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    • 专利摘要:
    The device for cooling the body (601) movable within the cryostat has a heat transfer portion (602) forming a contact surface for said body (601) and means for attaching the heat transfer portion (602) to the cooling structure (105, 107, 111, 604) so that said the contact surface remains free. The device has a spring portion (605) separate from said heat transfer portion (602) and arranged to apply a spring force (606) to the heat transfer portion (602) which presses said contact surface in the direction in which it is intended to contact said body (601). .
    公开号:FI20205481A1
    申请号:FI20205481
    申请日:2020-05-13
    公开日:2021-10-29
    发明作者:Rob Blaauwgeers；Pieter Vorselman；Anssi Salmela
    申请人:Bluefors Oy；
    IPC主号:
    专利说明:

    APPARATUS AND METHOD FOR MAKING HEAT CONDUCTING
    FIELD OF THE INVENTION The invention relates generally to cryostats in which the body to be cooled can be introduced into the cryostat so that heat must be dissipated from the cryostat structures. In particular, the invention relates to how a thermally conductive connection can be made efficient.
    BACKGROUND OF THE INVENTION Cryostats are used to cool bodies to very low temperatures. The body to be cooled has been commonly referred to as the sample and the place where it cools to its lowest temperatures is the target region. There are two different options for obtaining a sample for the target area. In the most conventional method, the entire cryostat is heated and opened, the sample is attached to the target area by hand, and the cryostat is closed, after which the entire cryostat and samples must be recooled. For faster sample changes, the cryostat can be equipped with a sample changer. N Figure 1 is a simplified representation of a cryostat equipped with a sample N exchanger. This is a cryostat using two-stage mechanical pre-cooling, with a dilution refrigerator in the inner part. The vacuum chamber 101, which acts as the outermost part of the cryostat, is shown in phantom. It is supported by a room temperature S flange 102 to which the upper part S 35 103 of the mechanical precooler is attached. The first stage 104 of the mechanical precooler is attached to the first cold flange
    105 and a second stage 106 in the second cold flange 107. The third cold flange 108 houses the dilution condenser evaporation vessel 109. The mixing chamber 110 of the dilution condenser is closed in the fourth cold flange 111. There may be no connections between the flanges for adjustable thermal conductivity presented here. The target area 112 to which the sample is attached is a portion of the fourth cold flange 111 or otherwise in as good a conductive connection to the mixing chamber 110 as possible. During operation, the temperature of the first cold flange 105 may be several tens of degrees Kelvin, the temperature of the second cold flange 107 about 4 K, the temperature of the third cold flange 108 about 1 K, and the temperature of the fourth cold flange 111 only a few millicelvins.
    The cryostat in Figure 1 has a bus-type sample loader; solutions of the bottom loader or attached to the side of the vacuum chamber are also known from the prior art. The sample exchanger includes a vacuum tube 113 which is hermetically attached to the vacuum chamber port valve
    114. The sample, not shown separately in Figure 1, is attached to the sample holder 115, which is initially inserted into the vacuum tube 113. Once the vacuum tube 113 is attached to the port valve 114 and evacuated, the sample holder 115 can be pushed into the target area 112 using the probe 116 or x-arms. To this end, all flanges and other structures on its route N must have 3 30 aligned holes forming a so-called transfer- © vaylan (clearshot).
    Ek If the sample and the sample holder 115 are at room * temperature upon entering the target area 112, this internal% of this heat must be transferred through the entire cryostat S 35 to the innermost portion. This is possible S but slow because, for understandable reasons, any heat transfer between the outside air and the cryostat
    between parts is minimized during use. In addition, the innermost cooling devices of the cryostat have the weakest cooling capacity, although they are able to reach the lowest temperatures. It is often more advantageous to try to pre-cool the sample and the sample holder on its way to the target area. Mechanical contact or thermally conductive gas may be used to form a thermally conductive connection between the sample holder and a suitable cooling portion.
    Figures 2 and 3 show the precooling principle known from EP 2409096 BI. The holes 201 and the sample holder 115 in it are not round but are shaped so that in one rotational position the outermost points of the sample holder 115 abut the flange next to the hole 201. These locations have screw holes 301. In addition to or instead of the central transfer arm 116, the sample exchanger has screw arms 202 whose threads at the outermost end (or through which separate bolts are rotated) allow the sample holder 115 to be temporarily attached to the flange as shown in Figure 2. . in place in the target area. N The solution according to Figures 2 and 3 has several N disadvantages. First, it limits the design of the sample holder and makes the machining of the holes in the flanges more complicated. Secondly, the friction caused by tightening the threads or bolts must be taken into account. Since the specific heat capacity of metals and other solids in the cold is very small, even a small amount of heat generated by friction may be sufficient to heat the bodies in contact with it by several degrees. The structure is also highly dependent
    due to the physical dimensions of the mechanical parts, which decrease with decreasing temperature. The requirement for mechanical compatibility can cause problems for the operation of the mechanism when cooling changes the dimensions of the parts.
    The use of thermally conductive springs is also known from the prior art, as illustrated in Figures 4 and 5. The sample 401 is attached to a sample holder 115, which in this case is substantially disc-shaped and made of a highly thermally conductive material. A plurality of springs 402 are attached around the hole in the flange 105, the material of which is both flexible and thermally conductive. As the sample holder 115 protrudes between the springs as shown in Figure 5, they spring outwardly and press against the edges of the sample holder 115 with their spring force.
    The disadvantages of the solution according to Figures 4 and 5 are that, at least for the time being, a material which is sufficiently flexible and at the same time has a sufficiently high thermal conductivity is not known. Good flexibility is needed because the thermal conductivity of two solid bodies in contact with each other depends significantly on the magnitude of the force exerted on them. Copper is a good example of a material that conducts heat well but is not very flexible: if copper tabs were used as 'springs', they would bend to their outer position the first time they were used and would not recover, leaving all subsequent pre-cooling attempts too weak. contact. Beryllium-copper alloy, on the other hand, has springs that retain its properties well, but its thermal conductivity is so poor that the springs have to be coated * with gold or silver, for example. However, the coating inevitably remains so thin that the total highly thermally conductive cross-section S 35 between the sample holder 115 S and the flange 105 is relatively small.
    SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for efficiently cooling an article introduced into a cryostat. It is also an object of the invention that the device and the method according to it withstand the use well without losing their power even after several uses. It is a further object of the invention that they are applicable to a wide variety of refrigerated objects of different sizes and shapes. It is a further object of the invention that the device parts required for it can be made from generally available materials and using conventional machining methods.
    The objects of the invention are achieved by using a heat transfer part and a separate spring part in the structure, the flexibility of which forces the heat transfer part into good contact with the object to be cooled.
    The device according to the invention for making a thermally conductive connection for cooling a body movable inside a cryostat comprises: - a heat transfer section forming a contact surface for said body, and o - a spring portion separate from said heat transfer portion N and arranged to apply to the heat transfer portion N a spring force pressing = 30 said contact surface in the direction in which it A is intended to contact said body.
    E According to one embodiment, the heat transfer portion has a plurality of circumferential heat transfer portions, said contact surface being formed by those surfaces of the N 35 heat transfer portions facing the circumference N. This has the advantage that a large part of the outer surface of the body to be moved inside the cryostat can be harnessed for heat transfer needs.
    According to one embodiment, said spring portion has one or more spring members which are or are outside said circumferential heat transfer members and which press or press the heat transfer members towards the circumferential center. This has the advantage that the compressive force required for efficient heat transfer can be applied symmetrically to the body to be moved inside the cryostat.
    According to an embodiment, the device has means for supporting said spring portion in said cooling structure. This has the advantage that the amount and direction of the spring force produced is simple to control.
    According to an embodiment, said heat transfer portion has a retaining ring having an inner edge and a plurality of heat transfer strips attached at one end to the inner edge of the retaining ring and the other, free end facing in a direction substantially opposite to the plane defined by the retaining ring. perpendicular. This has the advantage that it is easy to make the heat transfer section exactly the desired size and shape.
    According to one embodiment, said spring portion has a support ring attached to said N mounting ring and having an inner surface, N and a plurality of spring strips resting on the inner surface of said support ring and arranged to align O with said heat transfer strips. z nittu spring force. This has the advantage that the spring force is applied to the heat transfer portion in the desired manner. S 35 According to one embodiment, said spring-S strips form a unitary strip of spring strip continuous around the inner surface of said support ring,
    which rests on one or more grooves in the inner surface of said support ring.
    This achieves a manufacturing advantage in the manufacture of the spring section.
    According to an embodiment, the device further comprises an upper retaining ring attached to said support ring and arranged to support the free end of each of said heat transfer strips in a position farther from the center line of the circumference formed by the heat transfer strips than the center of the heat transfer strips.
    This has the advantage that the position of the heat transfer strips is particularly good for moving the part to be moved inside the cryostat.
    According to an embodiment, said heat transfer portion is made of copper or silver.
    This has the advantage that the thermal conductivity of the heat transfer section is high.
    According to one embodiment, the heat transfer portion made of copper or silver is plated with gold.
    This has the advantage that the important surfaces of the heat transfer section are not oxidized and that their thermal conductivity remains good for a long time.
    According to one embodiment, said spring portion is made of a beryllium-copper alloy.
    This has the advantage that the elastic properties of the spring section are well suited for use in a cryostat-like N environment with very low temperatures.
    N In the arrangement according to the invention for cooling the body to be moved inside the cryostat, there is a cooling structure and attached to it a device z according to one of the above descriptions. * According to one embodiment, the arrangement has a first cooling structure and a first device attached thereto, as described above.
    The arrangement may then have a second cooling structure and a second device attached to it,
    which is also as described above. The first cooling structure may have an opening concentric with said first and second devices. In said first device, the contact surface of the device may form a circumference having a first diameter. In said second device, the contact surface of the device may form a perimeter having a second diameter smaller than the first diameter. The diameter of said opening may be larger than said first and second diameters. This has the advantage that the body movable inside the cryostat can have two parts of different diameters, each of which is adapted to correspond to heat transfer through a specific device.
    According to one embodiment, said second cooling structure forms a target area in the cryostat for attaching the body to be cooled. This has the advantage that in this location the heat transfer serves to make the part as cold as possible.
    According to one embodiment, the arrangement comprises a sample holder which forms at least a part of said body movable inside the cryostat. The sample holder may then have a first portion which is compatible in diameter with said first diameter and a second portion which is compatible in diameter with N of said second diameter. Said second portion may be in a portion of the sample holder that is in the same direction as said second cooling structure relative to said first cooling structure. This has the advantage that a second percentage is saved from scratches in the previous cooling steps and can be used as scratch-free as possible in the dedicated cooling step.
    LIST OF FIGURES Figure 1 shows a cryostat, Figure 2 shows a known pre-cooling solution, Figure 3 shows a later step in the use of the solution according to Figure 2, Figure 4 shows a known pre-cooling solution, Figure 5 shows a later step in the use of the solution according to Figure 4, Fig. 6 shows the principle of efficient precooling, Fig. 7 shows an embodiment for implementing precooling, Fig. 8 shows a part of the solution of Fig. 7, Fig. 9 shows an embodiment for implementing precooling, Fig. 10 shows an embodiment for implementing precooling, Fig. 11 shows an embodiment for precooling and Figure 12 shows a further development of the embodiment of Figure 11.
    o DETAILED DESCRIPTION OF THE INVENTION O Fig. 6 is a schematic diagram of a device for making a thermally conductive connection for cooling a movable body 601 inside a cryostat. another © moving piece. The actual purpose D may be to move and cool another object, for example a sample attached to a sample holder. In practice, however, such an indirectly movable object (such as a sample) and an object used to move it (such as a sample holder) can generally be thought of as a single object 601 movable within a cryostat.
    According to the principle shown in Figure 6, the device has a heat transfer portion 602 which forms a contact surface for the body 601. It is thus intended that the movable body 601 and the heat transfer portion 602 be brought into physical contact with each other so that heat can be transferred between them due to the solid body. The thermally conductive connection based on physical contact between the pieces is shown in cross-section in Figure 6. The heat transfer section 602 may consist of one or more pieces.
    According to the principle shown in Figure 6, the device has means 603 for attaching the heat transfer portion 602 to the cooling structure 604. This attachment is made in such a way that the contact surface of the heat transfer portion 602 intended to contact the movable body 601 remains free. The latter condition is natural in that, if the contact surface were not free, it could be difficult or impossible to bring the movable body 601 into thermally conductive contact with the heat transfer portion 602. There is a thermally conductive N connection between the heat transfer section 602 and the cooling structure 604, which is illustrated in FIG.
    3 30 In accordance with the principle shown in Fig. 6, the device has a spring portion 605 separate from the heat transfer portion 602 and arranged to apply a spring force 606 to the heat transfer portion 602. The force% 606 presses the contact portion of the heat transfer portion 602. the surface in the direction in which it is intended to contact the movable body 601.
    The separation of the spring portion 605 and the heat transfer portion 602 means that, unlike the prior art, no attempt is made to provide heat conduction between the body 601 and the cooling structure 604 and a thermal conductive contact with the same structural portion. Separation does not mean that the spring section 605 and the heat transfer section 602 should be located completely separate from each other, in different parts of the structure. That is, the spring portion 605 may be one piece (or a plurality of pieces) and the heat transfer portion 602 may be another piece (or a plurality of other pieces). The body or bodies forming the spring portion 605 may be made of a different material than the second body or bodies forming the heat transfer portion. This is even preferred because very different properties are required of these sections: the most important feature of the heat transfer section 602 is the most efficient conduction of heat between the movable body 601 and the cooling structure 604, while the main feature of the spring section 605 is good spring force 606.
    The spring portion 605 may be supported on the cooling structure 604, as shown in Figure 6 by reference numeral 607. However, this is not necessary. Examples of both supported and unsupported embodiments are described in more detail below. Fig. 7 shows a device according to an embodiment for making a thermally conductive connection 3 inside a cryostat for cooling a movable body. The mobile device is not shown in Fig. 7, but can be assumed to be, for example, a circular disc of the same type as in the prior art description and Figs. 4 and 5. The cooling structure is a cryostat flange 105. It is provided that a cooling device, such as some stage of a cryostat mechanical precooler or a dilution condenser evaporator, is connected to the flange 105 (outside the range shown in Figure 7). The flange 105 has a circular opening through which the body to be moved is to be passed. If the mobile device is a sample holder to be transported to the target area, the opening in the flange 105 is part of the transfer path used for this purpose. The heat transfer part of the device shown in Fig. 7 has a plurality of circumferential heat transfer parts 701. The shape of the heat transfer parts 701 resembles the heat-conducting springs used in the prior art solutions. The difference, however, is that in the embodiment shown in Figure 7, they do not require any resilience. The heat transfer parts 701 can be made of copper, for example, whereby they are relatively easy to bend but have an inherent tendency to remain in the position in which they are bent.
    The embodiment according to Figure 7 also has means for attaching the heat transfer portion to the cooling structure. These means include a retaining ring 702 and screws 703 securing the retaining ring 70 to the flange 105. The outermost end of each heat transfer section 701 is tightly clamped between the retaining ring 702 and the flange 105. This ensures that the thermally conductive connection 7 between the heat transfer parts 701 and the flange 105 acting as a cooling structure remains good. The contact surface of the heat transfer portion for the body movable inside the cryostat is formed by the surfaces of the heat transfer portions 701 facing the perimeter formed therein. By comparing Fig. 7 with Figs.
    In the embodiment shown in Figure 7, the spring portion of the device includes a spring portion 704 that is outside the circumferential heat transfer portions 701 and presses the heat transfer portions 701 toward the center of the circumference. The spring portion 704 is shown detached in the figure
    8. It is annular and made of spring steel, beryllium-copper alloy or other similar material which retains its elasticity even when the cryostat is cold.
    The spring portion 704 is dimensioned so that in the resting state (when the movable body is not in contact with the heat transfer portions 701) it compresses the circumferential contact surface formed by the heat transfer portions 701 together to be smaller in diameter than the opening in the flange 105 (and thus smaller than its movable cap). - the diameter of the piece to be cooled). When the movable body is then pressed into the center of the circumference, it twists the free ends of the heat transfer portions 701 outwardly, bending each heat transfer portion 701 at the bend where the vertical portion of the heat transfer portion changes to a horizontal portion. Terms referring to directions, such as vertical and horizontal, throughout this text refer only to the representation used in the figures and have no limiting effect on the orientation of the respective parts in the correct N device. N The spring force produced by the spring portion 704 resists the bending of the heat transfer portions 701 described above. © This creates a force which presses the heat transfer parts 701 z strongly against the surface of the body * inside the cryostat, so that heat transfer between these% parts is efficient. Then, when the movable body S 35 is moved away from the center of the perimeter formed by the heat transfer portions 701, the spring portion 704 compresses the heat transfer portions 701 back to the position they were in before the movable body entered. Thus, the device shown in Fig. 7 for making a thermally conductive connection is completed the next time the body to be moved inside the cryostat has to be cooled at it.
    Figure 9 shows an apparatus according to another embodiment for making a thermally conductive connection inside a cryostat for cooling a movable body. In the apparatus of Fig. 9, the heat transfer portion forming a contact surface for said body consists of a plurality of circumferential heat transfer portions 901. Here too, the contact surface is formed by the surfaces of the heat transfer portions 901 facing the circumference. The heat transfer parts 901 are made of a material that conducts heat well at cryostat operating temperatures, such as copper or silver. In addition, they can be coated with a coating that improves heat transfer properties, such as a gold layer.
    Here again, a cryostat flange 105 is shown as the cooling structure. In the embodiment of Fig. 9, the means for attaching the heat transfer portion to the cooling structure consist of slide rails 902, one for each heat transfer portion 901.
    Each heat transfer member 901 is mounted on a corresponding slide rail so that it can easily move in the direction of the radius N of the circumference formed by the heat transfer members 901. The portion of the heat transfer portion 901 inside the slide rail 902 and / or the slide rail itself 3 may, if necessary, be coated with a coating having both good thermal conductivity properties and low friction at temperatures corresponding to the operation of the cryostat. * In the embodiment of Figure 9, according to the% principle described above, there is a spring section separate from the heat transfer section S 35. The spring portion is arranged to apply a spring force to the heat transfer portion, which presses the contact surface of the heat transfer portion in that direction.
    where it is intended to contact a body moving inside the cryostat.
    In the embodiment of Figure 9, the spring portion has a plurality of spring portions 903 that are outside the circumferential heat transfer portions 901.
    Exactly in this embodiment there are as many spring parts 903 as there are heat transfer parts.
    A spring portion corresponding to each heat transfer section 901 presses it toward the center of the circumference.
    The spring parts 903 are compression springs made of spring steel, beryllium-copper alloy or the like, which retains its elasticity even in the cold of the cryostat.
    In contrast to the embodiment of Figure 7, the embodiment of Figure 9 has means for supporting the spring portion in the cooling structure.
    These means include a retaining ring 904 and bolts 905 that secure the retaining ring 904 to the flange 105. The inner surface of the retaining ring 904 most preferably has a recess for the end of each spring member 903 to maintain the spring members 903 in place and in the correct orientation.
    The embodiment of FIG.
    On the other hand, the disadvantage of the embodiment of Fig. 9 is the friction which inevitably occurs in the slide rails 902 and which can produce harmful amounts of N heat, and the thermal conductivity of the slide rail mechanism, which may be lower than in the compression joints of Fig. 7. 3 30 If metal fatigue is not a significant problem, © the principles shown in Figures 7 and 9 can be z combined, for example, as shown in Figure 10. * The embodiment shown in Fig. 10 has similar% heat transfer portions 701 as in Fig. 7, but the spring portion S35 consists of similar spring portions 903 as in Fig. 9. S
    specially shaped to press the horizontal ends of the heat transfer members 701 against the flange 105. Of course, it is also possible to use one common ring that combines the features of the rings 904 and 1001 shown in Figure 10. Yet another possible variation of the embodiment of Figure 9 is to use hinges instead of slide rails 902. Thus, at the base of the vertical portion of each heat transfer section 901, there would be a hinge with a horizontal axis of rotation parallel to the circumferential tangent, on which the vertical portion could rotate toward and away from the center of the circumference. The hinges are more complex in construction than the slide rails and require more separate parts and work during the assembly phase, but they have the potential to achieve less friction and thus more reliable operation and less extra heat generation than the slide rails.
    Figure 11 shows an apparatus for making a thermally conductive connection within a cryostat for cooling a device to be moved. The embodiment of Figure 11 is consistent with the above in that the device has a heat transfer portion, means for attaching it to the cooling structure (e.g., flange 105 in Figure 11) and a spring portion separate from the heat transfer portion. The heat transfer portion forms a contact surface x for the body to be moved inside the cryostat, which is to be cooled. The attachment to the cooling structure 3 30 is such that this contact surface is left free. The spring portion is arranged to apply a spring force to the heat transfer portion which presses the contact surface in the direction in which it is intended to contact said body. S 35 As in the other S embodiments described above, Fig. 11 assumes that the body to be cooled is at least partially cylindrical.
    and intended to be moved up and down through the opening in the flange 105. The heat transfer portion has a plurality of circumferential heat transfer portions 1101, which in this embodiment may also be referred to as heat transfer strips. The contact surface is formed by the surfaces of the heat transfer strips 1101 facing the circumference. The spring portion has a plurality of spring members 1102 that are outside the circumferential heat transfer strips 1101 and that press the heat transfer strips 1101 toward the center of the circumference. the device also has means for supporting the spring portion in the cooling structure. These means include rings 1103, 1104 and 1105 and bolts 1106, the construction and operation of which are described in more detail below.
    The heat transfer portion of the device according to the embodiment of Figure 11 has a retaining ring 1104. Its inner edge may be approximately the same size as the opening in the flange 105, but may also be larger or smaller. The heat transfer strips 1101 adhere at one end to the inner edge of the retaining ring 1104. The other, free end of the heat transfer strips 1101 extends in a direction substantially perpendicular to the plane defined by the retaining ring 1104. In the position shown in Fig. 11, the free end of the heat transfer strips 1101 thus faces upwards. The assembly of heat transfer strips 1101 and retaining ring 1104 is preferably made of a material that conducts heat as well as possible at the relatively low temperatures associated with normal operation of the cryostat. Such materials include copper and silver. % In addition, the heat transfer strips 1101 and the retaining ring S 35 1104 may be plated with gold and / or provided with another coating or surface treatment that enhances their ability to form a thermally conductive connection with the parts with which they are in contact. In particular, the contact surface formed by the surfaces of the heat transfer strips 1101 facing the circumference is preferably made quite hard so as not to be scratched by repeated sliding contacts with the body to be cooled. The heat transfer strips 1101 can be made by cutting a comb-like portion of a suitably thick sheet of material, the length of which corresponds to the circumference of the inner edge of the fixing ring 1104. The unitary edge of the comb-like portion may be secured to rotate the inner edge of the retaining ring 1104 using a suitable method of securing metals such as welding or soldering.
    The spring portion of the device according to the embodiment of Figure 11 has a support ring 1103 attached to the mounting ring 1104. The spring portions of the spring portion are a plurality of spring strips 1102 resting on the inner surface of the support ring 1103 and arranged to apply to the heat transfer strips 1101 the spring force which presses them toward the center of the circumference of the heat transfer strips 1101.
    The spring strips 1102 may be detached or may form a continuous spring strip strip extending around the inner surface of the support ring 1103, which rests on one or more grooves in the inner surface of the support ring 1103. Instead of the spring strips 1102, helical springs can be used as in the embodiments of Figures 9 and 10, or a spring ring as in the embodiment of Figure 7.
    © The spring strips 1102 or other spring parts used in their place are preferably made of a material that retains its resilience at the low% temperatures common in cryostat operation. Examples of such materials are many spring steels and beryllium copper alloys.
    There may be a different number of heat transfer strips 1101 and spring strips 1102.
    Such a solution achieves several advantages.
    First, both the heat transfer strips 1101 and the spring strips 110 the dimensions can then be optimized according to their different function (heat transfer / spring force generation): for example, the heat transfer strips 1101 should not be made very narrow with respect to their length, because the narrow strip would have less heat transfer cross-sectional area.
    Second, when the heat transfer strips 1101 and the spring strips are different, their vertical edges do not coincide, at least in many places.
    This can help to cause the adjacent heat transfer strips 1101 to press at each point with as uniform a force as possible against the part to be cooled.
    A third advantage is that when the number is not so important that the parts have to be manufactured from the outset, especially for this purpose, it is possible to use parts which are more easily accessible in other contexts.
    In addition to the parts described above, the device according to the embodiment of Fig. 11 has an upper mounting ring 1105 attached to the support ring 1103 and arranged to support the free end of each of said heat transfer strips 1101 farther from the circumference of the heat transfer strips 1101 N midpoint (R2> RI in Figure 11). Together with the spring strips 1102, the upper fixing ring 1105 thus ensures that each heat transfer strip 1101 is bent into an arc so that the body movable inside the cryostat can be easily moved to the center of the perimeter formed by the heat transfer strips 1101 from either mouth. - S 35 pins of any kind.
    The upper retaining ring 1105 is not required if the movable body has sufficiently conical shapes from the heat transfer strips 1101.
    to open the collapsible circumference and / or the free end of each heat transfer strip 1101 is otherwise obtained bent sufficiently away from the center line of the circumference.
    In the embodiment shown in Figure 11, the mounting bolts 1106 pass through the mounting ring 1104, the support ring 1103, and the upper mounting ring 1106. This in itself is not necessary, but each ring can be fastened to the structure below it with its own, in the case of rings 1104 and 1103, its countersunk bolts or in another suitable way.
    In general, whenever a body movable within a cryostat slides in contact with another part (such as the contact surface of a device used to cool it), the surfaces in contact with each other can be scratched and worn. This phenomenon is repeated in essentially the same type, regardless of the technical implementation of the device used for cooling, although the amount of scratches and wear may vary in different implementations. Any scratching and wear is undesirable because it can impair the heat conduction between the body to be cooled and the contact surface of the device used to cool it.
    It would be particularly desirable for the heat-conducting connection through which the sample is cooled to the lowest temperatures in the target area, N, to be as good as possible. However, if the same method of conducting heat N is used at those locations where the sample (or in general: the sample holder) is pre-cooled before it enters the target area, z they may cause exactly the scratches and wear that would be avoided. . % It is therefore an object to provide an S 35 ly system which can ensure the best possible S-conductive connection inside the cryostat to cool the movable body in the target area, although it can also be precooled in other parts of the cryostat before it enters the target area. This object is achieved in that when the body to be moved inside the cryostat has entered the target area, a different thermally conductive connection is formed between it and the cooling structure than that used to pre-cool the body to be moved.
    Figure 12 shows an example of an arrangement inside a cryostat for cooling a movable body. The arrangement has a first cooling structure (here: flange 108) and a first device 1201 attached thereto, substantially shown here as in Figure 11, but which may be a device according to any of the embodiments described above. The arrangement has a second cooling structure (here: flange 111) and a second device 1202 attached thereto. It is also shown herein to be substantially similar to Figure 11, but the second device 1202 may also be in accordance with any of the above embodiments. The first cooling structure, i.e. the flange 108, has an opening 1203 which is concentric with the first device 1201 and the second device 1202.
    What is special about the arrangement according to Fig. 12 is that the first device 1201 and the second device N 1202 are not exactly the same size. In the first N device 1201, the contact surface of the device forms a body having a first diameter. In the second device 1202, the contact surface of the device forms a perimeter Ek having a second diameter. This second diameter is * smaller than the first diameter. According to one embodiment, the second cooling structure 111 forms a target area S 35 to which the body S to be cooled in the cryostat is to be attached. In this case, the circumferential contact surface in the device in the target area
    is smaller in diameter than that or in the equipment used to pre - cool the body before it enters the target area.
    Figure 12 shows a body movable within a cryostat, which in this case is the sample holder 1204. Specifically, the sample holder 1204 forms only a portion of the body movable within the cryostat because the sample 1205 attached to the sample holder 1204 and the transfer arm move with it in this example. 1206. The sample holder 1204 has a first portion 1207 that is compatible in diameter with the diameter of the contact surface of said first device, i.e., the first device 1201.
    In addition, the sample holder 1204 has a second portion 1208 that is compatible in diameter with the diameter of the contact surface of said second device, i.e., the second device 1202.
    The compatibility of the diameter of the portion in the sample holder 1204 with the diameter of the contact surface of the corresponding cooling device is illustrated by a comparison comparing the first device 1201 to the second device 1202 in the situation shown in Figure 12.
    The sample holder 1204 is at the point where the first device 1201 is used to cool it. The larger diameter portion 1207 of the sample holder 1204 is depressed against the contact surface of the first device 1201.
    In accordance with the principle previously described, this means that the heat transfer strips in the first device 1201 have been pushed outwards from the so-called from the rest position © where they would be if the sample holder 1204 were not Ek at them.
    The diameter of the first portion 1207 of the sample holder 1201 is thus not equal to% of the smallest diameter of the contact surface of the first device 1201 in the rest position, but slightly larger - but only so large that the sample holder 1201 can pass through the first device when pressed. the heat transfer tabs outward as shown in Figure 12.
    Important factors for heat transfer are the force with which the heat-conducting surfaces press against each other, but also the area through which they contact each other. Figure 12 shows how the heat transfer strips of the first device 1201 are depressed into a position where a large portion of the length of each heat transfer strip is in contact with the larger diameter portion 1207 of the sample holder. Such an operation can be achieved by carefully dimensioning the structures. A mechanical simulation can be used, which simulates the deformation of the heat transfer strips and the spring strips weighing them under the influence of a force which presses them outwards.
    Similarly, the diameter of the second portion 1208 of the sample holder 1201 is not equal to the smallest diameter of the contact surface of the second device 1202 in the rest position, but slightly larger. This is illustrated in Figure 12 by the vertical dashed lines 1209 and 1210 drawn from the lower edge of the second portion 1208 toward the heat transfer strips of the second device 1202. If the sample holder were moved down so far from the position shown in Figure 12 that the second portion 1208 was at the second device 1202, the heat transfer strips of the second device 1202 would be in a position similar to where the heat transfer strips of the first device 1201 N are shown in Figure 12. the heat transfer strips naturally returned to their rest position when pressed by the spring strips of the first part 1201 as soon as the first portion 1207 of the sample holder z 1204 had left their + position. The opening S 35 1203 in the cooling structure 108 is larger in diameter than the diameter of each portion 1207 or 1208 of the sample holder S 1204. This condition arises from the fact that the sample holder 1204 is not intended to hit the edges of the opening 1203 at any stage, but only to pass smoothly therethrough.
    The sample holder 1204 advances to the target area with the second section 1208 ahead.
    Thus, for the operation described above to be possible, the second portion 1208 must be in a portion of the sample holder 1204 that is in the same direction as the target region (or, more generally, the second cooling structure 111) relative to the first portion 1207. with respect to the cooling structure 108.
    Upon reaching the target area, the second portion 1208 has not yet touched any previous portion and, in particular, has not slid along any previous contact surface, so it is completely scratch-free and wear-free.
    Although each sample change naturally causes two sliding movements between the contact surface of the second portion 1208 and the second device 1202 (one entering the target area, the other disengaging from there), these sliding movements accumulate substantially less than if the same portion of the sample holder were also sliding. against all pre-cooling contact surfaces both on and off.
    When comparing the device according to the embodiments presented here, for example, to the arrangement according to the prior art shown in Figures 4 and 5, one important factor is the thermally conductive cross-sectional area.
    In the prior art arrangement, the springs 402 were typically a beryllium-copper alloy N plated with gold.
    The thermal conductivity of the beryllium-copper alloy N at cryogenic temperatures is so poor that heat from the sample holder 115 to the flange 105 © was almost exclusively due to the gold plating of the springs.
    Its thickness z was typically only a few micrometers, while in the devices according to Figures 7 and 9-12 the heat transfer parts may be solid, highly heat-conducting copper, and even in strip-like embodiments S may be, for example, half a millimeter thick.
    riin.
    It is clear that the heat-conducting cross-sectional area is then up to hundreds of times larger than in the prior art solution.
    The embodiments disclosed herein have a number of such advantageous features associated with making a thermally conductive connection from the sides of a body movable within a sample holder or other cryostat. One of them is insensitivity to changes in dimensions due to temperature variation. For example, when the transfer arm shortens as it cools, it moves the sample holder in the same direction that the sample holder would otherwise move. This does not significantly alter the nature of the thermally conductive connection or the mechanical compatibility between the parts in the above embodiments. Another advantage is that a fairly large, substantially flat surface (lower surface in Figure 12) can be provided in the sample holder, which is completely usable for purposes other than making thermally conductive connections. For example, connectors for transmitting electronic signals can be placed on the surface, which will press into counterparts in the target area when the sample holder enters the target area. The above exemplary embodiments are not intended to be limiting, but many features of the apparatus and arrangement may be implemented in other ways. For example, nothing requires that neither the device nor the sample holder be rotationally symmetrical. The same principle described above can well be used, for example, in an arrangement in which the sample holder and the O-channel openings are oval, rectangular or = some other polygonal. Thus, in such an arrangement, the device for making the thermally conductive connection would not% form a rotationally symmetrical contact surface,
    which are on the opening side. Another example of an extension to more than just the embodiments described above is that the body within the cryostat does not always have to be a sample holder. Using the same principle, for example, a thermal switch can be constructed, i.e. a controllable means for regulating the conduction of heat between the two parts of the cryostat. The movable body may be in thermally conductive contact with the first part, and the device according to one of the embodiments discussed above may be attached to the second part. Using a mechanism controlled from outside the cryostat, the movable body can be moved either in contact with or away from the contact surface of the device. In this case, it is selected whether or not the two parts of the cryostat are in thermally conductive communication with each other. oO OF O OF
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    权利要求:
    Claims (15)
    [1]
    An apparatus for making a thermally conductive connection within a cryostat for cooling a movable body (601), the apparatus comprising: - a heat transfer portion (602) forming a contact surface for said body (601), and - means for the heat transfer portion (602); ) to the cooling structure (105, 107, 111, 604) so that said contact surface remains free, characterized in that the device has: - a spring portion (605) separate from said heat transfer portion (602) and arranged applying to the heat transfer portion (602) a spring force (606) which presses said contact surface in the direction in which it is intended to contact said body (601).
    [2]
    Device according to claim 1, characterized in that the heat transfer portion (602) has a plurality of circumferential heat transfer portions (701, 901, 1101), said contact surface being formed by the heat transfer portions (701, 901, 1101). ) on the surfaces facing the perimeter.
    [3]
    Apparatus according to claim 2, characterized in that said spring portion (605) has one or more spring portions (704, 903, 1102) which are N or which are part of said circumferential heat transfer portions (701, 901). 1101) and 3 which press or press the heat transfer portions (701, © 901, 1101) towards the center of the circumference.
    [4]
    Device according to any one of the preceding claims, characterized in that it has means D (607, 904, 905, 1001, 1103, 1106) for supporting said spring section (605) on said cooling structure (105). , 107, 111, 604).
    [5]
    Device according to any one of the preceding claims, characterized in that said heat transfer section (602) has: - a retaining ring (1104) having an inner edge, and - a plurality of heat transfer strips (1101) attached at one end to the inner edge of the retaining ring (1104) and the other free end of which is directed in a direction substantially perpendicular to the plane defined by the retaining ring (1104).
    [6]
    Device according to claim 5, characterized in that said spring portion (605) has: - a support ring (1103) attached to said fixing ring (1104) and having an inner surface, and - a plurality of spring strips (1102) supported by on the inner surface of said support ring (1103) and arranged to apply said spring force (606) to said heat transfer strips (1101).
    [7]
    Device according to claim 6, characterized in that said spring strips (1102) form a continuous spring strip strip extending around the inner surface of said support ring (1103) which abuts one or more grooves in the inner surface of said support ring (1103).
    [8]
    Device according to claim 6 or 7, characterized in that it further comprises an upper mounting ring (1105) attached to said support ring (1103) and arranged to support © each of said heat transfer strips (110). 1101) the free z 30 end to a position farther from the center line of the circumference formed by the heat transfer strips * (1101) than the center of the heat transfer strips (1101).
    LO
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    [9]
    Device according to one of the preceding claims, characterized in that said
    the transfer portion (602) is made of copper or silver.
    [10]
    Device according to Claim 9, characterized in that the heat transfer section (602) made of copper or silver is coated with gold.
    [11]
    Device according to any one of the preceding claims, characterized in that said spring section (605) is made of a beryllium-copper alloy.
    [12]
    Arrangement for cooling a body movable inside a cryostat, characterized in that it has a cooling structure (105, 107, 108, 111) and a device (1201, 1202) attached to it according to one of the preceding claims.
    [13]
    An arrangement according to claim 12, characterized in that: - the arrangement has a first cooling structure (108) and attached to it a first device (1201) according to any one of claims 1 to 11, - the arrangement has a second cooling structure (108); 111) and attached thereto a second device (1202) according to any one of claims 1 to 11, - the first cooling structure (108) has an opening (1203) concentric with said first and second devices (1201); 1202), a - in said first device (1201) the contact surface of the device ro forms a perimeter having a first diameter,> - in said second device (1202) the contact surface of the device forms a perimeter having a second diameter, which is smaller than the first diameter and D - the diameter of said opening (1203) is larger than O said first and second diameters.
    [14]
    An arrangement according to claim 13, characterized in that said second cooling structure (111) forms a target area in the cryostat for attaching the body to be cooled.
    [15]
    An arrangement according to any one of claims 13 to 14, characterized in that: - the arrangement comprises a sample holder (1204) forming at least a part of said body movable inside the cryostat, - the sample holder has a first portion (1207) which is compatible with said first diameter, - the sample holder has a second portion (1208) that is compatible with said second diameter, and - said second portion (1208) is in a portion of the sample holder (1204) that is in the first portion (1207). ) in the same direction as said second cooling structure (111) with respect to said first cooling structure (108).
    oO
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    同族专利:
    公开号 | 公开日
    FI129268B|2021-10-29|
    WO2021229149A1|2021-11-18|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US4344302A|1981-06-08|1982-08-17|Hughes Aircraft Company|Thermal coupling structure for cryogenic refrigeration|
    NL2001755C2|2008-07-03|2010-01-05|Giorgio Frossati|Holder for a preparation to be cooled to a low temperature in a vacuum space and a 3-he-4 th mixing cooling machine adapted to receive such a holder.|
    GB0904500D0|2009-03-16|2009-04-29|Oxford Instr Superconductivity|Cryofree cooling apparatus and method|
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    FI20205481A|FI129268B|2020-05-13|2020-05-13|Device and method for providing a thermally conductive coupling|FI20205481A| FI129268B|2020-05-13|2020-05-13|Device and method for providing a thermally conductive coupling|
    PCT/FI2021/050347| WO2021229149A1|2020-05-13|2021-05-11|Device and method for providing a thermally conductive coupling|
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