US4055780A
Expired / Lapsed
US
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Thermionic emission cathode having a tip of a single crystal of lanthanum hexaboride
Assignee: National Institute for Materials Science
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Filing: 1976-04-12
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Granted: 1977-10-25
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Expires: 1996-04-12
Abstract
Abstract A single crystal of lanthanum hexaboride is used as a tip of a thermionic emission cathode.
Inventors
- 👤 Shichio Kawai
- 👤 Takaho Tanaka
- 👤 Eisuke Bannai
- 👤 Kenji Uchida
- 👤 Ryuichi Shimizu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:59
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13; H01J1/14; H01J1/148
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
17 words
A thermionic emission cathode which comprises a tip which includes only a single crystal of lanthanum hexaboride.
Claim 2
Dependent Claim
17 words
A thermionic emission cathode which comprises a tip which includes only a single crystal of lanthanum hexaboride.
Claim 3
Dependent Claim
30 words
The thermionic emission cathode of claim 1 wherein the tip of a single crystal of lanthanum hexaboride is fixed on a holder which can be heated by passage of current.
Claim 4
Dependent Claim
22 words
The thermionic emission cathode of claim 1 wherein the tip is fixed on a holder made of tantalum, rhenium, molybdenum or silicide.
Claim 5
Dependent Claim
20 words
The thermionic emission cathode of claim 1 wherein the tip is fixed on a holder made of carbon or carbide.
Claim 6
Dependent Claim
28 words
The thermionic emission cathode of claim 1 wherein the tip is cut from a single crystal of lanthanum hexaboride and its sharp end is formed by electrolytic polishing.
Claim 7
Dependent Claim
32 words
The thermionic emission cathode of claim 5 wherein the electrolytic polishing is conducted by inserting the tip in a ring, forming a film of electrolyte thereon and passing current through the electrolyte.
Claim 8
Dependent Claim
28 words
The thermionic emission cathode of claim 5 wherein the single crystal of lanthanum hexaboride is formed by induction heating a sintered rod prepared by compressing powdered lanthanum hexaboride.
Claim 9
Dependent Claim
25 words
The thermionic emission cathode of claim 1, wherein the tip is fixed on a holder which is held on a frame mounted on an insulator.
References Cited (Backward Citations)
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US3462635A
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US3631291A
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US3823337A
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US3833494A
Cited
US3928783A
Cited
US3932314A
Cited
US3944866A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-10-24 | 1981-04-25 | 1981-10-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-24 | 1985-04-25 | 1985-10-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-24 | 1989-04-25 | 1989-10-25 | $7700.00 | Window Closed / Lapsed |