US4551649A
Expired / Lapsed
US
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Rounded-end protuberances for field-emission cathodes
Assignee: Boeing North American Inc
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Filing: 1983-12-08
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Granted: 1985-11-05
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Expires: 2003-12-08
Abstract
Abstract Protuberances, or posts 14, for field-emission cathodes, the posts 14 having rounded emitting tips 12. Control of the radius R, of the emitting tips 12 controls the factor 10 8 /βV upon which the current density of each post 14 depends. Proper radius selection for a given value of applied voltage, V, keeps the operating point of the cathode 10 on a region of the current density vs 10 8 /βV curve well below the region of impedance collapse, CG.
Inventors
- 👤 Roy E. Olson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:31
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/30; H01J1/304
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
90 words
A field-emission device cathode comprising: a cathode base member; and a plurality of spaced protuberances extending from said base member, the tip of each said protuberance being a spherical zone, each spherical zone having a radius R which is approximately equal to 1/β where β is the field enhancement factor, said R being a value so that the operating point of the tip lies on a point on the curve of the log of emitter current density vs (10 8 /βV) well below the point at which impedance collapse occurs.
Claim 2
Dependent Claim
90 words
A field-emission device cathode comprising: a cathode base member; and a plurality of spaced protuberances extending from said base member, the tip of each said protuberance being a spherical zone, each spherical zone having a radius R which is approximately equal to 1/β where β is the field enhancement factor, said R being a value so that the operating point of the tip lies on a point on the curve of the log of emitter current density vs (10 8 /βV) well below the point at which impedance collapse occurs.
Claim 3
Dependent Claim
15 words
A cathode as in claim 1, wherein: each said spherical zone is hemispherical in contour.
Claim 4
Dependent Claim
14 words
A cathode as in claim 1, wherein: the protuberance is substantially a cylindrical post.
Claim 5
Dependent Claim
14 words
A cathode as in claim 1, wherein: the protuberance is substantially a conical post.
Claim 6
Dependent Claim
35 words
A cathode as in claim 1, wherein: the separation between the axes of any two adjacent protuberances is (d) and the value of the ratio (d/R) lies in the range of about 8 to 32.
Claim 7
Dependent Claim
42 words
A cathode as in claim 1, wherein: the (10 8 /βV) value is above about 2×10 8 , 3.6×10 8 , 4.5×10 8 and 5.5×10 8 cm/volt for emitting materials having work functions, φ, of 4.5, 3.19, 2.80 and 2.44 eV, respectively.
Claim 8
Dependent Claim
22 words
A cathode as in claim 1, wherein: the (10 8 /βV) value is above about 2×10 8 cm/volt for all emitting materials.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-11-04 | 1989-05-06 | 1989-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-04 | 1993-05-06 | 1993-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-04 | 1997-05-06 | 1997-11-05 | $7700.00 | Window Closed / Lapsed |