US4417173A
Expired / Lapsed
US
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Thermionic electron emitters and methods of making them
Assignee: E M I-Varian Ltd
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Filing: 1981-03-06
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Granted: 1983-11-22
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Expires: 2001-03-06
Abstract
Abstract A thermionic cathode (FIG. 1) comprises a porous matrix of tungsten (4) impregnated with alkaline earth activator. A coating (5) 1 μm thick is formed on the matrix (4). The coating is of σ phase alloy of molybdenum and osmium. Alternative σ phase alloys are disclosed, and various methods of making cathodes are disclosed.
Inventors
- 👤 Richard A. Tuck
- 👤 Heather B. Skinner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:10
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13; H01J1/14
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
65 words
A thermionic electron emitter comprising at least an emissive surface layer formed predominantly of a σ phase alloy selected from the group of σ phase alloys consisting of: ______________________________________
Mo/Os 54-44% Mo 46-56% Os
Ir/Ta 17-38% Ir 83-62% Ta
W/Re 54-35% W 46-65% Re
Nb/Rh 69-58% Nb 31-42% Rh
Nb/Ir 29-25% Nb 71-75% Ir
Rh/Ta 15-26% Rh 85-74% Ta
______________________________________ and an alkaline earth activator.
Claim 2
Dependent Claim
65 words
A thermionic electron emitter comprising at least an emissive surface layer formed predominantly of a σ phase alloy selected from the group of σ phase alloys consisting of: ______________________________________
Mo/Os 54-44% Mo 46-56% Os
Ir/Ta 17-38% Ir 83-62% Ta
W/Re 54-35% W 46-65% Re
Nb/Rh 69-58% Nb 31-42% Rh
Nb/Ir 29-25% Nb 71-75% Ir
Rh/Ta 15-26% Rh 85-74% Ta
______________________________________ and an alkaline earth activator.
Claim 3
Dependent Claim
13 words
An emitter according to claim 1 wherein the alloy is a binary alloy.
Claim 4
Dependent Claim
28 words
An emitter according to claim 2 comprising a substrate of tungsten and/or molybdenum impregnated with said alkaline earth activator, said emissive surface layer being formed on said substrate.
Claim 5
Dependent Claim
19 words
An emitter according to claim 3 wherein said layer has a thickness in the range 2000Å to 2 μm.
Claim 6
Dependent Claim
15 words
An emitter according to claim 3 wherein said layer has a thickness of 1 μm.
Claim 7
Dependent Claim
23 words
An emitter according to claim 2 wherein said emissive surface layer is a porous matrix which is impregnated with said alkaline earth activator.
Claim 8
Dependent Claim
88 words
A thermionic electron emitter comprising at least an emissive surface layer predominantly of an alloy taken from the group of alloys ______________________________________
Mo/Os 55-34% Mo 45-66% Os
Ir/Ta 17-48% Ir 83-52% Ta
W/Re 54-25% W 46-75% Re
Nb/Rh 69-48% Nb 31-52% Rh
Nb/Ir 34-20% Nb 66-80% Ir
Rh/Ta 15-36% Rh 85-64% Ta
______________________________________ and an alkaline earth activator, the atoms in one layer of the atomic structure of said alloy having a spacing which is large compared to the spacing between that layer and its adjacent parallel layer.
Claim 9
Dependent Claim
88 words
A thermionic electron emitter comprising at least an emissive surface layer predominantly of an alloy taken from the group of alloys ______________________________________
Mo/Os 55-34% Mo 45-66% Os
Ir/Ta 17-48% Ir 83-52% Ta
W/Re 54-25% W 46-75% Re
Nb/Rh 69-48% Nb 31-52% Rh
Nb/Ir 34-20% Nb 66-80% Ir
Rh/Ta 15-36% Rh 85-64% Ta
______________________________________ and an alkaline earth activator, the atoms in one layer of the atomic structure of said alloy having a spacing which is large compared to the spacing between that layer and its adjacent parallel layer.
Claim 10
Dependent Claim
13 words
An emitter according to claim 7, wherein the alloy is a binary alloy.
Claim 11
Dependent Claim
19 words
An emitter according to claim 8, wherein the alloy comprises 54 to 44% molybdenium and 46 to 56% osmium.
Claim 12
Dependent Claim
19 words
An emitter according to claim 8, wherein the alloy comprises 54 to 35% tungsten and 46 to 65% rhenium.
Claim 13
Dependent Claim
26 words
An emitter according to claim 8, comprising a substrate of tungsten and/or molybdenum impregnated with the activator, the said alloy being a layer on the substrate.
Claim 14
Dependent Claim
20 words
An emitter according to claim 11 wherein the said layer has a thickness in the range 2000Å to 2 μm.
Claim 15
Dependent Claim
16 words
An emitter according to claim 11 wherein the said layer has a thickness of 1 μm.
Claim 16
Dependent Claim
19 words
An emitter according to claim 8, wherein the alloy forms a porous matrix and is impregnated with the activator.
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) | 1986-11-21 | 1987-05-23 | 1987-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-21 | 1991-05-23 | 1991-11-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-21 | 1995-05-23 | 1995-11-22 | $7700.00 | Window Closed / Lapsed |