US3992893A
Expired / Lapsed
US
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Method for the production of superfluid helium under pressure at very low temperature and an apparatus for carrying out said method
Assignee: Commissariat à l'Énergie Atomique et Aux Énergies Alternatives
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Filing: 1975-02-11
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Granted: 1976-11-23
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Expires: 1995-02-11
Abstract
Abstract A bath of helium-4 is cooled to a temperature below the λ point so as to convert the lower portion of the bath to a superfluid-helium zone. A narrow stream between a top and a bottom portion of the zone is subjected to a critical heat flux corresponding to a temperature gradient by cooling the bath in the bottom portion of the superfluid-helium zone, the temperatures thus attainable being considerably lower than the λ transition point.
Inventors
- 👤 Gerard Claudet
- 👤 Pierre Roubeau
- 👤 Jacques Verdier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 11:37
CPC Classifications
F; F25; F25B; F25B9/00; F25B9/12; Y; Y10; Y10S; Y10S505/00; Y10S505/825; Y10S505/888; Y10S505/899
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
111 words
A method for the production of superfluid helium under pressure at very low temperature, of the type in which a lower portion of a bath of helium-4 is cooled locally in order to cause its temperature to fall below the λ point, the lower portion of said bath being then converted into a superfluid-helium zone, wherein said method consists in connecting an upper portion of the superfluid zone to a lower portion of the superfluid zone by means of narrow stream of superfluid helium and in imposing within said stream a critical heat flux corresponding to the establishment of a temperature gradient by carrying out said cooling within said lower portion.
Claim 2
Independent Claim
111 words
A method for the production of superfluid helium under pressure at very low temperature, of the type in which a lower portion of a bath of helium-4 is cooled locally in order to cause its temperature to fall below the λ point, the lower portion of said bath being then converted into a superfluid-helium zone, wherein said method consists in connecting an upper portion of the superfluid zone to a lower portion of the superfluid zone by means of narrow stream of superfluid helium and in imposing within said stream a critical heat flux corresponding to the establishment of a temperature gradient by carrying out said cooling within said lower portion.
Claim 3
Dependent Claim
32 words
A method according to claim 1, wherein the temperature difference between said lower and upper portions of the superfluid zone is adjusted by modifying the value of said imposed critical heat flux.
Claim 4
Dependent Claim
29 words
A method according to claim 2, wherein the cooling applied to said lower portion of the superfluid zone is modified in order to change the value of said flux.
Claim 5
Dependent Claim
28 words
A method according to claim 2, wherein the dimensions and consequently the thermal conduction of said stream are modified in order to change the value of said flux.
Claim 6
Independent Claim
143 words
An apparatus for the production of superfluid helium under pressure at very low temperature, said apparatus being of the type comprising a cryostat containing a liquid-helium bath, means for maintaining the helium pressure at the desired value, local cooling means immersed in said helium bath for causing the temperature of said bath to fall below the λ point, wherein said cryostat comprises: an upper chamber in which superfluid helium collects at the lower portion of said chamber whilst normal helium remains in the upper portion of said chamber; and at least one lower superfluid-helium chamber which is placed beneath said upper chamber and communicates therewith through at least one passageway having suitable dimensions for permitting the conduction of a critical heat flux having a thermal gradient, said cooling means being placed in at least one of said lower chambers containing the superfluid helium.
Claim 7
Independent Claim
143 words
An apparatus for the production of superfluid helium under pressure at very low temperature, said apparatus being of the type comprising a cryostat containing a liquid-helium bath, means for maintaining the helium pressure at the desired value, local cooling means immersed in said helium bath for causing the temperature of said bath to fall below the λ point, wherein said cryostat comprises: an upper chamber in which superfluid helium collects at the lower portion of said chamber whilst normal helium remains in the upper portion of said chamber; and at least one lower superfluid-helium chamber which is placed beneath said upper chamber and communicates therewith through at least one passageway having suitable dimensions for permitting the conduction of a critical heat flux having a thermal gradient, said cooling means being placed in at least one of said lower chambers containing the superfluid helium.
Claim 8
Dependent Claim
31 words
An apparatus according to claim 5, wherein said cooling means immersed in superfluid helium is constituted by means for the evaporation of liquid helium, said helium being derived from said bath.
Claim 9
Dependent Claim
37 words
An apparatus according to claim 5, wherein said cooling means immersed in superfluid helium are constituted by an autonomous refrigeration circuit with evaporation of helium-3 equipped if necessary with a precooling heat-exchanger immersed in the helium-4 bath.
Claim 10
Dependent Claim
35 words
An apparatus according to claim 5, wherein said cooling means immersed in the superfluid helium are constituted by an autonomous helium-3/helium-4 dilution refrigerator equipped if necessary with a precooling heat-exchanger immersed in said helium-4 bath.
Claim 11
Dependent Claim
26 words
An apparatus according to claim 5, wherein said passageway is constituted by a cylindrical tube of small diameter and especially of the order of one millimeter.
Claim 12
Dependent Claim
17 words
An apparatus according to claim 9, wherein the passageway is partially obstructed by a positionally-adjustable cone-point screw.
Claim 13
Dependent Claim
18 words
An apparatus according to claim 5, wherein said passageway is constituted by the orifice of a perforated partition-wall.
Claim 14
Dependent Claim
17 words
An apparatus according to claim 11, wherein the passageway is partially obstructed by a positionally-adjustable cone-point screw.
Claim 15
Dependent Claim
39 words
An apparatus according to claim 5, wherein said passageway is obtained by means of a disc mounted with clearance within a casing, said passageway being formed by the space provided between the casing and the periphery of said disc.
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) | 1979-11-23 | 1980-05-24 | 1980-11-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-11-23 | 1984-05-24 | 1984-11-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-11-23 | 1988-05-24 | 1988-11-23 | $7700.00 | Window Closed / Lapsed |