Superconducting magnet device

Abstract

[Solution] This medical device 10 is configured to be inserted into a channel 511 of an insertion part 510 of an endoscope device 500 so as to be capable of moving forward and backward. The medical device includes: a puncture device 100; an outer sheath 200 into which the puncture device is inserted; and a handle part 300 disposed on the proximal end side of the puncture device and the outer sheath. The handle part includes: a first connection part 320 connected to the outer sheath; and a second connection part 330 that is connected to at least a portion of the puncture device and moves forward and backward relative to the first connection part, thereby projecting the tip of the puncture device from the tip of the outer sheath.

Description

Superconducting magnet device

[0001] The present invention relates to a superconducting magnet device.

[0002] Superconducting magnet devices are used as magnetic field sources in single crystal pulling systems using the MCZ (Magnetic Field Applied Czochralski) method. Single crystal pulling systems typically include a single crystal pulling furnace and a cryostat surrounding the furnace, housing multiple superconducting coils. The superconducting coils typically use saddle coils or round coils. The strong magnetic field generated by the superconducting coils can suppress thermal convection in the melt inside the furnace.

[0003] Japanese Patent Application Laid-Open No. 2008-28147

[0004] In an existing design of a single crystal pulling apparatus using a saddle coil as a superconducting coil, the coil core used to manufacture the saddle coil is used as a support structure for the saddle coil. The saddle coil is housed in a cryostat along with the core. The saddle coil is wound around the outside of the core, while the single crystal pulling furnace, to which the magnetic field is applied by the superconducting coil, is located inside the cryostat, i.e., inside the core. In other words, the core is located between the magnetic field application location and the saddle coil. In this configuration, the saddle coil is located farther from the magnetic field application location by the space occupied by the core. According to Biot-Savart's law, the magnetic field generated by a coil is proportional to the negative cube of the distance. Therefore, even if the coil is located slightly farther from the magnetic field application location, the magnetomotive force of the coil required to generate the same magnetic field can significantly increase. This results in an increase in the amount of superconducting wire required, which can undesirably increase the manufacturing costs of the superconducting magnet system.

[0005] Furthermore, in single crystal pulling apparatuses, a magnetic shield is often installed around the cryostat to reduce leakage magnetic fields. When a magnetic field is generated, a correspondingly strong electromagnetic force acts on the superconducting coil in a direction toward the magnetic shield, i.e., radially outward. In a configuration using a core as a support structure for a saddle-shaped superconducting coil as described above, this electromagnetic force acts to pull the superconducting coil away from the core. To avoid this, it may be necessary to add structural members or strengthen the support structure in order to press the superconducting coil against the core. The resulting increase in weight and size may also increase the manufacturing cost of the superconducting magnet device.

[0006] It is an exemplary object of certain aspects of the present invention to provide a superconducting magnet apparatus having an improved support structure for saddle-type superconducting coils.

[0007] According to one aspect of the present invention, a superconducting magnet device includes an inner peripheral wall arranged radially outside the bore so as to surround the bore, and an outer peripheral wall arranged radially outside the inner peripheral wall so as to surround the inner peripheral wall, a cryostat that provides a vacuum environment in an internal space defined between the inner peripheral wall and the outer peripheral wall, a pair of saddle-shaped superconducting coils facing each other across the bore, the pair of saddle-shaped superconducting coils being arranged in the internal space so as to be exposed to the vacuum environment, and a support frame that is arranged radially outside the pair of saddle-shaped superconducting coils in the internal space and supports the pair of saddle-shaped superconducting coils.

[0008] According to the present invention, it is possible to provide a superconducting magnet apparatus having an improved support structure for a saddle-type superconducting coil.

[0009] FIG. 1 is a cross-sectional view schematically showing a single crystal pulling apparatus equipped with a superconducting magnet device according to an embodiment. FIG. 2 is a cross-sectional view schematically showing a single crystal pulling apparatus equipped with a superconducting magnet device according to an embodiment. FIG. 3 is a perspective view schematically showing an appearance of a superconducting magnet device according to an embodiment. FIG. 4 is a perspective view schematically showing a superconducting coil arrangement in a superconducting magnet device according to an embodiment. FIG. 5 is a cross-sectional view schematically showing a superconducting magnet device according to an embodiment. FIG. 6 is a schematic view showing a part of a developed view of a saddle-shaped superconducting coil and a support frame as seen from the radially inner side according to an embodiment. FIG. 7 is a front view schematically showing a support frame as seen from the radially outer side according to an embodiment. FIG. 8 is a perspective view schematically showing another example of a superconducting coil arrangement in a superconducting magnet device according to an embodiment.

[0010] 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.

[0011] 1 and 2 are cross-sectional views schematically showing a single crystal pulling apparatus 100 equipped with a superconducting magnet device 10 according to an embodiment. FIG. 3 is a perspective view schematically showing the appearance of the superconducting magnet device 10 according to an embodiment. FIG. 4 is a perspective view schematically showing the superconducting coil arrangement in the superconducting magnet device 10 according to an embodiment. FIG. 5 is a cross-sectional view schematically showing the superconducting magnet device 10 according to an embodiment. FIG. 1 shows the B-B cross section of FIG. 2, and FIG. 2 shows the A-A cross section of FIG. 1. Furthermore, FIG. 5 shows the C-C cross section of FIG. 3.

[0012] The single crystal pulling apparatus 100 includes a single crystal pulling furnace 102 and a superconducting magnet device 10. The single crystal pulling apparatus 100 is, for example, a silicon single crystal pulling apparatus using the HMCZ (Horizontal-MCZ; transverse magnetic field type MCZ) method.

[0013] As shown in FIG. 1, the single crystal pulling furnace 102 includes a crucible 104, a single crystal pulling mechanism 106, and a heater 108.

[0014] The crucible 104 is a container for storing molten material (for example, molten silicon) and is made of, for example, quartz.

[0015] The single crystal pulling mechanism 106 is a drive device that pulls the single crystal 110 upward from the molten material in the crucible 104 along a single crystal pulling axis 112, and includes a pulling drive source disposed above and outside the single crystal pulling furnace 102. The single crystal pulling axis 112 is an axis that extends vertically (i.e., perpendicular to a horizontal plane). The single crystal pulling mechanism 106 is configured to pull the single crystal 110 while rotating it around the single crystal pulling axis 112.

[0016] The heater 108 is disposed around the crucible 104 in the single crystal pulling furnace 102 and heats the crucible 104. The molten material in the crucible 104 is maintained in a molten state by the heating provided by the heater 108.

[0017] The superconducting magnet apparatus 10 includes a cryostat 12, a pair of saddle-shaped superconducting coils 20, a heat shield 24, a magnetic shield 26, and a support frame 30. The superconducting magnet apparatus 10 is used as a magnetic field generation source for a single crystal pulling apparatus 100.

[0018] The cryostat 12 has an internal space 14 isolated from an ambient environment 16 surrounding the cryostat 12, and the saddle-type superconducting coil 20, a heat shield 24, and a support frame 30 are disposed in the internal space 14. The internal space 14 is a cylindrical space. The cryostat 12 is an insulated vacuum vessel, and during operation of the superconducting magnet apparatus 10, an extremely low temperature vacuum environment suitable for bringing the saddle-type superconducting coil 20 into a superconducting state is provided in the internal space 14 of the cryostat 12.

[0019] The cryostat 12 defines a bore 18 therein and has a cylindrical shape extending along a central axis, i.e., a single crystal pulling axis 112, passing through the bore 18. When the superconducting magnet device 10 is mounted on a single crystal pulling apparatus 100, a single crystal pulling furnace 102 is disposed in the bore 18. The bore 18 is part of an ambient environment 16 surrounding the cryostat 12 (i.e., it is outside the cryostat 12) and is, for example, a cylindrical space surrounded by the cryostat 12.

[0020] The cryostat 12 includes an inner peripheral wall 12a disposed radially outside the bore 18 so as to surround the bore 18, and an outer peripheral wall 12b disposed radially outside the inner peripheral wall 12a so as to surround the inner peripheral wall 12a. Both the inner peripheral wall 12a and the outer peripheral wall 12b have a cylindrical shape, and a saddle-shaped superconducting coil 20, a heat shield 24, and a support frame 30 are disposed between them. The inner peripheral wall 12a and the outer peripheral wall 12b are disposed coaxially around the single crystal pulling shaft 112. The cryostat 12 also includes a top plate 12c and a bottom plate 12d that connect the inner peripheral wall 12a and the outer peripheral wall 12b at the top and bottom, respectively. The top plate 12c and the bottom plate 12d are annular in shape and have generally flat surfaces. The internal space 14 of the cryostat 12 is defined between an inner peripheral wall 12a and an outer peripheral wall 12b in the radial direction, and between a top plate 12c and a bottom plate 12d in the vertical direction (the direction of the single crystal pulling axis 112).

[0021] At least the inner peripheral wall 12a of the cryostat 12 is made of a non-magnetic material (e.g., a non-magnetic metal material such as stainless steel) so as not to prevent the saddle-shaped superconducting coil 20 from generating a magnetic field in the bore 18. Other parts of the cryostat 12, i.e., the outer peripheral wall 12b, the top plate 12c, and the bottom plate 12d, may also be made of the same material as the inner peripheral wall 12a.

[0022] The pair of saddle-shaped superconducting coils 20 are arranged opposite each other across the bore 18 and symmetrically with respect to the single crystal pulling axis 112. Each of the saddle-shaped superconducting coils 20 is curved concavely toward the bore 18, for example, curved in an arc shape that conforms to the cylindrical shape of the cryostat 12. These two saddle-shaped superconducting coils 20 have the same shape and the same size.

[0023] One of the two saddle-shaped superconducting coils 20 generates a magnetic field radially inward, i.e., toward the single crystal pulling axis 112, and the other saddle-shaped superconducting coil 20 generates a magnetic field radially outward, i.e., away from the single crystal pulling axis 112. By superposing these magnetic fields, the pair of saddle-shaped superconducting coils 20 generates a composite magnetic field 22. The composite magnetic field 22 is on the single crystal pulling axis 112 and is perpendicular to the single crystal pulling axis 112.

[0024] 2 and 3, an XY coordinate plane perpendicular to the single crystal pulling axis 112 is considered. The origin of this coordinate plane is on the single crystal pulling axis 112, the X axis extends in the direction of the resultant magnetic field 22 on the single crystal pulling axis 112, and the Y axis is perpendicular to the single crystal pulling axis 112 and the X axis. The single crystal pulling axis 112 can also be considered as the Z axis.

[0025] The heat shield 24 is disposed in the internal space 14 of the cryostat 12 so as to surround the saddle-type superconducting coil 20 and the support frame 30. The heat shield 24 is provided to suppress the intrusion of radiant heat from the surrounding environment 16 into the saddle-type superconducting coil 20.

[0026] In order to prevent the magnetic field generated by the saddle-shaped superconducting coil 20 from leaking to the outside, a magnetic shield 26 covers the outer peripheral wall 12b, the top plate 12c, and the bottom plate 12d of the cryostat 12. The magnetic shield 26 is formed of a magnetic material such as iron, and is disposed adjacent to the outer peripheral wall 12b, the top plate 12c, and the bottom plate 12d of the cryostat 12. The magnetic shield 26 does not cover the inner peripheral wall 12a of the cryostat 12 so as not to prevent the saddle-shaped superconducting coil 20 from generating a magnetic field in the bore 18.

[0027] The cryostat 12 is equipped with a pair of cryogenic refrigerators 28 that cool the pair of saddle-shaped superconducting coils 20, the heat shield 24, and the support frame 30. An exemplary arrangement of the cryogenic refrigerators 28 in the cryostat 12 is shown in Figures 2 and 3.

[0028] The cryogenic refrigerator 28 is, for example, a two-stage Gifford-McMahon (GM) refrigerator, and includes a first cooling stage cooled to a first cooling temperature and a second cooling stage cooled to a second cooling temperature lower than the first cooling temperature. The cryogenic refrigerator 28 is installed in the cryostat 12 such that the first cooling stage and the second cooling stage are disposed in the interior space 14 of the cryostat 12. The first cooling stage of the cryogenic refrigerator 28 cools the heat shield 24 to the first cooling temperature, and the second cooling stage cools the saddle-shaped superconducting coil 20 and the support frame 30 to the second cooling temperature. The first cooling temperature may be, for example, in the range of 30 K to 80 K, and the second cooling temperature may be, for example, in the range of 3 K to 20 K.

[0029] The pair of saddle-shaped superconducting coils 20, the heat shield 24, and the support frame 30 are disposed in the internal space 14 so as to be exposed to a vacuum environment. These internal components of the cryostat 12 are cooled by a cryogenic refrigerator 28 through so-called conduction cooling. The heat shield 24 is thermally coupled to a first cooling stage of the cryogenic refrigerator 28 via a first heat transfer member and is directly cooled by the first cooling stage. The saddle-shaped superconducting coil 20 is thermally coupled to a second cooling stage of the cryogenic refrigerator 28 via a second heat transfer member and is directly cooled by the second cooling stage.

[0030] Therefore, in this embodiment, the cryostat 12 does not use immersion cooling, which involves immersing the saddle-shaped superconducting coil 20 in a cryogenic liquid refrigerant such as liquid helium to cool it. The cryostat 12 is not provided with a liquid refrigerant tank that contains the saddle-shaped superconducting coil 20 together with the cryogenic liquid refrigerant. The support frame 30 merely adjoins the saddle-shaped superconducting coil 20 in the internal space 14 of the cryostat 12, and does not form a closed compartment surrounding the saddle-shaped superconducting coil 20.

[0031] One of the pair of cryogenic refrigerators 28 is installed in the cryostat 12 between the pair of saddle-shaped superconducting coils 20 in the circumferential direction of the cryostat 12 and on one side of the bore 18. The other cryogenic refrigerator 28 is installed in the cryostat 12 between the pair of saddle-shaped superconducting coils 20 in the circumferential direction of the cryostat 12 and on the opposite side of the bore 18. For example, as shown in the figure, the pair of cryogenic refrigerators 28 may be arranged on the Y axis. One of the pair of cryogenic refrigerators 28 may be arranged on the +Y side and the other on the −Y side of the single crystal pulling shaft 112. As an example, the cryogenic refrigerator 28 is installed on the top plate 12c of the cryostat 12. As shown in FIG. 3, a portion of the cryogenic refrigerator 28 protrudes upward from the upper plate of the magnetic shield 26 adjacent to the top plate 12c.

[0032] Such a symmetrical arrangement of the cryogenic refrigerators 28 makes it possible to equalize the heat transfer distance from each cryogenic refrigerator 28 to the saddle-shaped superconducting coil 20. As a result, the pair of saddle-shaped superconducting coils 20 can be cooled evenly.

[0033] Furthermore, the strong magnetic field generated by the saddle-type superconducting coil 20 affects the behavior of the cryocooler 28 and, in some cases, may result in a decrease in refrigeration capacity. On the XY plane, the magnetic field is strongest on the X axis and weakest on the Y axis. Therefore, the installation position of the above-mentioned cryocooler 28 is selected to be a location with a low magnetic field. This makes it possible to reduce the adverse effects of the magnetic field on the cryocooler 28.

[0034] Note that, to achieve such advantageous effects, it is not essential that the two cryogenic refrigerators 28 be arranged strictly on the Y-axis. As shown in Fig. 2, the cryogenic refrigerators 28 may be arranged at angular positions spaced apart from the circumferential ends of the saddle-shaped superconducting coil 20 by an angle Δθ in the circumferential direction. The angle Δθ may be, for example, at least 4 degrees. By arranging the cryogenic refrigerators 28 at a distance from the saddle-shaped superconducting coil 20 in the circumferential direction in this manner, adverse effects of the magnetic field on the cryogenic refrigerators 28 can be reduced.

[0035] The support frame 30 is disposed radially outside the pair of saddle-type superconducting coils 20 in the internal space 14 of the cryostat 12, and supports the pair of saddle-type superconducting coils 20. The support frame 30 is formed in a ring shape so as to surround the bore 18. The support frame 30 is a structure that rigidly connects the saddle-type superconducting coils 20 so as to maintain the relative positions of the saddle-type superconducting coils 20 against electromagnetic forces acting on the saddle-type superconducting coils 20 during operation of the superconducting magnet device 10, and can also be called a rigid frame. To achieve the required rigidity, the support frame 30 is formed of a metallic material such as stainless steel or other suitable high-strength material.

[0036] The support frame 30 includes a pair of coil mounts 32 having a curved shape based on the curvature of the saddle-type superconducting coil 20 , and a pair of linear connecting beams 34 connecting the pair of coil mounts 32 .

[0037] The coil mount 32 is a portion of the support frame 30 on which the saddle-shaped superconducting coil 20 is mounted. The coil mount 32 is curved along the saddle-shaped superconducting coil 20, and is adjacent to the radially outer side of the saddle-shaped superconducting coil 20 to support the saddle-shaped superconducting coil 20. By making the coil mount 32 have a curved shape that matches the saddle-shaped superconducting coil 20 in this way, when an electromagnetic force acts on the saddle-shaped superconducting coil 20 during operation of the superconducting magnet device 10, the coil mount 32 can effectively support this electromagnetic force and suppress deformation that may occur in the saddle-shaped superconducting coil 20.

[0038] One connecting beam 34 connects one ends of the coil mounts 32 together, and the other connecting beam 34 connects the other ends of the coil mounts 32 together. Since the connecting beams 34 are not the parts where the saddle-shaped superconducting coil 20 is installed, they do not need to have a curved shape that follows the saddle-shaped superconducting coil 20 like the coil mounts 32. By making the connecting beams 34 flat, they can be manufactured more easily than if they have a curved shape. This can lead to a reduction in the manufacturing cost of the support frame 30.

[0039] 3, the pair of linear connecting beams 34 may have a smaller vertical dimension (i.e., the direction of the single crystal pulling axis 112) than the pair of coil mounts 32. This allows the connecting beams 34 and, in turn, the support frame 30 to be lighter than when the connecting beams 34 and the coil mounts 32 have the same vertical dimension. In addition, by utilizing the fact that the height of the connecting beams 34 is lower than that of the coil mounts 32, it is possible to ensure space above the connecting beams 34 for arranging the cryogenic refrigerator 28.

[0040] As an alternative, the connecting beams 34 may be curved in an arc shape to fit the cylindrical shape of the cryostat 12, similar to the coil mounts 32. The support frame 30 may be formed in an annular shape from the coil mounts 32 and the connecting beams 34. Alternatively, the coil mounts 32 and the connecting beams 34 may be prepared as separate members and connected to form the support frame 30. Alternatively, the support frame 30 may be formed as a single structure in which the coil mounts 32 and the connecting beams 34 are integrated.

[0041] 3 and 5, the superconducting magnet apparatus 10 is provided with a plurality of horizontal load supports 36 that horizontally support the support frame 30. The horizontal load supports 36 support the radially outward electromagnetic force that acts on the saddle-shaped superconducting coils 20 during operation of the superconducting magnet apparatus 10.

[0042] The horizontal load support 36 has a rod-like shape extending in the radial direction of the cryostat 12, and is supported at one end by the magnetic shield 26 and at the other end by the coil mount 32 of the support frame 30. The horizontal load support 36 extends from the magnetic shield 26 through the outer peripheral wall 12b of the cryostat 12 and the thermal shield 24 to the coil mount 32. The radially outward electromagnetic force acting on the saddle-shaped superconducting coil 20 is supported by the horizontal load support 36, with the magnetic shield 26 as a fulcrum.

[0043] At least a part of the horizontal load support 36, for example, the end of the horizontal load support 36, may be made of a metal material such as stainless steel. In addition, in order to suppress heat input from the magnetic shield 26 to the saddle-type superconducting coil 20 through the horizontal load support 36, at least a part of the horizontal load support 36, for example, a rod-shaped body connecting both ends of the horizontal load support 36, may be made of a heat insulating material such as fiber-reinforced plastic.

[0044] The support frame 30 has a recess 38 formed radially inward from the outer circumferential surface of the support frame 30. This recess 38 is provided in the coil mount 32 of the support frame 30 to receive the end of the horizontal load support 36 on the support frame 30 side. The support frame 30 is supported by the horizontal load support 36 at the recess 38. The recess 38 is also formed in the coil mount 32 as a protrusion 39 that protrudes radially into the inner space of the saddle-shaped superconducting coil 20.

[0045] In this way, a portion of the horizontal load support 36 is housed in the recess 38 of the support frame 30, so the total radial dimension of the horizontal load support 36 and the support frame 30 can be reduced. This can lead to a reduction in the size of the superconducting magnet device 10. At the same time, the radial length of the horizontal load support 36 can be increased. This makes it possible to ensure a heat insulating distance between the magnetic shield 26 and the support frame 30 by the horizontal load support 36, and to reduce the thermal load on the saddle-type superconducting coil 20.

[0046] Two horizontal load supports 36 are arranged for one saddle-type superconducting coil 20. When an electromagnetic force acts on the saddle-type superconducting coil 20, bending stress is likely to occur in the coil at its corners (i.e., at the ends of the coil in the circumferential direction of the cryostat 12). To effectively suppress bending deformation of the coil due to this bending stress, the horizontal load supports 36 may be arranged near the corners of the saddle-type superconducting coil 20. Therefore, recesses 38 for receiving the horizontal load supports 36 may be formed in the circumferential ends of the coil mounts 32 of the support frame 30. Note that, if necessary, an additional (i.e., a third) horizontal load support 36 may be arranged for each saddle-type superconducting coil 20.

[0047] 6 is a schematic diagram showing a part of a developed view of the saddle-type superconducting coil 20 and the support frame 30 as viewed from the radially inner side according to the embodiment. As shown in FIGS. 5 and 6, a first support 40 and a second support 42 are attached to the support frame 30 in order to fix the saddle-type superconducting coil 20 to the support frame 30.

[0048] The first support 40 is a plate disposed radially inward of the saddle-type superconducting coil 20, and is attached to the coil mount 32 of the support frame 30 to press the saddle-type superconducting coil 20 radially outward toward the support frame 30. Each saddle-type superconducting coil 20 has a first coil end face 20a facing radially outward and a second coil end face 20b facing radially inward, with the first coil end face 20a in contact with the coil mount 32 and the second coil end face 20b in contact with the first support 40. The first support 40 is attached to the support frame 30 so as to sandwich the saddle-type superconducting coil 20 between these two coil end faces. The first support 40 may be attached to the support frame 30 via the second support 42, or may be attached directly to the support frame 30.

[0049] In this way, by pressing the saddle-type superconducting coil 20 against the support frame 30 using the first support 40, displacement of the saddle-type superconducting coil 20 in the radial direction of the cryostat 12 can be suppressed, and the radial position of the saddle-type superconducting coil 20 on the support frame 30 can be maintained.

[0050] Each saddle-shaped superconducting coil 20 has two coil side surfaces connecting the first coil end surface 20 a and the second coil end surface 20 b, i.e., a first coil side surface 20 c on the outer circumferential side of the coil and a second coil side surface 20 d on the inner circumferential side of the coil. The second support 42 is attached to the support frame 30 so as to sandwich the saddle-shaped superconducting coil 20 between these two coil side surfaces.

[0051] The second support 42 includes a first member 42a and a second member 42b, with the first member 42a contacting the first coil side surface 20c and the second member 42b contacting the second coil side surface 20d. The first member 42a abuts against a wall covering a portion of the first coil side surface 20c, and the second member 42b abuts against a wall covering a portion of the second coil side surface 20d. The first member 42a and the second member 42b are each attached to the support frame 30. To sandwich the saddle-shaped superconducting coil 20 between the first member 42a and the second member 42b, one of the first member 42a and the second member 42b, for example, the second member 42b, is provided with a pressing tool such as a leveling block, a screw jack, or a leaf spring.

[0052] In this way, by sandwiching the saddle-type superconducting coil 20 between the second supports 42, it is possible to suppress bending of the saddle-type superconducting coil 20 that may occur when an electromagnetic force acts on the saddle-type superconducting coil 20.

[0053] By providing both the first support 40 and the second support 42, the displacement and deformation of the saddle-type superconducting coil 20 relative to the support frame 30 is effectively suppressed, which helps to suppress the occurrence of quenching in the saddle-type superconducting coil 20.

[0054] 6, these coil supports are provided not only at the top and bottom portions of the saddle-type superconducting coil 20 but also at the corner portions. In this way, the first supports 40 and the second supports 42 are provided at multiple locations along the saddle-type superconducting coil 20, thereby enabling the saddle-type superconducting coil 20 to be firmly fixed to the support frame 30 over the entire periphery.

[0055] The first support 40 and the second support 42 are provided discretely at a plurality of locations instead of being provided continuously along the entire set of the saddle-type superconducting coil 20. By adopting such a divided structure, the first support 40 and the second support 42 can be easily manufactured.

[0056] FIG. 7 is a front view showing a schematic view of the support frame 30 as viewed from the radially outer side according to an embodiment. The superconducting magnet device 10 is provided with a plurality of vertical load supports 44 that support the support frame 30 in the vertical direction. The vertical load supports 44 can support the weight acting on the internal components of the cryostat 12, such as the saddle-type superconducting coil 20. The plurality of vertical load supports 44 may be arranged at equal angular intervals around the circumference of the cryostat 12. For example, six vertical load supports 44 may be arranged at 60-degree intervals. Note that FIG. 7 also shows the cryogenic refrigerator 28 together with the support frame 30.

[0057] The vertical load support 44 has a rod-like shape extending in the vertical direction, one end of which is supported on the bottom surface of the cryostat 12, and the other end of which is supported by the coil mount 32 of the support frame 30. At least a portion of the vertical load support 44, for example, the ends of the vertical load support 44, may be made of a metal material such as stainless steel. In addition, in order to suppress heat input from the cryostat 12 to the saddle-type superconducting coil 20 through the vertical load support 44, at least a portion of the vertical load support 44, for example, the rod-like bodies connecting both ends of the vertical load support 44, may be made of a heat insulating material such as fiber-reinforced plastic.

[0058] 7 , the support frame 30 has ribs 46 formed radially outward from the outer circumferential surface of the support frame 30, and is supported by the vertical load supports 44 at the ribs 46. The ribs 46 extend in the circumferential direction on the outer circumferential surface of the coil mounts 32 of the support frame 30. By connecting the vertical load supports 44 to the horizontally extending ribs 46 in this way, the ribs 46 act as a sort of buffer material, and it is possible to reduce the direct load on the vertical load supports 44 due to impact loads on the support frame 30 (for example, the electromagnetic force of the saddle-type superconducting coil 20, impacts that may occur during transportation of the superconducting magnet device 10, etc.).

[0059] Although not shown, the cryostat 12 may be provided with other components such as a current introduction terminal connected to the saddle-type superconducting coil 20, a vacuum exhaust port for evacuating the cryostat 12, and a measurement port connected to a measuring device inside the cryostat 12. At least one of the current introduction terminal, the vacuum exhaust port, and the measurement port may be installed on the top or bottom surface of the cryostat 12.

[0060] As mentioned at the beginning of this document, in existing designs of single crystal pulling apparatuses using saddle-type superconducting coils, the support structure for the saddle-type superconducting coil is often attached radially inside the saddle-type superconducting coil. In this case, the saddle-type superconducting coil is positioned radially away from the single crystal pulling furnace to which the magnetic field is to be applied, due to the space occupied by the support structure. Because the magnetic field generated by the coil is proportional to the negative cube of the distance, the required magnetomotive force of the coil can increase significantly as the saddle-type superconducting coil is further away from the single crystal pulling furnace. In other words, the magnetic field generation efficiency tends to decrease. This results in an increase in the amount of superconducting wire required for the coil, which can undesirably increase the manufacturing cost of the superconducting magnet apparatus.

[0061] In contrast, according to the embodiment, the saddle-type superconducting coil 20 is supported by the support frame 30 at its radially outer side, so that the saddle-type superconducting coil 20 can be disposed close to the bore 18. This improves the efficiency of magnetic field generation, reduces the amount of superconducting wire used, and further reduces the manufacturing cost of the superconducting magnet device 10.

[0062] Furthermore, during operation of the superconducting magnet device 10, a strong electromagnetic force acts on the saddle-shaped superconducting coil 20 in a direction toward the magnetic shield 26, i.e., radially outward, in response to the strong magnetic field generated by the saddle-shaped superconducting coil 20. The saddle-shaped superconducting coil 20 is strongly pulled toward the magnetic shield 26.

[0063] In the above-mentioned existing designs, the support structure of the saddle-shaped superconducting coil is located radially inward, so that radially outward forces acting on the coil tend to pull the coil away from the support structure. To prevent the coil from separating from the support structure, additional structural members or a reinforced support structure may be required. This may result in increased weight and size, which is undesirable as it may increase the manufacturing cost of the device.

[0064] In contrast to this, according to the embodiment, the radially outward force acting on the saddle-type superconducting coil 20 acts to press the saddle-type superconducting coil 20 against the support frame 30. Therefore, contrary to the existing technology, the support frame 30 can effectively support the saddle-type superconducting coil 20 with a relatively simple configuration. As a result, the weight of the superconducting magnet device 10 can also be reduced.

[0065] Typically, the cryostat 12 mounted in the single crystal pulling apparatus 100 has an outer diameter that is approximately 1.5 times its inner diameter (i.e., the diameter of the bore 18). To accommodate a cryostat 12 having such radial dimensions, the pair of saddle-type superconducting coils 20 may be preferably disposed in the internal space 14 of the cryostat 12 within a range of 1.05 to 1.32 times the diameter of the bore 18. In other words, the lower limit of the inner diameter of the saddle-type superconducting coil 20 may be set to 1.05 times the diameter of the bore 18 of the cryostat 12. Furthermore, the upper limit of the outer diameter of the saddle-type superconducting coil 20 may be set to 1.32 times the diameter of the bore 18 of the cryostat 12.

[0066] A heat shield 24 is disposed radially inside the saddle-shaped superconducting coil 20 in the internal space 14. In order to cool the saddle-shaped superconducting coil 20 to a temperature lower than that of the heat shield 24, it is desirable to reliably avoid physical contact between the saddle-shaped superconducting coil 20 and the heat shield 24. From this viewpoint, the above-mentioned lower limit value of 1.05 times is set.

[0067] A heat shield 24 is also disposed radially outside the support frame 30 in the internal space 14. The support frame 30, together with the saddle-type superconducting coil 20, is cooled to a temperature lower than that of the heat shield 24. It is desirable to reliably avoid physical contact between the support frame 30 and the heat shield 24. Furthermore, in order to provide the desired rigidity, the support frame 30 needs to have a certain radial size. From this perspective, the above-mentioned upper limit value of 1.32 times is set.

[0068] Similarly, the pair of linear connecting beams 34 may be disposed within a range of 1.05 to 1.32 times the diameter of the bore 18 in the internal space 14 of the cryostat 12. In this manner, taking into consideration avoiding physical contact between the connecting beams 34 and the heat shield 24 and ensuring thermal insulation therebetween, the lower limit of the radially inner dimension of the connecting beams 34 may be set to 1.05 times the diameter of the bore 18, and the upper limit of the radially outer dimension of the connecting beams 34 may be set to 1.32 times the diameter of the bore 18.

[0069] 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.

[0070] 8 is a perspective view schematically showing another example of a superconducting coil arrangement in the superconducting magnet device 10 according to the embodiment. As shown in the figure, the superconducting magnet device 10 may be provided with an additional superconducting coil 50 in addition to a pair of saddle-shaped superconducting coils 20 to assist in adjusting the magnetic field distribution in the superconducting magnet device 10. The additional superconducting coil 50 may be a coil smaller than the saddle-shaped superconducting coil 20, and may be arranged inside the saddle-shaped superconducting coil 20. The additional superconducting coil 50 may be a circular coil or a saddle-shaped coil. Both the saddle-shaped superconducting coil 20 and the additional superconducting coil 50 may be supported by the support frame 30 described above.

[0071] The single crystal pulling apparatus equipped with the superconducting magnet apparatus 10 according to the embodiment may be a single crystal pulling apparatus for producing single crystals of semiconductor materials other than silicon or other materials.

[0072] If applicable, the superconducting magnet device 10 may be mounted on an apparatus other than a single crystal pulling apparatus. The superconducting magnet device 10 is mounted on a high magnetic field device as a magnetic field source for the high magnetic field device, and can generate the high magnetic field required for the device.

[0073] 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.

[0074] The present invention can be used in the field of superconducting magnet devices.

[0075] 10 Superconducting magnet device, 12 Cryostat, 12a Inner peripheral wall, 12b Outer peripheral wall, 14 Internal space, 18 Bore, 20 Saddle-shaped superconducting coil, 20a First coil end surface, 20b Second coil end surface, 28 Cryogenic refrigerator, 30 Support frame, 32 Coil mount, 34 Connecting beam, 36 Horizontal load support, 38 Recess, 40 First support, 42 Second support, 44 Vertical load support, 46 Rib.

Claims

1. A superconducting magnet device comprising: a cryostat having an inner wall arranged radially outside a bore so as to surround the bore, and an outer wall arranged radially outside the inner wall so as to surround the inner wall, providing a vacuum environment in an internal space defined between the inner wall and the outer wall; a pair of saddle-shaped superconducting coils facing each other across the bore, the pair of saddle-shaped superconducting coils arranged in the internal space so as to be exposed to the vacuum environment; and a support frame arranged radially outside the pair of saddle-shaped superconducting coils in the internal space, supporting the pair of saddle-shaped superconducting coils.

2. A superconducting magnet apparatus according to claim 1, characterized in that the pair of saddle-shaped superconducting coils are arranged in the internal space within a range of 1.05 to 1.32 times the diameter of the bore.

3. The superconducting magnet device according to claim 1, characterized in that the pair of saddle-shaped superconducting coils are curved concavely toward the bore, and the support frame comprises a pair of coil mounts having a curved shape based on the curvature of the saddle-shaped superconducting coils, and a pair of linear connecting beams connecting the pair of coil mounts.

4. A superconducting magnet apparatus according to claim 3, wherein said pair of straight connecting beams have a smaller vertical dimension than said pair of coil mounts.

5. A superconducting magnet apparatus according to claim 3, characterized in that said pair of linear connecting beams are disposed within a range of 1.05 to 1.32 times the diameter of said bore in said internal space.

6. A superconducting magnet device as described in any one of claims 1 to 5, further comprising a horizontal load support for supporting the support frame in a horizontal direction, the support frame having a recess formed radially inward from the outer circumferential surface of the support frame, and the support frame being supported by the horizontal load support at the recess.

7. A superconducting magnet device as described in any one of claims 1 to 5, further comprising a vertical load support that supports the support frame in the vertical direction, the support frame having ribs formed radially outward from the outer circumferential surface of the support frame, and the support frame being supported by the vertical load support at the ribs.

8. A superconducting magnet apparatus according to any one of claims 1 to 5, further comprising a first support attached to said support frame so as to press said saddle-shaped superconducting coil radially outward against said support frame.

9. A superconducting magnet device as described in any one of claims 1 to 5, characterized in that each saddle-shaped superconducting coil has a first coil end face facing radially outward, a second coil end face facing radially inward, and two coil side faces connecting the first coil end face and the second coil end face, and further comprises a second support attached to the support frame so as to sandwich the saddle-shaped superconducting coil between the two coil side faces.

10. A superconducting magnet device as described in any one of claims 1 to 5, characterized in that the cryostat is provided with a pair of extremely low temperature refrigerators for cooling the pair of saddle-shaped superconducting coils, one of the pair of extremely low temperature refrigerators is installed in the cryostat on one side of the bore between the pair of saddle-shaped superconducting coils in the circumferential direction of the cryostat, and the other of the pair of extremely low temperature refrigerators is installed in the cryostat on the opposite side of the bore between the pair of saddle-shaped superconducting coils in the circumferential direction of the cryostat.

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