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3. Vacuum technologies
Electron tubes are ultra-high-vacuum devices subjected to high static and RF electromagnetic fields. Vacuum envelopes are made by high-temperature brazing of perfectly sealed metals and ceramics, and the quality of the vacuum during a tube's life reflects the quality of the vacuum at the end of the pump-and-bake stage. However, this vacuum does degrade: for example, the barium contained in the cathode evaporates, then redeposits on the inner walls of the tube, which can and do release atoms when subjected to heating. Residual particles adhering to an electrode can detach. Inadvertent outgassing will cause defocusing, and a particle, electric arcs, the parasitic phenomenon most detrimental to the "good image" of tubes.
3.1 Vacuum quality
Once assembled, each...
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Vacuum technologies
Grid tubes
Bibliography
Events
The proceedings issue of the IVEC (International Vacuum Electronics Conference, an annual event sponsored by the IEEE) is the essential publication for keeping abreast of developments in electronic tube technologies and their applications.
Statistical and economic data
The list of players is as complete as possible, but inevitably contains a few omissions, which the author hopes will not be held against him. Size differences between these players are not indicated, as they can be significant.
The industrial players (table 1...
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