JP6685990B2 - Dilution refrigerator - Google Patents

Description

  The present invention relates to a dilution refrigerator.

Dilution refrigerators that utilize the physical properties of isotopes ( ³ He and ⁴ He) of helium gas are known (Patent Document 1 and Non-Patent Document 1). Dilution refrigerator liquefies the ³ He and ⁴ He, the ³ He in ⁴ He By serially diluted in the mixing chamber, has achieved cryogenic about 0.1 K. Like the dilution refrigerator described in Patent Document 1, a conventional dilution refrigerator uses a mechanical refrigerator such as a GM refrigerator to precool ³ He to several K and then supply ³ He to the mixing chamber. is doing.

Dilution refrigerators are generally large. FIG. 2 is a schematic diagram showing the configuration of a conventional dilution refrigerator.
The dilution refrigerator 101 shown in FIG. 2 includes a vacuum container 110, a first radiation shield 120, a second radiation shield 130, a third radiation shield 140, a first heat exchanger 126, and a second heat exchanger 127. And a mixing chamber 142 and a fractionation pipe 150. Further, a flange 120B is provided on the upper end of the first radiation shield 120, and a flange 131 is provided on the upper end of the second radiation shield 130. In the dilution refrigerator 101, by cooling the flange 120B and the flange 131 to about 4 to 40K using a mechanical refrigerator, the inside of the first radiation shield 120, the inside of the second radiation shield 130, and the third radiation shield. The inside of 140 is gradually cooled in this order. Then, the dilution refrigerator 101 achieves an extremely low temperature in the cold head near the mixing chamber 142.

  However, mechanical refrigerators inevitably generate vibrations because the compression and expansion of helium gas are repeated periodically. When cooling the detector of an analyzer such as an electron microscope using a dilution refrigerator, if the vibration of the mechanical refrigerator propagates to the analyzer via the cold head, the analysis accuracy and sensitivity of the analyzer will be impaired. There is a risk that For example, when cooling a few millimeter square X-ray detector with a dilution refrigerator, even if the position of the X-ray detector deviates by 1 mm, fluorescent X-rays of the sample cannot be detected, and the position of the X-ray detector is readjusted. Need to do.

  Further, as shown in FIG. 2, the dilution refrigerator 101 employs a structure in which the fractional distillation pipe 150 is vertically arranged so as to penetrate a plurality of radiation shields extending coaxially in the vertical direction. , Large. In the case where a vibration isolator is used together for the purpose of removing the vibration of the mechanical refrigerator in the dilution refrigerator 101, the device configuration is further increased. Was difficult to apply.

Therefore, in Non-Patent Document 1, in order to reduce the influence of vibration of the mechanical refrigerator on the analyzer, a pre-cooling unit for pre-cooling ³ He using the mechanical refrigerator and a pre-cooled liquid of ³ He are diluted. There is disclosed a separation-type dilution refrigerator including a dilution refrigerator. FIG. 3 is a schematic diagram for explaining the configuration of the separation-type dilution refrigerator.

  The dilution refrigerator 201 shown in FIG. 3 includes a vacuum container 210, a first radiation shield 220, a second radiation shield 230, a third radiation shield 240, a first heat exchanger 226, and a second heat exchanger 227. And a mixing chamber 242 and a fractionation pipe 250. The vacuum container 210 accommodates the first support 211 and the first radiation shield 220. The first support body 211 fixes the first radiation shield 220 in the vacuum container 210. The first radiation shield 220 houses the piping member 221, the bellows 223, the first heat exchanger 226, the second heat exchanger 227, and the second support body 229. In the dilution refrigerator 201, heat exchange is performed between the flange 220B and the flange 231 and a refrigerant supply line (not shown) in which the refrigerant precooled to about 4 to 40K in the mechanical refrigerator flows, and thus the first radiation shield 220. The inside, the inside of the second radiation shield 230, and the inside of the third radiation shield 240 are gradually cooled.

  The dilution refrigerator 201 employs a structure in which the fractionation pipe 250 is folded back inside the first radiation shield 220 for the purpose of downsizing. Specifically, the fractionation pipe 250 is folded back at the portion of the pipe member 221, and is connected to the bellows 223 which is arranged apart from the fractionation pipe 250. As a result, downsizing of the dilution refrigerator 201 is achieved.

  In the dilution refrigerator 201, the pipe outlet 212 is connected to a pump (not shown). Therefore, the helium gas is discharged from the mixing chamber 242 through the fractional distillation pipe 250, the piping member 221, and the bellows 223 in this order to the outside of the vacuum container 210, and then through the circulation unit (not shown). 242 is supplied again.

  In the dilution refrigerator 201, the temperature inside the first radiation shield 220 is about 40K, while the temperature outside the vacuum container 210 is room temperature (about 300K). Therefore, the dilution refrigerator 201 employs the bellows 223 in order to cope with the thermal contraction of the pipe due to the temperature difference between the inside of the first radiation shield 220 and the outside of the vacuum container 210. As a result, even if there is a temperature difference between the inside of the first radiation shield 220 and the outside of the vacuum container 210, the bellows 223 expands and contracts according to the temperature difference, thus stabilizing the structure inside the vacuum container 210.

JP, 2001-304709, A

Takuji Ito and Yoshihiro Yamanaka, "Small Refrigerant Dilution Refrigerator for Scanning Transmission Electron Microscope", Taiyo Nippon Sanso Technical Report, No. 33 (2014).

However, in the dilution refrigerator 201, when the bellows 223 is evacuated and helium gas is exhausted, the pressure fluctuation in the bellows 223 is large, and the bellows 223 further expands and contracts each time it is exhausted. Specifically, expansion and contraction of the bellows 223 may cause the bellows 223 to be skewed as shown in FIG.
When the bellows 223 is distorted obliquely or repeatedly expanded and contracted, a load may be intermittently applied to the first support body 211, the piping member 221, and the second support body 229.

  Further, in the first support 211 and the second support 229, glass-reinforced fiber (FRP) and polyimide resin-based fixing parts are used in order to have strength necessary for fixing and to suppress heat intrusion. Is desirable. However, with the miniaturization of the dilution refrigerator 201, the space where the first support 211 and the second support 229 can be placed can be restricted, and the thickness and thickness of the branch pipes 221A and 221B are limited. Therefore, it is difficult to secure the rigidity that can withstand the stress due to the expansion and contraction of the bellows 223 when a vacuum is applied, by the first support body 211 and the second support body 229, and the first support body 211 and the second support body 229. The position of is easy to move. As a result, even if the position of the shaft of the mixing chamber 242 is adjusted while the analyzer is in use, the shaft of the mixing chamber 242 may be displaced from the adjusted position due to expansion and contraction of the bellows 223.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a dilution refrigerator in which the position of the shaft of the mixing chamber is unlikely to shift and which can be easily applied to an analyzer.

In order to solve the above problems, the present invention has the following configurations.
[1] A dilution refrigerator in a mixed solution containing a ⁴ He in ³ He and the liquid in the liquid includes a mixing chamber for diluting the ³ He in liquid, a vacuum vessel containing said mixing chamber, said mixing chamber From the piping member, which is connected to the fractionation pipe, is connected to the fractionation pipe in the space inside the vacuum container, and has a branch pipe through which the helium gas separated from the mixed liquid flows. A first pipe having a first end opening in a direction parallel to the direction toward the mixing chamber and a second end opening in the same direction as the first end; and a side surface of the vacuum container. A second pipe arranged over the inside of the vacuum container and the outside of the vacuum container via a pipe outlet formed in, and a pair of bellows arranged so as to cancel the expansion and contraction forces generated by mutual expansion and contraction, And a pair of bellows One of the two connects the branch pipe and the first end of the first pipe, and the remaining one of the pair of bellows is the second end of the first pipe and the second end of the first pipe. A dilution refrigerator that connects to piping.
[2] The first pipe has a pipe portion connected to the first end portion and the second end portion, and an angle of a connecting portion between the first end portion and the pipe portion, and [2] The dilution refrigerator according to [1], wherein the angle between the end portion of 2 and the connection portion between the pipe portion is a right angle.
[3] The dilution refrigerator of [1] or [2], wherein the second pipe has a pipe portion that extends coaxially with one of the pair of bellows.

  INDUSTRIAL APPLICABILITY The dilution refrigerator of the present invention does not easily shift the position of the shaft of the mixing chamber and is easy to apply to an analyzer.

It is a schematic diagram which shows an example of a structure of the dilution refrigerator which concerns on embodiment to which this invention is applied. It is a schematic diagram which shows the structure of the conventional dilution refrigerator. It is a schematic diagram for demonstrating the structure of a separation-type dilution refrigerator.

  Hereinafter, a dilution refrigerator according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that, in the drawings used in the following description, in order to make the features easy to understand, there may be a case where the featured portions are enlarged for convenience, and the dimensional ratios of the respective constituent elements are not necessarily the same as the actual ones. Absent.

Hereinafter, the configuration of the dilution refrigerator 1 according to the embodiment of the present invention will be described.
FIG. 1 is a schematic diagram showing an example of the configuration of the dilution refrigerator 1. The dilution refrigerator 1 includes a vacuum container 10, a first radiation shield 20, a second radiation shield 30, a third radiation shield 40, and a fractionation pipe 50.
The other components of the dilution refrigerator 1 will be described in detail below.

  In this embodiment, the vacuum container 10 is a heat insulating container extending in the vertical direction. The vacuum container 10 can be composed of, for example, a vacuum heat insulating member.

  The vacuum container 10 has an upper body 10A, a top flange 10B, and a lower body 10C. A through hole H1 is formed in the center of the top flange 10B. The first radiation shield 20 is inserted into the through hole H1. The top flange 10B is fixed between the upper body 10A and the lower body 10C by a method such as flange joining.

  The upper body 10A and the lower body 10C of the vacuum container 10 may have a cylindrical shape, for example. In this case, the outer diameter of the main body upper portion 10A can be 170 to 200 mm, the outer diameter of the main body lower portion 10C can be 170 to 200 mm, and the vertical height of the vacuum container 10 is 650 to 750 mm. Can be

The vacuum container 10 accommodates the first support 11, a part of the second pipe 23, and the first radiation shield 20 in the inner space.
The first support 11 is fixed between the top flange 10B and a flange 20B described later. As a result, the first support 11 can fix the first radiation shield 20 in the vacuum container 10 via the flange 20B.
A pipe outlet 12 is formed on the lower side surface of the upper body 10A of the vacuum container 10. The second pipe 23 is taken out of the vacuum container 10 to the outside of the vacuum container 10 through the pipe outlet 12. Outside the vacuum vessel 10, the second pipe 23 is connected to a helium circulation unit (not shown). The circulation unit is not particularly limited as long as it has a vacuum pump and a circulation line for supplying the helium gas to the dilution refrigerator 1 again.

  In the present embodiment, the first radiation shield 20 is a container extending in the same direction as the vacuum container 10 extends. The first radiation shield 20 can be made of a member having a high thermal conductivity such as copper or aluminum.

The first radiation shield 20 has a main body upper portion 20A, a flange 20B, a main body middle portion 20C, a flange 20D, and a main body lower portion 20E.
A through hole H2 and a through hole H3 are formed in the flange 20B. The second radiation shield 30 is inserted into the through hole H2, and the second pipe 23 is inserted into the through hole H3. The flange 20B is fixed between the main body upper portion 20A and the main body middle portion 20C by a method such as flange joining.
The main body middle portion 20C is inserted into the vacuum container 10 via a through hole H1 formed in the top flange 10B.
A through hole H4 is formed in the flange 20D. The second radiation shield 30 is inserted into the through hole H4. The flange 20D is fixed between the middle portion 20C of the main body and the lower portion 20E of the main body by a method such as flange joining.
The lower part 20E of the main body is arranged such that the lower end thereof is located above the bottom surface of the vacuum container 10.

  The main body upper part 20A, the main body middle part 20C, and the main body lower part 20E of the first radiation shield 20 can be, for example, cylindrical in shape. In this case, the outer diameter of the main body upper portion 20A can be set to 160 to 180 mm, the outer diameter of the main body middle portion 20C can be set to 70 to 100 mm, and the outer diameter of the main body lower portion 20E can be set to 140 to 160 mm. The height of the first radiation shield 20 in the vertical direction can be 600 to 700 mm.

  The first radiation shield 20 includes a pipe member 21, a first pipe 22, a part of a second pipe 23, a first bellows 24, a second bellows 25, and a first bellows 25 in an inner space. The first heat exchanger 26, the second heat exchanger 27, the flange 28, the second support body 29, and the second radiation shield 30 are accommodated. The pipe member 21, the first pipe 22, the second pipe 23, the first bellows 24, and the second bellows 25 will be described later.

  The first heat exchanger 26 is fixed to the upper side of the flange 20B. For example, in the first heat exchanger 26, heat exchange is performed between the flange 20B and a first refrigerant supply line (not shown) in which the refrigerant precooled to about 40K by a mechanical refrigerator (not shown) flows. As a result, the flange 20B is cooled to about 40K.

  The second heat exchanger 27 is fixed between the flange 28 and a flange 31 described later. For example, in the second heat exchanger 27, heat is exchanged between the flange 31 and a second refrigerant supply line (not shown) in which the refrigerant precooled to about 4K by a mechanical refrigerator (not shown) flows. As a result, the flange 31 is cooled to about 4K. In addition, in the present embodiment, the second heat exchanger 27 is configured as a structure in which the fractionation pipe 50 and the pipe member 21 are integrated.

A through hole H5 is formed in the flange 28. The second heat exchanger 27 is arranged around the through hole H5.
The flange 28 is supported by the second support body 29. The second support body 29 is fixed to the upper side of the flange 20B. This allows the flange 28 to fix the second heat exchanger 27 within the first radiation shield 20. The second support 29 is preferably made of FRP having a low thermal conductivity. This makes it easier to maintain the temperature difference between the flange 20B and the flange 28.

  In this embodiment, heat exchange is performed between the flange 20B and the first refrigerant supply line (not shown) through which the refrigerant precooled to about 40K flows. Therefore, the temperature of the first radiation shield 20 is maintained at a low temperature of about 40K.

  The second radiation shield 30 accommodates the third radiation shield 40 in the inner space. In the present embodiment, the second radiation shield 30 is a container that extends in the same direction as the extending direction of the first radiation shield 20. The second radiation shield 30 can be composed of a member having a high thermal conductivity such as copper or aluminum.

The second radiation shield 30 has a main body upper portion 30A, a flange 30B, and a main body lower portion 30C.
The upper end of the main body upper portion 30A is fixed to the lower end of the second heat exchanger 27 via the flange 31. The main body upper portion 30A is inserted into through holes H2 and H4 formed in the flanges 20B and 20D, respectively.
A through hole H6 is formed in the flange 30B. The third radiation shield 40 is inserted into the through hole H6. The flange 30B is fixed between the upper body 30A and the lower body 30C by a method such as flange joining.
The lower part 30C of the main body is arranged such that the lower end is located above the bottom surface of the lower part 20E of the main body of the first radiation shield 20.

  The main body upper portion 30A and the main body lower portion 30C of the second radiation shield 30 can be, for example, cylindrical shapes. In this case, the outer diameter of the upper body 30A can be 70 to 90 mm, the outer diameter of the lower body 30C can be 120 to 140 mm, and the height of the second radiation shield 30 in the vertical direction is 430. Can be ~ 480 mm

A through hole H7 is formed in the flange 31. The fractionation pipe 50 is inserted into the through hole H7.
In the state where the fractionation pipe 50 is inserted in the through hole H7, heat exchange is performed between the flange 31 and the second refrigerant supply line (not shown) in which the refrigerant precooled to about 4K flows. As a result, the temperature inside the second radiation shield 30 is maintained at a low temperature of about 4.2K.

The third radiation shield 40 houses the mixing chamber 42 in the inner space. In the present embodiment, the third radiation shield 40 is a container extending in the same direction as the extending direction of the second radiation shield 30. The third radiation shield 40 can be made of a member having a high thermal conductivity such as copper or aluminum.
The third radiation shield 40 has a main body upper portion 40A, a flange 40B, and a main body lower portion 40C.
The upper body 40A is inserted into a through hole H6 formed in the flange 30B.
A through hole H8 is formed in the flange 40B. The fractionation pipe 50 is inserted into the through hole H8. The flange 40B is fixed between the upper body 40A and the lower body 40C by a method such as flange joining.
The lower portion 40C of the main body is arranged such that the lower end thereof is located above the bottom surface of the lower portion 30C of the main body of the second radiation shield 30.

  The shape of the upper body 40A and the lower body 40C of the third radiation shield 40 can be, for example, a cylindrical shape. In this case, the outer diameter of the main body upper portion 40A can be, for example, 55 to 75 mm, the outer diameter of the main body lower portion 40C can be 90 to 110 mm, and the vertical height of the third radiation shield 40 can be set. Can be 258-308 mm.

The upper end of the upper body 40A is fixed to the fractionation pipe 50 via a flange 41. A through hole H9 is formed in the flange 41. The fractionation pipe 50 is inserted into the through hole H9. Here, inside the fractionation pipe 50, a fractionation chamber (not shown) is arranged at the position of the flange 41. A liquid surface of a mixed liquid containing liquid ³ He and liquid ⁴ He is formed in a fractionation chamber (not shown). In this state, the pressure inside the fractionation pipe 50 is reduced, so that the inside of the fractionation pipe 50 is cooled to about 1K. As a result, the temperatures of the flange 41 and the third radiation shield 30 that are in contact with the fractionation pipe 50 are cooled to a low temperature of about 1K.

The mixing chamber 42 is a container for diluting liquid ³ He into a mixed liquid containing liquid ³ He and liquid ⁴ He.
In the mixing chamber 42, a second heat exchanger 27, a fractionation chamber (not shown), and a fractionation pipe 50 (not shown) arranged below the fractionation chamber via a helium supply line (not shown). Further cooled liquid ³ He is supplied by way of the third heat exchanger. Thus in the mixing chamber 42 and ³ He dense phase comprising ³ He in liquid, ³ He and dilute phase is a mixture containing the ⁴ He in ³ He and the liquid in the liquid are formed. ^{The 3} He rich phase is formed on the upper side of the ³ He lean phase.

The inside of the third radiation shield 40 is cooled to a temperature of 1 K or lower by reducing the pressure of the gas ³ He. Therefore, the temperature inside the mixing chamber 42 becomes about 1K in the initial stage of cooling. Mixing chamber is absorbed by diluting reaction ^{in 3} He contained in the ³ He dense phase dissolves in ³ He dilute phase occurs further mixing chamber 42 is within 42 is cooled, the temperature in the mixing chamber 42 is 0 It becomes an extremely low temperature of about 1K.

  The fractionation pipe 50 is a pipe connected to the mixing chamber 42. In this embodiment, the lower end of the fractionation pipe 50 is connected to the mixing chamber 42, and the upper end is connected to the pipe member 21 around the through hole H5. The fractionation pipe 50 is fixed to the first heat exchanger 27 by the flange 28. In this state, the fractionation pipe 50 extends coaxially with the second radiation shield 30 and the third radiation shield 40, and the first radiation shield 20, the second radiation shield 30, and the third radiation shield 20 extend. It is arranged in the shield 40.

The pipe member 21 is connected to the fractionation pipe 50 in the first radiation shield 20, and has a first branch pipe 21A and a second branch pipe 21B.
The first branch pipe 21A is a pipe through which the helium gas separated from the mixed liquid in the mixing chamber 42 flows. 21 A of 1st branch piping is branched from the side of the piping member 21, and is bent in the direction parallel to the fractional piping 50 and an axial direction. 21 A of 1st branch piping has the end part 21a opened in the direction which goes to the piping member 21 from the mixing chamber 42. The first branch pipe 21A is connected to the first bellows 24 at the end 21a. The second branch pipe 21B is a pipe extending coaxially with the fractionation pipe 50.

The first bellows 24 and the second bellows 25 are a pair of bellows 24, 25 that are arranged so as to cancel out the expansion and contraction forces generated by the expansion and contraction of each other. The pair of bellows 24, 25 is not particularly limited as long as it is a telescopic tube. However, it is preferable that the pair of bellows 24 and 25 are both metal bellows.
The first bellows 24 connects the first branch pipe 21A and a first end 22A of a first pipe 22 described later. As a result, the first branch pipe 21A and the first pipe 22 communicate with each other.
The second bellows 25 connects the second end portion 22B of the first pipe 22 described later and the main pipe 23A of the second pipe 23 described later. As a result, the first pipe 22 and the second pipe 23 communicate with each other.

  The first pipe 22 has a first end 22A that opens in a direction parallel to the direction from the pipe member 21 to the mixing chamber 42 along the fractionation pipe 50, and opens in the same direction as the first end 22A. And a pipe portion 22C connecting the first end portion 22A and the second end portion 22B. The first pipe 22 is connected to the first bellows 24 at the first end 22A and is connected to the second bellows 25 at the second end 22B. As a result, the expansion / contraction direction of the first bellows 24 becomes parallel to the expansion / contraction direction of the second bellows 25.

  In the present embodiment, the pipe portion is formed such that the angle of the connecting portion between the first end portion 22A and the pipe portion 22C and the angle of the connecting portion between the second end portion 22B and the pipe portion 22C are both right angles. 22C is connected to the first end 22A and the second end 22B. This makes it easier to keep the distance between the fractional distillation pipe 50 and the second pipe 23 constant.

In this embodiment, the second pipe 23 is inserted into the through hole H3. As a result, the second pipe 23 is arranged between the inside of the vacuum container 10 and the outside of the vacuum container 10 via the pipe outlet 12 formed on the lower side surface of the upper body 10A of the vacuum container 10.
The second pipe 23 has a main pipe 23A, a curved portion 23B, and a take-out pipe 23C.
The main pipe 23A is connected at its upper end to the second bellows 25, and is connected at its lower end to the curved portion 23B. Thereby, the second bellows 25 can absorb the thermal contraction of the second pipe 23.

In the present embodiment, the main pipe 23A is a pipe portion that extends coaxially with the second bellows 25. Thereby, the expansion / contraction direction of the second bellows 25 coincides with the coaxial direction of the second pipe 23, and the second bellows 25 easily absorbs the thermal contraction of the second pipe 23.
The curved portion 23B is arranged between the main pipe 23A and the take-out pipe 23C. The take-out pipe 23C is a pipe that is inserted into the pipe take-out port 12 and extends in a direction orthogonal to the extending direction of the fractionation pipe 50. As a result, the helium gas flowing in the main pipe 23A is exhausted to the outside of the vacuum container 10 from the extraction pipe 23C via the curved portion 23B.

  In the present embodiment, the pair of bellows 24, 25 are arranged so as to be spaced apart so that the expansion and contraction directions of the first bellows 24 and the second bellows 25 are parallel. As a result, due to the pressure fluctuation in the pair of bellows 24, 25, the remaining one bellows expands and contracts even if one of the pair of bellows expands and contracts, and the expansion and contraction forces generated by the expansion and contraction of the bellows cancel each other out. There is.

Next, an example of an operating method of the dilution refrigerator 1 having the above-described configuration will be described. First, liquid ³ He cooled stepwise to about 1 K by the first heat exchanger 26, the second heat exchanger 27, and a fractionation chamber (not shown) is mixed by a helium supply line (not shown). It is supplied into the chamber 42. In the mixing chamber 42, a ³ He rich phase is formed above the ³ He lean phase. In the mixing chamber 42 by serially diluted ³ He in liquid contained in the ³ He dense phase in ³ He dilute phase, cryogenic about 0.1K is achieved.

A fractionation chamber (not shown) in the fractionation pipe 50 has a liquid surface of a mixed liquid containing liquid ³ He and liquid ⁴ He, and helium is in a gas-liquid equilibrium state. On the gas phase side in the fractionation pipe 50, ³ He, which is a gas separated from a mixed liquid mainly containing liquid ³ He and liquid ⁴ He, flows in the fractionation pipe 50. The separated helium gas is supplied to the first branch pipe 21A, the first bellows 24, the first pipe 22, the second bellows 25, and the second pipe 23 from the inside of the fractionation pipe 50 by a circulation unit (not shown). It is exhausted to the outside of the vacuum container 10 via this order.

(Action effect)
As described above in the present specification, in the conventional dilution refrigerator 201 as shown in FIG. 3, when the bellows 223 is evacuated in order to exhaust the helium gas, the first dilution via the piping member 221. There is a problem that the first support 211 and the second support 229 are loaded.
Furthermore, when a detector of several millimeters square is arranged and used in the mixing chamber of the dilution refrigerator, it is necessary to adjust the position of the detector in units of 1 mm or less. In the conventional dilution refrigerator, the pipes and the like inside the apparatus shrink due to the pressure reduction and heat shrinkage of the pipes such as the bellows 223, and the resulting stress may cause the support to be distorted. In this case, the position of the detector is displaced and analysis cannot be performed, and it is necessary to readjust the position of the detector.

  According to the dilution refrigerator 1 of the present embodiment, since the pair of bellows 24, 25 is provided, it is possible to expand and contract so as to cancel the expansion and contraction force generated in each of the pair of bellows 24, 25. Therefore, the second pipe 23 is evacuated to exhaust the helium gas from the gas phase in the fractionation pipe 50, and even if the pressure changes in the pair of bellows 24, 25, the pipe member 21 is not distorted. The structure is such that no load is applied to the first support 11 and the second support 29.

  According to the dilution refrigerator 1 of the present embodiment, even if the pair of bellows 24, 25 repeatedly expands and contracts, the first support 11 and the second support 29 are less likely to be loaded, and the position of the shaft of the mixing chamber 42 is reduced. Since it is difficult to change, the reliability of the analyzer can be greatly improved. Furthermore, the frequency of readjusting the position of the detector during measurements with the analyzer is also reduced.

  In the dilution refrigerator 1, the first branch pipe 21A, the first pipe 22, and the second pipe 23 constitute one fractional distillation pipe, and the portion of the first pipe 22 corresponds to the one fractional pipe. Since the retaining pipe is bent so as to form a Japanese "U" shape, the vertical height is smaller than the conventional product. Therefore, it can be easily connected to the analyzer and can be easily transported. Therefore, the dilution refrigerator 1 is easy to apply to an analyzer.

  Since the dilution refrigerator 1 includes the pair of bellows 24 and 25, distortion is unlikely to occur even if the second pipe 23 contracts due to heat contraction. Therefore, according to the dilution refrigerator 1, the degree of freedom in assembly is improved as compared with the case of using one bellows.

  Although some embodiments of the present invention have been described above, the present invention is not limited to these particular embodiments. Further, the present invention may have additions, omissions, substitutions, and other modifications of the configuration within the scope of the gist of the present invention described in the claims.

For example, the dilution refrigerator 1 of the present embodiment may be used in combination with a pre-cooling unit that pre-cools ³ He using a mechanical refrigerator. In this case, the flange 20B may be cooled by the first refrigerant supply line and the flange 31 may be cooled by the second refrigerant supply line by using the refrigerant supply line through which the refrigerant precooled by the mechanical refrigerator flows. .

  1, 101, 201 ... Diluting refrigerator, 10, 110, 210 ... Vacuum container, 11, 211 ... First support, 12, 212 ... Piping outlet, 20, 120, 220 ... First radiation shield, 21 , 121, 221 ... Piping member, 22 ... First piping, 23 ... Second piping, 24 ... First bellows, 25 ... Second bellows, 26, 126, 226 ... First heat exchanger, 27 , 127, 227 ... Second heat exchanger, 28 ... Flange, 29, 229 ... Second support, 30, 130, 230 ... Second radiation shield, 31, 131, 231 ... Flange, 40, 140, 240 ... 3rd radiation shield, 41 ... Flange, 42, 142, 252 ... Mixing chamber, 50, 150, 250 ... Fractionation piping, H1-H9 ... Through hole.

Claims (3)

A dilution refrigerator comprising a mixing chamber for diluting the ³ He and ³ He in liquid mixture containing the ⁴ He liquid fluid,
A vacuum container that houses the mixing chamber,
A fractionation pipe connected to the mixing chamber,
A pipe member having a branch pipe connected to the fractionation pipe in the space inside the vacuum container and in which helium gas separated from the mixed liquid flows.
A first pipe having a first end that opens in a direction parallel to the direction from the pipe member to the mixing chamber and a second end that opens in the same direction as the first end;
A second pipe arranged across the inside of the vacuum container and the outside of the vacuum container through a pipe outlet formed on a side surface of the vacuum container;
A pair of bellows arranged so as to cancel the stretching force generated by the stretching of each other,
Equipped with
Any one of the pair of bellows connects the branch pipe and the first end of the first pipe,
The dilution refrigerator in which the remaining one of the pair of bellows connects the second end of the first pipe and the second pipe. The first pipe has a pipe portion connected to the first end and the second end,
The dilution refrigeration according to claim 1, wherein an angle of a connecting portion between the first end portion and the pipe portion and an angle of a connecting portion between the second end portion and the pipe portion are both right angles. Machine.   The dilution refrigerator according to claim 1 or 2, wherein the second pipe has a pipe portion that extends coaxially with one of the pair of bellows.

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