US3603088A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ion thruster cathode
Assignee: National Aeronautics and Space Administration
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Filing: 1970-05-18
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Granted: 1971-09-07
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Expires: 1990-05-18
Abstract
Abstract An encapsulated heater forms a hollow body for a cathode used in an ion thruster. A radiation shield surrounds the heater and supports an end cap.
Inventors
- 👤 Shigeo Nakanishi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 12:06
CPC Classifications
H; H01; H01J; H01J3/00; H01J3/02; H01J3/025; F; F03; F03H; F03H1/00; F03H1/0037; H01J27/00; H01J27/02; H01J27/20; H01J27/205
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
109 words
An enclosed cathode for an ion thruster comprising an electrically conducting tubular member for directing propellant flow into the ion thruster, means for heating an end portion of said tubular member, insulating means covering said heating means and said tubular member, an electrode mounted on the end of said insulating means adjacent said heating means, said electrode and said insulating means forming an enclosure about the extreme outermost end portion of said tubular member adjacent said heating means to maintain a predetermined propellant atom number density adjacent said outermost end portion at low propellant flow rates, and means for initiating an arc between said tubular member and said electrode.
Claim 2
Dependent Claim
109 words
An enclosed cathode for an ion thruster comprising an electrically conducting tubular member for directing propellant flow into the ion thruster, means for heating an end portion of said tubular member, insulating means covering said heating means and said tubular member, an electrode mounted on the end of said insulating means adjacent said heating means, said electrode and said insulating means forming an enclosure about the extreme outermost end portion of said tubular member adjacent said heating means to maintain a predetermined propellant atom number density adjacent said outermost end portion at low propellant flow rates, and means for initiating an arc between said tubular member and said electrode.
Claim 3
Dependent Claim
33 words
An enclosed cathode as claimed in claim 1 including means in the enclosure about the extreme outermost end portion of the tubular member for protecting the heating means from sputtering and coating damages.
Claim 4
Dependent Claim
20 words
An enclosed cathode as claimed in claim 1 including a tantalum tube for directing mercury vapor into the ion thruster.
Claim 5
Dependent Claim
28 words
An enclosed cathode as claimed in claim 1 wherein the means for heating the end portion of the tubular member comprises a wire coil forming a resistance heater.
Claim 6
Dependent Claim
34 words
An enclosed cathode as claimed in claim 4 wherein one end of the wire coil is connected to an electrical lead wire and the opposite end is connected to said electrically conducting tubular member.
Claim 7
Dependent Claim
25 words
An enclosed cathode as claimed in claim 5 including a layer of flame sprayed alumina over said wire coil and said electrically conducting tubular member.
Claim 8
Dependent Claim
33 words
An enclosed cathode as claimed in claim 1 including a tube of alumina surrounding the heating means and the electrically conducting tubular member to provide a radiation shield and support for the electrode.
Claim 9
Dependent Claim
26 words
An enclosed cathode as claimed in claim 7 including adhesive means for securing said alumina tube to said heating means and said electrically conducting tubular member.
Claim 10
Dependent Claim
53 words
An enclosed cathode as claimed in claim 7 including an electrode mounted on the alumina tube adjacent the outermost end portion of said electrically conducting tube, said electrode being rigidly secured to said alumina tube to maintain alignment and a predetermined sPacing between said electrode and the end of said electrically conducting tube.
Claim 11
Dependent Claim
19 words
An enclosed cathode as claimed in claim 9 wherein the electrode comprises a tantalum cap having an aperture therein.
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) | 1974-09-06 | 1975-03-08 | 1975-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-06 | 1979-03-08 | 1979-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-06 | 1983-03-08 | 1983-09-07 | $7700.00 | Window Closed / Lapsed |