Cryogenic cooler system

Abstract

A cryogenic cooling system comprising a cold finger and a compressor unit connected by a compressor transfer line is provided, for example for cooling of a detector or similar device. Either or both of the cold finger and compressor unit which may be provided with one or more heat pipes passing partially or wholly through the mounting body of the cold finger and / or housing of the compressor. In preferred embodiments, each lumen is situated so as to pass through the greatest possible thickness of said mounting body, and as close as possible to the working fluid present therein, whilst ensuring the integrity of the cryogenic circuit. In preferred embodiments, where the cold finger and / or housing of the compressor are substantially cylindrical, the lumens provided for the heat pipes describe chords of the circular cross section. Figure 8

Description

FIELD OF THE INVENTION The present invention relates to the field of s including cryogenic cold finger element and / or a compressor, and methods for constructing BACKGROUND PRIORART Figure 1 shows a typical as known in the art. As shown in figure 1, a cooler system 100 comprises a cold fingerelement 110 comprising a hot end 111 and a cool end 112. The cold fingerelement is coupled to a compressor 130 via a compressor transfer line 120. The described elements may this typically constitute a Stirling cooler system or a pulse-tube cooler system. Such a system may be used for example to provide cooling for a sensor such as an infrared optical detector. The shown system thus constitutes a thermodynamic system in which energy is evacuated from the cool end of the cold finger and accumulated at the warm end and in the compressor body, from whence it must be safely sunk. Conventional solutions to this problem comprise the application of cooling fins to the relevant parts of the system, and / or immersion of the relevant parts of the system in a flow of a coolant fluid. Such solutions tend to be bulky and voluminous. Another technology which is known generally in the field of heat transfer is the so-called heat pipe. A heat pipe is a heat-transferdevice that employs phase transition to transfer heatbetween two solid interfaces. At the hot interface of a heat pipe, a volatile liquid in contact with a thermally conductive solid surface turns into a vapor by absorbing heat from that surface. The vaporthen travels along the heat pipe to the cold interface and condenses back into a liquid, releasing the latent heat. The liquid then returns to the hot interface through capillary action, centrifugal force, or gravity and the cycle repeats. Due to the very high heat transfer coefficients for boiling and condensation, heat pipes are highly effective thermal conductors. The effective thermal conductivity varies with heat pipe length and can approach 100 kW / (m-K) for long heat pipes, in comparison with approximately 0.4 kW / (m-K) for copper. Modern CPU heat pipes are typically made of copper and use water as the working fluid. They are common in many consumer electronics like desktops, laptops, tablets, and high- end smartphones. (Vlkipedia contributors. "Heat pipe." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 21 Aug. 2024. Web. 8 Oct. 2024.) Certain prior art attempts to use heat pipe technology in are known, for example JPH11223403A and JPH11237130A, however the proposed configurations maintain many of the disadvantages of simple heat sink based implementations. It is accordingly desired to develop new cryogenic cooler structures better addressing the foregoing considerations. SUMMARYOF THE INVENTION In accordance with the present invention in a first aspect there is provided a cryogenic cold finger element for a , the cold finger element having a warm end and a cool end defining a first axis, and a mounting body comprising a coupling to receive working fluid from a compressor, the mounting body being connected to the warm end of the cold finger element, the system characterized in that the mounting body is provided with a lumen, the lumen intersecting at least one outer surface of the mounting body, the cryogenic cold finger element further comprising at least one heat pipe partially situated in the lumen and partial extending from the lumen. In a development of the first aspect, the lumen is provided orthogonal to the axis and offset therefrom. In a development of the first aspect, the mounting body is provided with a plurality of the Iumens arranged orthogonal to the axis and offset therefrom, and parallel to each other, each lumen intersecting at least one outer surface of the mounting body, the cryogenic cold finger element further comprising a respective plurality of heat pipes partially situated in the Iumens. In a development of the first aspect, the or each lumen is situated so as to pass through the greatest possible thickness of the mounting body, and as close as possible to the working fluid present therein, whilst ensuring the integrity of the cryogenic circuit. In a development of the first aspect, the cryogenic cold finger element is a Stirling cooler cold finger element. In a development of the first aspect, the cryogenic cold finger element is a pulse tube cooler cold finger element. In accordance with the present invention in a second aspect there is provided a method of constructing a cryogenic cold finger element comprising the steps of providing a cryogenic cold fingerelement having a warm end and a cool end defining a first axis, and a mounting body comprising a coupling to receive working fluid from a compressor, the mounting body being connected to the warm end of the cold finger element, and providing a lumen, the lumen intersecting at least one outer surface of the mounting body, and inserting a heat pipe partially into the lumen. In a development ofthe second aspect, the step of providing a lumen comprises machining the lumen in the mounting body. In a development of the second aspect, the method comprises a further step of providing a layer ofthermal conductive interface material on a surface ofthe lumen so as to thermally couple the heat pipe to the mounting body when the heat pipe is inserted in the lumen. In accordance with the present invention in a third aspect there is provided a compressor for a comprising a cryogenic cold finger element and a coupling to receive working fluid from the compressor, the compressor comprising a housing, the housing being provided with a lumen, the compressor further comprising at least one heat pipe partially situated in the lumen and partial extending from the lumen. In a development of the third aspect, the or each lumen is situated so as to pass through the greatest possible thickness of the housing, and as close as possible to the working fluid present therein, whilst ensuring the integrity of the cryogenic circuit. In a development of the third aspect, the at least one heat pipe is arranged parallel to a compressor transfer line for connecting to a cryogenic cold finger element. In accordance with the present invention in a fourth aspect there is provided a method of constructing a compressor for a comprising a cryogenic cold finger element and a coupling to receive working fluid from the compressor, the method comprising providing a housing of the compressor, providing the housing with a lumen and providing at least one heat pipe partially situated in the lumen and partial extending from the lumen. In a development of the fourth aspect, the step of providing a lumen comprises machining the lumen in the housing. In a development ofthe fourth aspect, method comprises a further step of providing a layer ofthermal conductive interface material on a surface ofthe lumen so as to thermally couple the heat pipe to the housing when the heat pipe is inserted in the lumen. In accordance with the present invention in a fifth aspect there is provided a comprising a cryogenic cold finger element of the first aspect and a compressor connected to the cold finger element by a compressor transfer line. In accordance with the present invention in a sixth aspect there is provided a comprising a cryogenic cold finger element, for example of the first aspect, and a compressor according to the third aspect, connected to the cold finger element by a compressor transfer line. In a development of the fifth or sixth aspect, the at least one heat pipe is arranged parallel to the compressor transfer line. In a development ofthe fifth or sixth aspect, the further comprises a layer of thermal conductive interface material between a surface ofthe lumen and a part of the heat pipe situated in the mounting body so as to thermally couple the heat pipe to the mounting body. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and its various features and advantages will emerge from the following description of a number of exemplary embodiments provided for illustration purposes only and its appended figures in which: Figure 1 shows a typical as known in the art; Figure 2 presents a cold finger element belonging to a in accordance with an embodiment; Figure 3 presents a in accordance with a further embodiment; Figure 4 presents a in accordance with a further embodiment; Figure 5 presents a method of constructing a pulse-tube cold finger for a pulse cooled cryogenic cooling module in accordance with an embodiment; Figure 6 presents a compressor for a cryogenic detector system in accordance with an embodiment; Figure 7 presents a method of constructing a compressor for a pulse cooled cryogenic cooling system in accordance with an embodiment; and Figure 8 presents a in accordance with a further embodiment. DETAILED DESCRIPTION OF THE INVENTION Figure 2 presents a cold finger element belonging to a in accordance with an embodiment. As shown in figure 2, a 200 comprises a cryogenic cold finger element 210 having a warm end 211 and a cool end 212 defining a first axis 213, and a mounting body 214 comprising a coupling (not shown) to receive working fluid from a compressor, the mounting body 214 being connected to the warm end 211 of the cold finger element. The system is characterized in that the mounting body214 is provided with a lumen 215 intersecting at least one outer surface of the mounting body. The cryogenic cold finger element further comprises at least one heat pipe 216 partially situated in the lumen and partially extending from the lumen. While only a single lumen is shown, with a single heat pipe, it will be appreciated that the mounting body may be provided with any number of Iumens and heat pipes, depending on the dimension of the mounting body, the Iumens and the orientation of each lumen. As shown, the lumen is provided orthogonal to the axis and offset therefrom. On this basis, multiple lumens may be disposed describing a plurality of chords at respective orientations in a given cross sectional plane of the mounting body or in respective cross sectional planes, and / or in symmetrical pairs on either side of the axis. The mounting body may be provided with a plurality of Iumens arranged orthogonal to the axis and offset therefrom, and parallel to each other, each lumen intersecting at least one outer surface of the mounting body, the cryogenic cold finger element further comprising a respective plurality of heat pipes partially situated lumens. It will be appreciated that lumens may occupy difference planes at right angles to the axis. Alternatively, Iumens may be oriented at other angles with respect to the axis, although preferred embodiments will retain an offset with respect to the axis of the cold finger element so as to avoid intersecting the axis. Generally, the or each lumen is preferably situated so as to pass through the greatest possible thickness of the mounting body, and as close as possible to the working fluid present therein, whilst ensuring the integrity of the cryogenic circuit and thereby containment of the working fluid, such that there will be no leaking of working fluid. This will generally mean as close as possible to the axis 213, without intersecting the hollow regions belonging to the cryogenic system at the center of the mounting body. The cryogenic cold finger element may be of any type, including for example a Stirling cooler cold finger element or a pulse tube cooler cold finger element. Optionally, the system may comprise a transducer element requiring cooling such as a detector, e.g. an infrared detector or the like. Such transducers will typically be situated at or near the cold end 212 of the cold finger element. The system may also optionally comprise a dewar (sealed, insulated vessel) enclosing the cool end of the cold finger and any transducer associated therewith. Figure 3 presents a in accordance with a further embodiment. As shown in figure 3, there is provided a system 300 comprising a cold finger 210 substantially as described with reference to figure 2, with like reference symbols corresponding to like features. As shown, the system further comprises a compressor 330 connected to the cold finger element 210 by a compressor transfer line 320. As shown, the at least one heat pipe 216 is arranged parallel the compressor transfer line 320. Figure 4 presents a in accordance with a further embodiment. As shown in figure 4, there is provided a system 400 comprising a cold finger 210 and compressor 430 substantially as described with reference to figures 2 and 3, with like reference symbols corresponding to like features. As shown, the compressor 430 has a housing 434, the housing being provided with a lumen 435 parallel to the compressor transfer line 320 and situated so as to pass through the greatest possible thickness of the housing body, and as close as possible to the working fluid present therein, whilst ensuring the integrity of the cryogenic circuit. In the embodiments presented herein, one or more lumens may be provided in the body of the cold finger and / or the compressor, with respective heat pipes provided therein. It will be appreciated that the purpose of these heat pipes is to conduct heat away from the respective body, which requires an effective thermal coupling between the respective body and heat pipe. This effective coupling may be achieved by any suitable means, including maximizing the common contact surface between each heat pipe and the surrounding lumen e.g. be providing engaging threads, splines, or the like, ensuring a sight physical engagement of the two elements, and / or providing a layer of thermal conductive interface material between a surface of the lumen and a part of the heat pipe situated in the mounting body so as to thermally couple the heat pipe to the mounting body. Suitable conductive interface materials may comprise a thermo-conductive paste, deformable tape, or the like. This may be achieved by adding a suitable interface material to a heat or adding a suitable interface material to the inside of the lumen or indeed using a two part composition such as an epoxy resin or the like, Similar benefits may be achieved with various adhesives, and indeed thread locking type compounds. Such compositions may be charged with a conductive fillersuch asAluminum oxide, boron nitride, zinc oxide, aluminum nitride, silver, etc. Figure 5 presents a method of constructing a pulse-tube cold finger for a pulse cooled cryogenic cooling module in accordance with an embodiment, As shown, the method starts at step 500 before proceeding to step 505 at which a cryogenic cold finger element is provided, having a warm end and a cool end defining a first axis, and a mounting body comprising a coupling to receive working fluid from a compressor, the mounting body being connected to the warm end of the cold finger element. The method then proceeds to step 510 of providing a lumen, which as discussed above may for example be disposed orthogonal to the axis and offset therefrom in the mounting body, the lumen intersecting at least one outer surface of the mounting body. The method then proceeds to step 515 of inserting a heat pipe partially into the lumen, before terminating at step 520. The step 510 of providing a lumen may comprise machining the lumen in the mounting body, or any other convenient means of providing the desired volume. The lumen may pass all the way through the mounting body, or only partially. Where the lumen passes all the way through the mounting body, a heat pipe inserted in the lumen may extend from the mounting body through either or both openings of the lumen. The method may comprise an optional step (not shown) of providing a layer of thermal conductive interface material on a surface of the lumen so as to thermally couple the heat pipe to the mounting body when the heat pipe is inserted in the lumen. This may be achieved by adding a suitable interface material to a heat pipe before inserting it into the lumen, or adding a suitable interface material to the inside of the lumen before inserting the heat pipe into the lumen, or indeed using a two part composition such as an epoxy resin or the like, in which case one part may be added to the lumen wall and the other to the heat pipe, such that the material sets when the heat pipe is inserted into the lumen, so as to establish not only an effective heat conductive connection, but also to physically secure the heat pipe in place. Similar benefits may be achieved with various adhesives, and indeed thread locking type compounds. Such compositions may be charged with a conductive fillersuch asAluminum oxide, boron nitride, zinc oxide, aluminum nitride, silver, etc. Similarly, the heat pipe may be soldered in place using a suitable low temperature solder based on galinstan or the like. Figure 6 presents a compressor for a cryogenic detector system in accordance with an embodiment. As shown, a 600 comprises a cryogenic cold finger element 210 and a compressor transfer line 320 to convey working fluid from compressor 630 to cold finger element 210. The compressor 630 comprises a housing 634 provided with a lumen 635 parallel to the compressor transfer line and situated so as to pass through the greatest possible thickness of the housing body 634, and as close as possible to the working fluid present therein, whilst ensuring the integrity of the cryogenic circuit and thereby containment of the working fluid, such that there will be no leaking of working fluid. The compressor further comprises at least one heat pipe 636 partially situated in the lumen and partial extending from the lumen 635. As shown, the at least one heat pipe 636 is preferably arranged parallel to compressor transfer line 320. lt will be appreciated that other configurations and alignments are within the scope of the invention. Figure 7 presents a method of constructing a compressor for a pulse cooled cryogenic cooling system in accordance with an embodiment. In particular, there is presented a method of constructing a compressor for a comprising a cryogenic cold finger element and a coupling to receive working fluid from the compressor. As shown, the method starts at step 700 before proceeding to step 705 of providing a housing of the compressor, and then to step 710 of providing the housing with a lumen, preferably parallel to the compressor transfer line and situated so as to pass through the greatest possible thickness of the housing body, and as close as possible to the working fluid present therein, whilst ensuring the integrity of the cryogenic circuit and thereby containment of the working fluid, such that there will be no leaking of working fluid. The method then proceeds to step 715 ofand providing at least one heat pipe partially situated in the lumen and partial extending from the lumen before terminating at step 720. Figure 8 presents a in accordance with a further embodiment. As shown in figure 8, there is provided a system 800 comprising a cold finger 210 and compressor 830 substantially as described with reference to figures 2, 3, and 4, with like reference symbols corresponding to like features. As shown, the compressor 830 has a housing 434, the housing being provided with a first lumen 435 parallel to the compressor transfer line 216 and situated so as to pass through the greatest possible thickness of the housing body, and as close as possible to the working fluid present therein, whilst ensuring the integrity of the cryogenic circuit. A first heat pipe 836 is situated in the first lumen 435. Meanwhile, housing 834 is further provided with a second lumen (not shown), also parallel to the compressor transfer line 320 and situated so as to pass through the greatest possible thickness of the housing body, and as close as possible to the working fluid present therein, whilst ensuring the integrity of the cryogenic circuit and thereby containment of the working fluid, such that there will be no leaking ofworking fluid. A second heat pipe 837 is situated in the second lumen. Meanwhile, mounting body 814 of cryogenic cold finger element810 is provided with a first lumen 215 intersecting at least one outer surface of the mounting body. The cryogenic cold finger element further comprises a third heat pipe 816 partially situated in the lumen and partially extending from the lumen. Furthermore, mounting body 814 of cryogenic cold finger element 810 is provided with a second lumen (not shown) intersecting at least one outer surface of the mounting body. The cryogenic cold finger element further comprises a fourth heat pipe 817 partially situated in the lumen and partially extending from the lumen. As such, the embodiment of figure 8 presents an optional variant of the preceding embodiments in which both the cold finger and compressor are provided with multiple lumens and respective heat pipes. In this particular implementation, all heat pipes are aligned with the compressor transfer line, and furthermore situated on facing sides of the respective cold finger and compressor. lndeed, as shown, the respective heat pipes of the cold finger and compressor overlap to some degree, and are offset with respect to opposing elements so as not to intersect. This configuration achieves a maximum degree of heat dispersion with a minimum of added bulk. Further heat pipes may be added while maintaining this configuration with heat pipes emerging from opposing faces. Accordingly, embodiments including a cryogenic cooling system comprising a cold finger and a compressor unit connected by a compressor transfer line are provided, for example for cooling of a detector or similar device. Either or both of the cold finger and compressor unit which may be provided with one ormore heat pipes passing partially or wholly through the mounting body of the cold finger and / or housing of the compressor. ln preferred embodiments, each lumen is situated so as to pass through the greatest possible thickness of the mounting body, and as close as possible to the working fluid present therein, whilst ensuring the integrity of the cryogenic circuit. ln preferred embodiments, where the cold finger and / or housing of the compressor are substantially cylindrical, the lumens provided for the heat pipes describe chords of the circular cross section. The examples described above are given as non-limitative illustrations of embodiments of the invention. They do not in any way limit the scope of the invention which is defined by the following claims.

Claims

1. A cryogenic cold finger element for a cryogenic cooling system, where the cold finger element has a hot end and a cool end and defines a first axis, and a mounting body comprising a coupling for receiving working fluid of a compressor, where the mounting body is connected to the hot end of the cold finger element, where the system is characterized by the fact that the fastening body is provided with a lumen, where the lumen affects at least one outer surface of the fastener body cuts, whereby the cryogenic cold finger element further at least one comprises a heat pipe that is partially located within the lumen and partially protrudes from the lumen.

2. The cryogenic cold finger element according to claim 1 where the lumen is perpendicular to the axis stands and is shifted relative to it.

3. The cryogenic cold finger element according to claim 1 or 2 where the mounting body is provided with a number of lumens that are perpendicular to the axis and relative to it are shifted, and parallel to each other, where each lumen has at least one cuts the outer surface of the fastening body, whereby the cryogenic cold finger element furthermore includes a number of heat pipes that are partially located in the lumens.

4. The cryogenic cold finger element according to one of the preceding conclusions whereby the mentioned or each lumen is situated in such a way that it passes through the greatest possible thickness of the fastener body goes, and as close as possible to the working fluid contained therein, while the the integrity of the cryogenic circuit remains guaranteed.

5. The cryogenic cold finger element according to one of the preceding conclusions whereby the A cryogenic cold finger element is a Stirling cooler cold finger element.

6. The cryogenic cold finger element according to one of the preceding conclusions whereby the A cryogenic cold finger element is a pulse tube cooler cold finger element.

7. A method for constructing a cryogenic cold finger element comprising the steps of providing a cryogenic cold finger element with a warm tip and a cool end and that defines a first shaft, and a mounting body comprising a coupling for receiving working fluid from a compressor, where the the fastening body is connected to the warm end of the cold finger element, and providing a lumen, where the lumen affects at least one outer surface of the cuts the mounting body, and partially inserts a heat pipe into the lumen.

8. The method according to claim 7 whereby the step of providing a lumen the involves machining the lumen in the mounting body.

9. The method according to claim 7 or 8 comprising a further step of applying a low thermal conductive interface material on a surface of the lumen around the heat pipe to be thermally coupled to the mounting body when the heat pipe is in the lumen inserted.

10. A compressor for a cryogenic cooling system comprising a cryogenic cold finger element and a coupling for receiving working fluid from the compressor, where the compressor comprises a housing, where the housing is equipped with a lumen, where the compressor furthermore comprises at least one heat pipe that is partially located in the lumen is located and partially protrudes from the lumen.

11. The compressor within the meaning of claim 10, where the or each lumen is situated such that it passes through the greatest possible thickness of the housing, and as close as possible to the one inside present working fluid, while the integrity of the cryogenic circuit remains guaranteed.

12. The compressor according to claim 10 or 11 where at least one heat pipe is parallel installed on a compressor transfer line for connection to a cryogenic Cold finger element.

13. A method for constructing a compressor for a cryogenic cooling system comprising a cryogenic cold finger element and a coupling for receiving compressor working fluid, where the method involves providing a housing of the compressor, providing the housing with a lumen and providing ten at least one heat pipe that is partially within the lumen and partially outside the lumen stings.

14. The method according to claim 13 whereby the step of providing a lumen the involves machining the lumen in the housing.

15. The method according to claim 13 or 14 comprising a further step of the application of a low thermal conductive interface material on a surface of the lumen to the heat to thermally couple the pipe to the housing when the heat pipe is in the lumen inserted.

16. A cryogenic cooling system comprising a cryogenic cold finger element according to one of conclusions 1 through 6 and a compressor connected to the cold finger element through a compressor transfer line.

17. A cryogenic cooling system comprising a cryogenic cold finger element, for example according to one of the conclusions 1 to 6, and a compressor according to one of the conclusions 10 through 12, which is connected to the cold finger element by a compressor transfer line.

18. The cryogenic cooling system referred to in claim 16 or 17 where the at least one heat pipe is installed parallel to the compressor transfer line.

19. The cryogenic cooling system according to one of the conclusions 16 through 18 onwards comprising a layer of thermally conductive interface material between a surface of the lumen and a part of the heat pipe located in the mounting body to the heat pipe to be thermally coupled to the mounting body.

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