JP2021082474A - Cryogenic feed-through structure and cryogenic cooling device - Google Patents

Abstract

To provide a cryogenic feed-through structure that is adaptable to a cryogenic pressure container, and a cryogenic cooling device using the same.SOLUTION: There is provided a cryogenic feed-through structure 10 subjected to cryogenic cooling together with a cryogenic pressure container 50. The cryogenic feed-through structure 10 includes: an insulating resin member 14 which is disposed adjacent to the outside of the cryogenic pressure container 50 and is airtightly attached to the cryogenic pressure container 50; and a metal conductor 12 penetrating through the insulating resin member 14 to extend from the inside of the cryogenic pressure container 50 to the outside. The metal conductor 12 is joined to the insulating resin member 14 on the outer peripheral surface of the metal conductor and the joining is retained in a cryogenically cooled state.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cryogenic feedthrough structure and a cryogenic device.

Parts that are attached to the container wall to pull out wiring and piping from inside the airtight container to the outside while maintaining airtightness inside the container are generally called feedthroughs, such as vacuum feedthroughs that pull out wiring from the vacuum container to the surrounding environment. , Various kinds are used.

Jikkensho 59-35958 Gazette

However, in reality, there are few examples of feedthrough proposals that can be used in cryogenic pressure vessels that contain cryogenic refrigerants that have been cooled to a cryogenic temperature and pressurized to a high pressure, such as liquid helium temperature. One such few examples are disclosed in the above literature. In this configuration, an insulating cylinder is inserted into the through hole of the low-temperature and high-pressure container, a conductive member is inserted into the central hole of the insulating cylinder, and an indium-made sealing packing is sandwiched between the insulating cylinder and the conductive member and pressed from both. As a result, the airtightness inside and outside the low-temperature and high-pressure container is maintained. The conductive member and the insulating cylinder each have a corresponding specific shape for pressing the sealing packing. Therefore, there are practical restrictions such as difficulty in using a general lead wire as a conducting member.

One of the exemplary objects of an aspect of the present invention is to provide a cryogenic feedthrough structure compatible with a cryogenic pressure vessel and a cryogenic device using the same.

According to certain aspects of the invention, a cryogenic feedthrough structure that is cryogenic cooled with a cryogenic pressure vessel is provided. The ultra-low temperature feedthrough structure is arranged adjacent to the outside of the ultra-low temperature pressure vessel, and has an insulating resin member that is airtightly mounted on the ultra-low temperature pressure vessel and an insulating resin member that penetrates the insulating resin member to the outside from the inside of the ultra-low temperature pressure vessel. With a metal conductor extending into. The metal conductor is joined to the insulating resin member on its outer peripheral surface, and the joint is held in a state of being cooled at an extremely low temperature.

According to an aspect of the present invention, the cryogenic device accommodates an object to be cooled together with a pressurized cryogenic refrigerant, and is cooled at a cryogenic temperature by the cryogenic refrigerant, and a cryogenic pressure by the cryogenic refrigerant. It has a cryogenic feed-through structure that is cooled at a cryogenic temperature together with the container. The ultra-low temperature feedthrough structure is arranged adjacent to the outside of the ultra-low temperature pressure vessel, and is connected to an insulating resin member that is airtightly mounted on the ultra-low temperature pressure vessel and an object to be cooled, and penetrates the insulating resin member to form a pole. It is provided with a metal conductor extending from the inside of the low temperature pressure vessel to the outside. The metal conductor is joined to the insulating resin member on its outer peripheral surface, and the joint is held in a state of being cooled at an extremely low temperature.

It should be noted that any combination of the above components or components and expressions of the present invention that are mutually replaced between methods, devices, systems, and the like are also effective as aspects of the present invention.

According to the present invention, it is possible to provide a cryogenic feedthrough structure compatible with a cryogenic pressure vessel and a cryogenic device using the same.

It is schematic cross-sectional view which shows the cryogenic feedthrough structure which concerns on embodiment. It is a schematic perspective view which shows the cryogenic feedthrough structure which concerns on embodiment. FIG. 3A is a schematic diagram showing the stress acting on the interface between the metal conductor and the insulating resin member in the cryogenic feedthrough structure according to the embodiment, and FIG. 3B is a diagram showing a comparative example. .. It is a graph which shows the example of the calculation result of the thermal stress which can act on the cryogenic feedthrough structure which concerns on embodiment. It is a graph which shows the heat shrinkage for some materials which can be used for the cryogenic feedthrough structure which concerns on embodiment. It is the schematic sectional drawing which shows the other use example of the cryogenic feedthrough structure shown in FIG. It is the schematic which shows the airtightness test apparatus for the cryogenic feedthrough structure which concerns on embodiment. 8 (a) to 8 (c) are views schematically showing a modified example of the cryogenic feedthrough structure. It is a schematic diagram which shows the cryogenic device which concerns on embodiment.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent components, members, and processes are designated by the same reference numerals, and duplicate description will be omitted as appropriate. The scales and shapes of the illustrated parts are set for convenience of explanation and are not to be interpreted in a limited manner unless otherwise specified. Embodiments are exemplary and do not limit the scope of the invention in any way. Not all features and combinations thereof described in the embodiments are essential to the invention.

FIG. 1 is a schematic cross-sectional view showing a cryogenic feedthrough structure 10 according to an embodiment. FIG. 2 is a schematic perspective view showing the cryogenic feedthrough structure 10 according to the embodiment.

The cryogenic feedthrough structure 10 includes a metal conductor 12 and an insulating resin member 14, and can be mounted on the cryogenic pressure vessel 50. The cryogenic feedthrough structure 10 is cooled to a cryogenic temperature together with the cryogenic pressure vessel 50.

Although the details will be described later, the metal conductor 12 penetrates the insulating resin member 14 and extends from the inside of the cryogenic pressure vessel 50 to the outside. The insulating resin member 14 is arranged adjacent to the outside of the ultra-low temperature pressure vessel 50, and is airtightly mounted on the ultra-low temperature pressure vessel 50. The metal conductor 12 is joined to the insulating resin member 14 on its outer peripheral surface, and this joint is held in a state of being cooled at an extremely low temperature.

The cryogenic pressure vessel 50 contains a cryogenic refrigerant cooled to a liquid helium temperature, a liquid nitrogen temperature, or another cooling temperature and pressurized to a high pressure. Therefore, the cryogenic high pressure environment 58 is maintained inside the cryogenic pressure vessel 50. The pressure of the cryogenic refrigerant may be, for example, higher than atmospheric pressure, or 0.5 MPa, or 1 MPa, or higher than 2 MPa. The pressure of the cryogenic refrigerant may be lower than 3 MPa or 4 MPa.

The ambient environment 18 is lower than the pressure in the cryogenic pressure vessel 50, and is, for example, a vacuum environment or an atmospheric pressure environment. The temperature of the ambient environment 18 is, for example, room temperature. Alternatively, the ambient environment 18 may also be cooled to an extremely low temperature.

The metal conductor 12 electrically connects a high-current device such as a superconducting coil or other internal device 40 arranged in the cryogenic high-voltage environment 58 to a coil power supply or other external device 42 arranged in the ambient environment 18. Connecting. The metal conductor 12 is drawn from the cryogenic and high pressure environment 58 to the ambient environment 18 through the cryogenic feedthrough structure 10.

The metal conductor 12 is, for example, a rod having a columnar shape or other shape, and an insulating resin member 14 is joined to a part of a side surface (outer peripheral surface) thereof. The metal conductor 12 extends along the center line of the insulating resin member 14. The metal conductor 12 inserts the conductor insertion hole 51 formed in the wall of the cryogenic pressure vessel 50, but is not in contact with the wall of the cryogenic pressure vessel 50.

In order to facilitate mounting, in this embodiment, an internal wiring mounting portion 12a is provided at the end of the metal conductor 12 arranged in the ultra-low temperature pressure vessel 50, and is provided outside the ultra-low temperature pressure vessel 50. An external wiring mounting portion 12b is provided at the end of the metal conductor 12 arranged in. The internal wiring 41 connected to the internal device 40 is attached to the internal wiring attachment portion 12a. When the internal device 40 is a superconducting coil, the internal wiring 41 may include a superconducting current lead formed of a superconducting wire. The external wiring 43 connected to the external device 42 is attached to the external wiring attachment portion 12b.

For the attachment of the internal wiring 41 to the internal wiring attachment portion 12a and the attachment of the external wiring 43 to the external wiring attachment portion 12b, for example, mechanical joining by a fastening member 16 such as a bolt or a rivet is used. Fastening holes 17 for mounting the fastening member 16 are formed in the internal wiring mounting portion 12a, the external wiring mounting portion 12b, the internal wiring 41, and the external wiring 43. The internal wiring 41 and the external wiring 43 may be joined to the metal conductor 12 by other appropriate joining means such as welding. Further, the end portion of the metal conductor 12 may be directly connected to the internal device 40 and / or the external device 42.

The metal conductor 12 is formed of a conductive metal material such as, for example, brass, aluminum (or an aluminum alloy), copper, stainless steel, iron, or an alloy thereof. The metal conductor 12 is preferably formed of a material that does not (or is unlikely to) undergo low temperature brittleness at the cooling temperature used (eg, liquid helium temperature or liquid nitrogen temperature).

The cryogenic feedthrough structure 10 may be used for connection between other devices. For example, the internal device 40 may be a temperature sensor or other measuring instrument and may be electrically connected to the external device 42 through the metal conductor 12, for example for power feeding and / or communication.

The insulating resin member 14 has a first end surface 14a, a second end surface 14b, and an outer peripheral surface 14c connecting the first end surface 14a to the second end surface 14b. The insulating resin member 14 is airtightly mounted on the ultra-low temperature pressure vessel 50 in a state where the first end surface 14a is in contact with the outer wall surface of the ultra-low temperature pressure vessel 50. The second end surface 14b is located on the opposite side of the first end surface 14a and is arranged outside the cryogenic pressure vessel 50. The outer peripheral surface 14c of the insulating resin member 14 is exposed to the outside of the cryogenic pressure vessel 50, similarly to the second end surface 14b. The second end surface 14b and the outer peripheral surface 14c are exposed to the surrounding environment 18. The insulating resin member 14 is, for example, a columnar or disc-shaped member, and the first end surface 14a and the second end surface 14b may both have a circular shape, for example, and their diameters may be the same.

The first end surface 14a is a flat surface that contacts the outer wall surface of the cryogenic pressure vessel 50, and the first end surface 14a and the outer wall surface of the cryogenic pressure vessel 50 come into surface contact. If required, the first end surface 14a may have a concave portion and / or a convex portion. For example, when the outer wall surface of the cryogenic pressure vessel 50 has some concave portion or convex portion, the first end surface 14a may have the corresponding convex portion or concave portion. The second end surface 14b is, for example, a flat surface, and may have a concave portion and / or a convex portion, if necessary.

Further, the insulating resin member 14 has a joint surface 14d with the metal conductor 12. The joint surface 14d is an interface between the metal conductor 12 and the insulating resin member 14, and extends cylindrically from the first end surface 14a to the second end surface 14b along the center line of the insulating resin member 14.

In the manufacturing process of the ultra-low temperature feedthrough structure 10, the insulating resin material forming the insulating resin member 14 is prepared as a liquid or a paste, molded around the metal conductor 12, for example, cured at room temperature or heating, and the metal conductor 12 is formed. It is joined by adhesion to. In this way, the insulating resin member 14 forms the joint surface 14d. The insulating resin material has adhesive ability even at extremely low temperatures, and the joint between the metal conductor 12 and the insulating resin member 14 is in a cryogenic cooled state (for example, liquid helium temperature, or liquid nitrogen temperature, or other cooling). It is held at temperature). The insulating resin member 14 is preferably formed of a resin material that does not (or is unlikely to) cause low temperature brittleness at the cooling temperature used.

The insulating resin material forming the insulating resin member 14 is, for example, an adhesive suitable for extremely low temperatures. The insulating resin member 14 may be formed of, for example, a resin material (for example, an epoxy resin) or an adhesive containing fine powders of ceramics or other materials. Such fine powder is used to adjust the amount of heat shrinkage of the insulating resin member 14 when cooled at an extremely low temperature to the same level as that of the metal conductor 12. Typical examples of the ultra-low temperature adhesive that can be used as the insulating resin member 14 include a particle-dispersed composite epoxy resin adhesive (for example, Stycast 2850) such as STYCAST manufactured by Emerson & Cuming, and Nitto Shinko Co., Ltd. Examples thereof include a two-component mixed epoxy resin adhesive such as Nitofix (registered trademark) manufactured by NITOFIX.

The insulating resin member 14 has a plurality of fastening holes 20 formed around the metal conductor 12, and the fastening member 22 can be fastened to each fastening hole 20, and the fastening member 22 causes the insulating resin member 14 to have an extremely low temperature. It is hermetically fastened to the pressure vessel 50. The fastening hole 20 penetrates the insulating resin member 14 from the second end surface 14b to the first end surface 14a. The fastening member 22 is, for example, a bolt, and the fastening hole 20 is, for example, a bolt hole. As shown in FIG. 2, the number of fastening holes 20 is, for example, 6, but the number is not particularly limited. Since a mechanical fastening means is used, it is easier to attach, remove, and replace the cryogenic feedthrough structure 10 to the cryogenic pressure vessel 50 as compared with using other joining means such as brazing, welding, and gluing. ..

Even if the ratio of the diameter Di of the joint surface 14d to the outer diameter Do of the insulating resin member 14 on the first end surface 14a (hereinafter, appropriately referred to as a radius ratio n (= Di / Do)) is 0.5 or less, for example. Good. In other words, the outer diameter Do of the insulating resin member 14 on the first end surface 14a is at least twice the diameter Di of the joint surface 14d, that is, the insulating resin member 14 is thick. Preferably, the radius ratio n may be, for example, 0.3 or less or 0.2 or less.

By having the insulating resin member 14 having such dimensions, it becomes easy to airtightly attach the first end surface 14a to the ultra-low temperature pressure vessel 50 in a state of being in contact with the ultra-low temperature pressure vessel 50. For example, it becomes easy to form the fastening hole 20 in the first end surface 14a. Even when other joining means such as brazing is used, the contact area is increased, so that the cryogenic feedthrough structure 10 can be easily joined to the feedthrough mounting flange 56. Further, by making the insulating resin member 14 relatively thick, the wiring has improved pressure resistance as compared with a typical feedthrough component through which a thin tube is inserted.

Further, the radius ratio n may be, for example, 0.05 or more. Preferably, the radius ratio n may be, for example, 0.1 or more. By doing so, it is possible to prevent the insulating resin member 14 from becoming excessively thick and the joint surface 14d from becoming too small (that is, the metal conductor 12 becoming too thin).

The cryogenic sealing member 24 is provided between the insulating resin member 14 and the cryogenic pressure vessel 50. The cryogenic sealing member 24 is sandwiched between the first end surface 14a and the wall surface of the cryogenic pressure vessel 50, and seals the cryogenic refrigerant so as not to leak into the ambient environment 18. The cryogenic sealing member 24 is arranged so as to surround the joint surface 14d inside the fastening hole 20 (that is, the fastening member 22) when the insulating resin member 14 is mounted on the cryogenic pressure vessel 50. The cryogenic sealing member 24 may be, for example, a metal O-ring, or a gasket or other sealing member suitable for cryogenic temperatures. The cryogenic seal member 24 is mounted on the first end surface 14a, but instead, it may be mounted on the wall surface of the cryogenic pressure vessel 50.

FIG. 3A is a schematic view showing the stress acting on the interface between the metal conductor 12 and the insulating resin member 14 in the cryogenic feedthrough structure 10 according to the embodiment, and FIG. 3B shows a comparative example. It is a figure.

When the cryogenic feedthrough structure 10 is cooled from room temperature to a cryogenic temperature, the metal conductor 12 and the insulating resin member 14 are respectively heat-shrinked. In general, the resin material shrinks more than the metal material and the resin material. Therefore, a radial compressive stress 26 is generated on the joint surface 14d as shown by an arrow in FIG. 3A. The compressive stress 26 acts to suppress the peeling of the metal conductor 12 and the insulating resin member 14 that may occur on the joint surface 14d. Therefore, the joint between the metal conductor 12 and the insulating resin member 14 is held in a cryogenic cooled state. Therefore, according to the cryogenic feedthrough structure 10 according to the embodiment, peeling of the metal conductor 12 and the insulating resin member 14 is suppressed, and the cryogenic feedthrough structure 10 can maintain airtightness.

Further, unlike the comparative example (described later) shown in FIG. 3B, in the cryogenic feedthrough structure 10 according to the embodiment, the outer peripheral surface 14c of the insulating resin member 14 is exposed to the outside of the cryogenic pressure vessel 50. Will be done. A metal member such as a metal cylinder is not adhered to the outside of the insulating resin member 14.

In the comparative example shown in FIG. 3B, the metal feedthrough member 28 has a through hole in the center, and a lead wire 30 such as a lead wire is inserted through the through hole and the insulating resin 32 is filled. As a result, the lead wire 30 is fixed to the feedthrough member 28. In this case, at the interface 34 between the metal feedthrough member 28 and the insulating resin 32, the insulating resin 32 shrinks more than the feedthrough member 28 when heat shrinks due to ultra-low temperature cooling, and a radial tensile stress 36 is applied. appear. If the tensile adhesive strength of the insulating resin 32 is lower than this thermal stress, the insulating resin 32 may peel off from the feedthrough member 28 and the airtightness may be impaired.

FIG. 4 is a graph showing an example of the calculation result of the thermal stress σs that can act on the cryogenic feedthrough structure 10 according to the embodiment. For each of the four curves shown in FIG. 4, the thermal stress σs acting on the joint surface 14d between the metal conductor 12 and the insulating resin member 14 was calculated for Examples 1 to 4, and the above-mentioned radius ratio n (= Di / Di /) was calculated. Do) is drawn as a parameter.

In Examples 1 to 4, the shape and dimensions of the cryogenic feedthrough structure 10 are the same, but the materials of the metal conductor 12 and the insulating resin member 14 are different. In the first embodiment, the metal conductor 12 is made of aluminum, and the insulating resin member 14 is made of nitofix. In the second embodiment, the metal conductor 12 is made of copper, and the insulating resin member 14 is made of nitofix. In the third embodiment, the metal conductor 12 is formed of aluminum, and the insulating resin member 14 is formed of a bib. In the fourth embodiment, the metal conductor 12 is formed of copper, and the insulating resin member 14 is formed of a bib.

Here, the thermal stress σs is
σs = (Ao-Ai) B
Is calculated by.

Ao indicates the material length ratio of the material forming the insulating resin member 14, and Ai indicates the material length ratio of the material forming the metal conductor 12. The "material length ratio" can be defined as the ratio of the reference length L _{0 at 0 K to the reference length L 300} at 300 K of the sample of the material (ie, L ₀ / L _300). The magnitude of heat shrinkage when cooled from room temperature to liquid nitrogen temperature usually reaches about 90% of the magnitude of heat shrinkage when cooled from room temperature to about 0 K, so the reference length L at 0 K _{Instead of 0} , the "material length ratio" may be defined as L ₇₇ / L _{300 using the reference length L 77 at liquid nitrogen temperature (77K).} That is, the material sample has a reference length L ₃₀₀ at 300 K and is reduced to a _{length L 77} when the reference length is cooled to 77 K. Therefore, the material length ratio can be obtained by measuring the length of the material sample at room temperature and extremely low temperature.

により計算される。ここで、Ｅｏ、νｏはそれぞれ、絶縁樹脂部材１４を形成する材料についてのヤング率とポアソン比を示し、Ｅｉ、νｉはそれぞれ、金属導体１２を形成する材料についてのヤング率とポアソン比を示す。これらの弾性定数が既知でない場合には、極低温下で材料サンプルの引張（圧縮）とひずみの関係を測定することによって得られる。 In addition, B in the above formula is

Is calculated by. Here, Eo and νo indicate the Young's modulus and Poisson's ratio for the material forming the insulating resin member 14, respectively, and Ei and νi indicate the Young's modulus and Poisson's ratio for the material forming the metal conductor 12, respectively. If these elastic constants are not known, they can be obtained by measuring the relationship between tension (compression) and strain of a material sample at a cryogenic temperature.

In FIG. 4, when the stress is a positive value, the tensile stress acts on the joint surface 14d, and when the stress is a negative value, the compressive stress acts on the joint surface 14d. According to the calculation results shown in FIG. 4, in Example 1 (aluminum / nitofix), Example 2 (copper / nitofix), and Example 4 (copper / stycast), compressive stress was applied to the joint surface 14d. I know it works. When the cryogenic feed-through structure 10 is cooled from room temperature to a cryogenic temperature, in Example 1, a compressive stress of about 5 MPa to about 4 MPa is applied to the joint surface 14d in a radius ratio n of about 0.1 to about 0.4. work. In Example 2, a compressive stress of about 6 MPa to about 5 MPa acts, and in Example 4, a compressive stress of about 0.5 MPa acts. As described with reference to FIG. 3A, the compressive stress suppresses the peeling of the metal conductor 12 and the insulating resin member 14 and helps maintain the airtightness of the ultra-low temperature feedthrough structure 10.

The compressive strength of the insulating resin material used in these examples reaches several hundred MPa. Therefore, even if a compressive stress of several MPa acts on the joint surface 14d as shown in FIG. 4, it is considered that the material cannot be destroyed by the compressive stress.

On the other hand, in Example 3 (aluminum / stycast), when the cryogenic feedthrough structure 10 is cooled from room temperature to a cryogenic temperature, the joint surface 14d of the metal conductor 12 and the insulating resin member 14 has a radius ratio n of about. A tensile stress of about 0.5 MPa acts in the range of 0.1 to about 0.4. However, in general, the tensile stress generated on the joint surface when peeling occurs is on the order of 100 MPa. The tensile stress in Example 3 is less than one-hundredth of this. Therefore, there is almost no possibility that peeling will occur in Example 3, and Example 3 can also be used.

FIG. 5 is a graph showing thermal shrinkage for some materials that can be used in the cryogenic feedthrough structure 10 according to the embodiment. FIG 5, 293 K samples of a material having, _L 293 each reference length in TK, is expressed as _{L T} (i.e. the material sample has a reference length _{L 293} at 293 K, this reference length when reduced to the length _{L T} when cooled to _TK), it is shown the magnitude of the thermal contraction, denoted _{(L 293 -L T) / L} 293.

As can be seen from FIG. 5, the thermal shrinkage of the Stycast 2850GT is quite large, for example, in the cryogenic region of 100 K or less. The heat shrinkage of aluminum is slightly larger than that of Stycast 2850GT. Therefore, when the metal conductor 12 is formed of aluminum and the insulating resin member 14 is formed of stycast as in the third embodiment, the heat shrinkage due to the extremely low temperature cooling is the metal conductor as compared with the insulating resin member 14. 12 is slightly larger, and tensile stress acts on the joint surface 14d.

Also, the thermal shrinkage of copper is smaller than that of the Stycast 2850GT. Therefore, when the metal conductor 12 is formed of copper and the insulating resin member 14 is formed of stycast as in the fourth embodiment, the insulating resin member 14 is larger than the metal conductor 12, and the joint surface 14d Compressive stress will act on. According to FIG. 5, the magnitude of heat shrinkage of stainless steel is about the same as that of copper or slightly smaller than that of copper. Therefore, even when the metal conductor 12 is made of stainless steel, for example, compressive stress acts on the joint surface 14d.

FIG. 6 is a schematic cross-sectional view showing another use example of the cryogenic feedthrough structure 10 shown in FIG. As shown in FIG. 6, the ultra-low temperature pressure vessel 50 to which the ultra-low temperature feedthrough structure 10 is mounted has a pressure vessel main body 52 and a high pressure pipe 54 extending from the pressure vessel main body 52 and having a feedthrough mounting flange 56. Have. The feedthrough mounting flange 56 is provided at the tip of the high pressure pipe 54. The insulating resin member 14 can be mounted on the feedthrough mounting flange 56.

The metal conductor 12 is drawn from the cryogenic high-pressure environment 58 to the ambient environment 18 through the high-pressure pipe 54 and the cryogenic feedthrough structure 10. The metal conductor 12 is not in contact with the high pressure pipe 54 and the feedthrough mounting flange 56. The insulating resin member 14 is airtightly mounted on the cryogenic pressure vessel 50 with the first end surface 14a in contact with the feedthrough mounting flange 56. The first end surface 14a is a flat surface that contacts the end surface of the feedthrough mounting flange 56, and the first end surface 14a and the feedthrough mounting flange 56 come into surface contact with each other. The first end surface 14a has a plurality of fastening holes 20 formed around the metal conductor 12, and a fastening member 22 can be fastened to each fastening hole 20, and the insulating resin member 14 is fed through by the fastening member 22. It is airtightly fastened to the mounting flange 56. Further, the cryogenic sealing member 24 is provided between the insulating resin member 14 and the feedthrough mounting flange 56.

Although the case where the insulating resin member 14 has a cylindrical shape has been described as an example, the present invention is not limited to this. The two end faces of the insulating resin member 14 may have different sizes, and for example, the second end face 14b may have a smaller diameter than the first end face 14a. The insulating resin member 14 is formed with a flange portion having a first end surface 14a, and this flange portion may be attached to the feedthrough mounting flange 56.

Alternatively, the insulating resin member 14 may have a conical trapezoidal shape. It is also not essential that the two end faces are circular. For example, the second end surface 14b may have a rectangular shape or other shape.

FIG. 7 is a schematic view showing an airtightness test apparatus for the cryogenic feedthrough structure 10 according to the embodiment. The feedthrough airtightness test device 60 includes a high pressure gas source 62, a gas leak inspection device 64, and a cryogenic cooling tank 66. The metal conductor 12 penetrates the insulating resin member 14 from the first end surface 14a to the second end surface 14b of the insulating resin member 14, and the insulating resin member 14 can be airtightly attached to the high pressure gas source 62 at the first end surface 14a. Yes, it can be airtightly attached to the gas leak inspection device 64 at the second end surface 14b.

The high-pressure gas source 62 is, for example, a tank of high-pressure helium gas, and is formed in the ultra-low temperature feed-through structure 10 via a pressure regulator 62a such as a valve provided at the outlet of the tank, a safety valve 62b, and a high-pressure side mounting flange 62c. Be connected. The first end surface 14a of the insulating resin member 14 is airtightly mounted on the high-pressure side mounting flange 62c. That is, instead of the cryogenic pressure vessel 50 shown in FIG. 1, the high pressure gas source 62 and the high pressure side mounting flange 62c are mounted on the insulating resin member 14.

The gas leak inspection device 64 is, for example, a helium leak detector, which is connected to the cryogenic feedthrough structure 10 via a valve 67 and a low pressure side mounting flange 68. The pump 69 may be connected to a pipe branched between the valve 67 and the low pressure side mounting flange 68.

The insulating resin member 14 can be airtightly attached to the gas leak inspection device 64 on the second end surface 14b. It is not easy to perform an airtightness test of the cryogenic feedthrough structure 10 in a state where it is actually mounted on the cryogenic pressure vessel 50 because the test apparatus becomes large. Even if a leak is found by such a large-scale test device, it is troublesome to replace it with a new cryogenic feedthrough structure 10 because it is already installed. However, according to the embodiment, the airtightness test of the cryogenic feedthrough structure 10 can be easily performed by itself before mounting on the cryogenic pressure vessel 50, which is convenient. A cryogenic feedthrough structure 10 that has passed the airtightness test and is guaranteed not to leak can be selected and mounted on the actual machine.

The insulating resin member 14 is airtightly mounted on the gas leak inspection device 64 in a state where the second end surface 14b is in contact with the low-voltage side mounting flange 68. The second end surface 14b has a plurality of fastening holes 20 formed around the metal conductor 12, and a fastening member 22 can be fastened to each fastening hole 20, and the insulating resin member 14 is placed on the low voltage side by the fastening member 22. It is airtightly fastened to the mounting flange 68. The fastening hole 20 penetrates the insulating resin member 14 from the first end surface 14a to the second end surface 14b. However, this is not essential, and the fastening hole 20 of the first end surface 14a and the fastening hole 20 of the second end surface 14b may not be connected to each other.

The cryogenic cooling tank 66 is filled with a cryogenic refrigerant such as liquid nitrogen, in which the cryogenic feedthrough structure 10 is immersed together with the high pressure side mounting flange 62c and the low pressure side mounting flange 68. The cryogenic feedthrough structure 10 is cooled to the temperature of liquid nitrogen or the cooling temperature of the refrigerant. Instead of the cryogenic cooling tank 66, the cryogenic feedthrough structure 10 may be cooled by a cryogenic refrigerator such as a GM refrigerator.

8 (a) to 8 (c) are views schematically showing a modified example of the cryogenic feedthrough structure 10. As shown in FIG. 8A, the cryogenic feedthrough structure 10 may include a detachment prevention shape 70. The detachment prevention shape 70 is provided on the outer peripheral surface of the metal conductor 12 and engages with the insulating resin member 14. The detachment prevention shape 70 may be at least one disc-shaped or polygonal collar-shaped portion extending radially outward from the metal conductor 12. A plurality of such brim-shaped portions may be provided at intervals in the longitudinal direction of the metal conductor 12, and in FIG. 8A, two brim-shaped portions are provided as an example.

A force acts on the metal conductor 12 in the direction from the first end surface 14a to the second end surface 14b due to the pressure of the cryogenic high pressure environment 58. Therefore, if the joint surface 14d has a constant diameter from the first end surface 14a to the second end surface 14b (that is, the metal conductor 12 is a cylinder) as shown in FIG. 1, the metal conductor at the joint surface 14d In the unlikely event that the 12 is peeled off from the insulating resin member 14, there is a risk that the metal conductor 12 will be separated from the second end surface 14b into the surrounding environment 18 due to the force acting on the metal conductor 12. When the pressure difference between the cryogenic high-pressure environment 58 and the ambient environment 18 is large, the metal conductor 12 may pop out from the second end surface 14b at high speed at the moment when the metal conductor 12 is peeled from the insulating resin member 14.

However, as shown in FIG. 8A, the metal conductor 12 is provided with the detachment prevention shape 70, and the joint surface 14d is formed with irregularities. Therefore, by any chance, the metal conductor 12 is made of an insulating resin on the joint surface 14d. Even if the metal conductor 12 is peeled off from the member 14, the metal conductor 12 engages with the insulating resin member 14. Therefore, it is possible to prevent the metal conductor 12 from leaving (jumping out) from the second end surface 14b into the surrounding environment 18.

The detachment prevention shape 70 provided on the metal conductor 12 can take various shapes. For example, as shown in FIG. 8B, the detachment prevention shape 70 may have a shape different from the disk shape, such as a conical shape or another cone-shaped shape. The detachment prevention shape 70 may be any protrusion provided on the outer peripheral surface of the metal conductor 12. As shown in FIG. 8C, the detachment prevention shape 70 may have a recess such as a groove provided on the outer peripheral surface of the metal conductor 12.

FIG. 9 is a schematic view showing a cryogenic device according to an embodiment. The cryogenic cooling system 100 is a circulation cooling system configured to cool an object to be cooled, for example, a superconducting coil 102 to a target temperature by circulating a cooling gas (for example, the above-mentioned cryogenic refrigerant). As the cooling gas, for example, helium gas is often used, but other appropriate gases depending on the cooling temperature may be used.

The coil case 104, which is a cryogenic pressure vessel, houses the superconducting coil 102 together with the pressurized cryogenic refrigerant, and is cooled at a cryogenic temperature by the cryogenic refrigerant. The coil case 104 has a feedthrough mounting flange 56, and the cryogenic feedthrough structure 10 is mounted on the coil case 104. The cryogenic feedthrough structure 10 is cooled to a cryogenic temperature together with the coil case 104 by a cryogenic refrigerant. As described above, the insulating resin member 14 is mounted on the feedthrough mounting flange 56. The coil case 104 and the cryogenic feedthrough structure 10 are housed in a vacuum vessel 106.

The superconducting coil 102 is connected to an internal wiring 41 such as a superconducting current lead, and the internal wiring 41 is connected to a metal conductor 12. The metal conductor 12 is pulled out of the coil case 104 through the cryogenic feedthrough structure 10. The metal conductor 12 is connected to the external wiring 43, and the external wiring 43 is pulled out of the vacuum container 106 through the vacuum feedthrough 110.

The cryogenic cooling system 100 includes a refrigerant circulation device 112, a cooling gas flow path 114 including a coil case flow path 118, a cryogenic refrigerator 122, and a heat exchanger 130. The cooling gas flow path 114 further includes a gas supply line 116, a gas recovery line 120, a flow rate control valve 132, a refrigerator supply line 134, and a refrigerator recovery line 136. The cryogenic refrigerator 122 includes a cold head 126 having a refrigerator stage 128. The refrigerator stage 128 and the heat exchanger 130 are arranged in the vacuum vessel 106 as in the coil case 104.

The refrigerant circulation device 112 is, for example, a compressor for helium gas, and circulates the gas in both the coil case flow path 118 and the cryogenic refrigerator 122. The refrigerant circulation device 112 is arranged outside the vacuum vessel 106. The cooling gas delivered from the refrigerant circulation device 112 is supplied to the inside of the vacuum vessel 106 through the gas supply line 116.

The heat exchanger 130 is configured such that the cooling gas flowing through the gas supply line 116 and the gas recovery line 120 exchange heat with each other. The cooling gas flowing through the gas supply line 116 is precooled by the cooling gas flowing through the gas recovery line 120. The heat exchanger 130 helps to improve the cooling efficiency of the cryogenic cooling system 100.

The cooling gas precooled by the heat exchanger 130 is further cooled by the refrigerator stage 128 and flows into the coil case flow path 118. The coil case flow path 118 is an annular flow path that matches the annular shape of the superconducting coil 102. The cooling gas flowing through the coil case flow path 118 cools the superconducting coil 102 and flows to the gas recovery line 120. The cooling gas is recovered from the gas recovery line 120 to the refrigerant circulation device 112 and sent back to the gas supply line 116.

In this case, the flow rate control valve 132 is provided to control the flow rate of the cooling gas flowing through the coil case flow path 118. The flow control valve 132 is installed in the gas supply line 116 outside the vacuum vessel 106. Alternatively, the flow control valve 132 may be installed on the gas recovery line 120 outside the vacuum vessel 106. In this way, a general-purpose flow rate control valve can be adopted as the flow rate control valve 132, which is advantageous in terms of manufacturing cost as compared with the case where the flow rate control valve 132 is installed in the vacuum vessel 106. However, the flow rate control valve 132 may be installed in the vacuum vessel 106.

A refrigerator supply line 134 is provided to supply the working gas from the refrigerant circulation device 112 to the cryogenic refrigerator 122, and a refrigerator recovery line 136 for recovering the working gas from the cryogenic refrigerator 122 to the refrigerant circulation device 112. Is provided. The refrigerator supply line 134 branches off from the gas supply line 116 outside the vacuum vessel 106 and connects to the cold head 126, and the refrigerator recovery line 136 branches off from the gas recovery line 120 outside the vacuum vessel 106 and is cold. It is connected to the head 126.

The refrigerant circulation device 112 and the cold head 126 constitute a working gas circulation circuit, that is, a refrigeration cycle of the cryogenic refrigerator 122, whereby the refrigerator stage 128 is cooled. The cryogenic refrigerator 122 is, for example, a Gifford-McMahon (GM) refrigerator, but may be a pulse tube refrigerator, a Stirling refrigerator, or another cryogenic refrigerator.

The pressure of the working gas supplied from the refrigerant circulation device 112 to the cold head 126 and the pressure of the working gas recovered from the cold head 126 to the refrigerant circulation device 112 are both considerably higher than the atmospheric pressure, and are the first high pressure and the second, respectively. It can be called high pressure. For convenience of explanation, the first high pressure and the second high pressure are also simply referred to as high pressure and low pressure, respectively. Typically, the high pressure is, for example, 2-3 MPa. The low pressure is, for example, 0.5 to 1.5 MPa, for example, about 0.8 MPa. Therefore, the pressure of the cooling gas supplied from the refrigerant circulation device 112 to the coil case 104 may also be considerably higher than the atmospheric pressure, for example, 2 to 3 MPa.

In this way, it is possible to provide the cryogenic cooling system 100 that cools the superconducting coil 102. Further, using the cryogenic feedthrough structure 10, the electrical wiring connected to the superconducting coil 102 can be pulled out from the inside of the coil case 104 to the outside of the coil case 104.

The present invention has been described above based on examples. It will be understood by those skilled in the art that the present invention is not limited to the above embodiment, various design changes are possible, various modifications are possible, and such modifications are also within the scope of the present invention. By the way. The various features described in relation to one embodiment are also applicable to other embodiments. The new embodiments resulting from the combination have the effects of each of the combined embodiments.

In the above-described embodiment, in the cryogenic feedthrough structure 10, one metal conductor 12 is bonded to the insulating resin member 14. However, the cryogenic feedthrough structure 10 includes a plurality of metal conductors 12, and each metal conductor 12 may penetrate the insulating resin member 14 and extend from the inside of the cryogenic pressure vessel 50 to the outside. The plurality of metal conductors 12 are arranged at intervals in the radial direction. For example, the cryogenic feedthrough structure 10 may have two metal conductors 12, one connected to a current lead on the positive electrode side and the other connected to a current lead on the negative electrode side.

Although the present invention has been described using specific terms and phrases based on the embodiments, the embodiments show only one aspect of the principles and applications of the present invention, and the embodiments are claimed. Many modifications and arrangement changes are permitted within the range not departing from the idea of the present invention defined in the scope.

10 Very low temperature feedthrough structure, 12 Metal conductor, 14 Insulating resin member, 14a 1st end face, 14b 2nd end face, 14c Outer surface, 20 Fastening hole, 22 Fastening member, 26 Compressive stress, 32 Insulating resin, 50 Very low temperature pressure Container, 62 High-pressure gas source, 64 Gas leak inspection device, 70 Detachment prevention shape.

Claims (8)

It has a cryogenic feedthrough structure that is cooled at a cryogenic temperature together with a cryogenic pressure vessel.
An insulating resin member arranged adjacent to the outside of the ultra-low temperature pressure vessel and airtightly mounted on the ultra-low temperature pressure vessel.
A metal conductor that penetrates the insulating resin member and extends from the inside of the cryogenic pressure vessel to the outside is provided.
A cryogenic feedthrough structure characterized in that the metal conductor is joined to the insulating resin member on its outer peripheral surface, and the joint is held in a state of being cooled at a cryogenic temperature. The ultra-low temperature feedthrough structure according to claim 1, wherein the outer peripheral surface of the metal conductor is provided with a detachment prevention shape that engages with the insulating resin member. The ultra-low temperature feedthrough structure according to claim 1 or 2, wherein compressive stress acts from the insulating resin member on the outer peripheral surface of the metal conductor in a state of being cooled at an extremely low temperature. The ultra-low temperature feedthrough structure according to any one of claims 1 to 3, wherein the outer peripheral surface of the insulating resin member is exposed to the outside of the ultra-low temperature pressure vessel. The insulating resin member has a plurality of fastening holes formed around the metal conductor, and the fastening member can be fastened to each fastening hole, and the insulating resin member is connected to the ultra-low temperature pressure vessel by the fastening member. The ultra-low temperature feedthrough structure according to any one of claims 1 to 4, wherein the ultra-low temperature feedthrough structure is hermetically fastened to. The cryogenic feedthrough structure according to any one of claims 1 to 5, wherein the insulating resin member contains an adhesive suitable for a cryogenic temperature. The insulating resin member has a first end face and a second end face, and the metal conductor penetrates the insulating resin member from the first end face to the second end face.
Any of claims 1 to 6, wherein the insulating resin member can be airtightly attached to a high-pressure gas source at the first end surface and airtightly attached to a gas leak inspection device at the second end surface. Ultra-low temperature feedthrough structure described in. A cryogenic pressure vessel that accommodates the object to be cooled together with the pressurized cryogenic refrigerant and is cooled at a cryogenic temperature by the cryogenic refrigerant.
A cryogenic feedthrough structure, which is cooled at a cryogenic temperature together with the cryogenic pressure vessel by the cryogenic refrigerant, is provided.
The cryogenic feedthrough structure
An insulating resin member arranged adjacent to the outside of the ultra-low temperature pressure vessel and airtightly mounted on the ultra-low temperature pressure vessel.
A metal conductor that is connected to the object to be cooled, penetrates the insulating resin member, and extends from the inside of the cryogenic pressure vessel to the outside.
A cryogenic device characterized in that the metal conductor is joined to the insulating resin member on its outer peripheral surface, and the joint is held in a state of being cooled at a cryogenic temperature.

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