JP4472715B2 - Cryogenic refrigerator - Google Patents

Description

  The present invention relates to a cryogenic refrigerator, and more particularly, to a cryogenic refrigerator having a regenerator filled with a magnetic regenerator material in a storage portion such as a cylinder.

  In general, Gifford McMahon type refrigerators (hereinafter referred to as GM refrigerators) and pulse tube refrigerators are known as refrigerators capable of generating extremely low temperatures (for example, about 4K). The GM refrigerator is configured to adiabatic expansion by reciprocally moving a displacer provided with a regenerator material in a cylinder by a driving means, thereby generating cold. On the other hand, the pulse tube refrigerator is expected as a refrigerator having a simple structure and less vibration, such as a displacer of a GM refrigerator, having no moving parts in the low temperature portion.

  These refrigerators are used as cooling devices for MRI (Magnetic Magnetic Resonance Imaging) and NMR (Nuclear Magnetic Resonance) used for generating diagnostic images in the medical field, for example. Thus, when applied to MRI and NMR, the refrigerator is used in a helium environment.

  By the way, in MRI and NMR, it is known that when magnetic noise is generated in a refrigerator, a magnetic field generated by MRI or NMR is disturbed and adversely affects a diagnostic image. However, in recent years, a magnetic regenerator material has been frequently used as a regenerator material used in various refrigerators. This is because the magnetic regenerator material has a higher regenerator efficiency than a general regenerator material, and by using this, a cryogenic temperature can be efficiently realized.

  When a magnetic regenerator material is used in this way, in the case of a GM refrigerator, the displacer reciprocates in the cylinder as described above. Therefore, the magnetic regenerator material provided in the displacer is also within the magnetic field generated by MRI or NMR. It will move and disturb the magnetic field.

  In the case of a pulse tube refrigerator, the magnetic regenerator material does not move significantly in the magnetic field generated by MRI or NMR as in the case of the GM refrigerator. Pulsates between a low pressure and a high pressure, which causes the regenerator to expand and contract in the axial direction by several tens of microns. The expansion and contraction of the regenerator moves the magnetic regenerator material in the regenerator and disturbs the magnetic field generated by MRI and NMR.

  Furthermore, a change occurs in the magnetic susceptibility of the magnetic regenerator material due to the temperature change of the magnetic regenerator material during the refrigeration cycle. This change in magnetic susceptibility also disturbs the magnetic field generated by MRI or NMR.

  As a method for preventing this, for example, as disclosed in Patent Document 1, by winding a portion where a magnetic regenerator material is disposed with a sheet-like shield material, against a magnetic field generated by MRI or NMR It is conceivable to magnetically shield the magnetic regenerator material. By the way, in order to perform an efficient magnetic shield using a shield material, it is necessary to cool the shield plate to an extremely low temperature. However, in the configuration in which the sheet-like shield material is disposed in the portion where the magnetic regenerator material is disposed, it is difficult to properly cool the shield plate, and the magnetic regenerator material is prevented from being generated by a magnetic field generated by MRI or NMR. There is a problem that it cannot be reliably shielded.

  On the other hand, as a method for reliably cooling the magnetic shield, a method of arranging the magnetic shield on the refrigeration stage can be considered. FIG. 7 shows an example in which this method is applied to the pulse tube refrigerator 100. The pulse tube refrigerator 100 shown in the figure is a so-called two-stage pulse tube refrigerator, and therefore, a first-stage pulse tube 112, a two-stage pulse tube 113, a first-stage regenerator tube 114, a first-stage stage 115, a two-stage stage. 116 and a two-stage stage 117.

  The pulse tube refrigerator 100 is configured such that a spacer 116A and a magnetic regenerator material 116B are provided in a cylinder 118 of a two-stage stage 116. The magnetic shield 119 that magnetically shields the magnetic regenerator material 116B from the outside is configured to be soldered to the two-stage stage 117. The magnetic shield 119 has a structure in which NbTi and Cu, which are superconductive materials, are alternately laminated, and has a cylindrical shape that can surround the two-stage pulse tube 113 and the two-stage stage 116.

In the pulse tube refrigerator 100 configured as described above, since the magnetic shield 119 is disposed on the two-stage stage 117 that is cooled to a very low temperature (for example, 4K), the magnetic shield 119 is cooled to the return temperature or lower. ing. For this reason, the magnetic shield 119 is in a superconducting state, so that even if the pulse refrigerating machine 100 is driven and the magnetic regenerator material 116B moves, and magnetic noise is generated by this, the magnetic shield 119 cancels this magnetic noise. A current flows through the magnetic field, so that the disturbance of the magnetic field can be canceled.
JP 2006-038446 A

  As described above, when used for MRI and NMR, the pulse tube refrigerator 100 is used in a helium environment. This helium has a relatively large heat capacity (5193 J / (kg * K)), and each cylinder of the two-stage pulse tube 113 and the two-stage stage 116 has a thermal gradient, and the two-stage stage 117 has 4K. However, the temperature on the high temperature end side (first stage 115) of the second stage 116 is about 10K.

  However, in order to maintain the superconducting state, the magnetic shield 119 is cooled to the return temperature or lower, and a temperature difference is generated between each cylinder of the second-stage pulse tube 113 and the second-stage stage 116. Therefore, due to the difference between the temperature gradient of the cylinder and the temperature gradient of the magnetic shield 119, helium convection as shown by arrows in FIG. 7 occurs in the helium atmosphere, which causes heat loss and the pulse tube refrigerator 100. There was a problem that the refrigerating capacity would be reduced.

  The present invention has been made in view of the above points, and even if a magnetic regenerator material is used, the effect on the external magnetic field is suppressed, and even if it is used in a helium environment, the refrigerating capacity is improved. It aims at providing the cryogenic refrigerator which can aim at.

  In order to solve the above problems, in the cryogenic refrigerator according to the present invention, a regenerator in which a magnetic regenerator material is disposed in a regenerator material storage member, and between the regenerator material storage member and the magnetic regenerator material. A magnetic shield that shields magnetic noise generated by the magnetic regenerator material, and is disposed between the magnetic shield and the regenerator material storage member, and is disposed so as to face the magnetic shield across its entire surface. In addition, the magnetic shield and the magnetic regenerator material are thermally connected to each other at a connection portion that is disposed between the first heat insulating material, the magnetic shield and the magnetic regenerator material, and is formed on the low temperature end side of the regenerator. And a second heat insulating material disposed so as to face the magnetic shield at a portion other than the connecting portion.

  In order to solve the above problems, in the cryogenic refrigerator according to the present invention, a regenerator in which a magnetic regenerator material is disposed in a cylinder, and a pulse tube having a low-temperature end connected to a low-temperature end of the regenerator. A phase adjusting mechanism connected to the high temperature end of the pulse tube, a magnetic shield disposed between the cylinder and the magnetic regenerator material, and shielding magnetic noise generated by the magnetic regenerator material, and the magnetic Disposed between a shield and the cylinder, disposed between the magnetic shield and the magnetic regenerator, a first heat insulating material disposed so as to face the magnetic shield and the entire surface thereof, The magnetic shield and the magnetic regenerator material are thermally connected at a connection portion formed on the low temperature end side of the regenerator, and at a portion other than the connection portion, the second is arranged to face the magnetic shield. Having heat insulation It is an butterfly.

  In order to solve the above problems, in the cryogenic refrigerator according to the present invention, a displacer in which a magnetic regenerator material is disposed inside a cylindrical portion, a moving mechanism for reciprocating the displacer in the cylinder, A magnetic shield disposed between the cylindrical portion of the displacer and the magnetic regenerator material for shielding magnetic noise generated by the magnetic regenerator material, and disposed between the magnetic shield and the cylindrical portion of the displacer. Provided between the magnetic shield and the magnetic regenerator, and formed on the low temperature end side of the regenerator. And thermally connecting the magnetic shield and the magnetic regenerator material at the connecting portion, and having a second heat insulating material disposed to face the magnetic shield at a portion other than the connecting portion. It is an butterfly.

  Further, the cryogenic refrigerator according to the invention can be applied to a superconducting device, a cryopump device, a cryogenic measurement analyzer, and a nuclear magnetic resonance apparatus.

  According to the present invention, since the magnetic shield is disposed between the cylinder and the magnetic regenerator material, convection does not occur between the regenerator and the magnetic shield, and heat loss can be reduced. In addition, since the magnetic shield has a configuration close to the magnetic regenerator material, it is possible to effectively reduce magnetic noise generated in the magnetic regenerator material.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows a refrigerator according to a first embodiment of the present invention. In this embodiment, a pulse refrigerator 1A is taken as an example of a refrigerator. This pulse refrigerator 1A is a two-stage 4K pulse tube refrigerator used for MRI and NMR, and is used in a helium environment.

  The pulse refrigerator 1A includes a cylinder part A and a housing B directly connected to the cylinder part A. The pulse refrigerator 1A is supplied with a working gas such as helium by a compressor 3 at a high pressure and exhausted at a low pressure by a compressor 3.

  The cylinder part A is roughly composed of a first stage pulse tube 12, a second stage pulse tube 13, a first stage regenerator 14, a first stage 15, a second stage regenerator 16, a second stage 17 and the like. The first stage pulse tube 12 has a high temperature end connected to the room temperature flange 11 and a low temperature end connected to the first stage 15. The two-stage pulse tube 13 has a high-temperature end connected to the room temperature flange 11 and a low-temperature end connected to the two-stage stage 17.

  The first stage regenerator 14 has a high temperature end connected to the room temperature flange 11 and a low temperature end connected to the first stage 15. A spacer and a regenerator material (not shown) are disposed inside the first-stage regenerator 14.

  The two-stage regenerator 16 has a high temperature end connected to the first stage 15 and a low temperature end connected to the second stage 17. The cylinder 18 constituting the two-stage regenerator 16 is filled with a spacer 16A at the top and a magnetic regenerator 16B at the bottom.

  Further, inside the first stage 15, a pipe connecting the first stage pulse tube 12 and the first stage regenerator 14, and a pipe connecting the first stage regenerator 14 and the second stage regenerator 16 (both are shown in the figure). (Not shown) is formed. Therefore, the working gas is configured to be movable between the first stage pulse tube 12 and the first stage regenerator 14 and between the first stage regenerator 14 and the second stage regenerator 16. In addition, a pipe (not shown) for connecting the two-stage pulse tube 13 and the two-stage regenerator 16 is formed in the second stage 17. Therefore, the working gas is configured to be able to move between the two-stage pulse tube 13 and the two-stage regenerator 16.

  The rectifying materials 12A and 12B are connected to the high-temperature end and the low-temperature end of the first-stage pulse tube 12, respectively, and the rectifying materials 13A and 13B are similarly connected to the high-temperature end and the low-temperature end of the two-stage pulse tube 13, respectively. .

  On the other hand, the housing B is configured such that a gas pipe 26, a first-stage reservoir 22, a second-stage reservoir 23, switching valves 24A and 25B, four orifices 25, and the like are provided therein.

  One ends of the switching valves 24A and 25B are connected to the gas pipe 26 compressor 3. The other ends of the switching valves 24A and 25B are connected to the first-stage pulse tube 12, the second-stage pulse tube 13, and the first-stage regenerator 14. The first-stage pulse tube 12 is connected to the first-stage reservoir 22 by a gas pipe 26, and the second-stage pulse tube 13 is connected to the second-stage reservoir 23 through the gas pipe 26.

  Further, in the gas pipe 26, the position where the first stage pulse tube 12 and the first stage reservoir 22 are connected, the position where the second stage pulse tube 13 and the second stage reservoir 23 are connected, the valves 24 A and 24 B and the first stage pulse tube 12. The orifices 25 are respectively arranged at positions where the two valves 24A and 24B are connected to the two-stage pulse tube 13. Each of the valves 24A and 24B and the orifice 25 constitute a phase adjustment mechanism that adjusts the phase difference between the fluctuating pressure of the working gas that changes periodically and the volume flow rate, and has a function of appropriately generating cold at each low temperature end. Play. Thereby, the second stage 17 is cooled to about 4K.

  However, in the pulse refrigerator 1A, the pressure in the two-stage regenerator 16 pulsates between a low pressure and a high pressure due to introduction / suction of the working gas, and the two-stage regenerator 16 extends and contracts in the axial direction within a range of several tens of microns. However, as described above, the magnetic regenerator material 16B also moves and disturbs the magnetic field generated by MRI or NMR due to this.

  The present embodiment is characterized in that a magnetic shield 19 is provided in the two-stage regenerator 16 in order to prevent the influence of magnetic noise caused by the magnetic regenerator material 16B filled in the two-stage regenerator 16. Hereinafter, the details of the magnetic shield 19 will be described with reference to FIG. 2 is an enlarged view of the area indicated by the arrow X1 in FIG.

  The magnetic shield 19 has a cylindrical shape and is provided so as to completely surround the position where the magnetic regenerator material 16B is disposed. The magnetic shield 19 has a multilayer structure of NbTi, Nb, and Cu, which are superconducting materials. The magnetic shield 19 is disposed between the cylinder 18 serving as a cold storage material storage member and the magnetic cold storage material 16B.

  There is also a temperature gradient in the cylinder 18 in which the magnetic shield 19 is disposed, and the temperature is about 4K on the low temperature side and about 10K on the high temperature side. In order to shield the magnetic noise generated in the magnetic regenerator material 16B by the magnetic shield 19, it is necessary to cool the magnetic shield 19 to a temperature lower than the return temperature and to be in a superconducting state. Therefore, the first and second heat insulating materials 20 and 21 are provided on the outer surface and the inner surface of the magnetic shield 19 in order to prevent intrusion heat due to the above-described thermal gradient to the magnetic shield 19. For example, Teflon (registered trademark) can be used as the material of the first and second heat insulating materials 20 and 21.

  The first heat insulating material 20 is disposed between the cylinder 18 and the magnetic shield 19 so as to face the entire surface of the magnetic shield 19. The second heat insulating material 21 is disposed between the magnetic regenerator material 16B and the magnetic shield 19 so as to face the magnetic shield 19 except for the thermal connection portion 21A.

  The thermal connection portion 21 </ b> A is an opening formed on the low temperature end side of the second heat insulating material 21. Therefore, in the formation part of this thermal connection part 21A, the magnetic shield 19 is configured to be in direct contact with the magnetic regenerator material 16B. Therefore, the low temperature end side of the magnetic regenerator material 16B is configured to be thermally connected to the magnetic shield 19 via the thermal connection portion 21A.

  Thus, the cold end side of the magnetic regenerator material 16B (about 4K) cools the low temperature end side of the magnetic shield 19 via the thermal connection portion 21A, and the magnetic shield 19 is cooled to the return temperature or lower. . Further, the magnetic shield 19 is surrounded by the first and second heat insulating materials 20 and 21 except for the position where the thermal connection portion 21A is formed, so that intrusion of heat from the outside is prevented.

  For this reason, even if there is a thermal gradient in the two-stage regenerator 16 (magnetic regenerator material 16B) as described above, the magnetic shield 19 maintains the state below the return temperature and maintains the superconducting state. Therefore, even if the magnetic regenerator material 16B is moved by driving the pulse refrigerator 1A and magnetic noise is generated by this, the magnetic shield 19 can flow the current so as to cancel the magnetic noise and cancel the disturbance of the magnetic field. it can. Therefore, even when the pulse refrigerator 1A according to the present embodiment is used for cooling MRI and NMR, the magnetic field of MRI and NMR is not disturbed, and it is possible to reliably prevent the generation of diagnostic images and the like. it can.

  On the other hand, in this embodiment, since the magnetic shield 19 is arranged inside the cylinder 18, even if the pulse refrigerator 1A is applied to MRI and NMR and is arranged in a helium environment, the conventional pulse is used. Unlike the tube refrigerator 100 (see FIG. 7), there is no helium gas between the cylinder 18 and the magnetic shield 19. Therefore, even if the pulse refrigerator 1A is driven in a helium environment, heat loss due to helium convection does not occur, and the refrigerating capacity of the pulse refrigerator 1A can be prevented from being lowered. Thus, the pulse refrigerator 1A according to the present embodiment can reliably shield the magnetic noise generated by the magnetic regenerator material 16B with the magnetic shield 19 and maintain a high cooling capacity even when used in a helium environment. Is possible.

  Next, a refrigerator according to a second embodiment of the present invention will be described.

  Also in this embodiment, a pulse refrigerator is taken as an example of a refrigerator. 3 and 4 show a pulse refrigerator 1B according to the second embodiment. 3 and 4, the same reference numerals are given to the components corresponding to those shown in FIGS. 1 and 2, and the description thereof is omitted. In FIG. 3, the illustration of the housing B shown in FIG. 1 is omitted.

  In the first embodiment described above, the configuration is shown in which the spacer 16A and the magnetic regenerator material 16B are disposed inside the cylinder 18 that is fixedly disposed between the first stage 15 and the second stage 17. On the other hand, the pulse refrigerator 1B according to the present embodiment is characterized in that the spacer 16A and the magnetic regenerator material 16B are accommodated in the regenerator cartridge 27 serving as a regenerator material storage member.

  In this way, by using the regenerator cartridge 27 instead of the fixed two-stage regenerator 16 of the first embodiment, it is possible to simply replace the used regenerator cartridge 27 with a new regenerator cartridge 27 at the time of maintenance. The replacement process of 16A and the magnetic regenerator material 16B can be performed, and the maintenance can be facilitated.

  FIG. 4 is an enlarged view showing a region indicated by an arrow X2 in FIG. The magnetic shield 19 is disposed between the outer cylinder 28 of the regenerator cartridge 27 serving as a regenerator material storage member and the magnetic regenerator material 16B. Further, the first heat insulating material 20 is disposed between the outer cylinder 28 and the magnetic shield 19 so as to face the entire surface of the magnetic shield 19. Further, the second heat insulating material 21 is arranged between the magnetic regenerator material 16B and the magnetic shield 19 so as to face the magnetic shield 19 except for the thermal connection portion 21A.

  Therefore, even in the pulse refrigerator 1B according to the present embodiment, even if there is a thermal gradient in the two-stage regenerator 16 (magnetic regenerator material 16B), the magnetic shield 19 maintains a state below the return temperature and is in a superconducting state. To maintain. Thus, even if the magnetic regenerator material 16B is moved by driving the pulse refrigerator 1B and magnetic noise is generated by this, current flows in the magnetic shield 19 so as to cancel the magnetic noise and cancel the disturbance of the magnetic field. Can do. Therefore, even if the pulse refrigerator 1B according to the present embodiment is applied to MRI and NMR, it is possible to prevent the generation of diagnostic images and the like from being adversely affected.

  Next, a third embodiment of the present invention will be described.

  In this embodiment, a Gifford McMahon refrigerator (GM refrigerator) is used as an example of a refrigerator. 5 and 6 show a GM refrigerator 30 according to the third embodiment. 5 and 6, the same reference numerals are given to the components corresponding to those shown in FIGS. 1 and 2, and the description thereof is omitted.

  The GM refrigerator 30 according to the present embodiment is also applied to MRI and NMR, and is used in a helium environment. The GM refrigerator 30 generally includes a first stage cylinder 32, a second stage cylinder 34, a first stage displacer 36, a second stage displacer 38, a first stage regenerator 40, a second stage regenerator 42, and the like.

  A first stage displacer 36 is disposed inside the first stage cylinder 32 so as to be capable of reciprocating in the vertical direction in the figure. In addition, a regenerator material 40 is disposed inside the first stage displacer 36. A two-stage displacer 38 is disposed inside the two-stage cylinder 34 so as to be reciprocally movable in the vertical direction in the figure. A magnetic regenerator material 42 is disposed inside the two-stage cylinder 34. Further, a magnetic shield 19 is disposed inside the two-stage cylinder 34.

  The first stage displacer 36 is connected to a scotch yoke mechanism 46. The scotch yoke mechanism 46 is driven by a drive motor 44. The rotation of the drive motor 44 is converted into a linear reciprocating motion by the Scotch yoke mechanism 46, whereby the first stage displacer 36 reciprocates in the first stage cylinder 32. Further, since the first stage displacer 36 and the second stage displacer 38 are connected, the first stage displacer 36 reciprocates, so that the second stage displacer 38 also reciprocates within the second stage cylinder 34.

  The first-stage cylinder 32 is connected to the compressor 50 via an intake / exhaust switching valve 52 (having an intake valve V1 and an exhaust valve V2). The opening / closing of the intake / exhaust switching valve 52 is synchronized with the movement of the displacers 36, 38 by the Scotch yoke mechanism 46, and accordingly, the first stage expansion chamber 55 formed on the cooling end side of the first stage cylinder 32 at a predetermined timing and Cold is generated in the two-stage expansion chamber 56 formed on the cooling end side of the two-stage cylinder 34 by adiabatic expansion. Thereby, the first stage cooling stage 33 is cooled to about 10 to 30K, and the second stage cooling stage 35 is cooled to about 4K.

  Next, the magnetic shield 19 used in this embodiment will be described with reference to FIG. FIG. 6 is an enlarged view showing a region indicated by an arrow X3 in FIG.

  The magnetic shield 19 is disposed between the cylindrical portion 38 a of the two-stage displacer 38 serving as a cold storage material storage member and the magnetic cold storage material 42. The first heat insulating material 20 is disposed between the tubular portion 38 a and the magnetic shield 19 so as to face the entire surface of the magnetic shield 19. The second heat insulating material 21 is disposed between the magnetic regenerator material 42 and the magnetic shield 19 so as to face the magnetic shield 19 except for the thermal connection portion 21A.

Therefore, even in the GM refrigerator 30 according to the present embodiment, even if there is a thermal gradient in the two-stage displacer 38 (magnetic regenerator material 42), the magnetic shield 19 maintains a state below the return temperature and maintains a superconducting state. maintain. As a result, even if the GM refrigerator 30 is driven and the two-stage displacer 38 moves in the two-stage cylinder 34 and magnetic noise is thereby generated, a current flows in the magnetic shield 19 so as to cancel the magnetic noise. Disturbance can be canceled. Therefore, even if the GM refrigerator 30 is applied to MRI and NMR, it is possible to prevent the generation of diagnostic images and the like from being adversely affected.
The present invention uses various two-stage or multi-stage pulse refrigerators, various superconducting devices, various superconducting magnet devices, various sensor cooling systems, cryogenic measurement analyzer, liquefier, liquefied gas, recondenser, cryopump, Applicable to physics and chemistry equipment.

FIG. 1 is a diagram for explaining a refrigerator according to a first embodiment of the present invention. FIG. 2 is an enlarged view showing the vicinity of the magnetic shield in FIG. FIG. 3 is a diagram for explaining a refrigerator that is a second embodiment of the present invention. FIG. 4 is an enlarged view showing the vicinity of the magnetic shield in FIG. FIG. 5 is a diagram for explaining a refrigerator according to a third embodiment of the present invention. FIG. 6 is an enlarged view showing the vicinity of the magnetic shield in FIG. FIG. 7 is a diagram for explaining a refrigerator as an example of the prior art.

Explanation of symbols

1A, 1B Pulse refrigerator 11 Room temperature flange 12 First stage pulse tube 12A First stage high temperature end rectifier 12B First stage low temperature end rectifier 13 Second stage pulse tube 13A Two stage high temperature end rectifier 13B Two stage low temperature end rectifier 14 First stage Regenerator 15 1st stage 16 2nd regenerator 16A Spacer 16B Regenerative material 17 2nd stage 18 Cylinder 19 Magnetic shield 20 1st heat insulating material 21 2nd heat insulating material 21A Thermal connection part 22 1st stage reservoir 23 2nd stage reservoir 27 Regenerator cartridge 28 Outer cylinder 30 GM refrigerator 32 First stage cylinder 33 Thermal load flange 34 Second stage cylinder 36 First stage displacer 38 Two stage displacer 38a Cylindrical part 40 First stage regenerator 42 Two stage regenerator A Cylinder part B Housing

Claims (7)

A regenerator in which a magnetic regenerator material is disposed in a regenerator storage member;
A magnetic shield disposed between the regenerator material storage member and the magnetic regenerator material to shield magnetic noise generated by the magnetic regenerator material;
A first heat insulating material disposed between the magnetic shield and the regenerator material storage member, and disposed so as to face the magnetic shield across its entire surface;
Thermally connecting the magnetic shield and the magnetic regenerator material at a connection portion disposed between the magnetic shield and the magnetic regenerator material and formed on the low temperature end side of the regenerator, and the connection portion A cryogenic refrigerator having a second heat insulating material disposed to face the magnetic shield at a portion other than the above. A regenerator in which a magnetic regenerator material is disposed in a cylinder;
A pulse tube whose cold end is connected to the cold end of the regenerator;
A phase adjusting mechanism connected to the high temperature end of the pulse tube;
A magnetic shield disposed between the cylinder and the magnetic regenerator material to shield magnetic noise generated by the magnetic regenerator material;
A first heat insulating material disposed between the magnetic shield and the cylinder, and disposed so as to face the magnetic shield across its entire surface;
Thermally connecting the magnetic shield and the magnetic regenerator material at a connection portion disposed between the magnetic shield and the magnetic regenerator material and formed on the low temperature end side of the regenerator, and the connection portion A cryogenic refrigerator having a second heat insulating material disposed to face the magnetic shield at a portion other than the above. A displacer in which the magnetic regenerator material is disposed inside the cylindrical portion;
A moving mechanism for reciprocating the displacer in a cylinder;
A magnetic shield that is disposed between the cylindrical portion of the displacer and the magnetic regenerator material and shields magnetic noise generated by the magnetic regenerator material;
A first heat insulating material disposed between the magnetic shield and the cylindrical portion of the displacer, and disposed so as to face the magnetic shield over its entire surface;
Thermally connecting the magnetic shield and the magnetic regenerator material at a connection portion disposed between the magnetic shield and the magnetic regenerator material and formed on the low temperature end side of the regenerator, and the connection portion A cryogenic refrigerator having a second heat insulating material disposed to face the magnetic shield at a portion other than the above.   A superconducting device comprising the cryogenic refrigerator according to any one of claims 1 to 3.   A cryopump device comprising the cryogenic refrigerator according to any one of claims 1 to 3.   A cryogenic measurement / analysis apparatus comprising the cryogenic refrigerator according to any one of claims 1 to 3.   A nuclear magnetic resonance apparatus comprising the cryogenic refrigerator according to any one of claims 1 to 3.

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