Superconducting magnet device

Abstract

The present invention provides a superconducting magnet device capable of more precisely controlling the generated magnetic field distribution. The superconducting magnet device (10) includes: a cylindrical cryostat (20) having a central cavity (24) defined inside thereof; a first superconducting coil group (30) and a second superconducting coil group (40) disposed inside the cylindrical cryostat (20) outside the central cavity (24); and a power supply system (50) capable of independently controlling the magnitude of a first excitation current supplied to the first superconducting coil group (30) and the magnitude of a second excitation current supplied to the second superconducting coil group (40). When the first excitation current is supplied, the first superconducting coil group (30) generates a magnetic field distribution in the central cavity (24) that bulges downward on the X-axis and upward on the Y-axis. When the second excitation current is supplied, the second superconducting coil group generates a magnetic field distribution in the central cavity that bulges upward on the X-axis and downward on the Y-axis.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2021-005646 filed on January 18, 2021. The entire content of the Japanese application is incorporated herein by reference. Technical Field

[0002] The present invention relates to a superconducting magnet device. Background Art

[0003] The superconducting magnet device is used as a magnetic field generation source of a single crystal pulling device based on the MCZ (Magnetic field applied Czochralski) method. By the strong magnetic field generated by the superconducting magnet, heat convection in the melt of the semiconductor material can be suppressed. The applied magnetic field distribution affects the degree of suppression of heat convection, and as a result, the oxygen concentration in the pulled single crystal changes. The preferred oxygen concentration varies depending on the use of the finally manufactured semiconductor device. Therefore, conventionally, a single crystal pulling device is known that switches the direction of the current flowing through a part of the superconducting coil to switch and generate two different magnetic field distributions.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-206396 Summary of the Invention

[0005] One exemplary object of an embodiment of the present invention is to provide a superconducting magnet device capable of more finely controlling the generated magnetic field distribution.

[0006] According to an embodiment of the present invention, the superconducting magnet device includes: a cylindrical cryostat that defines a central cavity inside; a first superconducting coil group and a second superconducting coil group that are disposed inside the cylindrical cryostat outside the central cavity; and a power supply system capable of independently controlling the magnitude of a first excitation current supplied to the first superconducting coil group and the magnitude of a second excitation current supplied to the second superconducting coil group. When the central axis of the cylindrical cryostat is set as the Z axis and two axes orthogonal to each other and orthogonal to the Z axis are set as the X axis and the Y axis, when the first excitation current is supplied, the first superconducting coil group generates a magnetic field distribution that bulges downward on the X axis and upward on the Y axis in the central cavity, and when the second excitation current is supplied, the second superconducting coil group generates a magnetic field distribution that bulges upward on the X axis and downward on the Y axis in the central cavity.

[0007] In addition, any combination of the above components or a manner of mutually replacing the components and expressions of the present invention between methods, devices, systems, etc. is also effective as an embodiment of the present invention.

[0008] According to the present invention, a superconducting magnet device capable of more finely controlling the generated magnetic field distribution can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a cross-sectional view schematically showing a main part of the superconducting magnet device according to the embodiment.

[0010] Figure 2 is schematically showing the setting in Figure 1 a perspective view of the superconducting coil arrangement of the superconducting magnet device shown.

[0011] Figure 3 is a diagram schematically showing the magnetic field distribution generated by the superconducting magnet device according to the embodiment.

[0012] Figure 4 is a chart exemplifying the magnetic field distribution formed by overlapping the magnetic fields generated by the first superconducting coil group and the second superconducting coil group.

[0013] Figure 5 is schematically showing Figure 1 a diagram of an example of the coil power supply circuit of the superconducting magnet device shown.

[0014] Figure 6 is a chart of an example of a contour map showing the magnetic field generated by the superconducting magnet device according to the embodiment with the first excitation current and the second excitation current as the horizontal axis and the vertical axis respectively.

[0015] Figure 7 is a perspective view schematically showing the appearance of the superconducting magnet device.

[0016] Figure 8 is exemplifying Figure 7 a schematic diagram of the arrangement position of the cryogenic refrigerator in the superconducting magnet device shown.

[0017] Figure 9 is a cross-sectional view schematically showing the coil support structure of the superconducting magnet device.

[0018] Figure 10 is a perspective view schematically showing another example of the superconducting coil arrangement in the superconducting magnet device according to the embodiment.

[0019] In the figures: 10 - superconducting magnet device, 20 - cylindrical cryostat, 24 - central cavity, 30 - first superconducting coil group, 40 - second superconducting coil group, 50 - power supply system, 52 - first power supply, 54 - second power supply, 56 - power control device, 70 - cryogenic refrigerator. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and drawings, the same or equivalent components, parts, and processes are denoted by the same reference numerals, and repeated descriptions are appropriately omitted. In each drawing, for the sake of convenience of explanation, the scales or shapes of the respective parts are simply set, and unless otherwise specifically stated, they are not to be construed restrictively. The embodiments are illustrative and do not limit the scope of the present invention in any way. All the features or combinations thereof described in the embodiments are not necessarily essential to the invention.

[0021] Figure 1 is a cross-sectional view schematically showing the main part of the superconducting magnet device 10 according to the embodiment. And, Figure 2 is schematically showing the arrangement of the superconducting coils provided in Figure 1 the superconducting magnet device 10 shown in a perspective view.

[0022] The superconducting magnet device 10 can be used as a magnetic field generation source for a single crystal pulling device based on the HMCZ (Horizontal - MCZ; horizontal magnetic field type MCZ) method. The single crystal pulling device is, for example, a single crystal silicon pulling device.

[0023] As Figure 1 shown, the superconducting magnet device 10 includes a cylindrical cryostat 20, a first superconducting coil group 30, a second superconducting coil group 40, and a power supply system 50.

[0024] The cylindrical cryostat 20 has an internal space isolated from the surrounding environment 22 of the cylindrical cryostat 20, and the first superconducting coil group 30 and the second superconducting coil group 40 are arranged in this internal space. The internal space is, for example, in the shape of an annular or cylindrical shape. The cylindrical cryostat 20 is a vacuum adiabatic container, and when the superconducting magnet device 10 is operating, a cryogenic vacuum environment suitable for maintaining the first superconducting coil group 30 and the second superconducting coil group 40 in a superconducting state is provided to the internal space of the cylindrical cryostat 20. The cylindrical cryostat 20 is made of, for example, a metal material such as stainless steel or other suitable high-strength materials to withstand the environmental pressure (e.g., atmospheric pressure).

[0025] The cylindrical cryostat 20 defines a central cavity 24 inside. The first superconducting coil group 30 and the second superconducting coil group 40 are arranged to surround the central cavity 24 on the outside of the central cavity 24. When the superconducting magnet device 10 is mounted on a single crystal pulling device, a crucible for containing a melt of a single crystal material is arranged in the central cavity 24. The central cavity 24 is a part of the surrounding environment 22 of the cylindrical cryostat 20 (i.e., outside the cylindrical cryostat 20), and is, for example, a cylindrical space surrounded by the cylindrical cryostat 20.

[0026] Hereinafter, for the sake of convenience of explanation, an orthogonal coordinate system is defined in which the central axis of the cylindrical cryostat 20 is set as the Z-axis, and two axes orthogonal to the Z-axis and orthogonal to each other are set as the X-axis and the Y-axis, respectively. In the case of a single crystal pulling apparatus, the crystal pulling axis corresponds to the Z-axis, and the X-axis and the Y-axis can be defined on the surface of the melt perpendicular to the crystal pulling axis. At this time, the direction parallel to the magnetic field generated at the center of the surface of the melt by the superconducting magnet apparatus 10 can be set as the X-axis, and the direction perpendicular thereto can be set as the Y-axis. In Figure 1 FIG. shows a cross section of the superconducting magnet apparatus 10 on the XY plane, and the Z-axis extends in a direction perpendicular to the paper surface.

[0027] Details will be described later, but when the power supply system 50 supplies the first excitation current I1, the first superconducting coil group 30 generates a magnetic field distribution in the central cavity 24 that bulges downward on the X-axis and bulges upward on the Y-axis. When the power supply system 50 supplies the second excitation current I2, the second superconducting coil group 40 generates a magnetic field distribution in the central cavity 24 that bulges upward on the X-axis and bulges downward on the Y-axis.

[0028] The power supply system 50 is provided as a power supply for the first superconducting coil group 30 and the second superconducting coil group 40, and is disposed outside the cylindrical cryostat 20. The power supply system 50 is configured to be able to independently control the magnitude of the first excitation current I1 supplied to the first superconducting coil group 30 and the magnitude of the second excitation current I2 supplied to the second superconducting coil group 40, respectively.

[0029] Figure 3 FIG. schematically shows the magnetic field distribution generated by the superconducting magnet apparatus 10 according to the embodiment. In Figure 3 FIG. (a), the magnetic field distributions generated by the first superconducting coil group 30 and the second superconducting coil group 40 in the central cavity 24 are represented, and the magnetic force lines passing through the centers of the respective superconducting coils are shown by arrows. In Figure 3 FIG. (b), the magnetic flux densities on the X-axis of the first superconducting coil group 30 and the second superconducting coil group 40 are shown respectively, and in Figure 3 FIG. (c), the magnetic flux densities on the Y-axis of the first superconducting coil group 30 and the second superconducting coil group 40 are shown respectively. Figure 3 In FIGS. (b) and (c), the horizontal axis represents the distance from the origin of the XYZ coordinate system (in the case of a single crystal pulling apparatus, the distance from the center of the surface of the melt).

[0030] Refer to Figure 1 , Figure 2 and Figure 3 to describe the coil configurations of the first superconducting coil group 30 and the second superconducting coil group 40 and the magnetic field distributions generated thereby.

[0031] Six superconducting coils are provided on the superconducting magnet device 10, two of which form the first superconducting coil group 30, and the remaining four form the second superconducting coil group 40. As shown in the figure, each superconducting coil of the first superconducting coil group 30 and the second superconducting coil group 40 has the same shape and the same size, and in this example, they are circular coils with the same diameter. Therefore, when viewed from above, these six superconducting coils are arranged in a regular hexagon shape.

[0032] The first superconducting coil group 30 includes a pair of first superconducting coils 30a and 30b that are arranged opposite to each other with a central cavity 24 therebetween on the X-axis. The pair of first superconducting coils 30a and 30b are respectively arranged such that the coil central axes coincide with the X-axis. The direction of the first excitation current I1 supplied to one of the first superconducting coils (in this example, 30a) is determined such that the superconducting coil generates a magnetic field toward the radially outer side (the magnetic field in the direction passing through the coil and exiting from the central cavity 24). The direction of the first excitation current I1 supplied to the other first superconducting coil (in this example, 30b) is determined such that the superconducting coil generates a magnetic field toward the radially inner side (the magnetic field in the direction passing through the coil and entering the central cavity 24). Therefore, as Figure 3 shown in (a) therein, the magnetic force lines passing through the centers of the first superconducting coils 30a and 30b extend linearly along the X-axis.

[0033] The first magnetic field generated by the first superconducting coil group 30 is the strongest at the centers of the first superconducting coils 30a and 30b, and weakens as it approaches the center of the central cavity 24 along the X-axis from the coil center (i.e., as it moves away from the coil center). Therefore, as Figure 3 shown in (b) therein, the first magnetic field generated by the first superconducting coil group 30 bulges downward on the X-axis.

[0034] And, as Figure 3 shown in (c) therein, the first magnetic field generated by the first superconducting coil group 30 bulges upward on the Y-axis. This is because, when moving away from the center of the central cavity 24 along the Y-axis toward the outside, the distance from the centers of the first superconducting coils 30a and 30b increases. Therefore, the first magnetic field generated by the first superconducting coil group 30 is the strongest at the center of the central cavity 24, and weakens as it moves away from the center toward the outside.

[0035] The second superconducting coil group 40 includes: a pair of second superconducting coils 40a and 40b that are arranged opposite to each other with a central cavity 24 therebetween and are adjacent to the pair of first superconducting coils 30a and 30b on the clockwise side in the direction around the Z-axis; and another pair of second superconducting coils 40c and 40d that are arranged opposite to each other with a central cavity 24 therebetween and are adjacent to the pair of first superconducting coils 30a and 30b on the counterclockwise side in the direction around the Z-axis. In the present embodiment, as Figure 1As shown, a pair of second superconducting coils 40a and 40b are arranged such that their coil central axes coincide with line 42 which rotates 60 degrees clockwise about the Z axis from the X axis, and a pair of second superconducting coils 40c and 40d are arranged such that their coil central axes coincide with line 44 which rotates 60 degrees counterclockwise about the Z axis from the X axis.

[0036] The directions of the second excitation currents I2 supplied to the second superconducting coils (in this example, 40a and 40d) adjacent to both sides of one first superconducting coil (in this example, 30a) that generates a magnetic field directed radially outward are determined such that these two second superconducting coils also generate a magnetic field directed radially outward. The directions of the second excitation currents I2 supplied to the second superconducting coils (in this example, 40b and 40c) adjacent to both sides of the other first superconducting coil (in this example, 30b) that generates a magnetic field directed radially inward are determined such that these two second superconducting coils also generate a magnetic field directed radially inward. Thus, as Figure 3 shown in (a) of the figure, the magnetic field lines passing through the centers of two adjacent second superconducting coils (40a and 40c, or 40b and 40d) are bent such that they penetrate into the central cavity 24 through one of the two second superconducting coils and exit the central cavity 24 through the other second superconducting coil.

[0037] The second magnetic field generated by the second superconducting coil group 40 is the strongest on the bent magnetic field lines passing through the centers of the coils, and weakens as it moves away from these magnetic field lines. Therefore, on the X axis, the second magnetic field is relatively strong at the center of the central cavity 24 and weakens as it moves away from the center along the X axis toward the outside. That is, as Figure 3 shown in (b) of the figure, the second magnetic field bulges upward on the X axis. And on the Y axis, the second magnetic field is relatively weak at the center of the central cavity 24 and strengthens as it moves away from the center along the Y axis toward the outside. That is, as Figure 3 shown in (c) of the figure, the second magnetic field bulges downward on the Y axis.

[0038] Figure 4 is a graph illustrating the magnetic field distribution formed by the overlapping of the magnetic fields generated by the first superconducting coil group 30 and the second superconducting coil group 40. In Figure 4 shown in (a) of the figure, the magnetic flux density on the X axis is shown, and in Figure 4 shown in (b) of the figure, the magnetic flux density on the Y axis is shown. These are all based on the calculation results of the inventor. The vertical axis of the graph represents the magnetic flux density normalized to 1 at the center of the central cavity 24, and the horizontal axis represents the distance from the center of the central cavity 24.

[0039] In Figure 4In FIGS. (a) and (b), three cases are shown where the ratios of the first exciting current I1 supplied to the first superconducting coil group 30 and the second exciting current I2 supplied to the second superconducting coil group 40 are different from each other. Case A is a case where the first exciting current I1 and the second exciting current I2 are set to 1:0 (that is, a case where current flows only in the first superconducting coil group 30 and does not flow in the second superconducting coil group 40). At this time, only the first superconducting coil group 30 generates a magnetic field. Therefore, as described above, a magnetic field distribution that bulges downward on the X-axis and upward on the Y-axis can be obtained. Case B is a case where the first exciting current I1 and the second exciting current I2 are set to 0:1 (that is, a case where current does not flow in the first superconducting coil group 30 and flows only in the second superconducting coil group 40). At this time, only the second superconducting coil group 40 generates a magnetic field. Therefore, as described above, a magnetic field distribution that bulges upward on the X-axis and downward on the Y-axis can be obtained.

[0040] Case C is a case where the first exciting current I1 and the second exciting current I2 are set to 1:1 (that is, a case where currents of the same magnitude flow through the first superconducting coil group 30 and the second superconducting coil group 40). In Case C, as Figure 4 shown in FIGS. (a) and (b), a magnetic field distribution having a convex shape that averages Case A and Case B can be obtained. For the same reason, it can be considered that in the case where the ratio of the first exciting current I1 and the second exciting current I2 is set to other values, a magnetic field distribution having a convex shape intermediate between Case A and Case B can be obtained according to this ratio.

[0041] In this way, by changing the magnitude of the first exciting current I1, the convex shape of the magnetic field distribution generated by the first superconducting coil group 30 in the central cavity 24 can be changed, and by changing the magnitude of the second exciting current I2, the convex shape of the magnetic field distribution generated by the second superconducting coil group 40 in the central cavity 24 can be changed.

[0042] It is known that: the magnetic field distribution of the first superconducting coil group 30 (a magnetic field distribution that bulges downward on the X-axis and upward on the Y-axis) is suitable for generating a single crystal with a relatively high oxygen concentration, while the magnetic field distribution of the second superconducting coil group 40 (a magnetic field distribution that bulges upward on the X-axis and downward on the Y-axis) is suitable for generating a single crystal with a relatively low oxygen concentration. The preferred oxygen concentration varies depending on the use of the finally manufactured semiconductor device. For example, in so-called horizontal devices such as CPUs or memories and vertical devices such as power devices, the required oxygen concentrations are different.

[0043] According to the superconducting magnet device 10 according to the embodiment, by independently controlling the first exciting current I1 and the second exciting current I2 respectively, the convex shape of the magnetic field distribution of the central cavity 24 formed by overlapping the magnetic fields generated by the first superconducting coil group 30 and the second superconducting coil group 40 can be controlled.

[0044] In conventional devices, only a single magnetic field distribution can be generated or only two magnetic field distributions can be switched, so the improvement in crystal quality is limited. In contrast, the superconducting magnet device 10 according to the embodiment can control the generated magnetic field distribution more precisely. Thereby, the degree of suppression of thermal convection in the melt can be finely adjusted and the oxygen concentration in the single crystal can be adjusted more precisely, so that the crystal quality can be improved.

[0045] The single crystal pulling device equipped with the superconducting magnet device 10 according to the embodiment can be used to manufacture single crystals with various oxygen concentrations required for the final product. Compared with conventional devices, the single crystal pulling device according to the embodiment can improve the operation rate at the manufacturing site and can achieve a more economical factory operation.

[0046] Figure 5 is schematically showing Figure 1 FIG. is an example of a coil power supply circuit of the superconducting magnet device 10 shown. The power supply system 50 includes: a first power supply 52 that supplies a first excitation current I1 to the first superconducting coil group 30; a second power supply 54 that supplies a second excitation current I2 to the second superconducting coil group 40; and a power supply control device 56 that controls the first power supply 52 and the second power supply 54.

[0047] As described above, the first superconducting coil group 30 is disposed inside the cylindrical cryostat 20, and the power supply system 50 is disposed outside the cylindrical cryostat 20. Therefore, the first circuit 53 connecting the first power supply 52 to the first superconducting coil group 30 has feedthrough portions 58 on both the positive side and the negative side. The feedthrough portion 58 is an airtight terminal for introducing current into the cylindrical cryostat 20, and is provided to penetrate the wall surface of the cylindrical cryostat 20. The two feedthrough portions 58 are respectively connected to the corresponding current lead portions 60. A pair of first superconducting coils 30a, 30b are connected in series inside the cylindrical cryostat 20. The positive electrode of the first power supply 52 is connected to one first superconducting coil 30a via one feedthrough portion 58 and the current lead portion 60, and the other first superconducting coil 30b is connected to the negative electrode of the first power supply 52 via the other feedthrough portion 58 and the current lead portion 60, thereby forming the first circuit 53.

[0048] In the second circuit 55 that connects the second power supply 54 to the second superconducting coil group 40, the positive electrode of the second power supply 54 is connected to the second superconducting coils 40a and 40b via the feedthrough portion 58 and the current lead portion 60. The second superconducting coils 40a and 40b are connected in series within the cylindrical cryostat 20. The second superconducting coils 40a and 40b and the second superconducting coils 40c and 40d are connected outside the cylindrical cryostat 20 via the current lead portion 60 on the side of the second superconducting coils 40a and 40b, the feedthrough portion 58, the external wiring 62 that connects the two feedthrough portions 58 outside, and the current lead portion 60 and the feedthrough portion 58 on the side of the second superconducting coils 40c and 40d. The second superconducting coils 40c and 40d are connected in series within the cylindrical cryostat 20. The second superconducting coils 40c and 40d are connected to the negative electrode of the second power supply 54 via the feedthrough portion 58 and the current lead portion 60.

[0049] Therefore, the first power supply 52 can supply the first excitation current I1 to the first superconducting coil group 30 through the first circuit 53, and the second power supply 54 can supply the second excitation current I2 to the second superconducting coil group 40 through the second circuit 55. The first circuit 53 and the second circuit 55 are not connected to each other.

[0050] The power supply control device 56 can determine the first excitation current I1 and the second excitation current I2 to achieve a desired magnetic field distribution. Here, the power supply control device 56 can control the magnitudes of the first excitation current I1 and the second excitation current I2 so that the total value of the magnetic fields generated by the first superconducting coil group 30 and the second superconducting coil group 40 at a specified position (e.g., the center) in the central cavity 24 does not exceed the upper limit value.

[0051] Figure 6 It is a diagram showing an example of a contour map of the magnetic field generated by the superconducting magnet device 10 according to the embodiment, with the first excitation current I1 and the second excitation current I2 as the horizontal axis and the vertical axis, respectively. The magnetic field values shown in the diagram represent the total value of the magnetic fields generated by the first superconducting coil group 30 and the second superconducting coil group 40 at a specified position (e.g., the center) in the central cavity 24. In this example, the higher the contour line towards the upper right, the larger the magnetic field value, and the lower the contour line towards the lower left, the smaller the magnetic field value.

[0052] The power supply control device 56 can select a certain contour line 64 (represented by a thick line) from among a plurality of contour lines and determine the combination of the first excitation current I1 and the second excitation current I2 from the region 66 that provides the magnetic field value of the selected contour line 64 or a lower magnetic field value. That is, it is prohibited to determine the first excitation current I1 and the second excitation current I2 from the region 68 that provides a magnetic field value higher than the selected contour line 64. The magnetic field value of the selected contour line 64 can be appropriately determined according to the specifications of the superconducting magnet device 10 or the single crystal pulling device, and can be input or stored in the power supply control device 56.

[0053] In this way, it is possible to avoid supplying an excessive first excitation current I1 and a second excitation current I2 that generate a magnetic field exceeding the magnetic field value equivalent to the selected contour line 64 to the first superconducting coil group 30 and the second superconducting coil group 40. By avoiding supplying an excessive current to the superconducting coil, it is possible to suppress the electromagnetic force and thermal load acting on the coil, thereby reducing the risk of superconducting breakdown. The superconducting magnet device 10 can be operated more safely.

[0054] Figure 7 It is a perspective view schematically showing the appearance of the superconducting magnet device 10. Figure 8 It is an example Figure 7 It is a schematic diagram showing the arrangement position of the cryocooler in the superconducting magnet device 10 shown.

[0055] As Figure 7 As shown, the superconducting magnet device 10 includes at least one cryocooler 70, and the first superconducting coil group 30 and the second superconducting coil group 40 disposed in the cylindrical cryostat 20 are thermally connected to the cryocooler 70. The cryocooler 70 can be, for example, a two-stage Gifford-McMahon (GM) cryocooler or other types of cryocoolers. Each superconducting coil is used in a cryogenic state cooled to below the superconducting transition temperature by the cryocooler 70. In the present embodiment, the superconducting magnet device 10 adopts a so-called conduction cooling method in which the superconducting coil is directly cooled by the cryocooler 70 instead of immersing the superconducting coil in a cryogenic liquid refrigerant such as liquid helium.

[0056] In Figure 7 In the example shown, four cryocoolers 70 are provided on the upper surface of the cylindrical cryostat 20. When viewed from the Z-axis direction, the cryocoolers 70 can be arranged between two superconducting coils adjacent to each other in the direction around the Z-axis. By arranging the cryocooler 70 using the free space between the coils, the cylindrical cryostat 20 can be designed to be more compact, thereby enabling miniaturization of the superconducting magnet device 10.

[0057] As Figure 8 As shown in (a) of, the first cryocooler 70 can be arranged between the first superconducting coil 30a and the second superconducting coil 40a, the second cryocooler 70 can be arranged between the first superconducting coil 30a and the second superconducting coil 40d, the third cryocooler 70 can be arranged between the first superconducting coil 30b and the second superconducting coil 40b, and the fourth cryocooler 70 can be arranged between the first superconducting coil 30b and the second superconducting coil 40c. In this way, each superconducting coil can be directly cooled by a certain cryocooler 70.

[0058] The number of cryocoolers 70 provided in the cylindrical cryostat 20 can also be smaller. For example, as Figure 8 shown in (b) thereof, three cryocoolers 70 can be provided in the cylindrical cryostat 20, and each cryocooler 70 can be disposed between two superconducting coils adjacent to each other in the direction around the Z axis. At this time, as shown in the figure, the cryocoolers 70 can be arranged at equal angular intervals in the direction around the Z axis.

[0059] Alternatively, as Figure 8 shown in (c) thereof, two cryocoolers 70 can be provided in the cylindrical cryostat 20, and they can be arranged at an interval of 180 degrees in the direction around the Z axis. In the illustrated example, the first cryocooler 70 is disposed between the first superconducting coil 30a and the second superconducting coil 40d, and the second cryocooler 70 is disposed between the first superconducting coil 30b and the second superconducting coil 40c. At this time, compared with other superconducting coils adjacent to the cryocooler 70, a part of the superconducting coils (for example, the second superconducting coils 40a, 40b) are arranged to be away from the cryocooler 70. These superconducting coils (40a, 40b) can be connected to the cryocooler 70 (or the superconducting coils adjacent to the cryocooler 70) via appropriate heat conducting members so as to be cooled.

[0060] Alternatively, more cryocoolers 70 can be provided on the cylindrical cryostat 20 as needed. For example, a cryocooler 70 can be provided for each superconducting coil. One superconducting coil can also be cooled by a plurality of cryocoolers 70.

[0061] Figure 9 is a cross-sectional view schematically showing the coil support structure 72 of the superconducting magnet device 10. In Figure 9 is shown a cross-section taken along the Figure 7 A-A line. The coil support structure 72 connects the superconducting coil (the first superconducting coil 30a in the illustrated example) belonging to the first superconducting coil group 30 or the second superconducting coil group 40 to the cylindrical cryostat 20, and supports the self-weight and electromagnetic force generated during operation acting on the superconducting coil. As Figure 9 shown, the coil support structure 72 includes a coil support plate 74 and a coil support body 76. The purpose of providing the coil support plate 74 is to connect the superconducting coil and the coil support body 76, and the coil support plate 74 is installed on one side of the superconducting coil (for example, the inner peripheral side of the cylindrical cryostat 20).

[0062] The coil support 76 supports the superconducting coil on the circumferential surface (e.g., the outer circumferential surface) of the cylindrical cryostat 20 and is disposed inside the superconducting coil. One end of the coil support 76 is mounted on the coil support plate 74 inside the superconducting coil, and the other end is mounted on the outer circumferential surface of the cylindrical cryostat 20. The coil support 76 has a rod-like shape and extends in the horizontal direction. In Figure 7 the end portion of the coil support 76 provided on the outer circumferential surface of the cylindrical cryostat 20 is shown. One superconducting coil may also be supported on the cylindrical cryostat 20 by a plurality of (e.g., two) coil supports 76.

[0063] Figure 10 is a perspective view schematically showing another example of the superconducting coil arrangement in the superconducting magnet device 10 according to the embodiment. As Figure 10 shown, the superconducting magnet device 10 may also use two saddle-shaped coils having different sizes.

[0064] The first superconducting coil group 30 includes a pair of first superconducting coils that are opposed to each other with a central cavity 24 therebetween on the X axis. The second superconducting coil group 40 includes a pair of second superconducting coils that are opposed to each other with a central cavity 24 therebetween on the X axis. The pair of first superconducting coils are disposed inside the pair of second superconducting coils.

[0065] Even in the case of using such a double saddle-shaped coil arrangement, similar to the above six-coil type, when the first excitation current I1 is supplied, the first superconducting coil group 30 generates a magnetic field distribution in the central cavity 24 that bulges downward on the X axis and upward on the Y axis. When the second excitation current I2 is supplied, the second superconducting coil group 40 generates a magnetic field distribution in the central cavity 24 that bulges upward on the X axis and downward on the Y axis. By independently controlling the first excitation current I1 and the second excitation current I2, the convex shape of the magnetic field distribution in the central cavity 24 formed by the overlapping of the magnetic fields generated by the first superconducting coil group 30 and the second superconducting coil group 40 can be controlled.

[0066] As described above, the present invention has been described based on the embodiments. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments, various design changes can be made, various modification examples can exist, and such modification examples are also within the scope of the present invention. The various features described in one embodiment can also be applied to other embodiments. The new embodiments generated by combination have the effects of the respective embodiments being combined.

[0067] In the above six coil-type embodiments, all the superconducting coils have the same shape and size, but this is not necessary. For example, in the first superconducting coil group 30 and the second superconducting coil group 40, the superconducting coils may have different shapes and / or different sizes.

[0068] In addition to being able to change the magnitudes of the first excitation current I1 and / or the second excitation current I2, the power supply system 50 can also change the directions of the first excitation current I1 and / or the second excitation current I2, or the power supply system 50 can change the directions of the first excitation current I1 and / or the second excitation current I2 instead of changing the magnitudes of the first excitation current I1 and / or the second excitation current I2.

[0069] The single crystal pulling apparatus equipped with the superconducting magnet apparatus 10 according to the embodiment may be a single crystal pulling apparatus for generating single crystals of semiconductor materials or other materials other than silicon.

[0070] As long as it can be applied, the superconducting magnet apparatus 10 can also be mounted on apparatuses other than the single crystal pulling apparatus. The superconducting magnet apparatus 10 can be mounted on a high magnetic field utilization apparatus as a magnetic field source of the high magnetic field utilization apparatus and generate the high magnetic field required by the apparatus.

[0071] As described above, the present invention has been described using specific statements based on the embodiments. However, the embodiments only represent one way of the principle and application of the present invention, and various modifications or configuration changes can be made to the embodiments without departing from the idea of the present invention defined by the scope of the technical solution.

Claims

1. A superconducting magnet device, characterized in that, Comprising: A cylindrical cryostat having a central cavity defined therein; A first superconducting coil group and a second superconducting coil group disposed inside the cylindrical cryostat outside the central cavity; and A power supply system capable of independently controlling the magnitude of a first excitation current supplied to the first superconducting coil group and the magnitude of a second excitation current supplied to the second superconducting coil group, In the case where the central axis of the cylindrical cryostat is set as the Z-axis and two axes orthogonal to each other and orthogonal to the Z-axis are respectively set as the X-axis and the Y-axis, The first superconducting coil group includes a pair of first superconducting coils disposed opposite to each other across the central cavity on the X-axis, The second superconducting coil group includes: a pair of second superconducting coils disposed opposite to each other across the central cavity and adjacent to the pair of first superconducting coils on the clockwise side in the direction around the Z-axis; And another pair of second superconducting coils disposed opposite to each other across the central cavity and adjacent to the pair of first superconducting coils on the counterclockwise side in the direction around the Z-axis, The superconducting magnet device further includes: A coil support plate mounted on the superconducting coils belonging to the first superconducting coil group or the second superconducting coil group; and A coil support body that supports the superconducting coils belonging to the first superconducting coil group or the second superconducting coil group on the circumferential surface of the cylindrical cryostat and is disposed inside the superconducting coils, One end of the coil support body is mounted on the coil support plate, and the other end of the coil support body is mounted on the circumferential surface of the cylindrical cryostat.

2. The superconducting magnet device according to claim 1, wherein The pair of second superconducting coils are disposed on a line rotated 60 degrees clockwise around the Z-axis from the X-axis, and the other pair of second superconducting coils are disposed on a line rotated 60 degrees counterclockwise around the Z-axis from the X-axis.

3. The superconducting magnet device according to claim 1 or 2, wherein It further includes at least one cryocooler for cooling the first superconducting coil group and the second superconducting coil group, When viewed from the Z-axis direction, the at least one cryocooler is disposed between two superconducting coils adjacent to each other in the direction around the Z-axis.

4. The superconducting magnet device according to claim 1 or 2, wherein The power supply system includes: a first power supply for supplying the first excitation current to each superconducting coil of the first superconducting coil group; and a second power supply for supplying the second excitation current to each superconducting coil of the second superconducting coil group.

5. The superconducting magnet device according to claim 1 or 2, wherein The power supply system includes a power supply control device that controls the magnitude of the first excitation current and the magnitude of the second excitation current so that the total value of the magnetic fields generated at a specified position in the central cavity by the first superconducting coil group and the second superconducting coil group does not exceed an upper limit value.

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