Surface condition and electron emission from cold cathodes in vacuum and in noble gas glow discharge

Бохан, П. А.; Zakrevsky, D. É.

doi:10.1134/s1063784207010185

Cited by 32 publications

(31 citation statements)

References 26 publications

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“…In simulations we take the emission coefficients reported in Ref. [17]. The photoemission coefficient γ ph =0.3, ion secondary emission coefficient γ i and fast atom secondary emission coefficient γ a were calculated from experimental data in [17] specially for the conditions of high-voltage discharge in helium, close to the considered in present work.…”

Section: -3mentioning

confidence: 98%

Subnanosecond breakdown development in high-voltage pulse discharge: Effect of secondary electron emission

Alexandrov

Schweigert

Zakrevskiy

et al. 2017

AIP Conference Proceedings

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Abstract. A subnanosecond breakdown in high-voltage pulse discharge may be a key tool for superfast commutation of high power devices. The breakdown in high-voltage open discharge at mid-high pressure in helium was studied in experiment and in kinetic simulations. The kinetic model of electron avalanche development was constructed, based on PIC-MCC simulations, including dynamics of electrons, ions and fast helium atoms, produced by ions scattering. Special attention was paid to electron emission processes from cathode, such as: photoemission by Doppler-shifted resonant photons, produced in excitation processes involving fast atoms; electron emission by ions and fast atoms bombardment of cathode; the secondary electron emission (SEE) by hot electrons from bulk plasma. The simulations show that the fast atoms accumulation is the main reason of emission growth at the early stage of breakdown, but at the final stage, when the voltage on plasma gap diminishes, namely the SEE is responsible for subnanosecond rate of current growth. It was shown that the characteristic time of the current growth can be controlled by the SEE yield. The influence of SEE yield for three types of cathode material (titanium, SiC, and CuAlMg-alloy) was tested. By changing the pulse voltage amplitude and gas pressure, the area of existence of subnanosecond breakdown is identified. It is shown that in discharge with SiC and CuAlMg-alloy cathodes (which have enhanced SEE) the current can increase with a subnanosecond characteristic time value as small as τ s = 0.4 ns, for the pulse voltage amplitude of 5÷12 kV. An increase of gas pressure from 15 Torr to 30 Torr essentially decreases the time of of current front growth, whereas the pulse voltage variation weakly affects the results.

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Section: -3mentioning

confidence: 98%

Subnanosecond breakdown development in high-voltage pulse discharge: Effect of secondary electron emission

Alexandrov

Schweigert

Zakrevskiy

et al. 2017

AIP Conference Proceedings

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“…Based on the data obtained in papers, 4,23,24 we have arrived at a conclusion that under certain conditions, first of all, at a large cathode surface area, highly efficient EB generation can be achieved in all inert gases, including heavy inert gases, and their mixtures with molecule gases.…”

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confidence: 94%

“…21 In addition, photoemission is enhanced, first, due to efficient stopping of fast electrons in the drift space and, second, due to enhanced photoemission coefficient ␥ ph , whose increase is due to the implantation of gas atoms into the cathode superficial layer. 23,24 Since the largest values of ␥ ph are achieved for resonance VUV emission of He and Ne atoms, all previous OD studies were performed with those gases.…”

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confidence: 99%

Electron-beam generation in a wide-aperture open gas discharge: A comparative study for different inert gases

Бохан

Zakrevsky

2010

Applied Physics Letters

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In the present study, electron-beam generation by open discharges was examined. The study was performed at gas pressures up to 20 Torr, and covered all inert gases. At voltages up to 8 kV, electron-beam currents up to 1600 A with current density ∼130 A/cm2 and a beam generation efficiency in excess of 93% were obtained. The production of electrons from cold cathode was concluded to be of photoemissive nature, enabling the production of high-intensity electron beams in any noble gas or in a mixture of a noble gas with molecular gases irrespective of cathode material.

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“…Potential profiles (1,2,3) and fast atom energy distributions (4,5,6) for different times, t = 44 ns (1,4), 52 ns (2,5), and 60 ns (3,6) for P = 6 Torr. Inset shows the electron emission yield γ i for ions (1) and γ a for fast atoms (2) from experiments [12] (triangles, in HV discharge) and [25] (circles, in vacuum). maximum to −100 V during 0.5 ns during breakdown.…”

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confidence: 99%

“…The SEE coefficients for photons, ions, and fast atoms were revised in Refs. [12,13] in HV discharge experiments. The value of γ ph = 0.3 was found for the resonant line of He (58.4 nm).…”

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confidence: 99%

Mechanism of formation of subnanosecond current front in high-voltage pulse open discharge

et al. 2014

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The mechanism of subnanosecond current front rise observed previously in the experiment in high-voltage pulse open discharge in helium is studied in kinetic particle-in-cell simulations. The Boltzmann equations for electrons, ions, and fast atoms are solved self-consistently with the Poisson equations for the electrical potential. The partial contributions to the secondary electron emission from the ions, fast atoms, photons, and electrons, bombarding the electrode, are calculated. In simulations, as in the experiment, the discharge glows between two symmetrical cathodes and the anode grid in the midplane at P=6 Torr and the applied voltage of 20 kV. The electron avalanche development is considered for two experimental situations during the last stage of breakdown: (i) with constant voltage and (ii) with decreasing voltage. For case (i), the subnanosecond current front rise is set by photons from the collisional excitation transfer reactions. For the case (ii), the energetic electrons swamp the cathode during voltage drop and provide the secondary electron emission for the subnanosecond current rise, observed in the experiment.

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Surface condition and electron emission from cold cathodes in vacuum and in noble gas glow discharge

Cited by 32 publications

References 26 publications

Subnanosecond breakdown development in high-voltage pulse discharge: Effect of secondary electron emission

Subnanosecond breakdown development in high-voltage pulse discharge: Effect of secondary electron emission

Electron-beam generation in a wide-aperture open gas discharge: A comparative study for different inert gases

Mechanism of formation of subnanosecond current front in high-voltage pulse open discharge

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