Катодном Слое Самостоятельного Объемного Разряда Высокого Давления

Лисенков¹

2020

Журнал Технической Физики

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Calculations of the formation of the cathode layer of an self-sustained high-pressure volume discharge with pre-ionization of the gas medium excited by nano-and subnanosecond voltage pulses are carried out. It is shown that at pressures of ~ 1 atm at the final stage of the cathode layer formation, conditions for the generation of escaping electrons arise. We also considered the transition of electrons into runaway mode from the area of electric field amplification in front of the plasma (streamer) channel, which originates from the top of the micro-spike on the cathode. It is shown that at pressures of ~ 10 atm, electrons can transfer into runaway mode immediately after emission from the top of micro-spike in amplified electric field. Thus obtained runaway electrons can create pre-ionization of the gaseous medium and provide the formation of the initial phase of the discharge in volume form in the system without external pre-ionization.

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Numerical Analysis of Electron Runaway in the Presence of Enhanced Field in the Vicinity of a Microtip

Cited by 16 publications

References 25 publications

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

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

Investigation of the switching characteristics of high-pressure subnanosecond gas dischargers with the purpose of a sharp increasing of the breakdown voltages and the switching speed

Численное Исследование Возможности Генерации Убегающих Электронов В Формирующемся Катодном Слое Самостоятельного Объемного Разряда Высокого Давления

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