JP2006078070A - Cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling device adapted to cool a plurality of cooling objects by a refrigerating machine, which can efficiently cool a plurality of cooling objects differed in cooling temperature stored in the device. <P>SOLUTION: In the refrigerating machine including a vacuum vessel 41, a superconductive magnet coil 54 provided within the vacuum vessel 41, a magnetic body salt pill 58 field-applied by the magnet coil 54, a GM (Giffort-McMahon) freezer 70 generating cold air, a first heat transfer passage thermally connecting the magnetic body salt pill 58 to the freezer 70, and a second heat transfer passage thermally connecting the magnet coil 54 to the freezer 70. In this refrigerating machine, the first heat transfer passage and the second heat transfer passage are constituted to be thermally independent from each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooling device, and more particularly to a cooling device configured to cool a plurality of objects to be cooled by a refrigerator.

  In general, an adiabatic demagnetization method is known as one of low temperature techniques. This adiabatic demagnetization method is a method in which the temperature is changed by controlling the magnetic field entropy of the magnetic material by a magnetic field. According to this adiabatic demagnetization method, it is possible to generate from a normal temperature to an ultra-low temperature of 1K or less by selecting a magnetic material and the strength of a magnetic field to be applied.

  A cooling device that generates ultra-low temperature using this adiabatic demagnetization method applies a magnetic field generated by a superconducting magnet to a magnetic material and, for example, a Gifford McMahon refrigerator (hereinafter referred to as a GM refrigerator) via a thermal switch. Is thermally connected to the magnetic body to control the temperature of the magnetic body. Therefore, a cooling device using the adiabatic demagnetization method inevitably forms a strong magnetic field inside.

  The cooling device using the above-described adiabatic demagnetization is applied to, for example, an X-ray analyzer (such as an energy dispersive X-ray analyzer) and used to cool an X-ray detection element. By cooling the X-ray detection element, noise can be reduced and analysis accuracy can be increased.

  Further, during operation of this cooling device, the superconducting magnet is cooled to about 4K, and the magnetic material is at an ultra-low temperature of 0.05K. For this reason, in this kind of cooling device, a superconducting magnet, a magnetic body, etc. are set as the structure mounted in the vacuum vessel in which the multistage radiation shield was performed (for example, refer patent document 1).

  FIG. 8 is a schematic configuration diagram illustrating an example of a cooling device 10 using a conventional adiabatic demagnetization. As shown in the figure, the cooling device 10 has a first radiation shield 13 and a second radiation shield 14 in a vacuum vessel 11, and a superconducting magnet coil 12 is arranged inside the second radiation shield 14. It is installed. The magnetic body 20 to which a magnetic field is applied by the superconducting magnet coil 12 is disposed inside the cylindrical superconducting magnet coil 12.

  The GM refrigerator 17 that cools the superconducting magnet coil 12 and the magnetic body 20 includes a first cooling unit 18 and a second cooling unit 19. The first cooling unit 18 is thermally connected to the first cooling stage 15 disposed on the first radiation shield 13. As a result, the first cooling stage 15 is cooled to 40K to 80K. The second cooling unit 19 is thermally connected to the first cooling stage 16 disposed on the second radiation shield 14. As a result, the first cooling stage 16 is cooled to about 4K.

Conventionally, both the superconducting magnet coil 12 and the magnetic body 20 are disposed in a state of being thermally connected to the first cooling stage 16, and thus the first cooling thermally connected to the GM refrigerator 17. It was set as the structure cooled by the stage 16 together.
JP-A-11-233332

  However, in the conventional cooling device 10, the superconducting magnet coil 12 and the magnetic body 20 that are cooled by the GM refrigerator 17 are both arranged on the first cooling stage 16. However, while the magnetic body 20 is cooled to an ultra-low temperature of 0.05K as described above, the superconducting magnet coil 12 can achieve superconductivity at about 6K.

  Thus, conventionally, since the superconducting magnet coil 12 and the magnetic body 20 having a large difference in cooling temperature are disposed on the same first cooling stage 16 for cooling, efficient cooling cannot be performed. There was a problem.

  In other words, the temperature of the superconducting magnet coil 12 inevitably rises when an electric current is passed through it, and this rise in temperature is conducted to the magnetic body 20 via the first cooling stage 16, and the magnetic body 20. The minimum temperature of adiabatic demagnetization operation increases.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a cooling device capable of efficiently cooling a plurality of objects to be cooled having different cooling temperatures in the device.

  In order to solve the above-mentioned problems, the present invention is characterized by the following measures.

The invention according to claim 1
A refrigerator that cools the object to be cooled;
In the cooling device having heat transfer means for thermally connecting the object to be cooled and the refrigerator,
The heat transfer means is constituted by a plurality of thermally independent heat transfer paths.

  According to the above invention, since a plurality of thermally independent heat transfer paths are provided between the object to be cooled and the refrigerator, different cooling processes can be performed for each heat transfer path.

The invention according to claim 2
The cooling device according to claim 1, wherein
A thermal switch is disposed in at least one of the plurality of heat transfer paths.

  According to the above invention, since the heat transfer path provided with the thermal switch can turn on / off heat conduction, it is possible to control the cooling of the object to be cooled.

The invention according to claim 3
The cooling device according to claim 1, wherein
The thermal resistances of the plurality of heat transfer paths are different.

  According to the said invention, the different cooling process according to the thermal resistance of each heat-transfer path | route can be performed by varying each thermal resistance of a several heat-transfer path | route.

The invention according to claim 4
A vacuum vessel;
A superconducting magnet coil installed in the vacuum vessel;
An object to be cooled which is applied with a magnetic field by the superconducting magnet coil;
A refrigerator that produces cold;
A first heat transfer path for thermally connecting the object to be cooled and the refrigerator;
A second heat transfer path that thermally connects the superconducting magnet coil and the refrigerator;
The first heat transfer path and the second heat transfer path are configured to be thermally independent.

  According to the above invention, since the first heat transfer path and the second heat transfer path are thermally independent, different cooling processes can be performed for each heat transfer path.

The invention according to claim 5
The cooling device according to claim 4, wherein
A thermal switch is provided in the first heat transfer path.

  According to the above invention, the object to be cooled and the refrigerator can be thermally connected or disconnected by the thermal switch, so that the cooling of the object to be cooled can be controlled.

Further, the invention described in claim 6
The cooling device according to claim 4, wherein
The heat resistance of the first heat transfer path is different from the heat resistance of the second heat transfer path.

  According to the above invention, the heat resistance of the first heat transfer path is different from the heat resistance of the second heat transfer path, so that different cooling processes are performed according to the heat resistance of each heat transfer path. Can do.

  According to the present invention, since a plurality of thermally independent heat transfer paths are provided between the object to be cooled and the refrigerator, different cooling processes can be performed for each heat transfer path by one refrigerator. It becomes possible.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing the overall configuration of a cooling device 40A according to an embodiment of the present invention, and FIG. 2 is an enlarged view showing the vicinity of a magnetic salt pill 58. As shown in each figure, the cooling device 40A is roughly composed of a vacuum vessel 41, a first radiation shield 46, a second radiation shield 49, an adiabatic demagnetization freezer 60, a heat switch 65, a Gifford McMahon refrigerator ( (Hereinafter referred to as GM refrigerator), heat link 66, low heat resistance flange 106 and the like.

  The vacuum vessel 41 is roughly constituted by a vacuum vessel main body 42, a top plate 43, a bottom plate member 44, and the like, and a sealed cylindrical space 41A is formed therein. The vacuum vessel main body 42 is provided with an outer cylinder 61, a shield member 64, a flange 95, and the like which will be described later.

  The vacuum vessel main body 42 has a cylindrical shape, and openings (not shown) are formed at upper and lower ends thereof. A top plate 43 is disposed at the upper end portion of the vacuum vessel main body 42 so as to cover the opening portion, and a bottom plate member 44 is disposed at the lower end portion so as to cover the opening portion.

  An opening 44 </ b> A for inserting the GM refrigerator 70 into the vacuum container 41 is formed in the bottom plate member 44 disposed at the lower end of the vacuum container body 42. Further, an outer cylinder 61 extending in the lateral direction is disposed on the side surface portion of the vacuum vessel main body 42.

  The outer cylinder 61 communicates with the cylindrical space 41A, and the inside thereof is configured to be in a vacuum atmosphere. A shield member 64 is disposed at the end (the right end in the drawing) opposite to the end connected to the vacuum vessel main body 42 of the outer cylinder 61.

  The shield member 64 is a bottomed cylindrical member, and a first shield member 63 and a second shield member 62 having the same bottomed cylindrical shape are disposed concentrically therein. A detector 68 is provided in the vicinity of the right end of the second shield member 62 located in the innermost periphery in the drawing.

  Measurement windows 62 </ b> A to 64 </ b> A are provided at ends of the shield members 62 to 64 facing the detector 68. The measurement windows 62 </ b> A to 64 </ b> A are windows for allowing light and electromagnetic waves to pass toward the detector 68.

  A cylindrical heat link 66 is disposed at the center position of the shield member 64, that is, at the internal position of the second shield member 62. The thermal link 66 is formed of a material having high thermal conductivity (for example, copper), the right end in the figure is thermally connected to the detector 68, and the left end in the figure is an adiabatic demagnetization refrigeration described later. It is configured to be thermally connected to the unit 60.

  A flange 95 is disposed on the outer peripheral portion of the vacuum vessel main body 42. A plurality of bolt holes 105 are formed in the flange 95 as shown in FIG. The bolt 96 is inserted into the bolt hole 105 and the flange 95 and the vacuum vessel support 100 are fastened by the bolt 96, whereby the vacuum vessel 41 is fixedly supported by the vacuum vessel support 100.

  The vacuum vessel support 100 supports the above-described vacuum vessel 41, and as shown in FIG. 4, two rectangular frame members 101 and 102 and four support columns erected at the corners thereof. The member 104 is configured. The vacuum container support 100 is configured to be vibrationally separated from a refrigerator support 80 described later. The vacuum vessel 41 is installed on the floor by the vacuum vessel support 100.

  On the other hand, the vacuum vessel 41 is configured such that a first radiation shield 46 and a second radiation shield 49 are provided therein. The first radiation shield 46 has a cylindrical shape, and a cylindrical space 46A is formed therein.

  The first radiation shield 46 is configured such that a gap is interposed between the first radiation shield 46 and the inner wall of the vacuum vessel body 42. In this way, by forming a gap between the vacuum vessel main body 42 and the first radiation shield 46, heat outside the vacuum vessel main body 42 is blocked from being directly radiated to the first radiation shield 46. be able to.

  The first shield member 63 described above is provided on the side surface of the first radiation shield 46. The first shield member 63 is formed so as to extend in the right direction in the figure, and is disposed in the outer cylinder 61 and the shield member 64 so that a gap is interposed between the outer cylinder 61 and the shield member 64.

  Further, the first radiation shield 46 is configured such that its lower end is opened, and a first cooling stage 47 is disposed at this lower end. The first cooling stage 47 is provided with an opening (not shown) for inserting the GM refrigerator 70.

  Further, a support column 45 is provided between the first cooling stage 47 and the bottom plate member 44, and the first cooling stage 47 and the first radiation shield 46 are connected to the bottom plate member 44 via the support column 45. It is supported by. The first cooling stage 47 is for cooling the inside of the first radiation shield 46 by the cold generated from the first cold head 75 described later.

  The second radiation shield 49 is disposed in the first radiation shield 46 (cylindrical space 46A) so that a gap is interposed between the second radiation shield 49 and the first radiation shield 46. The second radiation shield 49 functions so that radiant heat is blocked between the second radiation shield 49 and the first radiation shield 46.

  The second radiation shield 49 also has a cylindrical shape, and a cylindrical space 49A is formed therein. The second shield member 62 is disposed on the side surface of the second radiation shield 49 with a gap between the first shield member 63 and the first shield member 63.

  In addition, the second radiation shield 49 is configured such that the lower end is opened, and the second cooling stage 50 is disposed at the lower end. The superconducting magnet coil 54 and the adiabatic demagnetizing / refrigeration unit 60 are disposed above the second cooling stage 50. Therefore, the second cooling stage 50 is provided with an opening (not shown) for inserting the magnetic salt pill 58 constituting the heat-insulating demagnetizing / refrigeration unit 60.

  A support column 51 is provided between the second cooling stage 50 and the first cooling stage 47, and the second cooling stage 50 and the second radiation shield 49 are connected to the first cooling stage 51 via the support column 51. It is supported by the cooling stage 47. The second cooling stage 50 is for cooling the superconducting magnet coil 54 and the magnetic salt pill 58 disposed in the second radiation shield 49 by the cold generated from the second cold head 81 described later. is there. In addition, a thermal switch 65 is provided between the second cooling stage 50 and the magnetic salt pill 58 to turn on / off transmission of the cold of the second cooling stage 50 to the magnetic salt pill 58. .

  The heat link 66 is a rod-shaped member made of copper disposed in the second shield member 63 as described above, and one end is thermally connected to the magnetic salt pill 58 and the other end. Is thermally connected to the detector 68. The thermal link 66 has a function of cooling the detector 66 by ultra-low temperature (for example, 0.05 K) generated in the magnetic salt pill 58.

  The detector 68 is provided in the second shield member 62, and is disposed so as to face the measurement windows 62A to 63A. The detector 68 detects an electron beam, an electromagnetic wave (X-ray), and the like, and is appropriately selected according to the contents of analysis / inspection for the sample.

  The refrigerator support 80 is for supporting the GM refrigerator 70, and is provided inside the region where the vacuum vessel support 100 is provided. In general, the refrigerator support 80 includes a base 91, a refrigerator fixing plate 89, and a support portion 85.

  Above the base 91, a refrigerator fixing plate 89 supported by four support portions 85 is disposed. The base 91 is installed on the floor. An opening 89 </ b> A for inserting the GM refrigerator 70 is formed at the center of the refrigerator fixing plate 89. The motor unit 71 of the GM refrigerator 70 is fixed to the refrigerator fixing plate 89 via bolts.

  Thus, by providing the refrigerator support body 80 inside the area where the vacuum container support body 100 is provided, compared with the case where the refrigerator support body 80 is provided outside the area where the vacuum container support body 100 is provided. Thus, the size (footprint) of the cooling device 40A can be reduced.

  The refrigerator support 80 and the bottom plate member 44 are connected by a vacuum bellows 88 provided so as to surround the GM refrigerator 70. As shown in FIG. 6, the vacuum bellows 88 that is a vibration suppressing member has a bellows structure, and is for suppressing the vibration from the GM refrigerator 70 from being transmitted to the vacuum container 41.

  In this way, by connecting the refrigerator support 80 that supports the GM refrigerator 70 and the vacuum vessel 41 with the vacuum bellows 88, vibration generated from the GM refrigerator 70 is prevented from being transmitted to the vacuum vessel 41. it can. Thereby, the vibration generated from the GM refrigerator 70 is suppressed from being transmitted to the detector 68 via the vacuum container 41, and the detection of the detector 68 can be performed with high accuracy.

  6 is an enlarged partial cross-sectional perspective view showing a portion corresponding to the region B of the cooling device shown in FIG. 2, and illustration of the internal structure of the GM refrigerator 70 is omitted in FIG.

  The adiabatic demagnetization freezer 60 is disposed in the second radiation shield 49. The adiabatic demagnetization refrigerator 60 includes a superconducting magnet coil 54, a magnetic salt pill 58, a thermal switch 65, and the like. The adiabatic demagnetization freezer 60 and the GM refrigerator 70 constitute a cooling device 40A based on the adiabatic demagnetization method.

  Here, the cooling principle by the adiabatic demagnetization method in the adiabatic demagnetization freezer 60 will be described. The magnetic moment of the magnetic atoms constituting the magnetic salt pill 58 is disordered unless the temperature is very high, and the entropy of the system is in a high state.

  Here, when a strong magnetic field is applied from the outside by the superconducting magnet coil 54, the magnetic moment aligns in the direction of the external magnetic field, is partially ordered, and the entropy of the entire system decreases. When an external magnetic field is applied with the magnetic salt pill 58 kept isothermal, the magnetic moments of the magnetic atoms constituting the magnetic salt pill 58 are arranged in the direction of the magnetic field, and the entropy of the entire system is reduced.

  When performing isothermal magnetization, heat of magnetization is generated and the temperature rises. After this heat is removed, the GM refrigerator 70 and the magnetic salt pill 58 are thermally separated by the thermal switch 65 to isolate the system into an adiabatic state. When the external magnetic field is gradually removed, the temperature of the magnetic salt pill 58 decreases as the magnetic field decreases. By this adiabatic demagnetization, it is possible to obtain an extremely low temperature cold below the liquid He temperature (4K).

  The superconducting magnet coil 54 has a configuration in which superconducting wires 52, 53, and 67 are wound around a winding frame 55. The superconducting magnet coil 54 has a cylindrical opening 53A formed at the center, and the magnetic salt pill 58 is disposed inside the cylindrical opening 53A. The superconducting magnet coil 54 having the above-described configuration is supported on the second cooling stage 50 by a heat conduction support member 56 provided below the superconducting magnet coil 54. As will be described later, the second cooling stage 50 is configured to be thermally connected to the second cooling unit 78 (GM refrigerator 70) via the second flexible high heat conducting member 84. Yes.

  The magnetic salt pill 58 has a structure in which a large number of gold wires and an iron alum that serves as a cooling medium in adiabatic demagnetization are stored in a storage container (not shown). The upper end portion of the magnetic salt pill 58 is thermally connected to a detector 68 that is an object to be cooled via a thermal link 66. The lower end of the magnetic salt pill 58 is connected to the low thermal resistance flange 106 via a thermal switch 65. The thermal switch 65 is for turning on / off the thermal connection between the magnetic salt pill 58 and the second cooling unit 78 (GM refrigerator 70).

  The low heat resistance flange 106 is thermally connected to the second cooling unit 78 (GM refrigerator 70) via the third flexible high heat conducting member 105. Further, a heat insulating member 112 having a high thermal resistance is provided between the low thermal resistance flange 106 and the second cooling stage 50. Therefore, the second cooling stage 50 and the low thermal resistance flange 106 are configured to be substantially thermally separated.

  The GM refrigerator 70 generally includes a motor unit 71, a first cooling unit 73, a second cooling unit 78, and the like. The GM refrigerator 70 has the largest weight among the components constituting the cooling device 40A. In this embodiment, the GM refrigerator 70 having such a large weight is arranged in the lower part, and the vacuum vessel 41 that is lighter than the GM refrigerator 70 is arranged at a position higher than the GM refrigerator 70. Thus, the stability of the cooling device 40A as a whole is achieved.

  The GM refrigerator 70 is arranged such that the motor unit 71 is located at the lowermost part. The motor unit 71 includes a motor for driving cylinders (not shown) provided in the first and second cooling units 73 and 78. The motor portion 71 is provided with a flange 70B, and the flange 70B is fixed to the refrigerator fixing plate 89 with bolts. Thereby, the GM refrigerator 70 is supported by the refrigerator support body 80.

  A first cooling portion 73 that penetrates the bottom plate member 44 is disposed on the motor portion 71. The first cooling unit 73 is configured integrally with the motor unit 71, and includes a first cylinder unit 74, a first cold head 75, a flange 76, and the like.

  The first cylinder portion 74 is disposed between the first cold head 75 and the motor portion 71. The first cylinder portion 74 is provided with a cylinder (not shown). The cylinder is driven in the vertical direction in the figure by a motor provided in the motor unit 71, thereby generating cold.

  The first cold head 75 generates a cold of about 40K. A disc-shaped flange 76 is disposed on the outer periphery of the first cold head 75. The flange 76 is thermally connected to the first cold head 75. The flange 76 is thermally connected to the first cooling stage 47 through the first flexible high heat conducting member 77.

  A plurality of first flexible high heat conducting members 77 are provided between the flange 76 and the first cooling stage 47 so as to surround the second cooling part 78. The first flexible high thermal conductive member 77 is a ribbon-like member that is flexible and has high thermal conductivity, and is curved in an S shape when viewed from the side. As the first flexible high heat conductive member 77, one obtained by superimposing at least one of the group consisting of gold foil, silver foil, copper foil, and aluminum foil can be used.

  As described above, the first flexible high heat conduction member 77 having flexibility between the flange 76 and the first cooling stage 47 and having high heat conductivity so as to surround the second cooling portion 78. And efficiently cooling the first cooling stage 47 and the first radiation shield 46 by thermally connecting the first cooling unit 73 and the first cooling stage 47, and It is possible to suppress the vibration generated from the GM refrigerator 70 from being transmitted to the first cooling stage 47 and the first radiation shield 46. Thereby, it is possible to suppress the vibration generated from the GM refrigerator 70 from being transmitted to the detector 68.

  The second cooling section 78 extends through the first cooling stage 47 upward in the drawing. The second cooling unit 78 is configured integrally with the first cooling unit 73 and is thermally connected to the superconducting magnet coil 54 and the magnetic salt pill 58. The second cooling unit 78 is roughly configured to include a second cylinder unit 79, a second cold head 81, and a flange 82.

  The second cylinder portion 79 is disposed between the second cold head 81 and the first cold head 75. A cylinder (not shown) is provided in the second cylinder portion 79, and coldness is generated when the cylinder is driven in the vertical direction in the drawing by the motor.

  The second cold head 81 is a part that generates a cold of about 4K. A flange 82 that is thermally connected to the second cold head 81 is disposed on the second cold head 81. The flange 82 is formed in a disk shape, and is thermally connected to the second cooling stage 50 via the second flexible high heat conductive member 84 and the third flexible high heat conductive member 105. It is thermally connected to the low thermal resistance flange 106 via

  A plurality of second flexible high heat conducting members 84 are provided between the flange 82 and the second cooling stage 50 so as to surround the second cooling unit 78. A plurality of third flexible high thermal conductive members 105 are provided between the flange 82 and the low thermal resistance flange 106 so as to surround the lower end of the low thermal resistance flange 106. Since the third flexible high heat conductive member 105 is disposed inside the second flexible high heat conductive member 84, the shape thereof is smaller than that of the second flexible high heat conductive member 84. It is said that.

  The second and third flexible high thermal conductive members 84 and 105 are flexible and have high thermal conductivity, and are ribbon-like members that are both curved in an S shape when viewed from the side. . As the second and third flexible high thermal conductive members 84 and 105, those obtained by superimposing at least one of the group consisting of gold foil, silver foil, copper foil, and aluminum foil can be used.

  Thus, between the flange 82 and the second cooling stage 50, and between the flange 82 and the low thermal resistance flange 106, the second and third flexibility having flexibility and high thermal conductivity are provided. By providing a plurality of high heat conducting members 84 and 105, the second cooling stage 50 and the low heat resistance flange 106 are efficiently cooled, and vibrations generated from the GM refrigerator 70 are generated by the second cooling stage 50 and the second cooling stage 50. Transmission to the radiation shield 49 can be suppressed. Thereby, it is possible to suppress the vibration generated from the GM refrigerator 70 from being transmitted to the detector 68.

  Here, the heat transfer path from the second cooling unit 78 (GM refrigerator 70) will be considered. As described above, the GM refrigerator 70 cools the superconducting magnet coil 54 and the magnetic salt pill 58.

  At this time, the second cooling unit 78 (GM refrigerator 70) and the magnetic salt pill 58 are thermally connected via the third flexible high thermal conductive member 105, the low thermal resistance flange 106, and the thermal switch 65. (Hereinafter, this heat transfer path is referred to as a first heat transfer path). On the other hand, the second cooling unit 78 (GM refrigerator 70) and the superconducting magnet coil 54 are heated via the second flexible high heat conducting member 84, the second cooling stage 50, and the heat conducting support member 56. (Hereinafter, this heat transfer path is referred to as a second heat transfer path). The members constituting each heat transfer path correspond to the heat transfer means described in the claims.

  In the present embodiment, the heat insulating member 112 is provided between the second cooling stage 50 and the low thermal resistance flange 106, so that the first heat transfer path and the second heat transfer path are thermally independent. It is configured. Further, the thermal resistance of the third flexible high thermal conductive member 105 and the low thermal resistance flange 106 constituting the first heat transfer path is equal to the second flexible high thermal conductive member 84 constituting the second heat transfer path. And it is set smaller than the thermal resistance of the second cooling stage 50.

  Thus, since the cooling device 40A according to the present embodiment has a configuration in which the first heat transfer path and the second heat transfer path are thermally independent, different cooling processes are performed for each heat transfer path. It becomes possible. Furthermore, by making the thermal resistance of the first heat transfer path different from the heat resistance of the second heat transfer path, cooling at different temperatures can be performed for each heat transfer path. At this time, since the cooling temperature correlates with the heat resistance value of each heat transfer path, it is possible to control the cooling temperature according to the heat resistance value by appropriately selecting the heat resistance value of each heat transfer path. is there.

  Therefore, in the cooling device 40A according to the present embodiment, the superconducting magnet coil 54 and the magnetic salt pill 58 can be cooled to different temperatures by one GM refrigerator 70. Specifically, by performing the adiabatic demagnetization operation, the superconducting magnet coil 54 can be cooled to about 6K while the magnetic salt pill 58 is cooled to an ultra-low temperature of 0.05K. Further, as described above, since the second cooling stage 50 and the low thermal resistance flange 106 are thermally separated by the heat insulating member 112, the heat of the superconducting magnet coil 54 is conducted to the magnetic salt pill 58. Absent. Furthermore, since a thermal switch 65 is provided between the low thermal resistance flange 106 and the magnetic salt pill 58, the cooling between the second cooling unit 78 (GM refrigerator 70) and the magnetic salt pill 58 is as follows. It is appropriately controlled by turning on / off the thermal switch 65.

  Therefore, even if a plurality of objects to be cooled (superconducting magnet coil 54 and magnetic salt pill 58) having different cooling temperatures required in the cooling device 40A are provided, the superconducting magnet coil 54 and the magnetic salt pill 58 are transferred from the GM refrigerator 70. By making independent heat transfer paths, it is possible to prevent adverse effects among a plurality of objects to be cooled, and to perform highly efficient cooling processing.

  FIG. 7 shows a modification of the cooling device 40A described above. In the embodiment described above, the cooling device 40A using the magnetic salt pill 58 as an object to be cooled by performing the adiabatic demagnetization operation has been described, but the application of the present invention is not limited to this.

  In the cooling device 40B according to the present modification, the object to be cooled is replaced with the magnetic salt pill 58, and the sample 110 is used for testing physical properties and the like. This physical property test measures physical properties when a magnetic field is applied while the sample 110 is kept at a low temperature. Also in this modification, a thermal switch 65 is provided. Therefore, the heat conduction (cooling) between the second cooling unit 78 and the sample 110 can be controlled by the thermal switch 65, and the degree of freedom in measuring physical properties can be increased.

  In addition, it is also possible to apply this invention with respect to to-be-cooled objects other than this modification. Furthermore, in the above-described embodiment, since there are two objects to be cooled (the superconducting magnet coil 54 and the magnetic salt pill 58), there are two heat transfer paths from the GM refrigerator 70. The number of heat transfer paths is not limited to two, and an appropriate number of heat transfer paths can be set according to the number of objects to be cooled, the number of refrigerators, and the like.

FIG. 1 is a cross-sectional view showing an entire cooling device according to an embodiment of the present invention. FIG. 2 is an enlarged view showing the vicinity of a magnetic salt pill of a cooling device according to an embodiment of the present invention. FIG. 3 is an enlarged view of a portion corresponding to region A of the cooling device shown in FIG. FIG. 4 is a side view of the vacuum vessel support. FIG. 5 is a plan view of the vacuum vessel support. FIG. 6 is a cross-sectional perspective view of a portion corresponding to a region B surrounded by a broken line in FIG. FIG. 7 is a cross-sectional view of a cooling device that is a modification of the cooling device shown in FIG. 1. FIG. 8 is a schematic configuration diagram showing a cooling device as an example of the prior art.

Explanation of symbols

40A, 40B Cooling device 41 Vacuum vessel 52, 54 Superconducting magnet coil 42 Vacuum vessel body 43 Top plate 44 Bottom plate member 46 First radiation shield 47 First cooling stage 49 Second radiation shield 50 Second cooling stage 56 Heat Conductive support member 58 Magnetic salt pill 60 Adiabatic demagnetization refrigerator 65 Thermal switch 66 Thermal link 70 GM refrigerator 73 First cooling section 74 First cylinder section 75 First cold head 77, 84, 105 Flexible high thermal conductivity Member 78 Second cooling part 79 Second cylinder part 81 Second cold head 88 Vacuum bellows 106 Low thermal resistance flange 110 Sample 112 Thermal insulation member

Claims (6)

A refrigerator that cools the object to be cooled;
In the cooling device having heat transfer means for thermally connecting the object to be cooled and the refrigerator,
A cooling device, wherein the heat transfer means is constituted by a plurality of thermally independent heat transfer paths. The cooling device according to claim 1, wherein
A cooling device comprising a thermal switch in at least one of the plurality of heat transfer paths. The cooling device according to claim 1, wherein
The cooling device according to claim 1, wherein each of the plurality of heat transfer paths has a different thermal resistance. A vacuum vessel;
A superconducting magnet coil installed in the vacuum vessel;
An object to be cooled which is applied with a magnetic field by the superconducting magnet coil;
A refrigerator that produces cold;
A first heat transfer path for thermally connecting the object to be cooled and the refrigerator;
A second heat transfer path that thermally connects the superconducting magnet coil and the refrigerator;
The cooling device characterized in that the first heat transfer path and the second heat transfer path are thermally independent. The cooling device according to claim 4, wherein
A cooling device comprising a thermal switch in the first heat transfer path. The cooling device according to claim 4, wherein
A cooling device characterized in that a thermal resistance of the first heat transfer path is different from a heat resistance of the second heat transfer path.