US3883764A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cathode structure for high current, low pressure discharge devices
Assignee: General Electric Co
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Filing: 1974-03-04
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Granted: 1975-05-13
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Expires: 1994-03-04
Abstract
Abstract An improved cathode structure for high current, low pressure electric discharge devices is described as comprising an oxide emissive mix coated filament mounted axially within a hollow open-ended refractory metal cylinder. Unusually high discharge currents on the order of 2 to 50 amperes are provided with this electrode structure for long periods of time.
Inventors
- 👤 Peter D Johnson
- 👤 John M Anderson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:48
CPC Classifications
H; H01; H01J; H01J61/00; H01J61/02; H01J61/04; H01J61/06; H01J61/067; H01J61/0672
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
81 words
In a high current, low pressure discharge device including an evacuable envelope having a partial pressure of an ionizable material therein and electrode structures for establishing an electric discharge therein, said electrode structures including an improved cathode structure comprising: a refractory metal cylinder; an emissive mix coated filament coaxially supported within said cylinder; means for electrically connecting the ends of said filament together; and means for applying a voltage to said electrode structures for establishing an electric discharge within said envelope.
Claim 2
Dependent Claim
81 words
In a high current, low pressure discharge device including an evacuable envelope having a partial pressure of an ionizable material therein and electrode structures for establishing an electric discharge therein, said electrode structures including an improved cathode structure comprising: a refractory metal cylinder; an emissive mix coated filament coaxially supported within said cylinder; means for electrically connecting the ends of said filament together; and means for applying a voltage to said electrode structures for establishing an electric discharge within said envelope.
Claim 3
Dependent Claim
61 words
The device of claim 1 wherein said evacuable envelope includes a partial pressure of a material selected from the group consisting of krypton, xenon and argon within the range of approximately 0.5 to 5 Torr and a quantity of mercury sufficient under lamp operating conditions to maintain a partial pressure of mercury of approximately 2 X 10 3 to 0.1 Torr.
Claim 4
Dependent Claim
25 words
The device of claim 2 wherein the operating conditions include maintaining the coldest portion of the envelope at a temperature of approximately 25* to 80*C.
Claim 5
Dependent Claim
18 words
The device of claim 1 wherein the inner wall of said cylinder includes an emissive mix coating thereon.
Claim 6
Dependent Claim
32 words
The device of claim 2 wherein said discharge comprises ionized mercury which when excited by current densities of approximately 2 to 50 amperes/cm2 emits ultraviolet radiation at wavelengths shorter than 2000 A.U.
Claim 7
Dependent Claim
13 words
The device of claim 5 wherein said radiation is principally at 1942 A.U.
Claim 8
Dependent Claim
21 words
The device of claim 1 wherein said refractory metal is selected from the group consisting of molybdenum, tantalum, tungsten, and rhenium.
Claim 9
Dependent Claim
14 words
The device of claim 1 wherein said evacuable envelope comprises an ultraviolet transmissive material.
Claim 10
Dependent Claim
28 words
The device of claim 1 wherein said cylinder substantially prevents evaporated or sputtered emissive mix emitted by said filament from depositing on the walls of said evacuable envelope.
Claim 11
Dependent Claim
35 words
The device of claim 5 wherein said current density is greater than 3 amp/cm2 and said electric discharge occupies said metal cylinder in a completely diffuse mode providing high current output with minimum cathode damage.
Claim 12
Dependent Claim
18 words
The device of claim 6 wherein the voltage drop of said cathode structure is less than 4 volts.
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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |