US4795940A
Expired / Lapsed
US
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Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile
Assignee: United States Department of Energy
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Filing: 1987-10-14
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Granted: 1989-01-03
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Expires: 2007-10-14
Abstract
Abstract A large area directly heated lanthanum hexaboride (LaB 6 ) cathode system (10) is disclosed. The system comprises a LaB 6 cathode element (11) generally circular in shape about a central axis. The cathode element (11) has a head (21) with an upper substantially planar emission surface (23), and a lower downwardly and an intermediate body portion (26) which diminishes in cross-section from the head (21) towards the base (22) of the cathode element (11). A central rod (14) is connected to the base (22) of the cathode element (11) and extends along the central axis. Plural upstanding spring fingers (37) are urged against an outer peripheral contact surface (24) of the head end (21) to provide a mechanical and electrical connection to the cathode element (11).
Inventors
- 👤 Ka-Ngo Leung
- 👤 Keith C. Gordon
- 👤 Dean O. Kippenham
- 👤 Peter Purgalis
- 👤 David Moussa
- 👤 Malcom D. Williams
- 👤 Stephen B. Wilde
- 👤 Mark W. West
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:56
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13; H01J1/15; H01J1/16
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
150 words
A directly heated lanthanum hexaboride cathode system comprising: a lanthanum hexaboride cathode element generally circular in shape about a central axis and having a head and base at opposite ends of a said central axis, said head end having a generally planar emission surface extending radially from said axis and an outer peripheral contact surface, said cathode element having an integral, axially-elongated, tapered, intermediate body extending along said central axis between said head to said base, said intermediate body having a progressively diminishing cross-section from said head towards said base, a first electrical connector in conducting engagement with and peripherally around said contact surface on said head of said cathode element, a second electrical connector in conducting engagement with said base of said cathode element, means for establishing a flow of electrical current from one of said electrical connectors through said cathode element to the other of said electrical connectors.
Claim 2
Dependent Claim
150 words
A directly heated lanthanum hexaboride cathode system comprising: a lanthanum hexaboride cathode element generally circular in shape about a central axis and having a head and base at opposite ends of a said central axis, said head end having a generally planar emission surface extending radially from said axis and an outer peripheral contact surface, said cathode element having an integral, axially-elongated, tapered, intermediate body extending along said central axis between said head to said base, said intermediate body having a progressively diminishing cross-section from said head towards said base, a first electrical connector in conducting engagement with and peripherally around said contact surface on said head of said cathode element, a second electrical connector in conducting engagement with said base of said cathode element, means for establishing a flow of electrical current from one of said electrical connectors through said cathode element to the other of said electrical connectors.
Claim 3
Dependent Claim
75 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 1, wherein said first electrical connector comprises a collar coaxial with said cathode element, said first electrical connector having a plurality of spring fingers extending from said collar generally parallel to said central axis of said cathode element, said spring fingers having tips thereon in electrical contact with said contact surface on said head end of said cathode element around the periphery thereof.
Claim 4
Dependent Claim
32 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 2, wherein said first and second electrical connectors are concentric and coaxial with said central axis of said cathode element.
Claim 5
Dependent Claim
52 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 3, wherein said outer peripheral contact surface on said head of said cathode element is inclined toward said emitting surface thereof, and wherein said tips of said spring fingers have inclined surfaces in engagement with said inclined peripheral contact surface.
Claim 6
Dependent Claim
28 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 4, wherein said outer peripheral contact surface is inclined downward and outwardly from said emission surface.
Claim 7
Dependent Claim
28 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 4, wherein said outer peripheral contact surface is inclined downwardly and inwardly from said emission surface.
Claim 8
Dependent Claim
27 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 1 wherein said head of said cathode element has a plurality of radial cuts therethrough.
Claim 9
Dependent Claim
74 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 7, wherein said first electrical connector comprises a collar coaxial with said cathode element, said first electrical connector having a plurality of spring fingers extending from said collar generally parallel to said central axis of said cathode element, said spring fingers having tips thereon in electrical contact with said contact surface of said head of said cathode element around the periphery thereof.
Claim 10
Dependent Claim
32 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 8, wherein said first and second electrical connectors are concentric and coaxial with said central axis of said cathode element.
Claim 11
Dependent Claim
52 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 9, wherein said outer peripheral contact surface on said head of said cathode element is inclined toward said emission surface thereof, and wherein said tips of said spring fingers have inclined surfaces in engagement with said inclined peripheral contact surface.
Claim 12
Dependent Claim
28 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 10, wherein said outer peripheral contact surface is inclined downward and outwardly from said emission surface.
Claim 13
Dependent Claim
28 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 10, wherein said outer peripheral contact surface is inclined downwardly and inwardly from said emission surface.
Claim 14
Dependent Claim
172 words
A directly heated lanthanum hexaboride cathode system comprising: a lanthanum hexaboride cathode element generally circular in shape about a central axis and having a head and base at opposite ends of said central axis, said head end having a generally planar emission surface extending radially from said axis and an outer peripheral contact surface, said cathode element having an integral, axially-elongated, tapered intermediate body extending along said central axis from said head to said base, said intermediate body having a diminishing cross-section from said head towards said base, said cathode element being shaped to provide substantially uniform heating throughout said cathode element when said cathode element is emitting from its emission surface, a first electrical connector in conducting engagement with and peripherally around said contact surface on said head of said cathode element, a second electrical connector in conducting engagement with said base of said cathode element, means for establishing a flow of electrical current from one of said electrical connectors through said cathode element to the other of said electrical connectors.
Claim 15
Dependent Claim
172 words
A directly heated lanthanum hexaboride cathode system comprising: a lanthanum hexaboride cathode element generally circular in shape about a central axis and having a head and base at opposite ends of said central axis, said head end having a generally planar emission surface extending radially from said axis and an outer peripheral contact surface, said cathode element having an integral, axially-elongated, tapered intermediate body extending along said central axis from said head to said base, said intermediate body having a diminishing cross-section from said head towards said base, said cathode element being shaped to provide substantially uniform heating throughout said cathode element when said cathode element is emitting from its emission surface, a first electrical connector in conducting engagement with and peripherally around said contact surface on said head of said cathode element, a second electrical connector in conducting engagement with said base of said cathode element, means for establishing a flow of electrical current from one of said electrical connectors through said cathode element to the other of said electrical connectors.
Claim 16
Dependent Claim
27 words
A directly heated lanthanum hexaboride cathode system as set forth in claim 13 wherein said head of said cathode element has a plurality of radial cuts therethrough.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-01-03 | 1992-07-04 | 1993-01-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-03 | 1996-07-04 | 1997-01-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-03 | 2000-07-04 | 2001-01-03 | $7700.00 | Window Closed / Lapsed |