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Thermionic Cathode for Electron Beam Apparatus

IP.com Disclosure Number: IPCOM000074905D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Loeffler, KH: AUTHOR

Abstract

The thermionic cathode of drawing A comprises a lanthanum hexaboride (LaB(6)) emitter 7 and an emission current-intercepting plate 6 of rhenium, containing an aperture 8, disposed adjacent the emitter. As shown in detail in drawing B, the separation between emitter 7 and plate 6 is made as small as possible without physical contact between them, typically 0.1 mm. The beam emitted through the aperture has high brightness and low-energy spread. To prevent corrosion of the emitter, it is housed in a cavity which is exposed to the vacuum of the apparatus only through the aperture 8. The cavity is contained by ceramic parts 2 and 4 and closed by plate 6. The electron beam system is completed by grid 14 and anode 16.

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Thermionic Cathode for Electron Beam Apparatus

The thermionic cathode of drawing A comprises a lanthanum hexaboride (LaB(6)) emitter 7 and an emission current-intercepting plate 6 of rhenium, containing an aperture 8, disposed adjacent the emitter. As shown in detail in drawing B, the separation between emitter 7 and plate 6 is made as small as possible without physical contact between them, typically 0.1 mm. The beam emitted through the aperture has high brightness and low-energy spread. To prevent corrosion of the emitter, it is housed in a cavity which is exposed to the vacuum of the apparatus only through the aperture 8. The cavity is contained by ceramic parts 2 and 4 and closed by plate 6. The electron beam system is completed by grid 14 and anode 16.

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