Superconducting coil device

Abstract

To suppress a heat input of a radiation into a current introduction line of a superconducting coil.SOLUTION: A superconducting coil device 10 comprises: a vacuum container 14; a super conducting coil 12 arranged in the vacuum container 14; a heat shield 16 arranged in such a way as to surround the superconducting coil 12 in the vacuum container 14; and a current introduction line 20 for conducting current into the super conducting coil 12. The current introduction line 20 comprises: an outside current lead portion 26 that is arranged outside the heat shield 16 in the vacuum container 14 and is thermally connected to the heat shield 16; and an inside current lead portion 28 that is arranged inside of the heat shield 16, and connects the outside current lead portion 26 to the super conducting coil 12. The outside current lead portion 26 comprises: a main body that becomes a current path to the superconducting coil 12; an insulation layer that coats the main body; and a shield heat layer that coats the insulation layer and has an emissivity smaller than that of the insulation layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a superconducting coil device and a current lead-in line to a superconducting coil device. [Background technology]

[0002] The superconducting coil is placed in a vacuum vessel and connected to an external power supply by a current lead-in line. The superconducting coil is cooled to a cryogenic temperature in the vacuum vessel to be in a superconducting state, and is supplied with power from the external power supply through the current lead-in line, enabling it to generate a high magnetic field. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-251564 Summary of the Invention [Problem to be solved by the invention]

[0004] It has been known that the current feed-in line causes heat input to the superconducting coil due to the following two factors. One is Joule heat generated when current flows through the current feed-in line. The other is heat input from the outside to the superconducting coil due to thermal conduction through the current feed-in line, which acts as a heat transfer path. This occurs because one end of the current feed-in line is drawn outside the vacuum vessel and is at ambient temperature (e.g., room temperature), while the other end is cooled to an extremely low temperature together with the superconducting coil.

[0005] The inventors have noticed that in addition to these two factors, there is a third heat input factor: radiant heat. A portion of the current feed-in line may be located near the vacuum vessel wall inside the vacuum vessel. Therefore, radiant heat emitted by the vacuum vessel wall may be incident on this portion of the current feed-in line and transmitted to the superconducting coil through the current feed-in line. To reliably maintain the superconducting coil in a superconducting state, it is desirable to minimize the heat input to the current feed-in line.

[0006] An exemplary object of an embodiment of the present invention is to suppress radiative heat input into a current feed line of a superconducting coil. [Means for solving the problem]

[0007] According to one aspect of the present invention, a superconducting coil device includes a vacuum vessel, a superconducting coil disposed within the vacuum vessel, a thermal shield disposed within the vacuum vessel so as to surround the superconducting coil, and a current introduction line for introducing current to the superconducting coil, the current introduction line including: an outer current lead portion disposed outside the thermal shield within the vacuum vessel and thermally coupled to the thermal shield, and an inner current lead portion disposed within the thermal shield and connecting the outer current lead portion to the superconducting coil. The outer current lead portion includes a main body serving as a current path to the superconducting coil, an insulating layer covering the main body, and a thermal shield layer covering the insulating layer and having a lower emissivity than the insulating layer.

[0008] According to one aspect of the present invention, there is provided a current introduction line for introducing current to a superconducting coil disposed within a vacuum vessel. The current introduction line includes an outer current lead portion disposed within the vacuum vessel outside a heat shield disposed to surround the superconducting coil within the vacuum vessel and thermally coupled to the heat shield. The outer current lead portion includes a main body serving as a current path to the superconducting coil, an insulating layer covering the main body, and a heat shield layer covering the insulating layer and having a lower emissivity than the insulating layer.

[0009] Any combination of the above components or mutual substitution of the components or expressions of the present invention between methods, devices, systems, etc. are also valid aspects of the present invention. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress radiant heat input to the current introduction line of the superconducting coil. [Brief explanation of the drawings]

[0011] [Figure 1]1 is a side view schematically showing a superconducting coil device according to an embodiment. [Figure 2] 1 is a diagram showing a cross section of a laminated structure of an outer current lead portion of a current introduction line according to an embodiment of the present invention; [Figure 3] FIG. 2 is a perspective view showing a schematic diagram of an exemplary outer current lead portion. [Figure 4] FIG. 2 is a diagram schematically showing a cross section of the superconducting coil device shown in FIG. 1 taken along line AA. [Figure 5] 10 is a diagram showing a schematic diagram of another example of the outer current lead portion 26. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description and drawings, identical or equivalent components, parts, and processes are designated by the same reference numerals, and redundant explanations will be omitted as appropriate. The scale and shape of each part shown in the drawings are set for convenience to facilitate explanation, and should not be interpreted as limiting unless otherwise specified. The embodiments are merely examples and do not limit the scope of the present invention in any way. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0013] 1 is a side view that schematically shows a superconducting coil device 10 according to an embodiment. The superconducting coil device 10 is mounted in high-magnetic-field equipment as a magnetic field source for, for example, a single crystal pulling device, an NMR system, an MRI system, an accelerator such as a cyclotron, a high-energy physics system such as a nuclear fusion system, or other high-magnetic-field equipment (not shown), and can generate a high magnetic field required for the equipment.

[0014] The superconducting coil device 10 includes a superconducting coil 12, a vacuum vessel 14, a heat shield 16, and a current lead-in line 20. The superconducting coil 12 is connected to an external power supply 18 located outside the vacuum vessel 14 by the current lead-in line 20. An excitation current is supplied from the external power supply 18 to the superconducting coil 12 through the current lead-in line 20. This enables the superconducting coil device 10 to generate a strong magnetic field.

[0015] The superconducting coil 12 is placed in a vacuum vessel 14. The superconducting coil 12 is thermally coupled to, for example, a two-stage Gifford-McMahon (GM) refrigerator or other type of cryogenic refrigerator 15 installed in the vacuum vessel 14, and is used in a state cooled to a cryogenic temperature below the superconducting transition temperature. In this embodiment, the superconducting coil device 10 is configured as a so-called conduction-cooled type in which the superconducting coil 12 is directly cooled by the cryogenic refrigerator 15, rather than as an immersion-cooled type in which the superconducting coil 12 is immersed in a cryogenic liquid refrigerant such as liquid helium. Note that the superconducting coil device 10 may also be an immersion-cooled type.

[0016] The vacuum vessel 14 is an insulated vacuum vessel, also called a cryostat, that provides a cryogenic vacuum environment suitable for bringing the superconducting coil 12 into a superconducting state. Typically, the vacuum vessel 14 has a cylindrical shape or a cylindrical shape with a hollow center. Therefore, the vacuum vessel 14 has a generally flat, circular or annular top plate 14a and bottom plate 14b, and a cylindrical side wall (a cylindrical outer wall, or coaxially arranged cylindrical outer and inner walls) connecting them. The cryogenic refrigerator 15 may be installed on the top plate 14a of the vacuum vessel 14. The vacuum vessel 14 is formed of a metallic material, such as stainless steel, or other suitable high-strength material to withstand ambient pressure (e.g., atmospheric pressure).

[0017] The heat shield 16 is disposed within the vacuum vessel 14 to surround the superconducting coil 12. The heat shield 16 is formed of a metal material such as copper or another material with high thermal conductivity. The heat shield 16 may be cooled by one cooling stage of the two-stage cryogenic refrigerator 15 that cools the superconducting coil 12, or by a single-stage cryogenic refrigerator separate from the two-stage refrigerator. During operation of the superconducting coil device 10, the heat shield 16 is cooled to a first cooling temperature, for example, 30 K to 50 K, and the superconducting coil 12 is cooled to a second cooling temperature, for example, 3 K to 20 K, which is lower than the first cooling temperature. The heat shield 16 can thermally protect low-temperature parts, such as the superconducting coil 12, which are disposed inside the heat shield 16 and cooled to a lower temperature than the heat shield 16, from radiant heat from the vacuum vessel 14.

[0018] The current introduction line 20 for introducing current to the superconducting coil 12 includes an external wiring 22, a feed-through portion 24, an outer current lead portion 26, and an inner current lead portion 28, and forms a current path from the external power supply 18 to the superconducting coil 12. For simplicity, only one current introduction line 20 is shown in Fig. 1. However, in general, multiple current introduction lines 20 may be provided in the superconducting coil device 10; for example, one current introduction line 20 on the positive side and one current introduction line 20 on the negative side may be provided.

[0019] External wiring 22 arranged outside the vacuum vessel 14 connects the external power supply 18 to a feedthrough portion 24 provided in the wall of the vacuum vessel 14. The external wiring 22 may be an appropriate power supply cable. The feedthrough portion 24 is an airtight terminal for introducing current into the vacuum vessel 14, and connects the external wiring 22 to internal wiring within the vacuum vessel 14 (i.e., the outer current lead portion 26 and the inner current lead portion 28). The feedthrough portion 24 allows the current introduction line 20 to pass through the wall of the vacuum vessel 14 while maintaining the airtightness of the vacuum vessel 14.

[0020] In this embodiment, as shown in the figure, the feed-through unit 24 is installed on the bottom plate 14b of the vacuum vessel 14, and the current introduction line 20 is arranged on the outer periphery below the vacuum vessel 14. This arrangement is advantageous from the viewpoint of workability. Depending on the application field of the superconducting coil device 10, the vacuum vessel 14 is often considerably larger than a worker (e.g., several meters or more in diameter). If the feed-through unit 24 is arranged on the outer periphery of the vacuum vessel 14, workers can easily access the current introduction line 20 from around the superconducting coil device 10. Alternatively, the feed-through unit 24 may be installed on the top surface of the vacuum vessel 14, and the current introduction line 20 may be arranged on the outer periphery above the vacuum vessel 14. Alternatively, the feed-through unit 24 and the current introduction line 20 may be arranged in other locations on the vacuum vessel 14.

[0021] The outer current lead portion 26 is disposed outside the heat shield 16 within the vacuum vessel 14 and connects the feedthrough portion 24 to the inner current lead portion 28. A thermal insulation layer 17 may be provided between the vacuum vessel 14 and the heat shield 16 to protect the heat shield 16 from radiant heat emitted from the vacuum vessel 14. The thermal insulation layer 17 may be, for example, a multilayer insulation (MLI), and may be disposed to surround the heat shield 16. The outer current lead portion 26 may be disposed outside this thermal insulation layer 17.

[0022] As will be described later, the outer current lead portion 26 has a first end, a second end, and a connection portion connecting these two ends, and is fixed to the feed-through portion 24 at the first end and to the inner current lead portion 28 at the second end. The outer current lead portion 26 and the feed-through portion 24 (and the inner current lead portion 28) can be fixed together by any appropriate joining method, such as bolt fastening or solder fastening.

[0023] The outer current lead 26 is thermally coupled to the heat shield 16. A second end of the outer current lead 26 is fixed to the heat shield 16 or connected to the heat shield 16 via an appropriate heat transfer member, and is cooled to the first cooling temperature in the same manner as the heat shield 16. However, the outer current lead 26 is electrically insulated from the heat shield 16.

[0024] In this embodiment, the outer current lead portion 26 extends along a wall portion (e.g., bottom plate 14b) of the vacuum vessel 14. As shown in the figure, when the vacuum vessel 14 is arranged with the top plate 14a facing upward and the bottom plate 14b facing downward, the outer current lead portion 26 extends laterally (horizontally) within the vacuum vessel 14. However, depending on the arrangement of internal equipment such as the superconducting coil 12 and heat shield 16 within the vacuum vessel 14, the outer current lead portion 26 may extend in another direction within the vacuum vessel 14, for example, vertically (vertically).

[0025] As an example, the outer current lead 26 may be a thin plate having a strip or rectangular shape. In this case, the longitudinal dimension (length) of the outer current lead 26 is greater than the lateral dimension (width), which is greater than the thickness of the outer current lead 26. In the illustrated example, the longitudinal direction of the outer current lead 26 corresponds to a first direction in a horizontal plane (the left-right direction in FIG. 1), and the thickness direction of the outer current lead 26 corresponds to a second direction perpendicular to the first direction in the horizontal plane (the depth direction in FIG. 1). The lateral direction of the outer current lead 26 corresponds to the vertical direction perpendicular to the horizontal plane (the up-down direction in FIG. 1).

[0026] The outer current lead portion 26 may have other shapes. For example, the outer current lead portion 26 may be formed as a bundle of many thin wires or many foils to provide flexibility. Furthermore, instead of a thin plate shape, the outer current lead portion 26 may have a rod shape such as a cylindrical shape.

[0027] The inner current lead 28 is disposed inside the thermal shield 16 and connects the outer current lead 26 to the superconducting coil 12. The inner current lead 28 may extend in a different direction from the outer current lead 26 within the vacuum vessel 14. In the illustrated example, the inner current lead 28 extends vertically from the second end of the outer current lead 26 to the superconducting coil 12. Alternatively, the inner current lead 28 may extend in the same direction as the outer current lead 26. The inner current lead 28 may include terminal portions at both ends connected to the outer current lead 26 and the superconducting coil 12, respectively, and a superconducting current lead connecting these terminal portions. The superconducting current lead may have a rod-like shape, such as a cylindrical shape, and may be made of a copper oxide superconductor or other high-temperature superconducting material. Alternatively, the superconducting current lead may be made of a low-temperature superconducting material, such as NbTi.

[0028] 2 is a diagram schematically illustrating a cross section of the layered structure of the outer current lead 26 of the current lead 20 according to the embodiment. As illustrated, the outer current lead 26 includes a main body 30, an insulating layer 32a, and a heat-shielding layer 34a. When the outer current lead 26 is in the form of a thin plate as described above, the insulating layer 32a and the heat-shielding layer 34a are layered on the main body 30 in the thickness direction of the outer current lead 26.

[0029] The body 30 of the outer current lead portion 26 is made of a conductive material, for example, a metal material with excellent conductivity, such as pure copper, such as oxygen-free copper, and serves as a current path to the superconducting coil 12 .

[0030] The insulating layer 32a covers the main body 30. The insulating layer 32a may be formed of an insulating synthetic resin material such as a polyimide film known as Kapton (registered trademark), or other insulating materials. The outer current lead 26 may include an insulating tape 32 having an insulating layer 32a on one side and an adhesive layer 32b for bonding to the main body 30 on the other side. In this way, the insulating layer 32a can be easily formed on the main body 30 by adhering the insulating tape 32 to the main body 30. Alternatively, the insulating layer 32a may be formed on the main body 30 by applying or otherwise adhering an insulating material to the surface of the main body 30.

[0031] The thermal barrier layer 34a covers the insulating layer 32a. The thermal barrier layer 34a is provided as the outermost layer of the outer current lead portion 26 and is exposed to the vacuum environment in the vacuum vessel 14. The thermal barrier layer 34a is formed of a material with a lower emissivity than the insulating layer 32a. The emissivity of the thermal barrier layer 34a needs only to be lower than that of the insulating layer 32a at a reference wavelength (e.g., a predetermined infrared wavelength such as 1 μm). To achieve a high emissivity, the thermal barrier layer 34a may have a surface with a metallic luster and be formed of a metal such as aluminum or copper. The emissivity of the insulating material forming the insulating layer 32a typically significantly exceeds 0.5, while most metal surfaces have an emissivity of less than 0.1, such as approximately 0.02 for an aluminum-coated surface and approximately 0.06 for a polished surface of phosphorus-deoxidized copper.

[0032] The outer current lead 26 may be provided with a heat-shielding tape 34 having a heat-shielding layer 34a on one side and an adhesive layer 34b on the other side with respect to the insulating layer 32a. In this way, the heat-shielding layer 34a can be easily provided on the insulating layer 32a by attaching the heat-shielding tape 34 to the insulating layer 32a or the insulating tape 32. Alternatively, the heat-shielding layer 34a may be formed on the insulating layer 32a by plating or otherwise adhering a metal material to the insulating layer 32a.

[0033] The insulating tape 32 does not necessarily have to be composed of two layers, the insulating layer 32a and the adhesive layer 32b, and may have at least one intermediate layer between the insulating layer 32a and the adhesive layer 32b. The insulating tape 32 may have at least one coating layer on the outside of the insulating layer 32a. The main body 30 may have some kind of coating layer covering its surface, and this coating layer may be covered with the insulating layer 32a, or the insulating tape 32 may be attached to the coating layer. Furthermore, the heat-shielding tape 34 does not necessarily have to be composed of two layers, the heat-shielding layer 34a and the adhesive layer 34b, and may have at least one intermediate layer between the heat-shielding layer 34a and the adhesive layer 34b. As long as the coating layer does not significantly affect the emissivity of the heat-shielding layer 34a, the heat-shielding layer 34a may be coated with at least one coating layer (e.g., a protective layer made of a transparent material), or the heat-shielding tape 34 may have at least one coating layer on the outside of the heat-shielding layer 34a.

[0034] Similarly, when the body 30 of the outer current lead 26 has another shape, the body 30 may be coated with the insulating layer 32a and the heat-shielding layer 34a. For example, when the body 30 is formed as a bundle of many thin wires or many foils, each of these thin wires or foils may be coated with the insulating layer 32a and the heat-shielding layer 34a. When the body 30 has a rod-like shape, it may also be coated with the insulating layer 32a and the heat-shielding layer 34a.

[0035] If the heat-shielding layer 34a were not present and the insulating layer 32a were exposed, there is a concern that the radiant heat input emitted from the inner wall surface of the vacuum vessel 14 and received by the outer current lead portion 26 would be correspondingly large, since the insulating layer 32a generally has a high emissivity as described above.

[0036] In contrast, according to the embodiment, the outer current lead 26 is covered with the heat shield layer 34a and has a low emissivity, which makes it difficult for the outer current lead 26 to absorb the radiant heat emitted from the inner wall surface of the vacuum vessel 14, thereby suppressing the radiant heat input to the outer current lead 26 and, in turn, the heat input to the superconducting coil 12 through the current lead line 20.

[0037] In particular, when the outer current lead 26 is disposed close to the vacuum vessel 14, for example, by being disposed outside the heat insulating layer 17 and extending along the wall surface of the vacuum vessel 14, radiant heat from the vacuum vessel 14 is likely to reach the outer current lead 26. However, according to the embodiment, the outer current lead 26 is covered with the heat shield layer 34a, and therefore the inflow of radiant heat can be effectively reduced.

[0038] Furthermore, even if the heat shield layer 34a comes into contact with the heat insulating layer 17, the insulating layer 32a is interposed between the heat shield layer 34a and the main body 30 of the outer current lead portion 26, so that leakage of electricity from the outer current lead portion 26 can be avoided.

[0039] FIG. 3 is a perspective view schematically illustrating an exemplary outer current lead 26. The outer current lead 26 has a first end 26a, a second end 26b, and a band-shaped connection portion 26c that connects the first end 26a and the second end 26b. As described above, the outer current lead 26 is fixed to the feed-through portion 24 at the first end 26a and to the inner current lead 28 at the second end 26b. The feed-through portion 24 and the terminal portions of the inner current lead 28, to which the first end 26a and the second end 26b are respectively fixed, are formed of a metal material with excellent conductivity, such as pure copper, similar to the outer current lead 26. These terminal portions are formed as rectangular parallelepiped blocks with contact surfaces that match the length and width dimensions of the first end 26a and the second end 26b, respectively. For electrical contact, the surfaces of the body 30 of the outer current lead portion 26 are in direct contact with and fixed to the feed-through portion 24 and inner current lead portion 28 at the first end 26a and the second end 26b, respectively. The insulating layer 32a and the heat-shielding layer 34a described above are not provided on the contact surfaces.

[0040] The connecting portion 26c does not necessarily have to be a simple elongated rectangle. As shown in Fig. 3, the connecting portion 26c may be thinner than the first end 26a and the second end 26b. That is, the width of the outer current lead portion 26 in the short direction (the vertical direction in the figure) is smaller at the connecting portion 26c than at the first end 26a and the second end 26b.

[0041] By narrowing the connection portion 26c in this way, the surface area of ​​the outer current lead portion 26 is reduced, thereby reducing radiant heat input. On the other hand, the first end portion 26a and the second end portion 26b can have a relatively large area, which increases the contact area between the first end portion 26a and the feed-through portion 24 and the contact area between the second end portion 26b and the inner current lead portion 28. Heat can be generated by passing current through such contact portions, but increasing the contact area reduces the effects of heat generation.

[0042] The connecting portion 26c connects the first end 26a and the second end 26b at the upper side in the short direction in the figure. The outer current lead 26 may be produced by cutting a region 26d below the connecting portion 26c in the figure from a thin, elongated rectangular plate. In this way, the outer current lead 26 can be produced inexpensively.

[0043] Fig. 4 is a schematic diagram showing a cross section of the superconducting coil device 10 shown in Fig. 1 taken along line AA. Fig. 4 shows the current introduction line 20 and the heat shield 16 as seen from below within the vacuum vessel 14. Note that the heat insulating layer 17 is not shown in Fig. 4.

[0044] As described above, the outer current lead 26 has a first end 26a on the vacuum vessel 14 side, a second end 26b on the heat shield 16 side, and a belt-shaped connecting portion 26c that connects the first end 26a and the second end 26b. The belt-shaped connecting portion 26c is bendable in the thickness direction. The outer current lead 26 is arranged so that thermal contraction caused by cooling of the heat shield 16 causes the second end 26b to displace in the thickness direction relative to the first end 26a, thereby bending the connecting portion 26c in the thickness direction.

[0045] More specifically, for example, if the vacuum vessel 14 and the heat shield 16 have a cylindrical shape, the inner current lead 28 is provided on the outer periphery of the heat shield (for example, the outer periphery of the lower surface of the heat shield as described above), and the feedthrough 24 is provided on the outer periphery of the vacuum vessel 14 (for example, the outer periphery of the lower surface of the vacuum vessel as described above). The feedthrough 24 and the inner current lead 28 are arranged at positions offset from each other in the circumferential direction of the vacuum vessel 14 so that the outer current lead 26 extends generally tangentially to the cylindrical shape of the heat shield 16 (the longitudinal direction of the outer current lead 26 generally coincides with the tangential direction of the heat shield 16). The connection portion 26c of the outer current lead 26 is arranged so that its thickness direction is oriented in the radial direction of the vacuum vessel 14 and the heat shield 16, and its short side is oriented in the vertical direction of the vacuum vessel 14 and the heat shield 16 (the depth direction of the paper in FIG. 4 ).

[0046] As the heat shield 16 cools, it thermally contracts radially toward the center. This thermal contraction causes the inner current lead portion 28 (and the second end 26b of the outer current lead portion 26) to be displaced radially relative to the feedthrough portion 24 (and the first end 26a of the outer current lead portion 26) (as shown by arrow B in FIG. 4). This radial displacement is absorbed by the connection portion 26c of the outer current lead portion 26 being elastically bent in the thickness direction. This prevents excessive thermal stress from occurring in other portions of the current feed-in line 20, which in turn prevents excessive deformation or damage to the current feed-in line 20.

[0047] As another example of the arrangement of the outer current lead portion 26, the outer current lead portion 26 may be arranged so that the thickness direction of the outer current lead portion 26 coincides with the vertical direction of the vacuum vessel 14. In this way, the outer current lead portion 26 can absorb the thermal contraction of the heat shield 16 in the vertical direction by bending the connection portion 26c.

[0048] FIG. 5 is a schematic diagram illustrating another example of the outer current lead 26. The outer current lead 26 may be provided with a tubular magnetic shield 36 surrounding it. The connection portion 26c connecting the first end 26a and the second end 26b of the outer current lead 26 is inserted into the magnetic shield 36. Without the magnetic shield 36, the Lorentz force due to the high magnetic field generated by the superconducting coil 12 acts on the outer current lead 26, which could result in deformation or breakage of the outer current lead 26. For example, if current flows from the first end 26a to the second end 26b through the connection portion 26c in the horizontal direction in FIG. 5 and the magnetic field generated by the superconducting coil 12 is in the vertical direction in FIG. 5, the Lorentz force acts on the outer current lead 26 so as to bend the outer current lead 26 in the thickness direction. By providing the magnetic shield 36 on the outer current lead 26, the Lorentz force can be suppressed, reducing the risk of deformation or breakage of the outer current lead 26.

[0049] The surfaces (external and internal surfaces) of the magnetic shield 36 may be plated with a metal such as aluminum and polished (for example, by electrolytic polishing) to have a low emissivity. This makes it possible to suppress radiant heat input from the vacuum vessel 14 to the magnetic shield 36 and from the magnetic shield 36 to the outer current lead 26.

[0050] The magnetic shield 36 is formed of a magnetic material such as iron. Such materials may be brittle at low temperatures, so it is preferable to avoid cooling them. Therefore, the magnetic shield 36 may be attached to the first end 26a side rather than the second end 26b, which is cooled. The magnetic shield 36 may also be attached to the feed-through part 24 to which the first end 26a is fixed.

[0051] 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-described embodiments, and that various design changes and modifications are possible, and that such modifications are also within the scope of the present invention. Various features described in relation to one embodiment can also be applied to other embodiments. A new embodiment created by combining embodiments will have the combined effects of the respective combined embodiments.

[0052] In the embodiment described above, the body 30 of the outer current lead portion 26, which provides the current path to the superconducting coil 12, is made solely of a metal such as copper. However, in some embodiments, the body 30 may have other configurations. For example, the body 30 may be made of other wire, such as high-temperature superconducting wire. Such a body 30 may be coated with an insulating layer 32a and a thermal barrier layer 34a.

[0053] Similarly, if necessary, the surface of the terminal portion of the feed-through portion 24 to which the first end 26a of the outer current lead portion 26 is attached, which is not in contact with the first end 26a and is exposed to the vacuum environment in the vacuum vessel 14, may also be covered with the insulating layer 32a and the heat-shielding layer 34a. Furthermore, the surface of the terminal portion of the inner current lead portion 28 to which the second end 26b of the outer current lead portion 26 is attached, which is not in contact with the second end 26b and is exposed to the vacuum environment in the vacuum vessel 14, may also be covered with the insulating layer 32a and the heat-shielding layer 34a.

[0054] The present invention has been described using specific terms based on the embodiments, but the embodiments merely illustrate one aspect of the principles and applications of the present invention, and many modifications and changes in arrangement are permitted to the embodiments as long as they do not deviate from the concept of the present invention as defined in the claims. [Explanation of symbols]

[0055] 10 superconducting coil device, 12 superconducting coil, 14 vacuum vessel, 16 heat shield, 20 current introduction line, 26 outer current lead portion, 26a first end, 26b second end, 26c connection portion, 28 inner current lead portion, 30 main body, 32 insulating tape, 32a insulating layer, 32b adhesive layer, 34 heat shielding tape, 34a heat shielding layer, 34b adhesive layer, 36 magnetic shield.

Claims

1. A vacuum vessel; a superconducting coil disposed within the vacuum vessel; a heat shield disposed within the vacuum vessel to surround the superconducting coil; a current introduction line for introducing a current to the superconducting coil, the current introduction line including: an outer current lead portion disposed outside the thermal shield in the vacuum vessel and thermally coupled to the thermal shield; and an inner current lead portion disposed inside the thermal shield and connecting the outer current lead portion to the superconducting coil; the outer current lead portion includes a main body serving as a current path to the superconducting coil, an insulating layer covering the main body, and a heat shield layer covering the insulating layer and having a lower emissivity than the insulating layer; A superconducting coil device, characterized in that the outer current lead portion is provided with a heat shield tape having the heat shield layer on one side and an adhesive layer with the insulating layer on the other side.

2. the outer current lead portion has a first end portion on the vacuum vessel side, a second end portion on the heat shield side, and a connecting portion that connects the first end portion and the second end portion and has a belt-like shape that can be bent in a thickness direction, 2. The superconducting coil device according to claim 1, wherein the outer current lead portion is arranged so that the second end portion is displaced in the thickness direction relative to the first end portion due to thermal contraction caused by cooling of the heat shield, and the connection portion is bent in the thickness direction.

3. A vacuum vessel; a superconducting coil disposed within the vacuum vessel; a heat shield disposed within the vacuum vessel to surround the superconducting coil; a current introduction line for introducing a current to the superconducting coil, the current introduction line including: an outer current lead portion disposed outside the thermal shield in the vacuum vessel and thermally coupled to the thermal shield; and an inner current lead portion disposed inside the thermal shield and connecting the outer current lead portion to the superconducting coil; a tubular magnetic shield surrounding the outer current lead; a heat-shielding layer that covers the insulating layer and has a lower emissivity than the insulating layer;

4. a heat insulating material is provided on the outside of the heat shield within the vacuum vessel; 4. The superconducting coil device according to claim 1, wherein the outer current lead portion is disposed outside the heat insulating material.

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