US3928783A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermionic cathode heated by electron bombardment
Assignee: Hitachi Ltd
•
Filing: 1973-12-10
•
Granted: 1975-12-23
•
Expires: 1993-12-10
Abstract
Abstract A structure wherein a cathode, which is made of a material, such as lanthanum hexa-borides, prone to react with metals at high temperatures and having a high electron emissivity, is held by a supporter which is made of an electrically insulating material. Concentric metal cylinders are arranged at the outer circumference of the supporter to surround a part of the cathode and a heating coil is arranged in the interstice between the metal cylinders. An electron-emissive metal oxide layer is formed on the inside surface of the inner metal cylinder. Thermions created from the oxide layer strike the cathode, and the cathode is heated by the heat of the electron bombardment.
Inventors
- 👤 Shigeru Hosoki
- 👤 Michio Ohtsuka
- 👤 Satoru Fukuhara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:24
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13; H01J1/20
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
166 words
A thermionic cathode structure comprising: a cathode made of a material having a high electron emissivity; a supporter made of an electrically-insulating and high temperature-resistant material for supporting a part of said cathode; a first cylinder held in contact with said supporter and arranged so as to surround a part of said cathode; a second cylinder arranged concentrically with said first cylinder; a cathode heating coil arranged in an interstitial space between said first and second cylinders; an electron-emissive metal oxide layer formed on an inside surface of said first cylinder; flange means, extending from said first cylinder toward said cathode past said oxide layer, for preventing electrons emitted from said oxide layer from being mixed with electrons emitted from a part of said cathode; a power source connected to said coil for supplying heating power to said coil; and a power source connected between said cathode and said first cylinder in order to cause electrons, emitted from said oxide layer, to strike against said cathode.
Claim 2
Dependent Claim
166 words
A thermionic cathode structure comprising: a cathode made of a material having a high electron emissivity; a supporter made of an electrically-insulating and high temperature-resistant material for supporting a part of said cathode; a first cylinder held in contact with said supporter and arranged so as to surround a part of said cathode; a second cylinder arranged concentrically with said first cylinder; a cathode heating coil arranged in an interstitial space between said first and second cylinders; an electron-emissive metal oxide layer formed on an inside surface of said first cylinder; flange means, extending from said first cylinder toward said cathode past said oxide layer, for preventing electrons emitted from said oxide layer from being mixed with electrons emitted from a part of said cathode; a power source connected to said coil for supplying heating power to said coil; and a power source connected between said cathode and said first cylinder in order to cause electrons, emitted from said oxide layer, to strike against said cathode.
Claim 3
Dependent Claim
14 words
The structure according to claim 1, wherein said cathode is made of a boride.
Claim 4
Dependent Claim
30 words
The structure according to claim 1, wherein said oxide layer is made of at least one member selected from the group consisting of barium oxide, strontium oxide and calcium oxide.
Claim 5
Dependent Claim
128 words
In a thermionic cathode structure having a cathode; an insulating body for insulatingly supporting said cathode; and a heating coil, disposed adjacent said cathode; the improvement comprising: means, disposed between said heating coil and said cathode and surrounding at least part of said cathode, for emitting thermions which impinge upon said cathode to heat said cathode, in response to the heating of said heating coil, wherein said means comprises a first cylinder supported by said insulating body and surrounding said cathode and a layer of electron-emissive material coated on the interior surface of said fist cylinder facing said cathode; and a flange extending from said first cylinder toward said cathode past said layer of electron-emissive material, said electron-emissive layer being confined between said flange and said insulating body.
Claim 6
Dependent Claim
128 words
In a thermionic cathode structure having a cathode; an insulating body for insulatingly supporting said cathode; and a heating coil, disposed adjacent said cathode; the improvement comprising: means, disposed between said heating coil and said cathode and surrounding at least part of said cathode, for emitting thermions which impinge upon said cathode to heat said cathode, in response to the heating of said heating coil, wherein said means comprises a first cylinder supported by said insulating body and surrounding said cathode and a layer of electron-emissive material coated on the interior surface of said fist cylinder facing said cathode; and a flange extending from said first cylinder toward said cathode past said layer of electron-emissive material, said electron-emissive layer being confined between said flange and said insulating body.
Claim 7
Dependent Claim
34 words
The improvement according to claim 4, wherein said means comprises a wall made of an electron-emissive material which, when heated by said coil, emits thermions which impinge upon said cathode to heat said cathode.
Claim 8
Dependent Claim
29 words
The improvement according to claim 4, wherein said means further includes a second cylinder surrounding said coil, with said coil disposed between said second cylinder and said first cylinder.
Claim 9
Dependent Claim
40 words
The improvement according to claim 6, wherein said means further includes a first power source for applying a potential between said first cylinder and said cathode and a second power source for applying a heating current to said heating coil.
Claim 10
Dependent Claim
34 words
The improvement according to claim 4, wherein said layer of electron-emissive material is made of a material selected from the group consisting of a metal oxide, a sintered body, and a porous metal-impregnated layer.
Claim 11
Dependent Claim
30 words
The improvement according to claim 8, wherein said metal oxide is made of at least one material selected from the group consisting of barium oxide, strontium oxiDe and calcium oxide.
Claim 12
Dependent Claim
14 words
The improvement according to claim 4, wherein said cathode is made of a boride.
Claim 13
Dependent Claim
20 words
The improvement according to claim 4, further including a layer of graphite disposed between said insulating body and said cathode.
Claim 14
Dependent Claim
21 words
The improvement according to claim 4, further including an evaporation preventing plate disposed between said insulating body and said electron-emissive wall.
Claim 15
Dependent Claim
39 words
The improvement according to claim 4, wherein said insulating body has an extended portion defining a shade area between said wall and said cathode to prevent the formation of an electrically conductive film between said wall and said cathode.
References Cited (Backward Citations)
US1210678A
Cited
US2159824A
Cited
US2386790A
Cited
US2585582A
Cited
US2561768A
Cited
US3333138A
Cited
US3369145A
Cited
US3474281A
Cited
US3440475A
Cited
US3621324A
Cited
US3727093A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |