High-current long-duration uniform electron beam generation in a diode with multicapillary carbon-epoxy cathode

Queller, T.; Gleizer, J. Z.; Krasik, Ya. E.

doi:10.1063/1.4822019

Cited by 17 publications

(11 citation statements)

References 9 publications

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“…1, 12 Many varieties of non-fabric cathodes have also been diagnosed optically, these include ferroelectric materials, [13][14][15] multicapillary dielectric cathodes, 16 carbon nanotube cathodes, 10 and carbon-epoxy cathodes. 17,18 The emission of carbon-epoxy cathodes has been compared in detail to velvet, carbon, and aluminum cathodes 17 indicating longer lifetimes of the carbon-epoxy cathodes at higher current densities. A limited investigation of the temporal response of the emission on the cathode face has been performed by a few authors, 1,3,5,11,15-17 but many of these studies include several variables in which the A-K gaps and electrode materials were varied.…”

Section: Introductionmentioning

confidence: 99%

Temporal response of a surface flashover on a velvet cathode in a relativistic diode

et al. 2015

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Surface flashover of a carbon fiber velvet cathode generates a discharge from which electrons are relativistically accelerated to c ranging from 4.9 to 8.8 through a 17.8 cm diode. This discharge is assumed to be a hydrocarbon mixture. The principal objective of these experiments is to quantify the dynamics over the $100 ns pulse of the plasma discharge generated on the surface of the velvet cathode and across the anode-cathode (A-K) gap. A qualitative comparison of calculated and measured results is presented, which includes time resolved measurements with a photomultiplier tube and charge-coupled device images. In addition, initial visible spectroscopy measurements will also be presented confirming the ion species are dominated by hydrogen. V C 2015 AIP Publishing LLC.

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Section: Introductionmentioning

confidence: 99%

Temporal response of a surface flashover on a velvet cathode in a relativistic diode

et al. 2015

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“…Recently, carbon-epoxy multicapillary (CEM) cathodes have shown to efficiently produce large-area electron beams [1]. In this case, the flashover plasma formation occurs at an electric field of around 15 kV/cm.…”

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confidence: 99%

Evaluating the Performance of a Carbon-Epoxy Capillary Cathode and Carbon Fiber Cathode in a Sealed-Tube Vircator Under UHV Conditions

Rocha

Kelly

Parson

et al. 2015

IEEE Trans. Plasma Sci.

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This paper evaluates the performance of a bimodal carbon fiber cathode and a carbon-epoxy multicapillary cathode operating within a reflex-triode sealed-tube virtual cathode oscillator (vircator). The experimental results reveal that both cathodes exhibit similar emission behavior, although with some significant operational differences. An eight-stage 84-J pulseforming network-based Marx generator serves to drive both cathodes at 250 kV and 3-4 kA with a ∼70-ns pulsewidth. Both cathodes undergo conditioning over 10 000 pulses to determine gas evolution as well as electrical changes over time. Gas evolution of both cathodes is observed using a residual gas analyzer to determine individual gas constituents. A comparison of diode voltage, diode current, RF output, and outgassing data for both cathodes during vircator operation over 10 000 pulses is presented to quantify cathode performance in a sealed-tube vircator. Changes in cathode surface morphology, from virgin to postmortem, are discussed. Data for various anode-cathode gap distances, from 3 to 15 mm, are presented. The evolution of voltage and current inputs to the vircator is discussed.

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“…As indicated by U.S. Government work not protected by U.S. copyright * ξ refs. [17,22,23], line intensities from the visible photon spectrum can be used for both ion Doppler broadening measurements (measure T i ) and gas impurity line measurements (infer T e ) [27].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to cathode imaging, visible spectroscopy measurements have been made with several different cathode materials and diode geometries with < 1.6 and < 0.78 and A-K gaps ranging from 1.3-5 cm [17,22,23]. Refs.…”

Section: Introductionmentioning

confidence: 99%

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Characterizing the photon spectrum in the DARHT Axis-I diode

Coleman¹,

Johnson²,

McCuistian³

et al. 2014

2014 IEEE 41st International Conference on Plasma Sciences (ICOPS) Held With 2014 IEEE International Conference on High-Power P

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An array of photon diagnostics have been deployed on a high power relativistic electron beam diode. Surface flashover of a carbon fiber velvet cathode generates a discharge from which electrons are accelerated through a 17.8 cm diode. This discharge is assumed to be a hydrocarbon mixture. A small portion of the off energy electrons (1-3 MeV) accelerated during the rise and fall of the 80 ns FWHM pulse impact the beam pipe and generate a Bremsstrahlung spectrum of 0.1-3 MeV photons. The principal objective of these experiments is to quantify the dynamics of the hard X-ray and -ray flux generated in the diode region, in addition to quantifying dynamics of the visible photons generated, and the ion species of the surface discharge on the velvet cathode. A qualitative comparison of different diagnostic results are presented, which include time resolved measurements with X-ray PIN diodes, a PMT, and CCD images. In addition initial visible spectroscopy measurements will also be presented.

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High-current long-duration uniform electron beam generation in a diode with multicapillary carbon-epoxy cathode

Cited by 17 publications

References 9 publications

Temporal response of a surface flashover on a velvet cathode in a relativistic diode

Temporal response of a surface flashover on a velvet cathode in a relativistic diode

Evaluating the Performance of a Carbon-Epoxy Capillary Cathode and Carbon Fiber Cathode in a Sealed-Tube Vircator Under UHV Conditions

Characterizing the photon spectrum in the DARHT Axis-I diode

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