Electron Back-Bombardment and Mitigation in a Short Gap, Thermionic Cathode RF Gun

Edelen, Jonathan; Biedron, Sandra; Harris, John R.; Lewellen, John W.; Milton, S.V.

doi:10.1109/tns.2014.2308910

Cited by 12 publications

(6 citation statements)

References 7 publications

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“…where f = 650 MHz is the fundamental frequency, E z,c is the penetrating field from the SRF cavity while E z,i and ϕ i are respectively the field amplitudes and phases of the fundamental (i = 1) and harmonic (i = 2) fields produced by a bimodal cavity [10]. The axial coordinate z is referenced w.r.t.…”

Section: Conceptmentioning

confidence: 99%

Initial beam dynamics simulations of a high-average-current field-emission electron source in a superconducting radiofrequency gun

Mohsen

Gonin

Kephart

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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High-power electron beams are sought-after tools in support to a wide array of societal applications. This paper investigates the production of high-power electron beams by combining a high-current field-emission electron source to a superconducting radio-frequency (SRF) cavity. We especially carry out beam-dynamics simulations that demonstrate the viability of the scheme to form ∼ 300 kW average-power electron beam using a 1+1/2-cell SRF gun.

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Section: Conceptmentioning

confidence: 99%

Initial beam dynamics simulations of a high-average-current field-emission electron source in a superconducting radiofrequency gun

Mohsen

Gonin

Kephart

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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“…As this injected current increases, we begin to see a modulation of the virtual cathode [22]. In RF guns we expect to see a similar virtual cathode depression forming especially at very high currents [23]. In order to study how the onset of space-FIG.…”

Section: Intense Space-charge Effectsmentioning

confidence: 99%

Current transmission and nonlinear effects in un-gated thermionic cathode RF guns

Edelen,

Harris

2017

Preprint

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Un-gated thermionic cathode RF guns are well known as a robust source of electrons for many accelerator applications. These sources are in principle scalable to high currents without degradation of the transverse emittance due to control grids but they are also known for being limited by back-bombardment. While back-bombardment presents a significant limitation, there is still a lack of general understanding on how emission over the whole RF period will affect the nature of the beams produced from these guns. In order to improve our understanding of how these guns can be used in general we develop analytical models that predict the transmission efficiency as a function of the design parameters, study how bunch compression and emission enhancement caused by Schottky barrier lowering affect the output current profile in the gun, and study the onset of space-charge limited effects and the resultant virtual cathode formation leading to a modulation in the output current distribution.

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“…Simulations were performed using a variety of operating frequencies, gap lengths, and peak fields. Two longitudinal field profiles were used: (1) a pillbox TM 010 mode which is a good approximation for many applications, and (2) a generated longitudinal field map from a representative single cell design [17]. Simulations were performed using SPIFFE [16], a 2.5-D, particle-in-cell, electromagnetic field solver.…”

Section: Comparison With Simulationsmentioning

confidence: 99%

“…Our recent studies of a short-gap gun design operating at many frequencies and beam currents [17] opened the discussion for a more general simulation-based description of the back-bombardment process, but still did not resolve an analytical model that clarifies the underlying physics. To address back-bombardment on a more fundamental level and provide a simple design tool, we developed an analytic theory for back-bombardment in single-cell, thermioniccathode rf guns and conducted a comparative study with simulation.…”

Section: Introductionmentioning

confidence: 98%

Theory and simulation of backbombardment in single-cell thermionic-cathode electron guns

Edelen

Biedron

Harris

et al. 2015

Phys. Rev. ST Accel. Beams

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This paper presents a comparison between simulation results and a first principles analytical model of electron back-bombardment developed at Colorado State University for single-cell, thermionic-cathode rf guns. While most previous work on back-bombardment has been specific to particular accelerator systems, this work is generalized to a wide variety of guns within the applicable parameter space. The merits and limits of the analytic model will be discussed. This paper identifies the three fundamental parameters that drive the back-bombardment process, and demonstrates relative accuracy in calculating the predicted back-bombardment power of a single-cell thermionic gun.

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Electron Back-Bombardment and Mitigation in a Short Gap, Thermionic Cathode RF Gun

Cited by 12 publications

References 7 publications

Initial beam dynamics simulations of a high-average-current field-emission electron source in a superconducting radiofrequency gun

Initial beam dynamics simulations of a high-average-current field-emission electron source in a superconducting radiofrequency gun

Current transmission and nonlinear effects in un-gated thermionic cathode RF guns

Theory and simulation of backbombardment in single-cell thermionic-cathode electron guns

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