US3814964A
Expired / Lapsed
US
⏱️ 0.0 years remaining
External photodetector cooling techniques
Assignee: ACE SOPHISTICATES Inc
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Filing: 1973-01-19
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Granted: 1974-06-04
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Expires: 1993-01-19
Abstract
Abstract A technique is disclosed for improving the performance of photoemissive devices such as the photocathode of a photomultiplier tube by reducing thermal electron emission noise and thus increasing the signal to noise ratio. A thermoelectric cooler is positioned outside the evacuated envelope of the photoemissive device but in thermal communication with the device through a thermally conductive link arranged within and extending through the wall of the envelope. This conductor places the photoemissive device in direct heat exchange relationship with the external thermoelectric cooler while isolating the cooler from the remainder of the tube structure whereby the device is efficiently cooled without the need for cooling the remaining elements of the tube. This permits efficient cooling while at the same time avoiding the expense and bulk of conventional cryostatic coolers.
Inventors
- 👤 R Ace
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:22
CPC Classifications
F; F25; F25B; F25B21/00; F25B21/02; H; H01; H01J; H01J29/00; H01J29/02; H01J43/00; H01J43/04
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
76 words
IN A PHOTOEMISSIVE DEVICE, MEANS FOR REDUCING THE THERMAL EMISSION OF ELECTRONS, COMPRISING AN EVACUATED ENVELOPE; A PHOTOEMISSIVE SURFACE WITHIN SAID ENVELOPE; A THERMAL LINK BETWEEN SAID SURFACE AND A PORTION OF SAID ENVELOPE; AND A THERMOELECTRIC COOLING ELEMENT OUTSIDE SAID ENVELOPE AND IN HEAT EXCHANGE RELATIONSHIP WITH SAID PORTION OF SAID ENVELOPE, SAID COOLING ELEMENT BEING ENERGIZABLE TO PUMP HEAT FROM SAID THERMAL LINK AND THUS FROM SAID SURFACE IN ORDER TO COOL SAID SURFACE.
Claim 2
Dependent Claim
76 words
IN A PHOTOEMISSIVE DEVICE, MEANS FOR REDUCING THE THERMAL EMISSION OF ELECTRONS, COMPRISING AN EVACUATED ENVELOPE; A PHOTOEMISSIVE SURFACE WITHIN SAID ENVELOPE; A THERMAL LINK BETWEEN SAID SURFACE AND A PORTION OF SAID ENVELOPE; AND A THERMOELECTRIC COOLING ELEMENT OUTSIDE SAID ENVELOPE AND IN HEAT EXCHANGE RELATIONSHIP WITH SAID PORTION OF SAID ENVELOPE, SAID COOLING ELEMENT BEING ENERGIZABLE TO PUMP HEAT FROM SAID THERMAL LINK AND THUS FROM SAID SURFACE IN ORDER TO COOL SAID SURFACE.
Claim 3
Dependent Claim
29 words
The photoemissive device of claim 1, wherein said thermal link comprises a highly thermally conductive element in intimate heat exchange relationship with said photoemissive surface and with said envelope.
Claim 4
Dependent Claim
21 words
The photoemissive device of claim 2, wherein at least said portion of said envelope is of a highly thermally conductive material.
Claim 5
Dependent Claim
20 words
The photoemissive device of claim 3, wherein said envelope is primarily of glass, said portion of said envelope being metal.
Claim 6
Dependent Claim
13 words
The photoemissive device of claim 4, wherein said photoemissive surface comprises a photocathode.
Claim 7
Dependent Claim
16 words
The photoemissive device of claim 5, wherein said thermal link support said photocathode within said envelope.
Claim 8
Dependent Claim
28 words
The photoemissive device of claim 5, wherein said thermoelectric cooling element comprises a Peltier effect device and means for applying electric power to said device for energization thereof.
Claim 9
Dependent Claim
14 words
The photoemissive device of claim 7, wherein said thermal link is an electrical insulator.
Claim 10
Dependent Claim
25 words
The photoemissive device of claim 8, further including a heat sink in thermal contact with said cooling element for dissipating heat pumped from said photocathode.
Claim 11
Dependent Claim
32 words
The photoemissive device of claim 9, wherein said cooling elemnt is in heat exchange relationship with only said portion of said envelope, whereby only said thermal link and said photocathode are cooled.
Claim 12
Dependent Claim
73 words
The photoemissive device of claim 10 wherein said portion of said envelope comprises thermally isolated section forming a portion of the wall of said envelope, said thermal link providing a heaT conductive path between said photocathode and said wall section, and the vacuum within said envelope thermally insulating said photocathode and said thermal link from the remainder of said envelope, whereby the remainder of said envelope is not cooled by said cooled element.
Claim 13
Dependent Claim
160 words
In an electron tube having an evacuated envelope and a photocathode having a photoemissive surface locating within said envelope, means for reducing the thermal generation of free electrons by said photocathode, comprising: a thermoelectric cooling element formed of material exhibiting the Peltier effect and energizable to produce a cold surface and a hot surface; means for mounting said cooling element adjacent to and exterior of said envelope with said cold surface in heat conductive relationship with the exterior surface of a selected segment of said envelope wall; a thermal link within said envelope and having a first portion in intimate heat exchange relationship with the interior surface of said selected segment of said envelope wall having a second portion in initmate heat exchange relationship with said photocathode; and means for energizing said thermoelectric cooling element whereby heat is pumped from said photocathode through said thermal link through said selected segment of said envelope wall to the exterior of said envelope.
Claim 14
Dependent Claim
160 words
In an electron tube having an evacuated envelope and a photocathode having a photoemissive surface locating within said envelope, means for reducing the thermal generation of free electrons by said photocathode, comprising: a thermoelectric cooling element formed of material exhibiting the Peltier effect and energizable to produce a cold surface and a hot surface; means for mounting said cooling element adjacent to and exterior of said envelope with said cold surface in heat conductive relationship with the exterior surface of a selected segment of said envelope wall; a thermal link within said envelope and having a first portion in intimate heat exchange relationship with the interior surface of said selected segment of said envelope wall having a second portion in initmate heat exchange relationship with said photocathode; and means for energizing said thermoelectric cooling element whereby heat is pumped from said photocathode through said thermal link through said selected segment of said envelope wall to the exterior of said envelope.
Claim 15
Dependent Claim
69 words
The device of claim 12, wherein said thermoelectric cooling element comprises at least one pair of coaxial loops, said loops being oppositely energized whereby any magnetic field produced by current flowing in one of said loops will be opposite to, and tend to cancel, any magnetic field produced by current flowing in the other of said loops, thereby minimizing the effect of said magnetic fields on said electron tube.
Claim 16
Dependent Claim
31 words
The device of claim 13, further including heat sink means mounted in heat exchange relationship with the hot surface of said thermoelectric cooling element for dissipating heat pumped from said photocathode.
Claim 17
Dependent Claim
67 words
The device of claim 14, wherein said selected segment of said envelope is highly thermally conductive, said thermal link providing a heat conductive path between said photocathode and said selected segment and the vacuum within said envelope thermally insulating said photocathode and said thermal link from the remainder of said electron tube, whereby the remainder of said tube is not cooled directly by said thermoelectric cooling element.
Claim 18
Dependent Claim
47 words
The device of claim 15, wherein said selected segment is an annular band in the wall of said envelope, said thermoelectric cooling element being annular and surrounding said tube with its interior circumference forming said cold surface and being in heat exchange relationship with said annular band.
Claim 19
Dependent Claim
44 words
The device of claim 12 wherein said selected segment is disc-shaped, said thermoelectric cooling element being generally disc-shaped and having a pair of spaced plates forming said hot and cold surfaces, said cold surface plate being in heat exchange relationship with said disc-shaped segment.
Claim 20
Dependent Claim
35 words
The device of claim 17 wherein said thermoelectric cooling element comprises a plurality of thermocouples secured between said spaced plates, said thermocouples being arranged to minimize the production of magnetic fields within said electron tube.
References Cited (Backward Citations)
US3064440A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-03 | 1977-12-03 | 1978-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-03 | 1981-12-03 | 1982-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-03 | 1985-12-03 | 1986-06-04 | $7700.00 | Window Closed / Lapsed |