CRYOGENIC REFRIGERATION DEVICE

Abstract

Cryogenic refrigeration device comprising an enclosure delimiting a sealed space closed by a cover, the device comprising at least one cryogenic cooler mounted through the cover and having a first end located outside of the enclosure and a second end located inside the enclosure, the cryogenic cooler being configured to produce cold at the second end thereof, the device comprising a set of heat-conducting plates which are arranged inside the enclosure and form thermal stages cooled by the cryogenic cooler, the device comprising a set of passages formed through the cover and plates for the sealed passage of one or more cables and/or equipment into the enclosure, characterised in that at least one part of the cover comprises a flange forming a support for the cryogenic cooler, wherein said flange bearing the cryogenic cooler is attached in a sealed manner and is removable from the remainder of the cover.

Description

FIELD OF THE INVENTION

The invention relates to a cryogenic refrigeration device.

The invention relates to a refrigeration device for cooling elements to a cryogenic temperature below 100 K, and notably below 50 K or below 4K.

Specifically, the invention relates to refrigeration devices used to cool to very low temperatures, in the order of millikelvins. These very low temperatures are conventionally obtained using a dilution refrigerator.

BACKGROUND OF THE INVENTION

A dilution refrigerator uses a mixture of helium-3 and helium-4 in a working circuit comprising a boiler, a mixing chamber and a circulating member for the helium flow. The cooling is obtained in the mixing chamber as a result of enthalpy of mixing when the helium-3 is diluted in the helium-4.

For example, a refrigeration device has a working circuit in the form of a loop containing a cycle fluid comprising a mixture of helium-3 (3He) and helium-4 (4He). The working circuit comprises a mixing chamber, a boiler and a fluid transfer member, which are arranged in series and fluidically connected via a first set of pipes. The first set of pipes is configured to transfer cycle fluid from an outlet of the mixing chamber to an inlet of the boiler and from an outlet of the boiler to an inlet of the transfer member. The working circuit comprises a second set of pipes connecting an outlet of the transfer member to an inlet of the mixing chamber. The working circuit comprises at least a first heat-exchange portion between at least some of the first set of pipes and the second set of pipes, this first heat-exchange portion being located between the boiler and the mixing chamber. A cooling member is usually in heat exchange with the working circuit and designed to transfer cold energy to the cycle fluid.

Such a dilution refrigerator typically comprises several cooling stages, each stage being configured to achieve a respective temperature during operation of the dilution refrigerator. The components to be cooled may be thermally coupled to these stages to meet the specific requirements of the application.

These dilution refrigerators are conventionally arranged in a cryogenic cooling device comprising an enclosure enabling the cold portions (cooling stages) to be accessed via dedicated passages. A supplementary mechanical cryogenic refrigerator is usually provided to cool the enclosure and to provide cold energy to the dilution refrigerator.

Such refrigeration devices are complex and expensive to manufacture. Specifically, the number of cryogenic refrigerators and the geometry (notably size) of the device have to be adjusted as a function of the required specifications relating to cold power, surface or volume to be cooled, and access. The fluidic and mechanical connections of the different components of the device make manufacturing and maintenance operations even more difficult.

One objective of this invention is to mitigate some or all of the drawbacks of the prior art as set out above.

SUMMARY OF THE INVENTION

The invention relates more specifically to a cryogenic refrigeration device comprising an enclosure delimiting a sealed volume closed by a cover, the device comprising at least one cryogenic refrigerator mounted through the cover and having a first end located outside the enclosure and a second end located inside the enclosure, the cryogenic refrigerator being configured to produce cold at the second end thereof, the device comprising a set of thermally conductive plates arranged in the enclosure to form thermal stages cooled by the cryogenic refrigerator, the device comprising a set of passages formed through the cover and plates enabling the sealed passage of cables and/or equipment into the enclosure.

In an effort to overcome the deficiencies of the prior art discussed, supra, the device according to the invention, while corresponding to the generic definition given in the preamble above, can include at least a portion of the cover that is a flange forming a support for the cryogenic refrigerator, said flange bearing the cryogenic refrigerator being fastened sealingly and removably in relation to the rest of the cover.

Furthermore, embodiments of the invention may have one or more of the following features:

• • the cover comprises a cutout or a recess delimiting a hole in the cover and the flange sealingly plugs said hole when the flange is fastened to the rest of the cover,
  • the cutout or the recess in the cover defines a mating seat for at least a portion of the flange, in the fastened position, the flange fitting at least partially into said seat,
  • the flange is fastened to the rest of the cover by a set of fastening pins, for example screws,
  • the device comprises at least one gasket interposed between the flange and the rest of the cover, and/or at least one gasket interposed between the cryogenic refrigerator and the flange,
    • the cryogenic refrigerator comprises a working fluid circuit subjected to a working cycle, and in which some of all of the components of the working circuit are also mounted rigidly on the flange,
  • at least one of the following components of the working circuit are rigidly mounted on the flange: at least one sheath, a dilution refrigeration system, a set of pipes for the working fluid, a set of stores designed to store the working fluid, a pumping member for the working fluid, a working-fluid injection member, a set of fluidic connections, a pumping member, notably a vacuum pump, a set of cables, for example for a thermometry and/or heating system, a thermal bonding braid, a pulse tube refrigerator, one or more thermal switches, one or more impurity getters, a bellows, and a mechanical damping system,
  • the device comprises several cryogenic refrigerators mounted on the respective support flanges,
  • the device comprises several cryogenic refrigerators mounted on a single flange,
  • the device comprises at least one cryogenic refrigerators that is one of the following: a pulse tube refrigerator, a Gifford-McMahon refrigerator, or a Stirling refrigerator, and/or at least one that is one of the following: a dilution refrigerator, a 3He or 4He Joule-Thompson refrigerator, or an adiabatic demagnetization refrigerator,
  • the device comprises at least one cryogenic refrigerator mounted in the central portion of the cover via the flange thereof and a set of several passages formed through the cover and located about the periphery of the at least one cryogenic refrigerator.

The invention may also relate to any alternative device or method comprising any combination of the features above or below within the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, claims, and accompanying drawings. It is to be noted, however, that the drawings illustrate only several embodiments of the invention and are therefore not to be considered limiting of the invention's scope as it can admit to other equally effective embodiments.

Other features and advantages are set out in the description below, provided with reference to the figures in which:

FIG. 1 is a schematic partial vertical cross-section view of an example embodiment of a cryogenic refrigeration device according to the invention,

FIG. 2 is a schematic partial perspective view of an example of a cryogenic cooling module that may be used in such a cryogenic refrigeration device,

FIG. 3 is a schematic perspective view, partially cut away, of an example of a detail of a cryogenic refrigeration device according to the invention,

FIG. 4 is a schematic partial top view of an example of a cover of such a cryogenic refrigeration device, disassembled,

FIG. 5 is a schematic partial top view of another example of a cover of such a cryogenic refrigeration device, assembled,

FIG. 6 is a schematic partial vertical cross-section view of another example of a cover of such a cryogenic refrigeration device, assembled,

FIG. 7 is a schematic partial perspective view of another example of a cover of such a cryogenic refrigeration device, disassembled.

DETAILED DESCRIPTION OF THE INVENTION

The cryogenic refrigeration device 1 shown in [FIG. 1] comprises an enclosure 2 delimiting a sealed volume closed by a top cover 3, 13. This type of device 1 is sometimes referred to as a “cryostat”. The enclosure 2 is for example cylindrical and may be made of stainless steel or aluminum, for example. When in operation, the internal volume of the enclosure 2 may be placed under vacuum, notably to provide thermal insulation.

In the example in FIG. 1, the device 1 comprises two cryogenic refrigerators 4, 40 mounted through the cover 3, 13, each having a first end located outside the enclosure 2 (at ambient temperature) and a second end located inside the enclosure 2 (at operating cryogenic temperature). Each cryogenic refrigerator 4, 40 is configured to produce or supply cold power at the second end thereof.

The device 1 comprises a set of thermally conductive plates 5, 6, 7, 8, 9 arranged vertically in the enclosure 2 to form thermal stages cooled at least by the cryogenic refrigerators 4, 40 (the plates are for example cooled from top to bottom to decreasing cryogenic temperatures). The plates 5, 6, 7, 8, 9 are made of a thermally conductive material, for example copper or any other alloy or any suitable material. The plates 5, 6, 7, 8, 9 may be spaced apart from one another by rods with low thermal conductivity (not shown, for the sake of simplicity).

In a manner known per se, at least one of the plates 5, 6, 7, 8, 9 may be the support for different equipment or samples to be cooled to a low temperature, for example quantum chips and/or superconducting sensors or circuits.

Each plate 5, 6, 7, 8, 9 may be connected to a thermal shield 23 that contains some or all of the subsequent lower plates. This means that the shields 23 form volumes that are contained within one another (“nested” volumes). Some or all of the shields 23 may be cooled by a cryogenic refrigerator 4, 40 by thermal coupling.

The device 1 comprises a set of passages 10, 11 formed through the cover 3 and the plates 5, 6, 7, 8, 9 for the sealed passage of cables and/or equipment (probes or other equipment) into the enclosure 2 and for example for accessing the plates 5, 6, 7, 8, 9. In particular, the holes 10, 11 may be provided in the device 1 to enable a test “probe” to enter the enclosure 2 to provide a sample to be cooled while maintaining a vacuum inside the enclosure 2.

The cryogenic refrigerator or refrigerators 4, 40 (two in the example in FIG. 1) are provided to supply cold power into the enclosure 2 to cool the plates (and thermal shields, where applicable) to set temperatures.

The device 1 in particular comprises at least one “mechanical” cryogenic refrigerator 4, for example a cryogenic refrigerator such as a pulse tube refrigerator, a Gifford McMahon refrigerator, or a Stirling refrigerator. Alternatively or cumulatively, the device 1 may in particular comprise at least one dilution cryogenic refrigerator 40.

According to an advantageous feature, at least a portion of the cover 3, 13 is a flange 13 forming a support for a cryogenic refrigerator 4, 40, said flange 13 bearing the cryogenic refrigerator 4, 40 being fastened sealingly and removably in relation to the rest of the cover 3.

This means that at least some of the cryogenic refrigerators 4, 40 (and preferably all of the cryogenic refrigerators 4, 40) are mounted on one or more flanges 13, which are removable from the rest of the cover 3.

This enables the cryogenic refrigerator or refrigerators 4, 40 to be removable and relatively independent of the rest of the device. The refrigerators 4, 40 may be mounted, tested separately from the rest of the device, and may be standard and mounted on different types of devices 1 (different geometries of the enclosures 2, covers 3, plates, etc.).

The flange 13 may be a molded and/or machined plate, for example made of the same material as the rest of the cover 3. The flange 13 may in particular form a plug for an open portion of the rest of the cover 3.

In particular, the cryogenic refrigerator or refrigerators 4, 40 may be characterized, dimensioned, manufactured and tested independently of the rest of the configuration of the device.

For example, these refrigerators 4, 40 on their support flange 13 may be identical for different ranges of devices. One or more cryogenic refrigerators 4, 40 may be mounted on the cover 13 of a device 1 as a function of requirements and specifications. This also facilitates removal, maintenance, repair and replacement.

A given module (cryogenic refrigerator or refrigerators on a flange 13) may be placed in the cover 3 centrally or eccentrically according to the geometry of the cover 3 and/or the architecture of the plates 5, 6, 7, 8, 9 or of the enclosures 23. The cryogenic refrigerator 4, 40 may comprise a working fluid circuit subjected to a working cycle and some or all of the components of the working circuit may also be rigidly mounted on the flange 13.

As shown for example in [FIG. 2], the flange 13 may bear at least one sealed sheath 15, 16 containing the cold portions, a dilution cooling system 16, a set 17, 21 of pipes for the working fluid, a set of (buffer) stores 18 configured to store the working fluid, a pumping member 19 for the working fluid, a working-fluid injection member 20, and a set of fluidic connections. Naturally, only some of these components may be mounted on the flange 13 and/or other components may be mounted on the flange 13, for example a pumping member, notably a vacuum pump, a set of cables, for example for a thermometry and/or heating system.

Thus, the flange 13 bears a set of lower components of the cryogenic refrigerator 4, 40 that project from the lower face of the flange 13 and that are seated in the enclosure 2 when the flange 13 is mounted on the cover 3 through a through-hole 30 in the cover 3.

The flange 13 also bears at least some of the upper components that project from the upper surface of the flange 13 (and that are located outside the enclosure 2 in the mounted position).

The lower components are dimensioned and/or arranged to pass through the hole 30 to enable mounting or removal of the flange 13 and the associated components of the cryogenic refrigerator in relation to the enclosure 2 through the cover 3.

The lower components of the cryogenic refrigerator 4, 40 extend for example in a longitudinal direction that is vertical when the flange 13 is mounted on the cover 3. Furthermore, the dimensions of these lower components of the cryogenic refrigerator 4, 40 transverse to the longitudinal direction are smaller than the dimensions of the hole 30 (to enable vertical passage).

These lower components of the cryogenic refrigerator 4, 40 are for example aligned in the longitudinal direction up to a terminal end to form a column of components. As illustrated, the transverse dimensions of the column are constant or decrease from the flange 13 toward the terminal end. This enables easy mounting and removal through the hole 30 in the cover.

The other components (not directly related to operation of the cryogenic refrigerator) may be mounted on the rest of the cover 3. For example and as illustrated in FIG. 4, the cover 3 (excluding the flange 13) may be the support for a thermometry housing 24 (measuring and/or heating). Similarly, the cover 3 (excluding the flange 13) may be the support for a pump 25 for placing the enclosure 2 under vacuum. Furthermore, a fluid pumping system or connection 26 for the dilution refrigeration fluid may nonetheless remain located on this cover 3.

Each cryogenic refrigerator module 4, 40 may be mounted (or removed and withdrawn) vertically in relation to the rest of the cover 3.

As shown notably in FIG. 4 and FIG. 7, the cover 3 may comprise a cutout or recess delimiting a hole 30 in the cover 3. When the flange 13 is fastened (mounted) on the rest of the cover 3, the flange 13 sealingly plugs said hole 30.

The cutout or the recess in the cover 3 for example defines a matching concave seat for at least a portion of the flange 13, so that, when in the fastened position, the flange 13 fits at least partially into said seat.

As shown notably in FIG. 1 and FIG. 6, the flange 13 may be fastened to the rest of the cover 3 by a set of fastening pins 14, for example screws. For example, the flange 13 is screwed from under the cover 3.

As shown schematically, the device 1 preferably comprises at least one gasket 22 interposed between the flange 13 and the rest of the cover 3 (see FIG. 6) and/or at least one gasket 22 interposed between the cryogenic refrigerator 4, 40 and the flange 13 (see FIG. 1). The gasket or gaskets 22 are for example O-rings.

As illustrated, the device 1 may comprise a single cryogenic refrigerator 4 (see FIG. 3, FIG. 4) or several cryogenic refrigerators 4, 40 (see FIG. 1, FIG. 5) in which each cryogenic refrigerator 4, 40 is mounted on a respective support flange 13 (a single cryogenic refrigerator 4, 40 is mounted on a support flange 13). Naturally, it is possible to envisage a single flange 13 supporting several cryogenic refrigerators 4, 40.

In the example in FIG. 5, the device comprises three cryogenic refrigerators 4, 40 mounted in the central portion of the cover 3 via the respective flanges 13 thereof. The passages 10 formed through the cover 3 may be located about the periphery of the cryogenic refrigerators 4, 40.

In the example in FIG. 1, a first cryogenic refrigerator 4 may be mechanical (for example a pulse tube refrigerator) and configured to cool a first upper plate 5 to a first cold temperature, for example about 50 K and a second plate 6 to a second cold temperature, for example about 5 K. The plates 7, 8, 9 are for example cooled to increasingly low temperatures, for example in the order respectively of 800 mK, 50 mK and 3 mK by the dilution refrigerator 16 of the other cryogenic refrigerator 40.

Naturally, any other combination of cryogenic refrigerators 4, 40 and plates may be envisaged, for example four mechanical cryogenic refrigerators 4 and two dilution refrigerators.

Alternatively or cumulatively, the cold source of at least one of the cryogenic refrigerators 4, 40 may be a liquefied cycle fluid such as helium, hydrogen or nitrogen. This means that the cryogenic refrigerator 4, 40 is connected to a cold source located outside the enclosure 2, this cold source supplying a liquefied fluid flow that is cooled outside the enclosure. This flow circulates in the cryogenic refrigerator 4, 40 and is placed in heat exchange with at least some of the plates 5, 6, 7, 8, 9 in the enclosure 2.

While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.

The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.

“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms “consisting essentially of” and “consisting of” unless otherwise indicated herein.

“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.

Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.

Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.

All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.

Claims

1-12. (canceled)

13. A cryogenic refrigeration device comprising: an enclosure delimiting a sealed volume closed by a cover;a cryogenic refrigerator mounted through the cover and having a first end located outside the enclosure and a second end located inside the enclosure, the cryogenic refrigerator being configured to produce cold at the second end thereof;a set of thermally conductive plates arranged in the enclosure to form thermal stages cooled by the cryogenic refrigerator;a set of passages formed through the cover and plates for the sealed passage of cables and/or equipment into the enclosure, at least a portion of the cover being a flange forming a support for the cryogenic refrigerator, said flange bearing the cryogenic refrigerator being fastened sealingly and removably in relation to the rest of the cover,wherein the cryogenic refrigerator further comprises a working fluid circuit subjected to a working cycle, some or all of the components of the cryogenic refrigerator and notably of the working circuit also being rigidly mounted on the flange,wherein the cryogenic refrigerator further comprises at least one of the following components rigidly mounted on the flange: at least one sheath, a dilution refrigeration system, a set of pipes for the working fluid, a set of stores designed to store the working fluid, a pumping member for the working fluid, a working-fluid injection member, a set of fluidic connections, a pumping member, a set of cables, for example for a thermometry and/or heating system, a thermal bonding braid, a pulse tube refrigerator, one or more thermal switches, one or more impurity getters, a bellows, and a mechanical damping system.

14. The device as claimed in claim 13, wherein the flange bears a set of lower components of the cryogenic refrigerator that project from the lower face of the flange and that are seated in the enclosure when the flange is mounted on the cover through a through-hole in the cover, and in that these lower components are dimensioned and/or arranged to pass through the hole to enable mounting or removal of the flange and the associated components of the cryogenic refrigerator in relation to the enclosure through the cover.

15. The device as claimed in claim 14, wherein the lower components of the cryogenic refrigerator projecting from the lower face of the flange extend in a longitudinal direction that is vertical when the flange is mounted on the cover, and in that the dimensions of these lower components of the cryogenic refrigerator transverse to the longitudinal direction are smaller than the dimensions of the hole.

16. The device as claimed in claim 15, wherein the lower components of the cryogenic refrigerator are aligned in the longitudinal direction up to a terminal end forming a column of components, and in that the transverse dimensions of the column are constant or decrease from the flange toward the terminal end.

17. The device as claimed in claim 15, wherein the cover comprises a cutout or a recess delimiting the hole in the cover, and in that the flange sealingly plugs said hole when the flange is fastened to the rest of the cover.

18. The device as claimed in claim 17, wherein the cutout or the recess in the cover defines a mating seat for at least a portion of the flange, in the fastened position, the flange fitting at least partially into said seat.

19. The device as claimed in claim 14, wherein the flange is fastened to the rest of the cover by a set of fastening pins, for example screws.

20. The device as claimed in claim 14, further comprising a gasket interposed between the flange and the rest of the cover, and/or a gasket interposed between the cryogenic refrigerator and the flange.

21. The device as claimed in claim 14, further comprising several cryogenic refrigerators mounted on respective support flanges.

22. The device as claimed in claim 14, further comprising several cryogenic refrigerators mounted on a single flange.

23. The device as claimed in claim 14, further comprising at least one cryogenic refrigerator that is one of the following: a pulse tube refrigerator, a Gifford-McMahon refrigerator, or a Stirling refrigerator, and/or at least one that is one of the following: a dilution refrigerator, a 3He or 4He Joule-Thompson refrigerator, or an adiabatic demagnetization refrigerator.

24. The device as claimed in claim 14, further comprising at least one cryogenic refrigerator mounted in the central portion of the cover via the flange thereof and a set of several passages formed through the cover and located about the periphery of the at least one cryogenic refrigerator.