Patent US3782181A successfully refreshed from Google Patents.
US3782181A
Expired / Lapsed
US
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Dual measurement ablation sensor
Assignee: National Aeronautics and Space Administration
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Filing: 1971-08-11
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Granted: 1974-01-01
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Expires: 1991-08-11
Abstract
Abstract A dual measurement ablation sensor for measuring both charinterface and surface recession at a point in an ablating material to allow an accurate calculation of the thickness of the char layer. Char-interface recession is indicated by a drop in the resistance to a current passed through the ablation material. Surface recession is indicated by the closing of an electrical circuit when melting causes the release of a spring switch.
Inventors
- 👤 C Gurtler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 08:08
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/041; G01B; G01B7/00; G01B7/02; G01B7/06
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
123 words
An ablation sensor comprising: an ablation material; a first electrode means imbedded full depth in said ablation material for conducting a current through said ablation material; a second electrode means implanted at a predetermined depth in said ablation material for conducting a current passed through said first electrode means and said ablation material; a first electrical circuit mEans for indicating a change in resistance when the inner surface of a char layer formed on said ablation material reaches said second electrode means; a second electrical circuit means for indicating a change in resistance when the outer surface of said char layer reaches the second electrode means whereby the time interval between the change in resistances is an indication of the char layer thickness.
Claim 2
Dependent Claim
123 words
An ablation sensor comprising: an ablation material; a first electrode means imbedded full depth in said ablation material for conducting a current through said ablation material; a second electrode means implanted at a predetermined depth in said ablation material for conducting a current passed through said first electrode means and said ablation material; a first electrical circuit mEans for indicating a change in resistance when the inner surface of a char layer formed on said ablation material reaches said second electrode means; a second electrical circuit means for indicating a change in resistance when the outer surface of said char layer reaches the second electrode means whereby the time interval between the change in resistances is an indication of the char layer thickness.
Claim 3
Dependent Claim
82 words
The sensor of claim 1 wherein said ablation material is electrically nonconducting, said electrode means are tubes constructed of a material which melts at or near the expected ablation surface temperature, said tubes are coated with a material which provides a low electrical resistance contact with the char layer, whereby electrical resistance between said electrode means decreases abruptly when the char layer reaches the depth of said second electrode means and this decreased resistance is indicated by said first electrical circuit means.
Claim 4
Dependent Claim
102 words
The sensor of claim 1 wherein said ablation material is an electrical conductor, said electrode means are tubes constructed of a material which melts at or near the expected ablation surface temperature, and said tubes are coated with an electrical insulating material which dissolves when exposed to the elevated temperatures of said char layer, whereby the insulation surrounding said second electrode means dissolves permitting contact between said second electrode means and said char layer whereupon a decrease in electrical resistance noted by said first electrical circuit means indicates that said char layer has progressed to the depth of said second electrode means.
Claim 5
Dependent Claim
15 words
The sensor of claim 2 wherein the material used for coating said tubes is gold.
Claim 6
Dependent Claim
14 words
The sensor of claim 3 wherein the material for coating said tubes is polytetrafluoroethylene.
Claim 7
Dependent Claim
90 words
The sensor of claim 1 wherein said second electrode means comprises a plurality of electrodes implanted at varying predetermined depths throughout said ablation material for conducting a current passed through said first electrode means and said ablation material, and wherein said first electrical current means is a plurality of electrical circuits to measure a plurality of electrical resistances between said first electrode means and each of said plurality of electrodes whereby a time history of the progress of said char layer through said ablation material during ablation may be obtained.
Claim 8
Dependent Claim
95 words
The sensor of claim 6 wherein said ablation material is electrically nonconducting, said first electrode means and said plurality of electrodes are tubes constructed of a material which melts at or near the expected ablation surface temperature, and said tubes are coated with a material which provides a low electrical resistance contact with the char layer whereby electrical resistance between said first electrode means and said electrodes decreases abruptly as the char layer reaches the depth of each of said plurality of electrodes and this decreased resistance is indicated by said first electrical circuit means.
Claim 9
Dependent Claim
15 words
The sensor of claim 7 wherein the material used for coating said tubes is gold.
Claim 10
Dependent Claim
107 words
The sensor of claim 6 wherein said ablation material is an electrical conductor said first electrode means and said plurality of electrodes are tubes constructed of a material which melts at or near the expected ablation surface temperature, and said tubes are coated with an electrical insulating material which dissolves when exposed to the elevated temperatures of said char layer whereby the insulation surrounding said electrodes dissolves permitting contact between said electrodes and said char layer and a decrease in electrical resistance noted by said electrical circuit means indicates the progress of said char layer to the depth of each of said plurality of electrodes in turn.
Claim 11
Dependent Claim
14 words
The sensor of claim 9 wherein the material for coating said tubes is polytetrafluoroethylene.
Claim 12
Dependent Claim
67 words
The sensor of claim 6 wherein said plurality of electrodes have a plurality of second electrical ciRcuit means for indicating a change in resistance, said plurality of first and second electrical circuit means provide a time history of the movement of the ablating surface of said ablation material whereby the rate of ablation, the rate of charring and the thickness of the char layer may be calculated.
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) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |