Over-injection and self-oscillations in an electron vacuum diode

Leopold, J. G.; Siman-Tov, M.; Goldman, A.; Krasik, Ya. E.

doi:10.1063/1.4993612

Cited by 10 publications

(7 citation statements)

References 14 publications

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“…The behavior described so far is similar to that presented in Ref. 10, apart from the period of the oscillations and the values of the currents and voltages because of the different conditions resulting from the cathode shape, dimensions, the voltage rise time, and electron collisions with the grids.…”

Section: Pic Simulations Of the Electron Dynamics In The Experimesupporting

confidence: 81%

“…We have experimentally demonstrated that our scheme proposed in Ref. 10 to produce a modulated electron beam by over-injecting a diode is feasible, but we have not been able to reproduce the periodic behavior with the expected frequency because our dispenser cathode did not emit uniformly over its entire surface. By PIC simulations, we have shown the complications introduced by having a finite area cathode, scattering from finite transmission grids, and the voltage applied on the cathode rising during a finite time.…”

Section: Discussionmentioning

confidence: 94%

“…These differences introduce a complex dynamical behavior which is interesting on its own and affects the scheme suggested in Ref. 10. In this paper, we present the analysis of the experiment, and our predicted results for this experimental scheme.…”

Section: Introductionmentioning

confidence: 84%

“…In Ref. 10, we assumed that a finite circular cathode C 1 , part of an infinite conducting area, biased negatively relative to a grounded anode A 1 , emits electrons with a uniform current density distribution across the beam's cross-sectional area. This electron beam, with current significantly below the SCL of the C 1 -A 1 gap, is accelerated in this gap by an applied potential difference DV 1 and decelerated in the A 1 -C 2 gap by a potential difference DV 2 formed by the negatively biased cathode C 2 .…”

Section: The Experimental Setupmentioning

confidence: 99%

“…In a recent paper, 10 we have suggested a different way to overinject a diode persistently and produce a beam consisting of periodic electron bunches. This idea was demonstrated by PIC simulations which triggered an experimental effort to reproduce these predictions.…”

Section: Introductionmentioning

confidence: 99%

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Self-oscillations in an over-injected electron diode – Experiment and analysis

2019

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An experimental setup to demonstrate a recent scheme [Leopold et al., Phys. Plasmas 24, 073116 (2017)] to persistently over-inject a vacuum electron diode so that it self-oscillates in the GHz-frequency range and releases a periodic train of electron bunches is described. We present simulations in which we account for the finite rise time of the voltage accelerating electrons from a finite radius cylindrical thermionic cathode and finite grid electrode transparency, which make the experiment different from the original theoretical scheme. It was found that these experimental conditions do affect the expected results but a self-oscillating behavior is still possible. Our experimental results so far indicate the presence of the self-oscillatory behavior, but because the cathode used emits from a few hot-spots rather than uniformly, the beam current modulations are different from those obtained in the simulations.

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Section: Pic Simulations Of the Electron Dynamics In The Experimesupporting

confidence: 81%

Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 84%

Section: The Experimental Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Self-oscillations in an over-injected electron diode – Experiment and analysis

2019

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Progress in vircators towards high efficiency: Present state and future prospects

Mumtaz,

Uhm,

Choi

2024

Physics Reports

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Generation of high-current pulses by a magnetized squeezed electron beam

et al. 2019

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The space charge limited current of an electron beam generated in a magnetically insulated foil-less diode by a cylindrical or hollow cathode and injected into a cylindrical drift tube depends on the energy of the electrons and on the ratio of the beam radius to the tube radius. When this beam drifts into a tube of larger radius, it exceeds the corresponding space charge limit. This leads to the formation of a virtual cathode and to the reduction of the energy of the beam. The latter is known as a squeezed beam state. When the cylindrical tube consists of more segments of different radii and lengths, the dynamics of the beam can be manipulated. We propose a simple configuration resulting in the production of a high-frequency periodic train of high-current electron beam pulses.

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Over-injection and self-oscillations in an electron vacuum diode

Cited by 10 publications

References 14 publications

Self-oscillations in an over-injected electron diode – Experiment and analysis

Self-oscillations in an over-injected electron diode – Experiment and analysis

Progress in vircators towards high efficiency: Present state and future prospects

Generation of high-current pulses by a magnetized squeezed electron beam

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