Modular cryogenic cooling system

Abstract

A modular cryogenic cooling system comprises an at least horizontal array of cryogenic modules (501, 502, 503, 504, 601, 701, 702, 703, 704, 1301, 1302, 1303, 1304, 1305) that together form a vacuum chamber. It comprises means (507, 707) for evacuating the vacuum chamber through a vertical end surface (401) of the horizontal array.

Description

[0001] CRYOGENIC COOLING MODULE AND CRYOGENIC COOLING SYSTEM

[0002] FIELD OF THE INVENTION

[0003] The invention is related to the technical field of cryogenic cooling systems . In particular the invention is related to structural and functional solutions that enable easier building, operating, maintenance, and later modification of a large cryogenic cooling system or a cryogenic platform.

[0004] BACKGROUND OF THE INVENTION

[0005] Cryogenic cooling systems are intricate pieces of machinery designed to cool a target region or payload volume down to very low temperatures and maintain such conditions for desired periods of time . The 13th International Congress of Refrigeration of the International Institute of Refrigeration established 120 K as the temperature of distinction between cryogenic and conventional refrigeration in 1971.

[0006] The payload to be cooled may contain e . g. a scientific experiment, a quantum computer, a measurement setup, and / or something else, the correct operation of which requires temperatures in the order of only some kelvins or even well below one kelvin. A cryogenic cooling system may also be called a cryostat . In some sources, the designation cryogenic cooling system is used for just that subsystem of a cryostat that produces the low temperatures, while the cryostat is additionally said to comprise other subsystems like mechanical support, vacuum pumping, radiation shielding, cabling, and the like . In this text the terms cryostat and cryogenic cooling system are used as synonyms of each other, possibly including an interpretation that a cryostat may be somewhat simpler, like a vacuum can with a single cold source (mechanical cooler or bath of liquid cryogen) , while a cryogenic cooling system may be moreelaborate with one or more outer cold sources for precooling and one or more inner cold sources (such as dilution refrigerators for example) to reach the coldest temperatures .

[0007] Fig . 1 is an exploded view of a modular cryogenic cooling system of the kind shown in a co-pending patent application FI 20245328, which is not yet available to public at the effective date of this text . The cryogenic cooling system of fig. 1 comprises two modules 101 and 102, as well as two end modules 103 and 104. In assembled configuration, these are connected to each other at the respective interfaces in the order 103-101-102-104 so that together, the outer shells of the modules and end modules form a vacuum chamber . Each module may comprise (parts of ) so-called cold plates, which are structures made of thermally conductive material (s) and configured to be actively cooled to and maintained at respective low temperatures during use of the cryogenic cooling system. Each module may also comprise (parts of ) actively cooled heat radiation shields, often provided in a nested configuration in which the purpose of each radiation shield is to block, absorb, and move out radiated heat from its surrounding structure . The number of radiation shields may vary; in one possible embodiment only one heat radiation shield at some suitably low intermediate temperature, like about 20 K for example, may be enough. In another example case, such a single intermediate temperature shield may be used together with one colder shield, like one at the temperature of the still of a dilution refrigerator .

[0008] Considering module 102 as an example, its outer shell is shown with reference designator 105. Three cold plate sections are shown with reference designators 106, 107 , and 108 inside the outer shell 105. Bottom plates of respective radiation shields are shown with reference designators 109, 110, and 111. Removable side plates of these three nested radiation shields are shownseparately with reference designators 112, 113, and 114. A removable part of one side face of the outer shell 105 constitutes an access door 115. Module 101 is shown with its respective radiation shields assembled and the respective access door 116 closed.

[0009] The interfaces between modules are essentially planar in fig. 1, so that in the assembled configuration, the cold plates 106, 107, and 108 may be thermally and / or mechanically coupled with respective cold plates in module 101 and the end modules 103 and 104. Similarly the radiation shields, parts of which are seen inside each module and the end module 103, will come together to form a structure of nested, shell-formed structures . Thermal and mechanical connections between adj acent cold plate sections and / or adj acent parts of radiation shields may be direct, with the appropriate parts directly attached to each other . Additionally, or alternatively, sealing strips or corresponding intermediate structures can be used to join adj acent sections and / or parts to each other .

[0010] A schematic cross section of a modular cryogenic cooling system of the kind shown in fig. 1 is shown in fig. 2. The modules 101 and 102 are in the middle, attached to each other, and the end modules 103 and 104 are at the ends . Assembled cold plates extend horizontally through the whole inside of the vacuum chamber so formed, consisting of the respective coplanar sections shown connected together in the drawing, with the lowest cold plate 201 singled out as an example . Similarly, three nested, shell-like radiation shields are formed of the mutually coupled sections within the modules 101 and 102 and end modules 103 and 104. The innermost radiation shield 202 is shown as an example .

[0011] In fig. 2, the modules 101 and 102 are not equal in function but specialized. Module 101 is equipped with refrigerators, vacuum pumps, and other general housekeeping functions as schematically shownwith block 203. Module 102 comprises actual payload, i . e . experiments and signal lines needed for conveying information between the cryogenically cooled domain and the surrounding room temperature domain, as schematically shown with block 204. It is also possible that each module in a modular cryogenic cooling system is relatively independent of the other modules, so that it comprises its own cooling and vacuum pumping systems, for example .

[0012] As cryogenic cooling systems grow larger and are required to house larger payloads, with more and more signal lines needed between the cryogenically cooled domain and the room temperature domain, problems arise concerning how all the required subsystems can find enough space in and around the outer shell that forms the main vacuum vessel . Problems also arise concerning how to ensure efficient cooling and standardized conditions (like constant temperature levels) throughout the system, as well as how to enable fluent operations in later maintaining, expanding, and modifying the modular cooling system.

[0013] In particular, it would be desirable to present solutions that enable providing large-scale cryogenic cooling systems in a flexible way that can be adapted to various and changing needs concerning cooling capacity, cooling technology, and base temperature, as well as payload size and shape . More advanced solutions would also be welcome in the sense of easier manufacturing of large-scale cryogenic systems and their transporting between manufacturing and installing locations .

[0014] SUMMARY

[0015] An obj ective is to present structural solutions that enable more efficient ways of using large cryogenic cooling systems .

[0016] These and further advantageous obj ectives are achieved by the features recited in the appended claims .According to a first aspect, there is provided a modular cryogenic cooling system, comprising an at least horizontal array of cryogenic modules that together form a vacuum chamber . The system comprises means for evacuating the vacuum chamber through a vertical end surface of the horizontal array.

[0017] According to an embodiment, the cryogenic modules in the horizontal array comprise a vacuum chamber module with one or more vertical sides, the vacuum chamber module having at least a first opening on a first one of said one or more vertical sides, with a vacuum finish arrangement on edges of said first opening for enabling gastight closing of said first opening. The cryogenic modules in the horizontal array may then comprise an end module, a shell of which fits said vacuum finish arrangement for gastightly closing said first opening with the end module . The means for evacuating the vacuum chamber through an end of the horizontal array may then comprise at least one vacuum pump subsystem configured to establish and maintain vacuum conditions inside a closed space limited by the vacuum chamber module and the end module . Said vacuum pump subsystem may be attached to a vertical section of said shell . This involves at least the advantage that a specialized end module may be provided, leaving more freedom form the design and contents of the vacuum chamber module ( s ) .

[0018] According to an embodiment, the at least one vacuum pump subsystem comprises at least one vacuum pump installed directly on said vertical section of said shell . This involves at least the advantage that a very short path is offered for gas molecules to leave the inside of the vacuum chamber and become affected by the vacuum pump .

[0019] According to an embodiment, the at least one vacuum pump subsystem comprises at least one vacuum pump coupled to said vertical section of said shell with aduct . This involves at least the advantage that mechanical vibration generated by such a vacuum pump is easier to isolate from the structure of the vacuum chamber .

[0020] According to an embodiment, the modular cryogenic cooling system comprises, supported inside said vacuum chamber module, a plurality of thermal stages spatially displaced from each other at least in the vertical direction and instrumentation connections to and from at least a subset of said thermal stages through a top side of the vacuum chamber module . This involves at least the advantage that vacuum pumping and instrumentation connections may be kept quite well separated from each other, leaving more space to each of them and facilitating easier servicing than if they would both be located in the same way in the cryogenic cooling system.

[0021] According to an embodiment, the modular cryogenic cooling system comprises, supported inside said vacuum chamber, one or more heat radiation shields that delimit respective subspaces inside the vacuum chamber and extend through the vacuum chamber in a horizontal direction defined by the horizontal array of cryogenic modules . A heat shield cooling subsystem may be configured to cool at least a subset of said one or more heat radiation shields with a refrigerator subsystem installed in a module that forms an end of the horizontal array. This involves at least the advantage that the cooling of heat shields may be kept separate from, and arranged in a different way than the cooling of payload structures, allowing more freedom and flexibility to the task of designing the cooling systems .

[0022] According to an embodiment, the heat shield cooling subsystem comprises one or more coolant circulation subsystems extending between parts of said heat radiation shields located in different ones of said cryogenic modules . Said one or more coolant circulation subsystems may then be thermally coupled with respectiveones of said parts of said heat radiation shields for cooling said parts of said heat radiation shields with coolant circulated in said one or more coolant circulation subsystems . This involves at least the advantage that relatively efficient cooling of the heat radiation shields may be achieved with structurally relatively simple solutions .

[0023] According to an embodiment, the modular cryogenic cooling system comprises a support system configured to support said one or more heat radiation shields inside said vacuum chamber, wherein said one or more coolant circulation subsystems comprise sections extending through respective parts of the support system. This involves at least the advantage that duplicate systems and structures inside the cryogenic cooling system can be at least partially avoided.

[0024] According to an embodiment, the modular cryogenic cooling system comprises connectors configured for repeated assembly and disassembly of module-specific parts of said one or more coolant circulation subsystems to and from each other, respectively. This involves at least the advantage that the cooling of heat radiation shields can be implemented in a modular way that allows relatively easy assembly and later modifications to the system.

[0025] According to an embodiment, the modular cryogenic cooling system comprises a mobile support system configured to allow moving at least a subset of said cryogenic modules in a direction that mechanically decouples two adj acent ones of said cryogenic modules from each other . This involves at least the advantage that later disassembling, modifying, and servicing of the system becomes easier .

[0026] According to an embodiment, said mobile support system comprises module-specific support modules attached to and supporting at least respective ones of said cryogenic modules and configured to be moved alongwith the respective module to which said module-specific support modules are attached. This involves at least the advantage that movement-facilitating features of the system may be designed separately from the cryogenic modules themselves, making designing tasks simpler and more straightforward.

[0027] According to an embodiment, the modular cryogenic cooling system comprises means for controllably moving said module-specific support modules in relation to each other in said direction that mechanically decouples two adj acent ones of said cryogenic modules from each other . This involves at least the advantage that even relatively heavy parts of the modular cryogenic cooling system can be moved in an accurate and highly controlled manner .

[0028] According to an embodiment, the modular cryogenic cooling system comprises vacuum-compliant compressible joints between at least a subset of mutually adj acent ones of said cryogenic modules . Each said vacuum-compliant compressible joint may then be removably attachable to at least one of the respective two cryogenic modules between which it is, and compressible for mechanically decoupling the two cryogenic modules between which it is . This involves at least the advantage that two cryogenic modules may be detached from each other without having to move any of them.

[0029] According to an embodiment, said vacuum-com-pliant compressible joints are bellows . This involves at least the advantage that a structural solution that is well known as such can be used.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with thedescription help to explain the principles of the invention. In the drawings :

[0032] Figure 1 is a schematic illustration of a modular cryogenic cooling system,

[0033] figure 2 is a schematic cross section of a modular cryogenic cooling system,

[0034] figure 3 is a schematic cross section of a modular cryogenic cooling system,

[0035] figure 4 illustrates an end of a horizontal array of modules of a modular cryogenic cooling system, figure 5 is a schematic cross section of a modular cryogenic cooling system,

[0036] figure 6 is a schematic cross section of a modular cryogenic cooling system,

[0037] figure 7 is a schematic cross section of a modular cryogenic cooling system,

[0038] figure 8 is a block diagram of a modular cryogenic cooling system,

[0039] figure 9 illustrates schematically the circulation of cooling fluid through parts of a modular cryogenic cooling system,

[0040] figure 10 is a schematic illustration of a modular cryogenic cooling system,

[0041] figure 11 illustrates a disassembling step of a modular cryogenic cooling system,

[0042] figure 12 illustrates a disassembling step of a modular cryogenic cooling system,

[0043] figure 13 illustrates steps of disassembling a modular cryogenic cooling system,

[0044] figure 14 illustrates steps of disassembling a modular cryogenic cooling system,

[0045] figure 15 illustrates an alternative embodiment of a modular cryogenic cooling system, and figure 16 illustrates an alternative embodiment of a modular cryogenic cooling system.

[0046] DETAILED DESCRIPTIONIn the following description, reference is made to the accompanying drawings, which form part of the disclosure, and in which are shown, by way of illustration, specific aspects in which the present disclosure may be placed. It is understood that other aspects may be utilised, and structural or logical changes may be made without departing from the scope of the present disclosure . The following detailed description, therefore, is not to be taken in a limiting sense, as the scope of the present disclosure is defined by the appended claims .

[0047] For instance, it is understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures . On the other hand, for example, if a specific apparatus is described based on functional units, a corresponding method may include a step performing the described functionality, even if such step is not explicitly described or illustrated in the figures . Further, it is understood that the features of the various example aspects described herein may be combined with each other, unless specifically noted otherwise .

[0048] In conventional cryogenic cooling systems, cold plates are typically arranged in a stack below the top flange of the vacuum chamber so that each cold plate is maintained at a lower temperature than those above it in the stack. A major reason for using the conventional approach is the dependency of certain cryogenic refrigerators, like dilution refrigerators for example, of an appropriate vertical or nearly vertical orientation. Also typically, the main vacuum chamber has been manufactured as a cylindrical shell that has as fewopenings, welding seams, or other potential weak spots as possible except its open top end that is closed by a room temperature flange . The conventional approach has meant that in a modular cryogenic cooling system like that in figs . 1 and 2, both the couplings required to operate the payload and the support functionalities like cooling, vacuum pumping, and general housekeeping (telemetry, movable mechanisms etc . ) have found their place in and on the top surface of the system.

[0049] It has now been found, however, that the concept of modularity may allow rethinking some of the previously obeyed principles . As an illustrative example, fig. 3 may be considered. Fig. 3 is a simplified side view of a module marked with the reference designator 102 to facilitate comparison to figs . 1 and 2. The side view in fig . 3 may be considered as the view into module 102 in fig. 2, taken from the right in fig. 2 with the end module 104 removed. The top surface of the module 102, which in a conventional arrangement should house functionalities such as payload couplings, vacuum pumping, cooling, and housekeeping, is marked with reference designator 301. In the direction therefrom towards the coldest parts inside the module are, supported inside the module 102, the cold plates or thermal stages 302, 303, 304, 305, and 306. These are parallel to each other and spatially displaced from each other in the vertical direction. Schematically shown with reference designators 307, 308, 309, 310, and 311 are the heat radiation shields . They are also supported inside the module and delimit respective subspaces inside the module . Considering a modular cryogenic cooling system in which the modules form an at least horizontal array, together forming a vacuum chamber, the heat radiation shields delimit respective subspaces inside the vacuum chamber . One or more of them may extend through the vacuum chamber in the horizontal direction defined by the horizontal array of cryogenic modules .The task of evacuating the vacuum chamber requires vacuum pumping. It also requires that the air and / or other gaseous mediums inside the vacuum chamber must have a relatively unobstructed passage to the inlet (s) of the pump (s) used for the evacuating. This latter requirement becomes the more prominent the lower the pressure gets inside the vacuum chamber, as the three-dimensional movement of gas atoms and molecules is stochastic by nature, formed of randomly directed essentially linear sections between collisions to the solid structures and the other particles . A gaseous particle inside the vacuum chamber can only get pumped out once it finds its way to the inlet of (one of) the pump (s) . It is easy to see in fig. 3 how a relatively small proportion of the enclosed space is such from which a particle moving along a straight line may hit a particular opening in the top surface 301 (where an inlet of a vacuum pump is located) .

[0050] Fig. 4 is a schematic illustration of an end of a modular cryogenic cooling system, where an opening on one of the sides of a vacuum module 102 is closed with an end module 104 . The end surface of the modular cryogenic cooling system, which is the vertical side of the end module 104, is marked with reference designator 401. In fig. 4 it is assumed that all five thermal stages and all five heat radiation shields seen in fig. 3 extend all the way to the internal volume of the end module 104, as shown with dashed lines in fig. 4.

[0051] From fig. 4 it can be seen how the end surface 401 is, to begin with, much larger than the top surface 301 seen in fig. 3. Additionally, as a significant portion of e . g. cooling and payload couplings may still go through the top side but there are few functionalities that would conventionally be placed on a surface like the end surface 401 , there may be a significant amount of free space on the end surface 401. Also additionally, it must be noted that the modular cryogenic coolingsystem may continue to the left from the part shown in fig . 4 for a significant distance . At least above, below, and on sides of the structural entity defined by the radiation shields there may be relatively large portions of the internal volume of the whole vacuum chamber from which a freely moving gaseous particle may reach a specific part of the end surface with a single stretch of linear movement .

[0052] As a general conclusion from that above, for efficient vacuum pumping it may be more advantageous to evacuate the vacuum chamber of a modular cryogenic cooling system through an end than through a top side of the (at least partly) horizontal array of modules . Among others, one significant advantage that may be gained this way involves leaving relatively more space on the top side for other functionalities than vacuum pumping.

[0053] Fig. 5 illustrates the principle of a modular cryogenic cooling system that builds on the findings described above . The modular cryogenic cooling system comprises an at least horizontal array of cryogenic modules, which in fig. 5 are the modules 501, 502, 503, and 504. Being at least horizontal means that the principle illustrated in fig. 5 and explained in this text does not exclude having one or more modules in the modular cryogenic cooling system on top of each other, forming a vertical section of the array of cryogenic modules . Being cryogenic modules means that the modules are built to withstand and support cryogenic cooling of at least a part of their internal volume .

[0054] Together, the cryogenic modules 501, 502, 503, and 504 form a vacuum chamber . This means that when assembled together, they delimit a gastightly closed space within which all materials and structures, as well as the interfaces between adj acent cryogenic modules, are designed to withstand an internal pressure of 1 Pa or lower with the outside of the vacuum chamber being at atmospheric pressure .A modular cryogenic cooling system that follows the principle of fig. 5 comprises means for evacuating the vacuum chamber through an end of the horizontal array of cryogenic modules . In fig. 5, such means are included in the block generally referred to with the reference designator 507. Examples of hardware that may be used as such means include, but are not limited to, rotary vane vacuum pumps, sliding vane pumps, rotating pumps, Roots pumps, diffusion pumps, turbo pumps, and absorption pumps . One or more such pumps may be included in the means 507 for evacuating the vacuum chamber through the end thereof .

[0055] Conceptually and for ease of reference in the following description, modules of a modular cryogenic cooling system may be categorized as vacuum chamber modules and end modules . While the distinction between a vacuum chamber module and an end module does not need to be completely unambiguous, in general it may be thought that a vacuum chamber module is a "basic" module or building block in the (at least) horizontal array of cryogenic modules, so that one may construct a modular cryogenic cooling system of a desired size by placing a corresponding number of vacuum chamber modules next to each other . An end module is, as the name indicates, a module that closes an end of the (at least) horizontal array of cryogenic modules . In fig. 5, modules 501 and 502 are vacuum chamber modules and modules 503 and 504 are end modules .

[0056] In more detail, a vacuum chamber module may be characterized as having one or more vertical sides and at least a first opening on a first one said one or more vertical sides . A vacuum finish arrangement such as a sealing surface and / or sealant should be provided on edges of the first opening for enabling gastight closing of the first opening. Similarly, an end module may be characterized as having a shell that fits the vacuum finish arrangement for gastightly closing the firstopening with the end module . In fig. 5, the vacuum chamber modules 501 and 502 have openings on their two opposite vertical sides, so that it would be possible to construct an arbitrarily long linear, horizontal array of cryogenic modules by placing as many similar vacuum chamber modules as needed in line and closing both ends with respective end modules .

[0057] The most basic approach described earlier in document FI 20245328 assumed that all instrumentation, be it for operating the payload or maintaining the internal conditions of the cryogenic cooling system, was built in those modules that would be called vacuum chamber modules according to the categorization above . Also according to the most basic approach, an end module would only comprise a set of end pieces to close those ends of the radiation shields and the vacuum chamber that the structure of the last vacuum chamber module left open. However, this is not necessarily so . First of all, as already described above, certain advantages are gained by placing at least means for evacuating the vacuum chamber in an end module (or possibly in a plurality of end modules, if there are two or more) . Second, as also mentioned above already, the distinction between a vacuum chamber module and an end module is not necessarily as strict as in the document FI 20245328. Fig. 6 illustrates a modular cryogenic cooling system that is otherwise similar to that of fig. 5 but in place of the vacuum chamber module 501 and end module 503 combination, there is a combined module 601. Notable is that module 601 fulfils the more detailed definitions of both a vacuum chamber module and an end module given above . It would be possible to construct a workable modular cryogenic cooling system just by placing two modules like module 601 against each other. It would also be possible to construct a workable modular cryogenic cooling system by having one or more modules like module 502in figs . 5 and 6 in the middle and a module like module 602 at each end.

[0058] Preferably, the means 507 for evacuating the vacuum chamber through an end of the (at least) horizontal array comprises at least one vacuum pump subsystem that is configured to establish and maintain vacuum conditions inside a closed space that is limited by the vacuum chamber module (s) and the end module ( s) . Such a vacuum pump subsystem may be attached to a vertical section of the shell of the respective end module . If there are two or more end modules in the horizontal array of cryogenic modules, a vacuum pump subsystem may be attached to a vertical section of the shell of one of them, or there may be two or more vacuum pump subsystems, each attached to a vertical section of the shell of the respective end module .

[0059] The vacuum pump subsystem 507 may comprise at least one vacuum pump installed directly on the vertical section 401 (see fig. 4 ) of the shell of the end module . This way the inlet to such a vacuum pump (or such vacuum pumps) can be brought as close as possible to the internal volume that is to be evacuated, which widens the spatial angle inside the vacuum chamber from which a gas particle may come directly to the working zone of the vacuum pump (s) .

[0060] Additionally, or alternatively, the vacuum pump subsystem may comprise at least one vacuum pump coupled to a vertical section 401 of the shell of the end module with a duct . Advantages of a duct coupling may include at least somewhat easier installing of a gate valve with which the opening in the vacuum chamber can be closed in case the pump must be taken for maintenance or repairs . A duct coupling may also help to reduce the conduction of mechanical vibrations between the pump and the vacuum chamber .

[0061] In addition to vacuum pumping, the subsystems included in the schematically shown block 507 in figs .5 and 6 may comprise other functionalities . As an example, at least a part of the cooling required to make the inner parts reach their operating temperatures and to maintain these temperatures may be implemented in one or more of the end modules included in the system. Additionally, or alternatively, functionalities that would count as housekeeping and that are not directly related to operating the payload may be implemented in one or more of the end modules included in the system. Housekeeping functionalities may comprise for example monitoring and / or control functions for parameters such as temperature, pressure, and the like .

[0062] In figs . 5 and 6 (as well as fig. 7 ) , the hatched horizontal blocks inside the vacuum chamber represent a plurality of thermal stages that are supported inside at least the respective vacuum chamber module (s) and spatially displaced from each other at least in the vertical direction. Instrumentation connections to and from at least a subset of such thermal stages may go through a top side of the respective vacuum chamber module (s) . in figs . 5, 6, and 7, such instrumentation connections are schematically represented by blocks 505, 506, 705, and 706. Instrumentation connections may comprise signal lines to and from electric, optical, and / or quantum processing circuits included in the cryogenically refrigerated payload, for example . Additionally, or alternatively, instrumentation connections of said kind may comprise electric connections and / or fluid piping required by parts of the refrigeration subsystems . For example, one or more of the vacuum chamber modules may comprise respective one or more dilution refrigerators configured to create and maintain the lowest temperatures inside the modular cryogenic cooling system.

[0063] The modular cryogenic cooling system may comprise one or more heat radiation shields supported inside the vacuum chamber . Each such heat radiation shield may delimit a respective subspace in the vacuum chamber .At least one such heat radiation shield may extend through the vacuum chamber in a horizontal direction defined by the (at least) horizontal array of cryogenic modules . In figs . 5, 6, and 7 , the three nested, horizontally oriented rectangular forms represent heat radiation shields . It should be noted that while all three heat radiation shields are shown to extend through the whole vacuum chamber in figs . 5, 6, and 7, this is only a schematic graphical representation. It is possible to have heat radiation shields inside the vacuum chamber that only delimit a subspace within one cryogenic module or a subset of the cryogenic modules in the system.

[0064] The purpose of a heat radiation shield of the kind referred to above is to prevent radiated thermal energy from entering the subspace delimited by the shield. The heat radiation shield (s) meant here should not be gastight, because it must be possible to use the vacuum pump subsystem of the modular cryogenic cooling system to pump all gaseous media out of also the subspace (s) delimited by the heat radiation shield (s) . While the heat radiation shield (s) should thus have opening (s) in them, it is advisable to equip such opening (s) with one or more maze structures to block all direct paths of externally propagating radiated thermal energy into the space delimited by the respective heat radiation shield.

[0065] If one or more heat radiation shields are provided, it is advantageous to make the heat shield cooling subsystem configured to cool at least a subset of them with a refrigerator subsystem installed in a module that forms an end of the horizontal array. In figs . 5 and 6, this means particularly the end module 504, although in fig. 6 it may mean also the module 601 that fulfils the definitions of both a vacuum chamber module .

[0066] A dedicated cooling subsystem for heat radiation shield (s) is not needed, if each heat shield in the modular cryogenic cooling system is thermally coupledto a respective thermal stage and hence cooled together therewith. It may, however, be advantageous to have a dedicated cooling subsystem for at least one of the heat shields, as this reduces the heat load on the subsystem (s) used to cool the thermal stages and may help to optimize the cooling powers dedicated to each purpose in the system. For example, it is not necessary to have a heat radiation shield at exactly the same temperature as the corresponding thermal stage, the specified temperature of which may come from some requirement of the payload. It may be more advantageous to dedicate some subsystem (s) to maintaining the thermal stage (s) accurately at the desired temperature ( s ) and to separately maintain the temperature of heat radiation shield (s) within ranges that suffice to reduce the inwards radiated heat below some acceptable threshold.

[0067] Fig. 7 illustrates an example of a modular cryogenic cooling system in which at least a majority of the subsystems used for cooling are implemented in the end modules 703 and 704, so that the vacuum chamber modules 701 and 702 in the middle can be completely dedicated for payload functionalities, if needed. Additionally in the embodiment of fig. 7, the cooling of heat radiation shields is at least partly separated from the cooling of thermal stages . The first end module 703 on the right comprises, as a part of block 707, a heat shield cooling subsystem configured to cool at least a subset of the heat radiation shields with a first refrigerator subsystem installed in the end module 703. The second end module 704 comprises, as a part of block 708, a thermal stages cooling subsystem configured to cool at least a subset of the thermal stages with a second refrigerator subsystem installed in the end module 704.

[0068] Performing all or at least most of the cooling of the thermal stages in one module, like in the second end module 704 of fig. 7, requires thermal couplingsbetween sections of such thermal stages located in different modules . Sections of thermal stages may be thermally coupled to each other for example by connecting them directly to each other, if their edges come close enough to the interface between modules . Additionally, or alternatively, intermediating structures like sealing strips, thermally conductive braids, controllable heat switches, or the like can be used between thermal stages .

[0069] Further examples shown in fig. 7 include the provision of means for evacuating the vacuum chamber through its rightmost end in end module 703; mechanics for performing operations inside the vacuum chamber in end module 703; delivery of operating power to instruments inside the vacuum chamber in end module 704 ; and telemetry subsystems for monitoring measured parameter values inside the vacuum chamber in end module 704.

[0070] A further example shown in fig. 7 is the possible provision of an optics subsystem 709 that can be used to set up and maintain optically conveyed couplings between a working area inside the modular cryogenic cooling system and the surrounding room temperature environment . In the embodiment of fig. 7, the optical interface between the inside of the modular cryogenic cooling system and the environment is in an end module 704. Advantages of such a solution can be based on reasons same as those described above with reference to fig. 3. From an end of the horizontal array of cryogenic modules, there may be a direct passage through empty space that goes through at least most of the length of the horizontal array of modules . Such an empty space can be used to convey optical radiation, such as a laser beam for example, from which desired portions can be coupled to or from hardware sections within individual modules by using half-reflective mirrors and / or other kinds of suitably located optical couplers .Another further example shown in fig. 7 is the possible provision of a mechanics subsystem 710 that can be used to operate one or more mechanisms in one or more of the interconnected modules of the modular cryogenic cooling system. An example of what a mechanics subsystem 710 could comprise is a shaft or axis penetrating through the outer shell of the end module 704 at a vacuum-proof sealing. By manipulating the outer end of such a shaft or axis, the operator might operate one or more mechanisms inside the modular cryogenic cooling system. If a mechanics subsystem 710 continues through two or more modules, it may be used to cause synchronized movements in such modules . The mechanics subsystem 710, if present, may be closely associated with some other subsystems like the optics subsystem 709; as an example, the mechanics subsystem 710 may offer a way to move one or more mirrors that have a function within the optics subsystem 709. A mechanics subsystem could also be used to manipulate one or more samples, one or more heat switches, or other targets inside the modular cryogenic cooling system.

[0071] In previously known cryogenic cooling systems, whether modular or not, two basic approaches to cooling heat radiation shields were used. The oldest approach involves one or more baths of liquid cryogens surrounding the heat radiation shield to be cooled. Later, cry-ogen-free cooling has been used in which one or more mechanical refrigerators, such as pulse tubes, Gifford-McMahon refrigerators, or the like, are thermally coupled to each heat radiation shield that is to be cooled. The conventional solutions involve some drawbacks that become distinctly visible when one tries to scale up the payload volume of a cryogenic cooling system, for example by using the modular approach. It would be desirable to provide new ways of cooling heat radiation shields, with particular applicability to modular cryogenic cooling systems .Fig. 8 illustrates a modular cryogenic cooling system in which an array of cryogenic modules 801, 802, 803, and 804 form a vacuum chamber together . Notable is that the modular cryogenic cooling system of fig. 8 may have one or more of the characteristics described earlier in this text, like the means for evacuating the vacuum chamber through an end of the horizontal array; various possible couplings between thermal stages; cooling of thermal stages arranged in any way described or pointed at above; installing of vacuum pump (s) directly on a vertical section of an end module or coupling with a duct; instrumentation connections through top side (s) of vacuum chamber module; various ways of distributing functionalities in (and / or between) end modules, and the like . However, the principle illustrated in fig. 8 and described in detail in the following is equally applicable to modular cryogenic cooling systems that do not have any of said characteristics described earlier in this text .

[0072] Supported inside the vacuum chamber are one or more heat radiation shields . In the example shown in fig, 8, there are two heat radiation shields 805 and 806 that delimit respective subspaces inside the vacuum chamber and extend through the vacuum chamber . The subspace delimited by the inner heat radiation shield 806 is inside the respective subspace delimited by the outer heat radiation shield 805. Both heat radiation shields 805 and 806 may comprise module-specific sections as shown in solid lines in fig. 8, coupled together as shown with dashed lines in fig. 8. The couplings may have the form of direct couplings between edges of the sections, or they may comprise extending sections therebetween .

[0073] The cooling of heat radiation shields inside the vacuum chamber represents a special case of a general principle described above with reference to figs .

[0074] 5, 6, and 7. In fig. 8, a heat shield cooling subsystem809 is installed in module 804 that forms the righthand end of the horizontal array of cryogenic modules 801, 802, 803, and 804. The modular cryogenic cooling system comprises one or more coolant circulation subsystems (see reference designators 807 and 808 in fig .

[0075] 8 ) extending between such parts of the heat radiation shields 805 and 806 that are located in different ones of the cryogenic modules 801, 802, 803, and 804.

[0076] The one or more coolant circulation subsystems 807 and 808 are thermally coupled with respective ones of the parts of said heat radiation shields 805 and 806. The purpose of such thermal coupling is to cooling the respective parts of the heat radiation shields 805 and 806 with coolant circulated in the one or more coolant circulation subsystems 807 and 808. Examples of coolants that may be circulated in the one or more coolant circulation subsystems 807 and 808 include, but are not limited to, liquid nitrogen; liquid helium; liquid carbon dioxide; liquid neon; gaseous helium; any of said substances in a mixed-phase form containing both gaseous and liquid components .

[0077] The heat shield cooling subsystem 809 comprises means for circulating refrigerated coolant through the one or more coolant circulation subsystems 807 and 808. Refrigeration of the coolant may take place in the heat shield cooling subsystem 809, i . e . in or at least in close association with the end module 804. Additionally, or alternatively, one or more parts of the heat shield cooling subsystem 809 may be located outside the cryostat . Such an externally located part of the heat shield cooling subsystem 809 may comprise for example a refrigeration plant used to cool down coolant ( s) that is to be circulated through the the one or more coolant circulation subsystems 807 and 808. Additionally, or alternatively, there may be coolant refrigeration units elsewhere, like intermittently along one or more of the coolant circulation subsystems 807 and 808, and / or builtin the structure (s) of some other module (s) , and / or more remotely located in relation to the modular cryogenic cooling system. Also pumping or other form of advancing the circulation of the coolant in the one or more coolant circulation subsystems 807 and 808 may be implemented in any or all of the locations mentioned above . Hence, in a very simple form, the heat shield cooling subsystem 809 may consist of only some fluid connectors through which externally provided, refrigerated coolant may be put into circulation in the one or more coolant circulation subsystems 807 and 808. At the other end of the complexity axis, the heat shield cooling subsystem 809 may be a self-contained unit comprising all refrigerating and pumping means that are necessary for the purpose explained above .

[0078] A modular cryogenic cooling system that employs the principle shown in fig. 8 may comprise a support system configured to support the one or more heat radiation shields 805 and 806 inside the vacuum chamber . An example of such a support system is shown with reference designator 901 in fig. 9. The one or more coolant circulation subsystems 807 and 808 may comprise sections that extend through respective parts of the support system 901. Additionally, or alternatively, the one or more coolant circulation subsystems 807 and 808 may comprise loop-formed portions, intermediate reservoirs, and / or other kind of additional parts that serve to offer more efficient transfer of heat between (at least some part of ) the heat radiation shields 805 and 806 and the coolant circuilated in the one or more coolant circulation subsystems 807 and 808.

[0079] According to the principle schematically shown in fig . 9, the support system 901 may consist of bars, tubes, and / or other elongate, relatively narrow pieces that in the assembled configuration support plate-like elements that constitute the heat radiation shields . An advantage of such a structural principle is that thesupport system 901 (or at least substantial part (s) of it) may remain in place inside the modular cryogenic cooling system even if some or all of the plate-like elements are temporarily removed to allow access to internal parts of the modular cryogenic cooling system. It may be possible to construct a support system 901 consisting of such narrow, elongate pieces so that it does not obstruct access to said internal parts to any significant extent .

[0080] Making one or more coolant circulation subsystems 807 and / or 808 comprise sections that extend through respective parts of the support system 901 brings about several additional advantages . Elements through which a coolant should flow may be naturally tubular in form, which means that a piece of the support system 901 may have double functions, saving space and reducing structural complexity. Also, as the coolant circulation subsystem (s) must be as leak-free as possible, it is advantageous if the coolant circulation subsystem (s) need not be disassembled for routine maintenance of the modular cryogenic cooling system and / or for temporary access to its working region. In the advantageous case, the coolant circulation subsystem (s) may remain in place just like the support system as explained above .

[0081] A further advantageous possibility shown in fig. 9 is the possible use of connectors 902 and 903 configured for repeated assembly and disassembly of module-specific parts of the one or more coolant circulation subsystems 807 and / or 808 to and from each other, respectively. An alternative is to make at least one of the coolant circulation subsystems consist of one or more complete loops of conduits so that each such coolant circulation subsystem can be assembled to and disassembled from the modular cryogenic cooling system as a whole .Once a modular cryogenic cooling systems has been assembled, there will certainly come a time when at least one of its modules should be taken apart . For example, the operator of the system may want to replace a module that has become obsolete with an updated one, or one of the modules should be taken apart for more extensive repairs or modifications than what are possible or practical when it remains as a part of the system assembled as a horizontal array of modules . Additionally, or alternatively, the order of vacuum chamber modules in an assembled system may need to be changed, and / or one or more modules should be taken out from or added to an existing system. This may involve practical difficulties, as the modules can be expected to be relatively heavy and difficult to move without damaging any of their structures or the vacuum finish on those interfaces that should be gastightly closed afterwards .

[0082] Figs . 10, 11, and 12 illustrate a process of taking a vacuum chamber module out of a modular cryogenic cooling system that consists of three vacuum chamber modules 1001, 1002, and 1003 as well as two end modules 1004 and 1005, all forming a linear horizontal array of modules . Together, the modules 1001, 1002, 1003, 1004, and 1005 form a vacuum chamber .

[0083] In this embodiment, each vacuum chamber module 1001, 1002, and 1003 has removable panels on those of its vertical sides that remain visible and accessible in the assembled system. Fig. 11 shows how the removable panels 1101 and 1102 of the centre module may be removed, providing access to the inside of the modular cryogenic cooling system. This way all couplings and connections between adj acent modules 1001 and 1002, and / or 1002 and 1003, if any, may be disassembled. Also, all bolts, clamps, and / or other attachment means that hold the modules 1001, 1002, and 1003 together and gastightly attached to each other may be removed. In embodiments where all such disassembling of couplings andconnections and removing of attachment means can be made with actions taking place outside the modules, there is no need to remove any side panels . Additionally, or alternatively, one or both of the end modules 1004 and 1005 may be removed for disassembling of couplings and connections and / or removing of attachment means, if needed .

[0084] Also shown in fig. 11 are the actions of moving the assembly of vacuum chamber module 1001 and end module 1005 outwards (towards back left in fig. 11 ) and moving the assembly of vacuum chamber module 1003 and end module 1004 outwards (towards front right in fig.

[0085] 11) from the centre module 1002. Fig. 12 then shows how the centre module 1002 may be removed from the horizontal array of modules by moving it in a direction perpendicular to the main orientation of the horizontal array of modules .

[0086] Fig. 13 illustrates a solution that facilitates reducing into practice the principle shown above in figs 10 to 12. Notable is that the modular cryogenic cooling system of fig. 13 may have one or more of the characteristics described earlier in this text, like the means for evacuating the vacuum chamber through an end of the horizontal array; various possible couplings between thermal stages; cooling of thermal stages arranged in any way described or pointed at above; installing of vacuum pump (s) directly on a vertical section of an end module or coupling with a duct; instrumentation connections through top side (s) of vacuum chamber module; various ways of distributing functionalities in (and / or between) end modules; cooling of radiation shields with at least one coolant circulation subsystems; and the like . However, the principle illustrated in fig. 13 and described in detail in the following is equally applicable to modular cryogenic cooling systems that do not have any of said characteristics described earlier in this text .The modular cryogenic cooling system of fig.

[0087] 13 comprises an array of cryogenic modules 1301, 1302, 1303, 1304, and 1305 that together form a vacuum chamber . It comprises also a mobile support system 1306 configured to allow moving at least a subset of the cryogenic modules 1301, 1302, 1303, 1304, and 1305 in a direction that mechanically decouples two adj acent ones of them from each other .

[0088] In the embodiment of fig . 13, the mobile support system 1306 comprises module-specific support modules 1307, 1308, and 1309 attached to and supporting at least respective ones of the cryogenic modules . 1301, 1302, 1303, 1304, and 1305. Here, such module-specific support modules appear under the vacuum chamber modules 1302, 1303, and 1304. It may be assumed that, at least in this embodiment, the end modules 1301 and 1305 are smaller in size and lighter in weight compared to the vacuum chamber modules to the extent that if needed, each of them can be lifted off without having to move it on any module-specific support module of its own. Additionally, or alternatively, each end module 1301 and 1305 may have a hinged connection to its adj acent vacuum chamber module 1302 or 1304, so that the end module 1301 or 1305 can be opened like a door, if needed.

[0089] Each of the module-specific support modules 1307, 1308, and 1309 is configured to be moved along with the respective module to which said module-specific support module 1307, 1308, or 1309 is attached. Each vacuum chamber module 1302, 1303, or 1304 may be for example bolted to its respective module-specific support module . If needed, rails 1310 or other kind of further support structures may be employed to facilitate easier moving of cryogenic modules on their respective support modules . If rails are used, they may extend linearly in one direction. Alternatively, there may be rails in at least two different directions to allow moving at least some of the cryogenic modules in respective differentdirections . Another example of a further support structure is an air caster, air bearing, or air cushion subsystem configured to form a thin air film on which heavy loads like cryogenic modules can be floated for easier moving. Notable is that the provision of module-specific support modules 1307, 1308, or 1309 is not necessary if similar movement-facilitating features are built in the cryogenic modules themselves .

[0090] The modular cryogenic cooling system may comprise means 1311 for controllably moving the modulespecific support modules 1307, 1308 , and 1309 in relation to each other in the direction that mechanically decouples two adj acent ones of said cryogenic modules 1301, 1302, 1303, 1304, or 1305 from each other . The means 1311 for controllably moving the module-specific support modules 1307, 1308, and 1309 may comprise any known elongate, telescopically extending and contracting actuators, like sets of worm wheels or threaded rods and corresponding toothed sections or threaded sleeves, for example . By selecting which sections of the telescopically extending and contracting actuators to actuate, the operator of the system may decide, which modules are to be mechanically decoupled.

[0091] In fig. 13 it is assumed that once the desired mechanical decoupling of modules from each other has been achieved, one or more of the modules may be detached from its module-specific support module and moved away using a crane, for example . It is also possible that the module-specific support modules could be detached from each other, so that the module that is to be removed could be moved away together with its module-specific support module .

[0092] In some cases, it may be desirable not to move any of those modules that are not to be removed from the assembled modular cryogenic cooling system. It may be desirable, though, to get some clearance between a module that is to be removed and those adj acent modulesthat are not to be moved. Fig. 14 illustrates a principle that makes it possible .

[0093] In fig. 14, a modular cryogenic cooling system, comprises an array of cryogenic modules 1301, 1302, 1303, 1304, and 1305 configured to form parts of a common vacuum chamber . Notable is that the modular cryogenic cooling system of fig. 14 may have one or more of the characteristics described earlier in this text, like the means for evacuating the vacuum chamber through an end of the horizontal array; various possible couplings between thermal stages; cooling of thermal stages arranged in any way described or pointed at above; installing of vacuum pump (s) directly on a vertical section of an end module or coupling with a duct; instrumentation connections through top side (s) of vacuum chamber module; various ways of distributing functionalities in (and / or between) end modules; cooling of radiation shields with at least one coolant circulation subsystems; a mobile support system configured to allow moving at least a subset of the cryogenic modules; further support structures to facilitate easier moving of cryogenic modules on their respective support modules; and the like . However, the principle illustrated in fig. 14 and described in detail in the following is equally applicable to modular cryogenic cooling systems that do not have any of said characteristics described earlier in this text .

[0094] As shown with reference designators 1401 and 1402, the modular cryogenic cooling system comprises vacuum-compliant compressible joints between at least a subset of mutually adj acent ones of the cryogenic modules; here between the vacuum chamber modules 1302, 1303, and 1304. Each such vacuum-compliant compressible joint 1401 and 1402 is removably attachable to at least one of the respective two cryogenic modules 1302, 1303, or 1304 between which it is . Each such vacuum-compliant compressible joint 1401 and 1402 is also compressible for mechanically decoupling the two cryogenic modules1302, 1303, or 1304 between which it is . The middle part of fig. 14 shows how the vacuum-compliant compressible joints 1401 and 1402 have been detached from the centre module 1303 and compressed towards the respective module in which the vacuum-compliant compressible joint is still attached. This provides a clearance on both sides of the centre module 1303, which can subsequently be safely removed as shown in the lowest part of fig. 14.

[0095] A non-limiting example of vacuum-compliant compressible joints 1401 and 1402 are bellows . Being vacuum-compliant means that the structure must remain gastight even after it has been compressed and extended a number of times .

[0096] Above, an end of the (at least) horizontal array of cryogenic modules, through which the vacuum chamber is to be evacuated, has been considered to consist of a single, planar, vertical surface oriented essentially perpendicular to a main direction defined by the horizontal array of modules . This is not necessarily the case, as the end of the (at least) horizontal array of cryogenic modules can be designed in different ways . Fig. 15 shows a modular cryogenic cooling system in which the end of the horizontal array of cryogenic modules consists of two planar, vertical surfaces 1501 and 1502 that are not oriented perpendicular to the main direction defined by the horizontal array of modules . Fig. 16 shows a modular cryogenic cooling system in which the end of the horizontal array of cryogenic modules consists of a curved, vertical surface . Fig. 17 shows a modular cryogenic cooling system in which the end of the horizontal array of cryogenic modules consists of a non-vertical surface 1701.

[0097] It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways . The invention and its embodiments are thus not limited tothe examples described above, instead they may vary within the scope of the claims .

Claims

CLAIMS1. A modular cryogenic cooling system, comprising an at least horizontal array of cryogenic modules (501, 502, 503, 504, 601, 701, 702, 703, 704, 1301, 1302, 1303, 1304, 1305) that together form a vacuum chamber,characterized in that it comprises means (507, 707 ) for evacuating the vacuum chamber through a vertical end surface (401 ) of the horizontal array.

2. A modular cryogenic cooling system according to claim 1, wherein the cryogenic modules in the horizontal array comprise :- a vacuum chamber module (501, 502, 601, 701, 702, 1302, 1303, 1304 ) with one or more vertical sides, the vacuum chamber module (501, 502, 601, 701, 702, 1302, 1303, 1304 ) having at least a first opening on a first one of said one or more vertical sides, with a vacuum finish arrangement on edges of said first opening for enabling gastight closing of said first opening, and - an end module (504, 703, 704, 1301, 1305) , a shell of which fits said vacuum finish arrangement for gas-tightly closing said first opening with the end module (504, 703, 704, 1301, 1305) ;wherein the means (507, 707 ) for evacuating the vacuum chamber through an end (401 ) of the horizontal array comprises at least one vacuum pump subsystem (507, 707 ) configured to establish and maintain vacuum conditions inside a closed space limited by the vacuum chamber module (501, 502, 601, 701, 702, 1302, 1303, 1304 ) and the end module (504, 703, 704, 1301, 1305) , and wherein said vacuum pump subsystem (507, 707 ) is attached to a vertical section (401 ) of said shell .

3. A modular cryogenic cooling system according to claim 2, wherein the at least one vacuum pump subsystem (507, 707 ) comprises at least one vacuumpump installed directly on said vertical section (401 ) of said shell .

4. A modular cryogenic cooling system according to claim 2, wherein the at least one vacuum pump subsystem (507, 707 ) comprises at least one vacuum pump coupled to said vertical section (401 ) of said shell with a duct .

5. A modular cryogenic cooling system according to any of claims 2 to 4, comprising:- supported inside said vacuum chamber module (501, 502, 601, 701, 702, 1302, 1303, 1304 ) , a plurality of thermal stages (302, 303, 304, 305, 306) spatially displaced from each other at least in the vertical direction, and- instrumentation connections (505, 506, 705, 706) to and from at least a subset of said thermal stages (302, 303, 304, 305, 306) through a top side (301 ) of the vacuum chamber module (501, 502, 601, 701, 702, 1302, 1303, 1304 ) .

6. A modular cryogenic cooling system according to any of the preceding claims, comprising:- supported inside said vacuum chamber, one or more heat radiation shields (307, 308, 309, 310, 311 ) that delimit respective subspaces inside the vacuum chamber and extend through the vacuum chamber in a horizontal direction defined by the horizontal array of cryogenic modules, and- a heat shield cooling subsystem configured to cool at least a subset of said one or more heat radiation shields (307, 308, 309, 310, 311 ) with a refrigerator subsystem (707 ) installed in a module (703) that forms an end of the horizontal array.

7. A modular cryogenic cooling system according to claim 6, characterized in that :- the heat shield cooling subsystem comprises one or more coolant circulation subsystems ( 807, 808 ) extending between parts of said heat radiation shields ( 805, 806) located in different ones of said cryogenic modules, and- said one or more coolant circulation subsystems ( 807, 808 ) are thermally coupled with respective ones of said parts of said heat radiation shields ( 805, 806) for cooling said parts of said heat radiation shields ( 805, 806) with coolant circulated in said one or more coolant circulation subsystems ( 807, 808 ) .

8. A modular cryogenic cooling system according to claim 7, comprising a support system ( 901 ) configured to support said one or more heat radiation shields ( 805, 806) inside said vacuum chamber, wherein said one or more coolant circulation subsystems ( 807, 808 ) comprise sections extending through respective parts of the support system ( 901 ) .

9. A modular cryogenic cooling system according to any of claims 7 or 8, comprising connectors ( 902, 903) configured for repeated assembly and disassembly of module-specific parts of said one or more coolant circulation subsystems ( 807, 808 ) to and from each other, respectively.

10. A modular cryogenic cooling system according to any of the preceding claims, characterized in that it comprises a mobile support system ( 1306) configured to allow moving at least a subset of said cryogenic modules ( 1301, 1302, 1303, 1304, 1305) in a direction that mechanically decouples two adj acent ones of said cryogenic modules ( 1301, 1302, 1303, 1304, 1305) from each other .

11. A modular cryogenic cooling system according to claim 10, wherein said mobile supportsystem ( 1306) comprises module-specific support modules ( 1307, 1308, 1309) attached to and supporting at least respective ones of said cryogenic modules ( 1301, 1302, 1303, 1304, 1305) , configured to be moved along with the respective module to which said module-specific support modules ( 1307, 1308, 1309) are attached.

12. A modular cryogenic cooling system according to claim 11, comprising means ( 1311 ) for con-trollably moving said module-specific support modules ( 1307, 1308, 1309) in relation to each other in said direction that mechanically decouples two adj acent ones of said cryogenic modules ( 1301, 1302, 1303, 1304, 1305) from each other .

13. A modular cryogenic cooling system according to any of the preceding claims, characterized in that it comprises vacuum-compliant compressible joints ( 1401, 1402 ) between at least a subset of mutually adj acent ones of said cryogenic modules ( 1302, 1303, 1304 ) , wherein each said vacuum-compliant compressible joint ( 1401, 1402 ) is- removably attachable to at least one of the respective two cryogenic modules ( 1302, 1303, 1304 ) between which it is, and- compressible for mechanically decoupling the two cryogenic modules ( 1302, 1303, 1304 ) between which it is .

14. A modular cryogenic cooling system according to claim 13, wherein said vacuum-compliant compressible joints ( 1401, 1402 ) are bellows .

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