Effect of cathode emissivity on runaway electron beam formation in gas-filled diode with inhomogeneous electric field

Shklyaev, V. A.; Ryzhov, V. V.

doi:10.1134/s1063785011010263

Cited by 18 publications

(11 citation statements)

References 2 publications

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“…In spite of numerous experimental, numerical, and theoretical investigations of RAE generation, there is no complete understanding of the processes that determine the RAE parameters; that is, the processes that accompany RAE formation and such issues as the locations of RAE generation and its termination are not yet well understood. As mentioned above, numerical simulations 13 have shown that RAE formation is terminated when the space charge of secondary electrons becomes sufficient to screen the applied electric field at the cathode surface. Another explanation for RAE termination is suggested by the results of numerical simulations 16 that showed that the RAE parameters are determined by the formation of the virtual cathode (VC) in the CA gap.…”

Section: Introductionmentioning

confidence: 86%

“…In order to describe the FIW propagation, the phenomenon of runaway electrons (RAEs) is considered. [4][5][6][7][8][9][10][11][12][13][14][15] These RAEs efficiently generate secondary electrons and ions, which produce gas pre-ionization during their propagation toward the anode. In addition, secondary electrons participate in ionization processes, forming plasma that could result in the shorting of the cathode-anode (CA) gap.…”

Section: Introductionmentioning

confidence: 99%

“…Comprehensive simulations of RAE generation in a non-uniform electric field for the initial stage (a few tens of picoseconds) of the gas discharge were carried out by Shklyaev et al 13 The developed numerical model considers the shielding of the FE and the self-consistent electric field distribution, i.e., the effect of the space charge of the secondary electrons and ions and emitted electrons was accounted for. The simulations showed that RAE generation occurred in the vicinity of the cathode during a few tens of picoseconds.…”

Section: Introductionmentioning

confidence: 99%

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Effect of explosive emission on runaway electron generation

Levko

Yatom

Vekselman

et al. 2012

Journal of Applied Physics

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The results of numerical simulations of the generation of runaway electrons in a nitrogen-filled coaxial diode with electron emission governed by field emission that transfers to explosive emission with a variable time delay are presented. It is shown that the time when the explosive emission turns on influences significantly the generation of runaway electrons. Namely, an explosive emission turn-on prior to the formation of the virtual cathode leads to an increase in the current amplitude of the runaway electrons and a decrease in its duration. Conversely, an explosive emission turn-on after the formation of the virtual cathode and during the high-voltage pulse rise time does not influence the generation of runaway electrons significantly. When the explosive emission turns on during the fall of the high-voltage pulse and after the virtual cathode formation, one obtains additional runaway electron generation. Finally, a comparison between electron energy distributions obtained with and without explosive emission turn-on showed that the former increases the number of electrons in the high-energy tail and the electrons' largest energy. The comparison of both the simulated electron energy distributions with the experimentally obtained electron spectrum has shown that the best fit is obtained when the explosive emission is considered in the simulation.

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Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of explosive emission on runaway electron generation

Levko

Yatom

Vekselman

et al. 2012

Journal of Applied Physics

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“…Nanosecond and subnanosecond discharge in air and helium at elevated pressures 10 5 Pa is a widely researched subject [1][2][3][4][5][6]. The common approach for formation of such a discharge without the use of external pre-ionization sources is the application of a high voltage (HV) pulse with amplitude and duration in the ranges 50-300 kV and 150 ps -20 ns, respectively [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

“…High-energy nonthermal runaway electrons (RAE) are generated during the discharge and are responsible for the pre-ionization of the discharge gap [1]. There are many experimental investigations and analytical and numerical modelings [5,6] related to studies of the formation of the RAE beam and the generation of optical and x-ray emission [7][8][9][10][11][12] during the discharge. While the emission of RAE from the cathode is a wide consensus [1][2][3]9], there are also experimental evidence [11] and models [2] for emission of RAE from the ionization front advancing from the cathode to the anode.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic study of plasma evolution in runaway nanosecond atmospheric-pressure He discharges

et al. 2013

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Time- and space-resolved visible-emission spectroscopy measurements are applied to study plasma parameters in nanosecond electrical discharges in He gas at pressure of 10(5) Pa, using a 150 kV, 5 ns duration high-voltage pulse. The plasma evolution during the discharge is investigated by applying line-shape analysis of several He I spectral transitions, with the Stark and opacity effects accounted for. The analysis shows that the discharge plasma is not in equilibrium and that significant electric fields of several kV/cm are present in the plasma during the discharge. Regions of plasma with significantly different electron densities are identified and a qualitative model of the plasma formation and evolution is proposed.

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Numerical simulations of runaway electron generation in pressurized gases

Levko

Yatom

Vekselman

et al. 2012

Journal of Applied Physics

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The results of a numerical simulation of the generation of runaway electrons in pressurized nitrogen and helium gases are presented. It was shown that runaway electrons generation occurs in two stages. In the first stage, runaway electrons are composed of the electrons emitted by the cathode and produced in gas ionization in the vicinity of the cathode. This stage is terminated with the formation of the virtual cathode, which becomes the primary source of runaway electrons in the second stage. Also, it was shown that runaway electrons current is limited by both the shielding of the field emission by the space charge of the emitted electrons and the formation of a virtual cathode. In addition, the influence of the initial conditions, such as voltage rise time and amplitude, gas pressure, and the type of gas, on the processes that accompany runaway electrons generation is presented.

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Effect of cathode emissivity on runaway electron beam formation in gas-filled diode with inhomogeneous electric field

Cited by 18 publications

References 2 publications

Effect of explosive emission on runaway electron generation

Effect of explosive emission on runaway electron generation

Spectroscopic study of plasma evolution in runaway nanosecond atmospheric-pressure He discharges

Numerical simulations of runaway electron generation in pressurized gases

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