KR101121232B1 - Refrigerating machine - Google Patents

Abstract

A cooling stage for cooling the object to be cooled, a He condensation portion on which the object to be cooled is seated, a reservoir filled with He gas in communication with the He condensation portion, and the He disposed between the cooling stage and the He condensation portion. Refrigerator with a heat transfer buffer made of a material having a lower thermal conductivity than the condensation unit.

Description

Freezer {Refrigerating machine}

The present invention relates to a refrigerator.

GM chillers are used to measure sample properties in cryogenic environments around 4K, and to measure various physical quantities using sensors using cryogenic environments. This refrigerator cools uncooled material to cryogenic temperature by repeating compression and expansion (freezing cycle) of refrigerant gas such as He gas. By the way, a temperature amplitude arises on the seating surface of a to-be-cooled object because of the pulsation of the heat flow resulting from the above-mentioned freezing cycle. In order to cool the to-be-cooled object stably, the reduction of this temperature amplitude is calculated | required.

Patent Literature 1 connects an accumulator means for accommodating helium gas or helium gas and liquid helium, which is provided in a cooling unit to which the object to be cooled, and a supply means for supplying compressed helium gas and the accumulator means. A cryogenic freezer comprising a helium gas introduction and discharge means is disclosed.

Patent Document 2 discloses a cryogenic temperature damper having a helium gas introduction tube for introducing a required amount of helium gas at room temperature, a condenser chamber for liquefying helium gas, and a liquid helium chamber for storing liquefied liquid helium.

Patent Document 1: Japanese Patent No. 2773793

Patent Document 2: Japanese Patent Application Laid-Open No. 2004-76955

However, since the said temperature amplitude in the cryogenic freezer of patent document 1 is about 30 mK, the reduction of temperature amplitude is calculated | required further.

On the other hand, the cryogenic temperature damper of Patent Literature 2 has a complicated structure and a long heat transfer path from the coolant, and is non-symmetrical, so that cooling may be uneven and unstable.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a refrigerator capable of reducing the temperature amplitude on the seating surface of the object to be cooled, and capable of uniform and stable cooling of the object to be cooled.

In order to solve the said subject, this invention employ | adopts the following means. That is, the refrigerator of the present invention includes a cooling stage for cooling the object to be cooled; A He condensation unit accommodating liquid He therein and having a table on which a surface to be cooled is seated; A reservoir filled with He gas in communication with the He condensation unit; And a heat transfer buffer made of a material having a lower thermal conductivity than the He condensation portion, disposed between the lower surface of the cooling stage and the upper surface of the He condensation portion.

According to this structure, the pulsation of the heat flow resulting from the freezing cycle of a refrigerator is absorbed by evaporation and condensation (phase transition) of He in a He condensation part. At that time, since the electrothermal shock absorber acts as a diaphragm mechanism for heat flow, the transmission of the temperature amplitude in the cooling stage is suppressed. As a result, the temperature amplitude at the mounting surface of the object to be cooled can be reduced. In addition, since the cooling stage, the heat transfer buffer, the He condensation part, and the object to be cooled are continuously arranged coaxially, uniform and stable cooling of the object to be cooled is possible.

The He condensation portion may be made of a material having a thermal conductivity of 200 W / (m? K) or higher at a temperature near 4K.

According to this structure, the to-be-cooled object can be cooled efficiently by the liquid He condensed in the He condensation part.

The electrothermal shock absorber may be made of a material having a thermal conductivity of less than 100 W / (m? K) at a temperature near 4K.

According to this structure, transmission of the temperature amplitude in a cooling stage can be prevented reliably.

The volume of the He condensation portion may be 10 cc or more and 100 cc or less.

According to this structure, the He condensation part can be made compact while ensuring the storage volume of the liquid He required for cooling the to-be-cooled object.

The volume of the said reservoir may be 5 times or more and 100 times or less of the volume of the said He condensation part.

According to this configuration, the storage can be made compact while securing the storage volume of He gas required for cooling the object to be cooled.

The pressure of the He gas filled in the reservoir may be 0.1 MPa or more and 1.0 MPa or less at room temperature.

According to this structure, even if the refrigerator stops and the liquid He of the He condensation part evaporates, it is possible to prevent the reservoir and the He condensation part from becoming high pressure.

A fin may be installed on the inner surface of the He condensation portion.

In addition, a porous structure may be mounted on the inner surface of the He condensation portion.

According to such a structure, since the contact area of the inner surface of the He condensation part with the liquid He becomes large, the cooled object seated on the He condensation part can be cooled efficiently.

Unevenness may be formed on the contact surface of the heat transfer buffer and the cooling stage or the He condensation portion.

According to this structure, since the contact area of the electrothermal shock absorber and the cooling stage or the He condensation portion becomes small, the transfer of the temperature amplitude in the cooling stage is suppressed. As a result, the temperature amplitude at the mounting surface of the object to be cooled can be reduced.

A temperature sensor and a heater mounted on said He condensation part, and the control part which drives the said heater based on the measurement result of the said temperature sensor may be further provided.

According to this configuration, when the temperature of the He condensation portion is lower than the predetermined value, the heater can be driven to return the temperature of the He condensation portion to the predetermined value. Therefore, the temperature amplitude at the mounting surface of the object to be cooled can be reduced.

According to the present invention, the transfer of the temperature amplitude in the cooling stage is prevented by providing the heat transfer buffer, and as a result, the temperature amplitude on the seating surface of the object to be cooled can be reduced. In addition, since the cooling stage, the heat transfer buffer, the He condensation part, and the object to be cooled are continuously arranged coaxially, uniform and stable cooling of the object to be cooled is possible.

1 is a schematic configuration diagram of a refrigerator according to a first embodiment of the present invention.

2 is a graph showing the relationship between the temperature of the second cooling stage and the temperature amplitude.

3 is a graph showing the relationship between the volume ratio of liquid He and the temperature amplitude in the He condensation section.

4 is a graph showing the relationship between the temperature of the second cooling stage and the freezing capacity.

5 is a graph showing the relationship between the cooling time and the temperature of the second cooling stage.

It is a schematic block diagram in the vicinity of He condensation part of the refrigerator which concerns on 2nd Embodiment of this invention.

It is a schematic block diagram in the vicinity of He condensation part of the refrigerator which concerns on 3rd Embodiment of this invention.

It is a schematic block diagram near He condensation part of the refrigerator which concerns on 4th Embodiment of this invention.

It is a schematic block diagram near He condensation part of the refrigerator which concerns on 5th Embodiment of this invention.

<Description of the code>

1: freezer

14: second cooling stage (cooling stage)

16: electrothermal buffer

18: unevenness

20: He condensation

30: storage

40: Coolant

50: He gas

62: control unit

64: temperature sensor

66: heater

222: first (휜)

224: 2nd (휜)

322: porous structure

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings.

(First embodiment)

1 is a schematic configuration diagram of a refrigerator according to a first embodiment of the present invention. The refrigerator 1 which concerns on this embodiment is provided in the 2nd cooling stage 14 which cools the to-be-cooled object 40, the He condensation part 20 and the He condensation part 20 in which the to-be-cooled object 40 is seated. Heat transfer made of a material having a lower thermal conductivity than the He condensation part 20, which is in communication with the reservoir 30 filled with the He gas 50, the second cooling stage 14, and the He condensation part 20. The shock absorbing material 16 is provided.

The refrigerator 1 mainly includes the compressor 4, the main body 2, and the cooling unit 15. The compressor 4 compresses the low pressure He gas supplied from the low pressure pipe 8 to make the high pressure He gas, and supplies it to the high pressure pipe 6. The main body 2 continuously switches the connection between the high pressure pipe 6 and the low pressure pipe 8 and the He gas flow path in the cooling unit 15 described later by power of a motor or the like.

The cooling unit 15 is provided continuously to the main body unit 2. The cooling part 15 is arrange | positioned inside the vacuum chamber 10 hold | maintained in a vacuum environment, and generate | occur | produces cold by expansion of the He gas which distributes the inside. The cooling part 15 is provided with the 1st cooling part 11, the 1st cooling stage 12, the 2nd cooling part 13, and the 2nd cooling stage 14 in order. The 1st cooling part 11 and the 2nd cooling part 13 are formed in column shape, and the 1st cooling stage 12 and the 2nd cooling stage 14 are formed in disk shape, and are arrange | positioned coaxially. A He gas flow path (not shown) is formed inside the cooling unit 15. The high pressure He gas supplied to this He gas flow path is endothermic-expanded in the second cooling stage 14 to change into a low pressure He gas.

The heat transfer buffer 16 is provided between the He condensation part 20 which is a lower surface of the 2nd cooling stage 14 mentioned later. The heat transfer shock absorber 16 is formed in a plate shape having a diameter of about several tens of mm and a thickness of about 2 mm, for example. The heat transfer buffer 16 is made of a stainless material having a lower thermal conductivity at a temperature near 4K than the He condensation portion 20 described later. In particular, when the thermal shock absorber 16 is formed of a material having a thermal conductivity of less than 100 W / (m? K) at a temperature near 4K, the temperature amplitude of the second cooling stage 14 is transmitted to the He condensation part 20. Can be suppressed.

The second cooling stage 14, the heat transfer buffer 16, and the He condensation portion 20 are fastened with In foil or the like on both sides of the heat transfer buffer 16 to increase thermal contact.

The He condensation part 20 in which the to-be-cooled object 40 is mounted is provided in the lower surface of the heat transfer buffer 16. As shown in FIG. The He condensation part 20 is comprised with materials, such as Cu, Ag, and Al, whose thermal conductivity in the temperature of 4K vicinity is higher than the electrothermal shock absorber 16 mentioned above. In this embodiment, the He condensation part 20 is formed of oxygen free copper. In particular, when the He condensation portion 20 is formed of a material having a thermal conductivity of 200 W / (m? K) or more at a temperature near 4K, the object to be cooled 40 is formed by the liquid He condensed in the He condensation portion 20. Can be cooled efficiently.

The He condensation part 20 is formed in the cylindrical shape which sealed both ends, and can store the liquid He inside. When the volume of the He condensation part 20 is set to 10 cc or more and 100 cc or less, the He condensation part 20 can be made compact while ensuring the storage volume of the liquid He required for cooling the object to be cooled 40. In this embodiment, the volume of the He condensation part 20 is set to 40 cc.

The table 41 is disposed on the lower surface of the He condensation part 20. The lower surface of the table 41 is in a cooling position, which is a seating position of the object to be cooled 40. The table 41 is made of a material having the same physical properties as that of the He condensation unit 20. In the present embodiment, the In condensation part 20 and the table 41 are placed between the He condensation part 20 and the table 41 and between the table 41 and the object to be cooled 40. It is fastened. The object to be cooled 40 may be heat-contacted to the He condensing part 20 without providing the table 41.

The second cooling stage 14, the heat transfer buffer 16, the He condensation unit 20, and the object to be cooled 40 of the cooling unit 15 described above constitute a heat transfer path from the object to be cooled. In this embodiment, it becomes possible to shorten the distance of a heat-transfer flow path by arrange | positioning them continuously coaxially. As a result, the cooling loss can be reduced, and the object to be cooled 40 can be efficiently cooled to the target temperature in a short time. Moreover, it becomes possible to make an axial symmetry of a heat-transfer flow path, and the whole to-be-cooled object 40 can be cooled uniformly and stably.

A capillary tube 32 extends from the He condensation unit 20, and is always connected to the storage 30 arranged outside the vacuum chamber 10. It is preferable that the volume of the storage 30 shall be 5 times or more and 100 times or less of the volume of the He condensation part 20. In this embodiment, the volume of the storage 30 is set to 3250 cc. Thereby, the storage 30 can be made compact while ensuring the storage volume of He gas required for cooling the to-be-cooled object 40.

He gas is filled in the reservoir 30. It is preferable that the pressure of the He gas be 0.1 MPa or more and 1.0 MPa or less at room temperature. In the present embodiment, the reservoir 30 is filled with He gas 50 having a pressure of 0.4 MPa at room temperature. Thereby, even if the refrigerator 1 stops and the liquid He 52 of the He condensation part 20 evaporates, the storage 30 does not become a high pressure. In the middle of the tubular 32, a heat anchor 34 for heat exchange with the first cooling stage 12 is formed.

Next, the operation of the refrigerator 1 according to the present embodiment will be described. As described above, the high pressure He gas supplied from the compressor 4 to the cooling unit 15 is endothermic expanded in the second cooling stage 14 to change into the low pressure He gas. The main body 2 continuously switches the connection between the high pressure pipe 6, the low pressure pipe 8, and the He gas flow path of the cooling unit 15. As a result, the compression and expansion of the He gas (refrigeration cycle) are repeated so that the temperature of the second cooling stage 14 becomes cryogenic.

The He condensation part 20 is provided below the 2nd cooling stage 14. When the He condensation unit 20 is cooled by the second cooling stage 14, the He gas inside the He condensation unit 20 is condensed and liquefied to generate a liquid He 52. In this embodiment, liquid He is produced so that volume ratio with respect to He condensation part 20 may be 30% or less (for example, about 20%).

By the way, the temperature amplitude arises in the 2nd cooling stage 14 because of the pulsation of the heat flow resulting from the above-mentioned refrigeration cycle. However, in this embodiment, the pulsation of the heat flow resulting from the refrigerating cycle is absorbed by the evaporation and condensation (phase transition) of He. Therefore, the temperature amplitude equivalent to the 2nd cooling stage 14 does not generate | occur | produce in the He condensation part 20, and the temperature amplitude of the He condensation part 20 becomes small.

In addition, in this embodiment, between the 2nd cooling stage 14 and the He condensation part 20, the electrothermal shock absorber 16 which consists of a material whose thermal conductivity is lower than the He condensation part 20 is provided. Since this electrothermal shock absorber 16 acts as a diaphragm mechanism of heat flow, it can suppress that the temperature amplitude in the 2nd cooling stage 14 is transmitted to the He condensation part 20. As shown in FIG. Therefore, the temperature amplitude at the mounting surface of the object to be cooled can be reduced.

2 is a graph showing the relationship between the temperature of the second cooling stage and the temperature amplitude. Here, temperature amplitudes were measured for three types of device configurations. Specifically (1) The temperature amplitude of the He condensation part 20 in the case where the second cooling stage 14, the heat transfer buffer 16, and the He condensation part 20 are provided in the same manner as in the present embodiment (rhombus plot) And (2) the temperature amplitude (triangle plot) of the He condensation part 20 when the second cooling stage 14 and the He condensation part 20 are provided without providing the heat transfer buffer 16, and (3 The temperature amplitude (circular plot) of the 2nd cooling stage 14 when the electrothermal shock absorber 16 and the He condensation part 20 were not provided was measured. On the horizontal axis, the temperature of the cooling position (measuring position of the temperature amplitude) which is a place to be cooled is taken. The volume of the reservoir 30 was set to 3250 cc, the filling pressure of He gas to the reservoir 30 was 0.4 MPa, and the volume ratio of the liquid He in the He condensation part 20 was set to 20%.

As a result, the magnitude | size of the temperature amplitude of each apparatus structure was the order of (3)> (2)> (1). The higher the temperature at the cooling location, the larger the difference in temperature amplitude between each device configuration. In addition, when the temperature of the cooling position is 4.2K in the apparatus configuration of (1), the temperature amplitude of the He condensation part 20 was suppressed to ± 9 mK. From the above measurement results, (3) Compared with the device configuration of only the second cooling stage 14, (2) In the device configuration in which the He condensation unit 20 is added, the temperature amplitude is significantly reduced, and (1) the heat transfer buffer material. It was confirmed that in the device configuration in which (16) and He condensation part 20 were added, the temperature amplitude further decreased compared with (2).

3 is a graph showing the relationship between the volume ratio of liquid He and the temperature amplitude in the He condensation section. Here, the temperature amplitude (diamond plot) when (1) the heat transfer buffer was provided and (2) the temperature amplitude (triangle plot) when the heat transfer buffer was not provided were measured similarly to this embodiment. The volume of the reservoir 30 was set at 3250 cc, the maximum filling pressure of He gas to the reservoir 30 at 0.48 MPa, and the temperature at the cooling position was 4.2K.

As a result, the magnitude of the temperature amplitude was (2)> (1) regardless of the volume ratio of the liquid He. In addition, the temperature amplitude when the liquid He was not increased, but when the liquid He even a little present, the temperature amplitude was small. Moreover, in (1), when the volume ratio of liquid He was 1%-30%, the temperature amplitude of the He condensation part 20 was suppressed to +/- 9 mK in all. From the above, it was confirmed that even a small amount of liquid He has an effect capable of significantly reducing the temperature amplitude.

By the way, in this embodiment, since the electrothermal shock absorber 16 which has a lower thermal conductivity than the He condensation part 20 was provided, it is thought that the freezing capacity of a refrigerator is reduced. Thus, the inventors of the present application investigated the difference in freezing capacity with or without the heat transfer buffer 16.

4 is a graph showing the relationship between the temperature of the cooling position and the freezing capacity at the cooling position. Here, (1) freezing capacity (a rhombus plot) when the heat transfer buffer 16 was provided in the same manner as in the present embodiment, and (2) freezing capacity (square plot) when the heat transfer buffer was not provided. The volume ratio of the liquid He inside the He condensation part 20 was set to 20%.

As a result, the reduction rate of the refrigerating capacity when the heat transfer buffer 16 was present was about 25% regardless of the temperature at the cooling position. Therefore, it was confirmed that the loss of freezing capacity is suppressed by several ten%.

In addition, in this embodiment, since the heat transfer shock absorber 16 which has a lower thermal conductivity than the He condensation part 20 was provided, it is thought that cooling time increases. Thus, the inventors of the present application investigated the difference in cooling time with or without the electrothermal shock absorber 16.

5 is a graph showing a relationship between a cooling time and a temperature of a cooling position. Here, the temperature (solid line) of the cooling position in the case of installing the heat transfer buffers (1) and the temperature (the square plot) of the cooling position in the case of not installing the heat transfer buffers were measured in the same manner as in the present embodiment. As a result, it was confirmed that there was almost no difference in cooling time with or without the heat transfer buffer 16.

As mentioned above, the refrigerator (refer FIG. 1) which concerns on this embodiment is a He condensation part (between He condensation part 20 and 2nd cooling stage 14 in which the to-be-cooled object 40 is seated). It was set as the structure provided with the electrothermal shock absorber 16 which consists of a material whose thermal conductivity is lower than 20). According to this structure, the pulsation of the heat flow resulting from the refrigerating cycle of the refrigerator 1 is absorbed by the evaporation and condensation (phase transition) of He in the He condensation part 20. At that time, since the heat transfer buffer 16 acts as a diaphragm mechanism for heat flow, the transfer of the temperature amplitude in the second cooling stage 14 is suppressed, and as a result, the temperature amplitude at the seating surface of the object to be cooled 40 is suppressed. Can be reduced. In addition, since the second cooling stage 14, the heat transfer buffer 16, the He condensation portion 20, and the object to be cooled 40 are continuously disposed coaxially, the heat transfer flow path from the object to be cooled is short-axis in an axisymmetric shape. Becomes Therefore, uniform and stable cooling of the to-be-cooled object 40 is attained.

In addition, in this embodiment, the volume ratio of the liquid He 52 in the He condensation part 20 can be suppressed to 30% or less. Therefore, it becomes possible to miniaturize the storage 30 in which the He gas 50 is filled. In addition, it is possible to lower the filling pressure of the He gas 50 at room temperature to the reservoir 30. As a result, even if the refrigerator 1 is stopped and the liquid He 52 of the He condensation part 20 is vaporized, it is possible to prevent the reservoir 30 and the He condensation part from becoming a high pressure.

(2nd embodiment)

Next, the refrigerator which concerns on 2nd Embodiment of this invention is demonstrated.

6 is a schematic configuration diagram near the He condensation portion of the refrigerator according to the present embodiment. The refrigerator according to the present embodiment is provided with the fins 222 and 224 standing on the inner surfaces 221 and 223 of the He condensing part 220. About the part which becomes the structure similar to 1st Embodiment, the detailed description is abbreviate | omitted.

The He condensation unit 220 is disposed between the second cooling stage 14 and the object to be cooled 40.

The He condensation part 220 is a cylindrical hollow container made of a material such as Cu, Ag, Al, etc., and He gas 50 is filled therein. When the He condensation unit 220 is cooled by the second cooling stage 14, He gas is condensed to generate the liquid He 52. The object to be cooled 40 is cooled by the liquid He 52.

A plurality of fins 222 and 224 are erected on the inner surface of the He condensation unit 220. Each of the fins 222 and 224 is preferably made of a material having high thermal conductivity similarly to the He condensation unit 220. Each fin 222, 224 may be integrally molded with the He condensation part 220, or may be molded separately and adhered to the He condensation part 220.

The first fin 222 is formed from the bottom surface 221 of the He condensation unit 220 toward the ceiling surface 223. This makes it possible to increase the contact area between the inner surface of the He condensation unit 220 and the liquid He 52. Therefore, the cooled object 40 seated on the He condensation part 220 can be cooled efficiently.

The second fin 224 is formed from the ceiling surface 223 of the He condensation unit 220 toward the bottom surface 221. As a result, the contact area between the inner surface of the He condensation unit 220 and the He gas 50 can be increased. Therefore, the He gas 50 inside the He condensation unit 220 can be efficiently cooled and condensed.

(Third embodiment)

Next, the refrigerator which concerns on 3rd Embodiment of this invention is demonstrated.

7 is a schematic configuration diagram near the He condensation portion of the refrigerator according to the present embodiment. The refrigerator according to the present embodiment is provided with the porous structure 322 on the inner surface of the He condensation part 320. In addition, the detailed description is abbreviate | omitted about the part which becomes the structure similar to 1st Embodiment.

The porous structure 322 is mounted on the inner surface of the He condensation part 320. The porous structure 322 is composed of a mesh, a expandable metal, a sintered metal, or the like. The porous structure 322 may be filled in the whole inside of the He condensation part 320, or may be filled only in part.

The porous structure 322 is attached to the inner surface of the He condensing part 320 by an adhesive or the like so as to maintain thermally good contact with the inner surface of the He condensing part 320.

By providing the porous structure 322, it is possible to increase the contact area between the inner surface of the He condensing part 320 and the liquid He 52. Therefore, the object to be cooled 40 seated on the He condensation part 320 can be cooled efficiently. In addition, by providing the porous structure 322, it is possible to increase the contact area between the inner surface of the He condensing part 320 and the He gas 50. Therefore, the He gas 50 inside the He condensation part 320 can be efficiently cooled and condensed.

(4th Embodiment)

Next, the refrigerator which concerns on 4th Embodiment of this invention is demonstrated.

8 is a schematic configuration diagram near the He condensation portion of the refrigerator according to the present embodiment. In the refrigerator according to the present embodiment, the unevenness 18 is formed on the contact surface with the second cooling stage 14 in the heat transfer buffer 16. About the part which becomes the structure similar to 1st Embodiment, the detailed description is abbreviate | omitted.

The heat transfer buffer 16 is made of a stainless material having a low thermal conductivity and the like. The unevenness | corrugation 18 is formed in the contact surface with the 2nd cooling stage 14. The unevenness | corrugation 18 may be formed regularly, and may be formed irregularly (random). Moreover, even if the unevenness | corrugation 18 may be formed in a weight shape so that the point cooling contact with the 2nd cooling stage 14 may be carried out, and if the unevenness | corrugation 18 is formed in a horn-shaped shape so that surface contact with the 2nd cooling stage 14 may be carried out. do. In addition, the unevenness 18 may be a projection of a cross-sectional triangle so as to be in linear contact with the second cooling stage 14, and the unevenness 18 may be in surface contact with the second cooling stage 14 in a strip shape. ) May be a trapezoidal cross section.

In this embodiment, since the unevenness | corrugation 18 was formed in the contact surface with the 2nd cooling stage 14 in the heat transfer shock absorber 16, the contact area of the heat transfer shock absorber 16 and the 2nd cooling stage 14 becomes small. As a result, the diaphragm function of the heat flow is enhanced as compared with the case where the electrothermal shock absorber 16 and the second cooling stage 14 are in front contact, so that the temperature amplitude in the second cooling stage 14 is He condensing portion 420. It is possible to suppress the transmission to. Therefore, the temperature amplitude at the mounting surface of the object to be cooled can be reduced.

In this embodiment, although the unevenness | corrugation 18 was formed in the contact surface with the 2nd cooling stage 14 of the heat transfer shock absorber 16, you may form an unevenness in the contact surface with the heat transfer shock absorber 16 of the 2nd cooling stage 14. As shown in FIG. In addition, unevenness may be formed in the contact surface with the He condensation part 420 of the heat transfer buffer 16, and unevenness may be formed in the contact surface with the heat transfer buffer 16 of the He condensation part 420. FIG. That is, the unevenness | corrugation should just be formed in the contact surface of the 2nd cooling stage 14 or He condensation part 420, and the heat transfer buffer 16. As shown in FIG. In any case, it is possible to suppress that the temperature amplitude in the second cooling stage 14 is transmitted to the He condensation portion 420. Therefore, the temperature amplitude at the mounting surface of the object to be cooled can be reduced.

(Fifth Embodiment)

Next, the refrigerator which concerns on 5th Embodiment of this invention is demonstrated.

9 is a schematic configuration diagram near the He condensation portion of the refrigerator according to the present embodiment. The refrigerator which concerns on this embodiment is the control part 62 which drives the heater 66 based on the measurement result of the temperature sensor 64, the heater 66, and the temperature sensor 64 attached to the He condensation part 520. It is equipped with. About the part which becomes the structure similar to 1st Embodiment, the detailed description is abbreviate | omitted.

In this embodiment, the temperature sensor 64 is attached to the mounting surface of the to-be-cooled object 40 in the He condensation part 520. In addition, the He condenser 520 is equipped with a heater 66 provided with a heating wire. These temperature sensors 64 and the heaters 66 are connected to the control unit 62. The control part 62 drives the heater 66 based on the measurement result of the temperature sensor 64. That is, the output signal of the temperature sensor 64 is converted into the drive current of the heater 66, and a return current is sent to the heater 66 to control the pulsation of the temperature resulting from the heat generation to a minimum.

Specifically, first, the set temperature of the mounting surface of the object to be cooled 40 and the measurement temperature of the temperature sensor 64 are compared. When the measured temperature is lower than the set temperature, the heater is driven to heat the He condensation unit 520. Thereby, it becomes possible to raise the temperature of the mounting surface of the to-be-cooled object 40, and to return to set temperature. Therefore, the temperature amplitude in the mounting surface of the to-be-cooled object 40 can be reduced.

The technical scope of this invention is not limited to embodiment mentioned above, Comprising: Various changes were added to embodiment mentioned above in the range which does not deviate from the meaning of this invention. That is, the specific material, structure, etc. which were mentioned in embodiment are only an example, and can be changed suitably.

It is possible to reduce the temperature amplitude on the seating surface of the object to be cooled, and to provide a refrigerator capable of uniform and stable cooling of the object to be cooled.

Claims (10)

A cooling stage for cooling the object to be cooled; A He condensation unit accommodating liquid He therein and having a table on which a surface to be cooled is seated; A reservoir filled with He gas in communication with the He condensation unit; And a heat transfer buffer made of a material having a lower thermal conductivity than the He condensation portion, disposed between a lower surface of the cooling stage and an upper surface of the He condensation portion. The method of claim 1, And said He condensation part is made of a material having a thermal conductivity of 200 W / (m? K) or more at a temperature near 4K. The method of claim 1, The electrothermal shock absorber is characterized in that the thermal conductivity at a temperature near 4K made of a material of less than 100W / (m? K). The method of claim 1, The He condensing unit has a volume of 10 cc or more and 100 cc or less. The method of claim 1, The refrigerator has a volume of 5 to 100 times the volume of the He condensation unit. The method of claim 1, And the pressure of the He gas filled in the reservoir is 0.1 MPa or more and 1.0 MPa or less at room temperature. The method of claim 1, And a fin is installed on an inner surface of the He condensation unit. The method of claim 1, And a porous structure is mounted on an inner surface of the He condensation unit. The method of claim 1, The unevenness | corrugation is formed in the contact surface of the said electrothermal shock absorber, the said cooling stage, or the said He condensation part. The method of claim 1, A temperature sensor and a heater mounted on the He condensation unit; And a control unit for driving the heater based on the measurement result of the temperature sensor.

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