Picosecond runaway electron beams in air

Abstract. Experimental studies connected with runaway electron beams generation convincingly shows the existence of electrons with energies above the maximum voltage applied to the discharge gap. Such electrons are also known as electrons with "anomalous energies". We explain the presence of runaway electrons having so-called "anomalous energies" according to physical kinetics principles, namely, we describe the total ensemble of electrons with the distribution function. Its evolution obeys Boltzmann kinetic equation. The dynamics of self-consistent electromagnetic field is taken into the account by adding complete Maxwell's equation set to the resulting system of equations. The electrodynamic mechanism of the interaction of electrons with a travelling-wave electric field is analyzed in details. It is responsible for the appearance of electrons with high energies in real discharges.

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“…Thus, the total yield is estimated to be 2·10 9 fast electrons per pulse. This value agrees well with typical experiment data [5,16,17].…”

Section: Momentum Of Electrons (P/mc)supporting

confidence: 82%

Why do Electrons with “Anomalous Energies” appear in High-Pressure Gas Discharges?

Kozyrev

Kozhevnikov

Semeniuk

2018

EPJ Web of Conferences

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“…The main feature of such discharges is a generation of runaway electrons and X-ray in the gap, which affect, including, on the breakdown. In [1][2][3][4][5][6][7][8][9] it was shown, that these processes provide the formation of discharges in diffuse form at the excitation of gas medium by high-voltage nanosecond pulses of both polarities. It was proposed to call this type of discharge runaway electrons preionized diffuse discharge (REP DD) [3,9].…”

Section: Introductionmentioning

confidence: 99%

“…Delays of onset of the radiation emission start from the region near the grounded electrode relatively of the one from the region near the potential electrode in nitrogen (1, 2) and mixture of SF6 with 2.5% N2(3,4) versus a pressure at positive (1, 3) and negative (2, 4) polarity of the voltage pulse.…”

mentioning

confidence: 99%

Breakdown features of a high-voltage nanosecond discharge initiated with runaway electrons at subnanosecond voltage pulse rise time

Ломаев¹,

Белоплотов

Тарасенко

et al. 2015

IEEE Trans. Dielect. Electr. Insul.

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In the wide pressure range of the pure nitrogen and sulfur hexafluoride with small admixture of nitrogen (2,5%) the development of the breakdown during the formation of diffuse discharges initiated by runaway electrons and X-Ray was investigated. Nanosecond voltage pulses of both polarities with an amplitude up to ~300 kV and risetime of ~0.5 ns applied across the discharge gap did provide sharply nonuniform electric field distribution. Estimations of average propagation velocity of the ionization wave in the nitrogen and mixture sulfur hexafluoride with nitrogen were performed on the basis of data on dynamics of radiation intensity of the second positive (2 + ) nitrogen system from various regions along of the longitudinal axis of interelectrode gap. Interrelation between the glow dynamics and the local value of the electric field strength has been defined. The results showed that the breakdown is developed in the form of the ionization wave propagating from the potential electrode with the highest concentration of the electric field to the flat-grounded one. In the regions near the grounded electrode practically simultaneous increasing of radiation intensity is registered, that indicates on a possible change of the breakdown mechanism in this part of the discharge gap.Index Terms -Gas discharges, electric breakdown, high-voltage breakdown, ionization wave propagation, spontaneous emission, electric fields.

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“…[1][2][3][4][5][6] The common approach to obtaining such a discharge without pre-ionization sources is the application of a high voltage (HV) pulse with amplitude of 50-300 kV and duration of 150 ps-20 ns. [1][2][3] The important feature of this discharge is the non-homogeneity of the electric field distribution in the cathode-anode (CA) gap, which is ensured by the form of the cathode. A cathode for such a discharge type has a small curvature radius and the main geometries used are tube, ball, and planar sharp-edge.…”

Section: Introductionmentioning

confidence: 99%

Time evolution of nanosecond runaway discharges in air and helium at atmospheric pressure

2012

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Time-and space-resolved fast framing photography was employed to study the discharge initiated by runaway electrons in air and He gas at atmospheric pressure. Whereas in the both cases, the discharge occurs in a nanosecond time scale and its front propagates with a similar velocity along the cathode-anode gap, the later stages of the discharge differ significantly. In air, the main discharge channels develop and remain in the locations with the strongest field enhancement. In He gas, the first, diode "gap bridging" stage, is similar to that obtained in air; however, the development of the discharge that follows is dictated by an explosive electron emission from micro-protrusions on the edge of the cathode. These results allow us to draw conclusions regarding the different conductivity of the plasma produced in He and air discharges. V C 2012 American Institute of Physics. [http://dx.

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Picosecond runaway electron beams in air

Cited by 87 publications

References 10 publications

Why do Electrons with “Anomalous Energies” appear in High-Pressure Gas Discharges?

Why do Electrons with “Anomalous Energies” appear in High-Pressure Gas Discharges?

Breakdown features of a high-voltage nanosecond discharge initiated with runaway electrons at subnanosecond voltage pulse rise time

Time evolution of nanosecond runaway discharges in air and helium at atmospheric pressure

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