New Japan Radio Co., Ltd.

Misao Iseki

Hideyuki Obata

Toru Kimura

Chikao Kimura

Manabu Arai

Hiroyuki Miyamoto

Hideaki Tamai

An electron gun comprising a cathode having an electron emitting surface and whose planar shape is circular, a heater to increase the temperature of the cathode, and an anode to apply a positive electric potential relative to the cathode to extract electrons in a predetermined direction is provided. The cathode comprises a through hole at a central portion thereof along a central axis of the cathode, and either the cathode comprises a no-emitting layer at at least one of an opening edge on the electron emitting surface side of the through hole and an inner surface of the through hole, or the opening edge on the electron emitting surface side of the through hole is a chamfered C surface or a chamfered R surface.

Electron gun and manufacturing method therefor

An electron gun comprising a cathode having an electron emitting surface and whose planar shape is circular; a heater; an anode being arranged to oppose the cathode; and a heat resistant member. The anode applies a positive potential relative to the cathode to extract electrons in a predetermined direction. The cathode has, in a central portion thereof, a through hole along a central axis of the cathode. The heat resistant member has a first portion to close the through hole and a second portion being positioned between the cathode and the heater.

Electron gun

There is provided a cathode which is easily operable, harmless, and stable at high temperature at least 1,400&deg; C. as well as excellent in electron emission characteristics at the same time, and the process for preparing the same. The cathode of the present invention comprises a polycrystalline substance or a polycrystalline porous substance of high-melting point metal material and an emitter material dispersed into said polycrystalline substance or polycrystalline porous substance in an amount of 0.1 to 30% by weight in the cathode, wherein the emitter material comprises at least one selected from the group consisting of hafnium oxide, zirconium oxide, lanthanum oxide, cerium oxide and titanium oxide.

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Fujimino, Japan

Misao Iseki