US3884539A
Expired / Lapsed
US
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Method of making a multialkali electron emissive layer
Assignee: RCA Corp
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Filing: 1974-03-04
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Granted: 1975-05-20
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Expires: 1994-03-04
Abstract
Abstract An S-20 response multialkali photocathode is produced by exposing a layer of antimony to activating vapors of potassium, sodium, and cesium. In one method the antimony layer is exposed to cesium at a temperature of about 240*C. prior to exposure to potassium or sodium, and the exposing to cesium is terminated before the photosensitivity reaches a peak. In another method, the antimony layer is exposed to cesium at a temperature of about 240*C. subsequent to exposure to potassium and sodium, and the exposing to cesium is terminated when the photosensitivity reaches a peak.
Inventors
- 👤 Alfred Hermann Sommer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:35
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/02; H01J9/12; H01J9/125; H01J2201/00; H01J2201/32
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
71 words
A METHOD OF ACTIVATING A MULTIALKALI ELECTRON-EMISSIVE CATHODE LAYER, OF THE TYPE WHEREIN A LAYER OF ANTIMONY IS EXPOSED AT ELEVATED TEMPERATURE, WITHIN AN EVACUATED BODY, TO VAPORS OF A PLURALITY OF ALKALI METALS INCLUDING CESIUM, TO FORM AN ELECTRON-EMISSIVE COMPOUND, WHEREIN THE IMPROVEMENT COMPRISES: EXPOSING THE CATHODE LAYER TO CESIUM VAPOR TO ACHIEVE A PHOTOSENSITIVITY EXCEEDING APPROXIMATELY 0.1 MICROAMPERE PER LUMEN WHILE MAINTAINING THE CATHODE AT A TEMPERATURE ABOVE 200*C.
Claim 2
Independent Claim
71 words
A METHOD OF ACTIVATING A MULTIALKALI ELECTRON-EMISSIVE CATHODE LAYER, OF THE TYPE WHEREIN A LAYER OF ANTIMONY IS EXPOSED AT ELEVATED TEMPERATURE, WITHIN AN EVACUATED BODY, TO VAPORS OF A PLURALITY OF ALKALI METALS INCLUDING CESIUM, TO FORM AN ELECTRON-EMISSIVE COMPOUND, WHEREIN THE IMPROVEMENT COMPRISES: EXPOSING THE CATHODE LAYER TO CESIUM VAPOR TO ACHIEVE A PHOTOSENSITIVITY EXCEEDING APPROXIMATELY 0.1 MICROAMPERE PER LUMEN WHILE MAINTAINING THE CATHODE AT A TEMPERATURE ABOVE 200*C.
Claim 3
Dependent Claim
19 words
The method defined in claim 1, wherein the antimony layer is activated by vapors of sodium, potassium, and cesium.
Claim 4
Dependent Claim
42 words
The method defined in claim 2, additionally comprising the steps of: exposing the cathode layer to cesium vapor prior to exposing it to potassium and sodium vapors, and terminating said exposing to cesium before the photosensitivity of the cathode reaches a peak.
Claim 5
Dependent Claim
22 words
The method defined in claim 3, wherein said terminating is before the photosensitivity of the cathode reaches about one-half microampere per lumen.
Claim 6
Dependent Claim
23 words
The method defined in claim 4, wherein the cathode is at a temperature above 200*C. during the exposing to sodium and potassium vapors.
Claim 7
Dependent Claim
110 words
The method defined in claim 2, comprising: exposing the cathode layer to cesium vapor until the photosensitivity of the exposed cathode layer is about one-tenth microampere per lumen, while maintaining the temperature of the cathode layer at between 220*C. and about 240*C.; then exposing the cathode layer to potassium vapor until the photosensitivity of the exposed cathode layer reaches a peak, while maintaining the temperature of the cathode layer at between about 220*C. and about 240*C.; then exposing the cathode layer to sodium vapor until the photosensitivity of the exposed cathode layer reaches a peak, while maintaining the temperature of the cathode layer at between about 220*C. and about 240*C.
Claim 8
Dependent Claim
23 words
The method defined in claim 2, additionally comprising the step of: exposing the cathode layer, in sequence, with potassium, sodium, and cesium vapors.
Claim 9
Dependent Claim
34 words
The method defined in claim 7, additionally comprising the step of: terminating said exposing to each of the vapors of potassium, sodium, and cesium vapor when the photosensitivity of the cathode reaches a peak.
Claim 10
Dependent Claim
36 words
The method defined in claim 8, wherein said cathode is maintained at a temperature of between about 220*C. and about 240*C. during said activation of said cathode with each of the vapors of sodium, and cesium.
Claim 11
Dependent Claim
23 words
The method defined in claim 9, wherein said cathode is maintained at a temperature exceeding about 160*C. during said activation with potassium vapor.
Claim 12
Dependent Claim
111 words
The method defined in claim 2, comprising: exposing the cathode layer to potassium vapor until the photosensitivity of the exposed cathode layer reaches a peak, while maintaining the temperature of the cathode layer within the range of about 160*C. and about 240*C. exposing the cathode layer, next, to sodium vapor until the photosensitivity of the exposed cathode reaches a peak, while maintaining the temperature of the cathode layer within the range of about 220*C. and about 240*C. exposing the cathode, next, to cesium vapor until the photosensitivity of the exposed cathode reaches a peak, while maintaining the temperature of the cathode layer within the range of about 200*C. and about 240*C.
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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) | 1978-05-19 | 1978-11-18 | 1979-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-19 | 1982-11-18 | 1983-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-19 | 1986-11-18 | 1987-05-20 | $7700.00 | Window Closed / Lapsed |