Emission uniformity and emittance of explosive field-emission cathodes

Explosive field-emission cathodes as well as plasma-flashover cathodes are important for high-power microwave tubes. These cathodes have the advantage of being lightweight as well as requiring no heater for electron emission. However, this class typically suffers from large amounts of outgassing, no...

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Bibliographic Details
Published in:IEEE transactions on plasma science 2002-08, Vol.30 (4), p.1592-1596
Main Authors: Shiffler, D.A., Ruebush, M., Zagar, D., LaCour, M., Golby, K., Collins Clark, M.C., Haworth, M.D., Umstattd, R.
Format: Article
Language:English
Subjects:
Anodes
Applied sciences
Carbon fiber reinforced plastics
Cathodes
Diodes
Electromagnetic heating
Electron beams
Electron emission
Electron guns
Electronic tubes, masers
Electronics
Emission
Emissions
Emittance
Exact sciences and technology
Explosions
Explosives
Gases
Heaters
Microwave tubes (eg, klystrons, magnetrons, traveling-wave, backward-wave tubes, etc.)
Polymers
Space vector pulse width modulation
Variability
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Summary:Explosive field-emission cathodes as well as plasma-flashover cathodes are important for high-power microwave tubes. These cathodes have the advantage of being lightweight as well as requiring no heater for electron emission. However, this class typically suffers from large amounts of outgassing, nonuniform emission, and very high emittance. In this paper, we review research into the uniformity and emittance of tufted carbon-fiber cathodes that have been coated with cesium iodide (CsI) salt. The CsI cathode is compared to polymer velvet, metal-dielectric, and carbon-slat cathodes. We find the uniformity and emittance are related for all of these cathodes. In general, the more uniform the electron emission, the lower the emittance of the cathode. This article shows that given proper diode design, the tufted carbon-fiber cathode with CsI has some promise as an electron emitter producing a good quality electron beam.
ISSN:0093-3813
1939-9375
DOI:10.1109/TPS.2002.804172