scholarly journals On the observed energy of runaway electron beams in air

2011 ◽  
Vol 29 (4) ◽  
pp. 425-435 ◽  
Author(s):  
G.A. Mesyats ◽  
A.G. Reutova ◽  
K.A. Sharypov ◽  
V.G. Shpak ◽  
S.A. Shunailov ◽  
...  
Keyword(s):  
Electric Field ◽  
Runaway Electron ◽  
Electron Beams ◽  
Beam Current ◽  
Acceleration Of Particles ◽  
Runaway Electrons ◽  
Electrode Gap ◽  
Cathode Voltage ◽  
Wide Range ◽  
Widespread Belief

AbstractExperiments with an air electrode gap have been performed where the current/charge of a picosecond beam of runaway electrons was measured over a wide range (up to four orders of magnitude) downstream of the absorbing foil filters. Measurements and calculations have made it possible to refer the beam current to the rise time of the accelerating voltage pulse to within picoseconds. It has been shown that, in contrast to a widespread belief, the runaway electron energies achieved are no greater than those corresponding to the mode of free acceleration of electrons in a nonstationary, highly nonuniform electric field induced by the cathode voltage. The experimental data agree with predictions of a numerical model that describes free acceleration of particles. It has been confirmed that the magnitude of the critical electric field that is necessary for electrons to go into the mode of continuous acceleration of electrons in atmospheric air corresponds to classical notions.

scholarly journals Modes of runaway electron beams during formation of diffuse discharges in air and nitrogen

2021 ◽  
Vol 9 (3) ◽  
pp. 202-215
Author(s):  
Victor Tarasenko ◽  
Dmitriy Beloplotov ◽  
Dmitriy Sorokin ◽  
Evgeniy Baksht
Keyword(s):  
Delay Time ◽  
Voltage Pulse ◽  
Runaway Electron ◽  
Electron Beams ◽  
Elevated Pressure ◽  
Beam Current ◽  
Small Radius ◽  
Radius Of Curvature ◽  
Runaway Electrons ◽  
Current Pulses

Investigations of the generation of runaway electron beams (REs) and the for-mation of diffuse discharges during breakdown of gaps with a cathode, which has a small radius of curvature, have been carried out. In air and nitrogen at elevated pressure, based on the registration and analysis of the characteristics of radiation from discharge, as well as parameters of the RE beam current and dynamic dis-placement current, it is shown that, depending on the conditions (E/N, gas type and its pressure, design and material of the cathode, amplitude and front of the voltage pulse), diffe- rent modes of generation of runaway electron beams are realized. It was found that the ratio of the velocity of the front of the ionization wave (streamer) and the runaway electrons, as well as the design of the cathode and the delay time before the explosion of cathode microinhomogeneities, significantly affect the generation of runaway electrons. The conditions for the realization of various modes are de-termined; oscillograms of the beam current pulses and photographs of the glow of the gap are presented.

scholarly journals Филаментация и самофокусировка электронных пучков в вакуумных и газовых диодах

2019 ◽  
Vol 45 (7) ◽  
pp. 3
Author(s):  
В.И. Олешко ◽  
В.Ф. Тарасенко ◽  
А.Г. Бураченко ◽  
V.V. Nguyen
Keyword(s):  
Energy Density ◽  
Electron Beams ◽  
Local Density ◽  
Beam Current ◽  
Beam Current Density ◽  
Runaway Electrons ◽  
Beam Current Pulse ◽  
Average Electron Energy ◽  
Interelectrode Gap ◽  
Average Electron

AbstractIn this paper, we experimentally studied pulsed electron beams with a high local density. The conditions in which the energy density cumulation is observed during the interaction of electrons with the anode are shown to develop in vacuum and gas diodes at nanosecond and subnanosecond durations of a beam current pulse and a decrease in the interelectrode gap. The average electron energy in filamentation and self-focusing of an electron beam in a vacuum diode of an accelerator at a current of ~2 kA and a no-load voltage of ~400 kV was established to be 50–100 keV while the energy density was 10^9–10^10 J/cm^3. It is confirmed that the beam current density in a gas diode can exceed 1 kA/cm^2. It is hypothesized that superdense electron beams in vacuum and gas diodes are formed as a result of avalanche multiplication of runaway electrons in the cathode–anode gap plasma.

scholarly journals Effect of plasma elongation on current dynamics during tokamak disruptions

2020 ◽  
Vol 86 (1) ◽  
Author(s):  
T. Fülöp ◽  
P. Helander ◽  
O. Vallhagen ◽  
O. Embreus ◽  
L. Hesslow ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Runaway Electron ◽  
Electron Beams ◽  
Coupled Dynamics ◽  
Avalanche Gain

Plasma terminating disruptions in tokamaks may result in relativistic runaway electron beams with potentially serious consequences for future devices with large plasma currents. In this paper, we investigate the effect of plasma elongation on the coupled dynamics of runaway generation and resistive diffusion of the electric field. We find that elongated plasmas are less likely to produce large runaway currents, partly due to the lower induced electric fields associated with larger plasmas, and partly due to direct shaping effects, which mainly lead to a reduction in the runaway avalanche gain.

Simple "Reactor model" of relativistic runaway electron avalanches dynamics

2021 ◽  
Author(s):  
Egor Stadnichuk ◽  
Daria Zemlianskay ◽  
Victoria Efremova
Keyword(s):  
Electric Field ◽  
Gamma Rays ◽  
Runaway Electron ◽  
Gamma Ray ◽  
Negative Charge ◽  
Feedback Mechanism ◽  
Runaway Electrons ◽  
Reactor Model ◽  
Discharge Model ◽  
Electron Avalanches

<p>A possible mechanism responsible for Terrestrial Gamma-ray Flashes (TGFs) is feedback in the relativistic runaway electron avalanches (RREA) dynamics. In this research, a new way of RREAs self-sustaining is suggested. This self-sustaining feedback can be described in the following way. Let the thundercloud consist of two regions with the electric field so that runaway electrons accelerated in one region move in the direction of another one and vice versa. For instance, such an electric field structure might appear with one positive charge layer situated between two negative charge layers. In this system, the following feedback mechanism occurs. An RREA developing in one region will produce bremsstrahlung gamma-rays. These gamma-rays will propagate into another region and produce RREAs within it. These RREAs will develop backward and radiate gamma-rays, which will penetrate the first region, generating secondary RREAs. In this way, the primary avalanche reproduced itself by the gamma-ray exchange between two sideways oriented areas with the electric field. In this work, it is shown that the electric field values required for TGF generation by this mechanism are lower than values required in Relativistic Feedback Discharge Model.</p>

scholarly journals Post-disruptive runaway electron beams in the COMPASS tokamak

2015 ◽  
Vol 81 (5) ◽  
Author(s):  
Milos Vlainic ◽  
J. Mlynar ◽  
J. Cavalier ◽  
V. Weinzettl ◽  
R. Paprok ◽  
...  
Keyword(s):  
Electric Field ◽  
Runaway Electron ◽  
Gas Injection ◽  
Plasma Current ◽  
Runaway Electron Beam ◽  
Runaway Electrons ◽  
Current Ramp ◽  
Maximum Current ◽  
Current Value ◽  
Almost All

For ITER-relevant runaway electron studies, such as suppression, mitigation, termination and/or control of a runaway beam, it is important to obtain the runaway electrons after the disruption. In this paper we report on the first discharges achieved with a post-disruptive runaway electron beam, termed a ‘runaway plateau’, in the COMPASS tokamak. The runaway plateau is produced by a massive gas injection of argon. Almost all of the disruptions with runaway electron plateaus occurred during the plasma current ramp-up phase. The Ar injection discharges with and without a runaway plateau were compared for various parameters. Parametrisation of the discharges shows that the COMPASS disruptions fulfil the range of parameters important for runaway plateau occurrence. These parameters include electron density, electric field, disruption speed, effective safety factor, and the maximum current quench electric field. In addition to these typical parameters, the plasma current value just before the massive gas injection proved to be surprisingly important.

scholarly journals On the relativistic large-angle electron collision operator for runaway avalanches in plasmas

2018 ◽  
Vol 84 (1) ◽  
Author(s):  
O. Embréus ◽  
A. Stahl ◽  
T. Fülöp
Keyword(s):  
Growth Rate ◽  
Kinetic Equation ◽  
Electric Field ◽  
Runaway Electron ◽  
Large Angle ◽  
Collision Operator ◽  
Electron Collision ◽  
Runaway Electrons ◽  
Avalanche Effect ◽  
Coulomb Collisions

Large-angle Coulomb collisions lead to an avalanching generation of runaway electrons in a plasma. We present the first fully conservative large-angle collision operator, derived from the relativistic Boltzmann operator. The relation to previous models for large-angle collisions is investigated, and their validity assessed. We present a form of the generalized collision operator which is suitable for implementation in a numerical kinetic equation solver, and demonstrate the effect on the runaway-electron growth rate. Finally we consider the reverse avalanche effect, where runaways are slowed down by large-angle collisions, and show that the choice of operator is important if the electric field is close to the avalanche threshold.

scholarly journals Repetitive nanosecond-pulse discharge in a highly nonuniform electric field in atmospheric air: X-ray emission and runaway electron generation

2012 ◽  
Vol 30 (3) ◽  
pp. 369-378 ◽  
Author(s):  
Tao Shao ◽  
Victor F. Tarasenko ◽  
Cheng Zhang ◽  
Evgeni KH. Baksht ◽  
Ping Yan ◽  
...  
Keyword(s):  
Electric Field ◽  
Runaway Electron ◽  
Pulse Repetition Frequency ◽  
Pulse Discharge ◽  
Nanosecond Pulse ◽  
X Rays ◽  
Runaway Electrons ◽  
Experimental Conditions ◽  
Diffuse Discharge ◽  
Nanosecond Pulse Discharge

AbstractRepetitive nanosecond-pulse discharge with a highly inhomogeneous electric field was investigated in air at atmospheric pressure. Three repetitive nanosecond generators were used, and the rise times of the voltage pulses were 15, 1, and 0.2 ns, respectively. Under different experimental conditions, X-rays and runaway electron beams were directly measured using various setups. The variables affecting X-rays and runaway electrons, including gap distance, pulse repetition frequency, anode geometry, and material, were investigated. It was shown that it was significantly easier to record the X-rays than the runaway electrons in the repetitive nanosecond-pulse discharge. It was confirmed that a volume diffuse discharge was attributed to the generation of runaway electrons and the corresponding X-rays.

The mechanism of the origin the NBE (CID) and the initiating event (IE) of lightning due to the volume phase wave of EAS-RREA synchronous ignition of streamer flashes

2020 ◽  
Author(s):  
Alexander Kostinskiy ◽  
Thomas Marshall ◽  
Maribeth Stolzenburg
Keyword(s):  
Electric Field ◽  
Runaway Electron ◽  
Strong Electric Field ◽  
Cosmic Ray ◽  
Relativistic Electrons ◽  
Runaway Electrons ◽  
Air Showers ◽  
Secondary Electrons ◽  
Lightning Initiation ◽  
Positive Streamer

<p>In an article by <em>Kostinskiy et al. (2019)</em> proposed the mechanism of the origin and development of lightning from initiating event to initial breakdown pulses (termed the Mechanism). The Mechanism assumes initiation occurs in a region of a thundercloud of 1 km<sup>3</sup> with electric field E > 0.4 MV/(m∙atm), which contains, because of turbulence, numerous small “E<sub>th</sub>-volumes” of 0.001-0.0001 m<sup>3</sup> with E ≥ 3 MV/(m∙atm). The Mechanism allows for lightning initiation by two observed types of initiating events: a high power VHF event called an NBE (narrow bipolar event or CID), or a weak VHF event. According to the Mechanism, both types of initiating events are caused by a group of relativistic runaway electron avalanche particles passing through many of the E<sub>th</sub>-volumes, thereby causing the nearly simultaneous launching of many positive streamer flashes, <em>Kostinskiy et al. (2019)</em>.</p><p>In this report, based on the Meek’s criterion for the initiation of streamers (<em>Raizer, 1991</em>) at different heights of lightning initiation and taking into account the number of all background electrons, positrons and photons of cosmic rays with energy ε < 10<sup>12</sup> eV (<em>Sato, 2015</em>) crossing E<sub>th</sub>-volumes sizes of E<sub>th</sub>-volumes are specified (3∙10<sup>-4</sup>-3∙10<sup>-5</sup> m<sup>3</sup>). The report also showed that synchronous injection with a high probability of relativistic electrons into such small E<sub>th</sub>-volumes requires of relativistic runaway electrons avalanches to be initiated by extensive air showers with energies ε > 10<sup>15</sup> eV, which would supply (injected) 10<sup>5</sup>-10<sup>7</sup> secondary electrons into a turbulent region of a thundercloud with a strong electric field.</p><p>References</p><p>Kostinskiy, A. Yu., Marshall, T.C., Stolzenburg, M. (2019), The Mechanism of the Origin and Development of Lightning from Initiating Event to Initial Breakdown Pulses arXiv:1906.01033</p><p>Raizer Yu. (1991), Gas Discharge Physics, Springer-Verlag, 449 p.</p><p>Sato T. (2015), Analytical Model for Estimating Terrestrial Cosmic Ray Fluxes Nearly Anytime and Anywhere in the World: Extension of PARMA/EXPACS, PLOS ONE, 10(12): e0144679.</p>

scholarly journals Формирование двух импульсов тока пучка убегающих электронов

2021 ◽  
Vol 91 (4) ◽  
pp. 589
Author(s):  
Д.В. Белоплотов ◽  
В.Ф. Тарасенко ◽  
Д.А. Сорокин ◽  
В.А. Шкляев
Keyword(s):  
Current Pulse ◽  
Runaway Electron ◽  
Electron Beams ◽  
Runaway Electron Beam ◽  
Runaway Electrons ◽  
Optimal Conditions ◽  
Current Pulse Duration ◽  
Current Pulses ◽  
Second Mode ◽  
Single Current Pulse

The conditions for the formation of two current pulses of runaway electron beams during the breakdown of a point-to-plane and tube-to-plane gaps in high-pressure air, nitrogen, and helium are studied. It has been shown experimentally that, depending on a pressure and kind of gas, a rise time of voltage pulse with an amplitude of tens of kilovolts, three modes of generation of runaway electron beams are observed. In the first mode, a single current pulse of runaway electron beam is observed at the maximum voltage across the gap, when a streamer appears in the vicinity of the pointed electrode (cathode). Its duration is ≈100 ps. In the second mode, two current pulses of runaway electron beams are observed at a lower pressure. The first pulse is generated as in the first mode. The second pulse is generated after the gap is bridged by the streamer (the first ionization wave). The electron energy in the second pulse is significantly less than in the first one, but the duration and amplitude of second current pulse under optimal conditions are greater. The third mode is implemented at lower pressures than in the second one. The generation of runaway electrons continues after the first pulse without a pause in the quasi-stationary stage. The total current pulse duration is hundreds of picoseconds.

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