Title :
Emission uniformity and emittance of explosive field-emission cathodes
Author :
Shiffler, Donald A. ; Ruebush, M. ; Zagar, D. ; LaCour, M. ; Golby, K. ; Clark, M.Collins ; Haworth, Michael D. ; Umstattd, R.
Author_Institution :
Air Force Res. Lab., Kirtland, NM, USA
fDate :
8/1/2002 12:00:00 AM
Abstract :
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.
Keywords :
carbon fibres; cathodes; electron field emission; microwave tubes; CsI; CsI cathodes; carbon-slat cathodes; cesium iodide salt coating; diode design; electron emission; emission uniformity; emittance; explosive field-emission cathodes; good quality electron beam production; high-power microwave tubes; lightweight cathodes; metal-dielectric cathodes; nonuniform emission; outgassing; plasma flashover cathodes; polymer velvet; tufted carbon-fiber cathodes; Anodes; Cathodes; Diodes; Electromagnetic heating; Electron beams; Electron emission; Electron guns; Explosives; Polymers; Space vector pulse width modulation;
Journal_Title :
Plasma Science, IEEE Transactions on
DOI :
10.1109/TPS.2002.804172