Superconducting magnet device

Abstract

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

Description

[0001] This application is a divisional application of the invention patent application with application date of January 7, 2022 and application number 202210017118.X.

[0002] This application claims priority based on Japanese Patent Application No. 2021-005646, filed on January 18, 2021. The entire contents of this Japanese application are incorporated herein by reference. Technical Field

[0003] The present invention relates to a superconducting magnet device. Background Art

[0004] Superconducting magnet devices are used as magnetic field generators in single crystal pulling systems based on the MCZ (Magnetic Field Applied Czochralski) method. The strong magnetic field generated by the superconducting magnets can suppress thermal convection in the semiconductor material melt. The applied magnetic field distribution affects the degree of thermal convection suppression, resulting in changes in the oxygen concentration in the pulled single crystal. The preferred oxygen concentration varies depending on the intended use of the semiconductor device being manufactured. Therefore, single crystal pulling systems are known that switch the direction of current flowing through a portion of the superconducting coils to generate two different magnetic field distributions.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-206396 Summary of the Invention

[0006] One of the exemplary objects of one embodiment of the present invention is to provide a superconducting magnet apparatus capable of more finely controlling the distribution of the generated magnetic field.

[0007] According to one embodiment of the present invention, a superconducting magnet apparatus includes: a cylindrical cryostat defining a central cavity within a cylinder; a first superconducting coil assembly and a second superconducting coil assembly disposed within 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 assembly and the magnitude of a second excitation current supplied to the second superconducting coil assembly. With the central axis of the cylindrical cryostat being the Z axis and two axes orthogonal to the Z axis and to each other being the X axis and the Y axis, respectively, when the first excitation current is supplied, the first superconducting coil assembly generates a magnetic field distribution in the central cavity that is convex downward on the X axis and convex upward on the Y axis. When the second excitation current is supplied, the second superconducting coil assembly generates a magnetic field distribution in the central cavity that is convex upward on the X axis and convex downward on the Y axis.

[0008] Furthermore, any combination of the above-described constituent elements or any substitution of constituent elements and expressions of the present invention in the form of methods, apparatuses, systems, etc. may also be practiced as additional embodiments of the present invention.

[0009] According to the present invention, it is possible to provide a superconducting magnet device capable of controlling the generated magnetic field distribution more finely. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a cross-sectional view schematically showing a main part of a superconducting magnet apparatus according to an embodiment.

[0011] Figure 2 It is a schematic representation of the Figure 1 A perspective view of the configuration of superconducting coils of a superconducting magnet device is shown.

[0012] Figure 3 It is a diagram schematically showing the magnetic field distribution generated by the superconducting magnet device according to the embodiment.

[0013] Figure 4 This is a graph illustrating a magnetic field distribution resulting from the superposition of magnetic fields generated by the first superconducting coil group and the second superconducting coil group.

[0014] Figure 5 It indicates schematically Figure 1 FIG. 1 is a diagram showing an example of a coil power supply circuit of a superconducting magnet device.

[0015] Figure 6 This is a graph showing an example of a contour map of a 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.

[0016] Figure 7 It is a perspective view schematically showing the appearance of a superconducting magnet device.

[0017] Figure 8 This is an example Figure 7 Schematic diagram of the configuration position of the ultra-low temperature refrigerator in the superconducting magnet device shown.

[0018] Figure 9 This is a cross-sectional view schematically showing a coil support structure of a superconducting magnet device.

[0019] Figure 10 It is a perspective view schematically showing another example of the arrangement of superconducting coils in the superconducting magnet apparatus according to the embodiment.

[0020] In the figure: 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 supply control device, 70 - ultra-low temperature refrigerator. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and drawings, identical or equivalent components, parts, and processes are marked with the same symbols, and repeated descriptions are omitted as appropriate. In each drawing, for the sake of convenience, the scale or shape of each part is simply set, and unless otherwise specified, it is not interpreted as a limitative measure. The embodiments are illustrative and do not limit the scope of the present invention in any way. All features or combinations thereof described in the embodiments are not necessarily the essence of the invention.

[0022] Figure 1 : is a cross-sectional view schematically showing the main part of the superconducting magnet device 10 according to the embodiment. Figure 2 It is a schematic representation of the Figure 1 FIG. 2 is a perspective view showing the arrangement of superconducting coils of superconducting magnet apparatus 10 .

[0023] Superconducting magnet device 10 can be used as a magnetic field generating source for a single crystal pulling device based on the HMCZ (Horizontal-MCZ; transverse magnetic field type MCZ) method. The single crystal pulling device is, for example, a single crystal silicon pulling device.

[0024] like Figure 1 As shown, the superconducting magnet apparatus 10 includes a cylindrical cryostat 20 , a first superconducting coil assembly 30 , a second superconducting coil assembly 40 , and a power supply system 50 .

[0025] The cylindrical cryostat 20 has an internal space isolated from the surrounding environment 22 of the cylindrical cryostat 20. A first superconducting coil assembly 30 and a second superconducting coil assembly 40 are disposed within this internal space. The internal space may be, for example, an annular or cylindrical shape. The cylindrical cryostat 20 is an insulated vacuum container. During operation of the superconducting magnet apparatus 10, the cylindrical cryostat 20 provides an ultra-low temperature vacuum environment within the internal space of the cylindrical cryostat 20 suitable for maintaining the first superconducting coil assembly 30 and the second superconducting coil assembly 40 in a superconducting state. The cylindrical cryostat 20 is made of, for example, a metal material such as stainless steel or other suitable high-strength material to withstand ambient pressure (e.g., atmospheric pressure).

[0026] The cylindrical cryostat 20 defines a central cavity 24 within. The first superconducting coil assembly 30 and the second superconducting coil assembly 40 are arranged to surround the central cavity 24 on the outside. When the superconducting magnet apparatus 10 is mounted on a single crystal pulling apparatus, a crucible containing a melt of a single crystal material is disposed within the central cavity 24. The central cavity 24 is a portion of the surrounding environment 22 of the cylindrical cryostat 20 (i.e., outside the cylindrical cryostat 20) and is a cylindrical space, for example, enclosed by the cylindrical cryostat 20.

[0027] For ease of explanation, an orthogonal coordinate system is defined below, 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 to each other are set as the X axis and the Y axis, respectively. In the case of a single crystal pulling device, the crystal pulling axis corresponds to the Z axis, and the X axis and the Y axis can be defined on the melt surface perpendicular to the crystal pulling axis. In this case, the direction parallel to the magnetic field generated by the superconducting magnet device 10 at the center of the melt surface can be set as the X axis, and the direction perpendicular to it can be set as the Y axis. Figure 1 , a cross section of the superconducting magnet apparatus 10 on the XY plane is shown in FIG. , where the Z axis extends in a direction perpendicular to the paper surface.

[0028] Although details will be described later, when the power supply system 50 supplies the first excitation current I1, the first superconducting coil assembly 30 generates a magnetic field distribution in the central cavity 24 that is convex downward on the X-axis and convex upward on the Y-axis. When the power supply system 50 supplies the second excitation current I2, the second superconducting coil assembly 40 generates a magnetic field distribution in the central cavity 24 that is convex upward on the X-axis and convex downward on the Y-axis.

[0029] The power supply system 50 is provided as a power source for the first superconducting coil assembly 30 and the second superconducting coil assembly 40 and is disposed outside the cylindrical cryostat 20. The power supply system 50 is configured to independently control the magnitude of the first excitation current I1 supplied to the first superconducting coil assembly 30 and the magnitude of the second excitation current I2 supplied to the second superconducting coil assembly 40.

[0030] Figure 3 Schematically shows the distribution of the magnetic field generated by the superconducting magnet device 10 according to the embodiment. Figure 3 In (a), the magnetic field distribution generated by the first superconducting coil group 30 and the second superconducting coil group 40 in the central cavity 24 is represented by arrows indicating the magnetic field lines passing through the center of each superconducting coil. Figure 3 (b) shows the magnetic flux density on the X axis of the first superconducting coil group 30 and the second superconducting coil group 40. Figure 3 (c) shows the magnetic flux density on the Y axis of the first superconducting coil group 30 and the second superconducting coil group 40 . Figure 3The horizontal axis in (b) and (c) 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 melt surface).

[0031] refer to Figure 1 、 Figure 2 and Figure 3 The coil arrangement of the first superconducting coil group 30 and the second superconducting coil group 40 and the generated magnetic field distribution will be described.

[0032] Superconducting magnet apparatus 10 is provided with six superconducting coils, two of which form a first superconducting coil assembly 30, and the remaining four form a second superconducting coil assembly 40. As shown in the figure, the superconducting coils of first superconducting coil assembly 30 and second superconducting coil assembly 40 have the same shape and size, and in this example, are circular coils with the same diameter. Therefore, when viewed from above, these six superconducting coils are arranged in a regular hexagonal shape.

[0033] The first superconducting coil group 30 includes a pair of first superconducting coils 30a and 30b that are arranged opposite to each other on the X-axis with the central cavity 24 therebetween. The pair of first superconducting coils 30a and 30b are respectively arranged so that the central axis of the coil is aligned with the X-axis. The direction of the first excitation current I1 supplied to one of the first superconducting coils (30a in this example) is determined so that the superconducting coil generates a magnetic field toward the radial outside (a magnetic field in the direction of passing through the coil from the central cavity 24). The direction of the first excitation current I1 supplied to the other first superconducting coil (30b in this example) is determined so that the superconducting coil generates a magnetic field toward the radial inside (a magnetic field in the direction of passing through the coil and entering the central cavity 24). Therefore, as Figure 3 As shown in (a), the magnetic force lines passing through the centers of the first superconducting coils 30a and 30b extend linearly along the X-axis.

[0034] The first magnetic field generated by the first superconducting coil group 30 is strongest at the center of the first superconducting coils 30a and 30b, and becomes weaker as it approaches the center of the central cavity 24 from the coil center along the X-axis (that is, as it moves away from the coil center). Figure 3 As shown in (b), the first magnetic field generated by the first superconducting coil group 30 is convex downward on the X-axis.

[0035] And, as Figure 3 As shown in (c), the first magnetic field generated by the first superconducting coil assembly 30 bulges upward on the Y-axis. This is because the distance from the centers of the first superconducting coils 30a and 30b increases as one moves outward from the center of the central cavity 24 along the Y-axis. Therefore, the first magnetic field generated by the first superconducting coil assembly 30 is strongest at the center of the central cavity 24 and weakens as one moves outward from the center.

[0036] The second superconducting coil group 40 includes: a pair of second superconducting coils 40a, 40b, which are arranged opposite to each other with the central cavity 24 interposed therebetween and are adjacent to the pair of first superconducting coils 30a, 30b in the clockwise direction around the Z axis; and another pair of second superconducting coils 40c, 40d, which are arranged opposite to each other with the central cavity 24 interposed therebetween and are adjacent to the pair of first superconducting coils 30a, 30b in the counterclockwise direction around the Z axis. In this embodiment, as Figure 1 As shown, the pair of second superconducting coils 40a and 40b are arranged so that the coil center axes thereof coincide with a line 42 which is a 60-degree clockwise rotation from the X-axis with the Z-axis as the center, and the pair of second superconducting coils 40c and 40d are arranged so that the coil center axes thereof coincide with a line 44 which is a 60-degree counterclockwise rotation from the X-axis with the Z-axis as the center.

[0037] The direction of the second excitation current I2 supplied to the second superconducting coils (40a and 40d in this example) on both sides of a first superconducting coil (30a in this example) that is adjacently arranged and generates a magnetic field directed radially outward is determined so that these two second superconducting coils also generate a magnetic field directed radially outward. The direction of the second excitation current I2 supplied to the second superconducting coils (40b and 40c in this example) on both sides of another first superconducting coil (30b in this example) that is adjacently arranged and generates a magnetic field directed radially inward is determined so that these two second superconducting coils also generate a magnetic field directed radially inward. Therefore, as Figure 3 As shown in (a), the magnetic lines of force passing through the centers of two adjacent second superconducting coils (40a and 40c, or 40b and 40d) are bent so as to pass through one of the two second superconducting coils and enter the central cavity 24, and pass through the other second superconducting coil and exit the central cavity 24.

[0038] The second magnetic field generated by the second superconducting coil assembly 40 is strongest on the curved magnetic field lines passing through the center of the coil and weakens as it moves away from the 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 toward the outside along the X-axis. That is, Figure 3 As shown in (b), the second magnetic field bulges upward on the X-axis. Also, on the Y-axis, the second magnetic field is relatively weak at the center of the central cavity 24 and becomes stronger as it moves away from the center toward the outside along the Y-axis. Figure 3 As shown in (c), the second magnetic field is convex downward on the Y-axis.

[0039] Figure 4 : is a graph illustrating the magnetic field distribution resulting from the superposition of magnetic fields generated by the first superconducting coil group 30 and the second superconducting coil group 40. Figure 4 (a) shows the magnetic flux density on the X-axis. Figure 4 (b) shows the magnetic flux density on the Y-axis. These are based on calculations by the inventors. 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.

[0040] exist Figure 4 Figures (a) and (b) show three cases with different ratios between the first excitation current I1 supplied to the first superconducting coil assembly 30 and the second excitation current I2 supplied to the second superconducting coil assembly 40. Case A is a case where the ratio of the first excitation current I1 to the second excitation current I2 is set to 1:0 (i.e., current flows only through the first superconducting coil assembly 30 and not through the second superconducting coil assembly 40). In this case, only the first superconducting coil assembly 30 generates a magnetic field, resulting in a magnetic field distribution that is convex downward on the X-axis and convex upward on the Y-axis, as described above. Case B is a case where the ratio of the first excitation current I1 to the second excitation current I2 is set to 0:1 (i.e., current flows only through the second superconducting coil assembly 40 and not through the first superconducting coil assembly 30). In this case, only the second superconducting coil assembly 40 generates a magnetic field, resulting in a magnetic field distribution that is convex upward on the X-axis and convex downward on the Y-axis, as described above.

[0041] Case C is a case where the first excitation current I1 and the second excitation current I2 are set to 1:1 (i.e., the same current flows through the first superconducting coil group 30 and the second superconducting coil group 40). Figure 4 As shown in (a) and (b), a convex magnetic field distribution can be obtained that is the average of Case A and Case B. Based on the same reasoning, it can be considered that when the ratio of the first excitation current I1 to the second excitation current I2 is set to other values, a convex magnetic field distribution can be obtained that is intermediate between Case A and Case B according to the ratio.

[0042] In this manner, by changing the magnitude of the first excitation 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 excitation 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.

[0043] It is known that the magnetic field distribution of the first superconducting coil group 30 (a magnetic field distribution that is convex downward on the X-axis and convex upward on the Y-axis) is suitable for growing single crystals with a relatively high oxygen concentration, while the magnetic field distribution of the second superconducting coil group 40 (a magnetic field distribution that is convex upward on the X-axis and convex downward on the Y-axis) is suitable for growing single crystals with a relatively low oxygen concentration. The preferred oxygen concentration varies depending on the application of the final semiconductor device being manufactured. For example, the required oxygen concentration differs between horizontal devices such as CPUs and memory devices and vertical devices such as power equipment.

[0044] According to the superconducting magnet apparatus 10 according to the embodiment, 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 superposition of the magnetic fields generated by the first superconducting coil assembly 30 and the second superconducting coil assembly 40 can be controlled.

[0045] Conventional devices can only generate a single magnetic field distribution or switch between two magnetic field distributions, resulting in limited improvements in crystal quality. In contrast, the superconducting magnet device 10 according to the embodiment can more finely control the generated magnetic field distribution. This allows for fine-tuning the degree of suppression of thermal convection in the melt and more finely adjusting the oxygen concentration in the single crystal, thereby improving crystal quality.

[0046] A single crystal pulling apparatus equipped with the superconducting magnet apparatus 10 according to the embodiment can be used to produce single crystals having various oxygen concentrations required for the final product. Compared to conventional apparatuses, the single crystal pulling apparatus according to the embodiment can improve the operating rate of the manufacturing site and achieve more economical factory operation.

[0047] Figure 5 It indicates schematically Figure 1 FIG2 is a diagram showing an example of a coil power supply circuit for superconducting magnet apparatus 10. Power supply system 50 includes a first power supply 52 for supplying a first excitation current I1 to first superconducting coil assembly 30; a second power supply 54 for supplying a second excitation current I2 to second superconducting coil assembly 40; and a power supply control device 56 for controlling first power supply 52 and second power supply 54.

[0048] As described above, the first superconducting coil assembly 30 is disposed within the cylindrical cryostat 20, while 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 assembly 30 includes feedthroughs 58 on both the positive and negative sides. The feedthroughs 58 are airtight terminals for introducing current into the cylindrical cryostat 20 and are provided so as to penetrate the wall of the cylindrical cryostat 20. The two feedthroughs 58 are connected to corresponding current leads 60, respectively. A pair of first superconducting coils 30a and 30b are connected in series within the cylindrical cryostat 20. The positive pole of the first power supply 52 is connected to one first superconducting coil 30a via one feedthrough 58 and current lead 60, while the other first superconducting coil 30b is connected to the negative pole of the first power supply 52 via the other feedthrough 58 and current lead 60, thereby forming the first circuit 53.

[0049] In the second circuit 55 connecting the second power supply 54 to the second superconducting coil assembly 40, the positive electrode of the second power supply 54 is connected to the second superconducting coils 40a and 40b via a feedthrough 58 and a current lead 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 to each other via the current lead 60 and the feedthrough 58 on the second superconducting coils 40a and 40b sides, an external wiring 62 connecting the two feedthroughs 58 outside the cylindrical cryostat 20, and the current lead 60 and the feedthrough 58 on the second superconducting coils 40c and 40d sides. The second superconducting coils 40c and 40d are connected in series within the cylindrical cryostat 20. The second superconducting coils 40 c and 40 d are connected to the negative electrode of the second power supply 54 via the feedthrough 58 and the current lead 60 .

[0050] Therefore, the first power supply 52 can supply the first excitation current I1 to the first superconducting coil assembly 30 via the first circuit 53, and the second power supply 54 can supply the second excitation current I2 to the second superconducting coil assembly 40 via the second circuit 55. The first circuit 53 and the second circuit 55 are not connected to each other.

[0051] The power supply control device 56 is capable of determining the first excitation current I1 and the second excitation current I2 to achieve a desired magnetic field distribution. The power supply control device 56 can control the magnitude of the first excitation current I1 and the magnitude of the second excitation current I2 so that the total value of the magnetic field generated by the first superconducting coil assembly 30 and the second superconducting coil assembly 40 at a predetermined position (e.g., the center) in the central cavity 24 does not exceed an upper limit.

[0052] Figure 6This graph shows an example of a contour plot of the magnetic field generated by superconducting magnet apparatus 10 according to the embodiment, with first excitation current I1 and second excitation current I2 as the horizontal and vertical axes, respectively. The magnetic field values shown in the graph represent the total value of the magnetic field generated by first superconducting coil assembly 30 and second superconducting coil assembly 40 at a predetermined position (e.g., the center) in central cavity 24. In this example, the magnetic field value increases toward the upper right contour line, and decreases toward the lower left contour line.

[0053] The power supply control device 56 can select a contour line 64 (indicated by a thick line) from a plurality of contour lines and determine the combination of the first excitation current I1 and the second excitation current I2 from a region 66 that provides a magnetic field value corresponding to or lower than the selected contour line 64. In other words, the power supply control device 56 is prohibited from determining the first excitation current I1 and the second excitation current I2 from a 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 based on the specifications of the superconducting magnet apparatus 10 or the single crystal pulling apparatus, and can be input or stored in the power supply control device 56.

[0054] In this manner, it is possible to prevent the supply of excessive first excitation current I1 and second excitation current I2 to first superconducting coil assembly 30 and second superconducting coil assembly 40, which would generate a magnetic field exceeding the magnetic field value corresponding to selected contour line 64. By preventing the supply of excessive current to the superconducting coils, the electromagnetic force and thermal load acting on the coils can be suppressed, thereby reducing the risk of superconductivity being destroyed. This allows for safer operation of superconducting magnet apparatus 10.

[0055] Figure 7 It is a perspective view schematically showing the appearance of superconducting magnet apparatus 10 . Figure 8 This is an example Figure 7 Schematic diagram of the arrangement position of the cryogenic refrigerator in the superconducting magnet apparatus 10 shown.

[0056] like Figure 7 As shown, the superconducting magnet apparatus 10 includes at least one cryogenic refrigerator 70. The first superconducting coil assembly 30 and the second superconducting coil assembly 40, which are disposed within the cylindrical cryostat 20, are thermally connected to the cryogenic refrigerator 70. The cryogenic refrigerator 70 may be, for example, a two-stage Gifford-McMahon (GM) refrigerator or another type of cryogenic refrigerator. Each superconducting coil is cooled by the cryogenic refrigerator 70 to a cryogenic temperature below the superconducting transition temperature during use. In this embodiment, the superconducting magnet apparatus 10 employs so-called conductive cooling, in which the superconducting coils are directly cooled by the cryogenic refrigerator 70, rather than being immersed in a cryogenic liquid refrigerant such as liquid helium.

[0057] exist Figure 7In the illustrated example, four cryogenic refrigerators 70 are installed on the upper surface of the cylindrical cryostat 20. When viewed in the Z-axis direction, the cryogenic refrigerators 70 can be positioned between two superconducting coils adjacent to each other in the direction around the Z-axis. By utilizing the free space between the coils to install the cryogenic refrigerators 70, the cylindrical cryostat 20 can be designed to be more compact, thereby miniaturizing the superconducting magnet apparatus 10.

[0058] like Figure 8 As shown in (a), the first cryogenic refrigerator 70 can be positioned between the first superconducting coil 30a and the second superconducting coil 40a, the second cryogenic refrigerator 70 can be positioned between the first superconducting coil 30a and the second superconducting coil 40d, the third cryogenic refrigerator 70 can be positioned between the first superconducting coil 30b and the second superconducting coil 40b, and the fourth cryogenic refrigerator 70 can be positioned between the first superconducting coil 30b and the second superconducting coil 40c. In this way, each superconducting coil can be directly cooled by a specific cryogenic refrigerator 70.

[0059] The number of ultra-low temperature refrigerators 70 provided in the cylindrical cryostat 20 may also be less. Figure 8 As shown in (b), three cryogenic refrigerators 70 can be installed in the cylindrical cryostat 20, and each cryogenic refrigerator 70 can be arranged between two superconducting coils adjacent to each other in the direction around the Z axis. In this case, as shown in the figure, the cryogenic refrigerators 70 can be arranged at equal angular intervals in the direction around the Z axis.

[0060] Or, as Figure 8 As shown in (c), two cryogenic refrigerators 70 can be installed in the cylindrical cryostat 20 and can be arranged 180 degrees apart in the direction around the Z axis. In the example shown, the first cryogenic refrigerator 70 is arranged between the first superconducting coil 30a and the second superconducting coil 40d, and the second cryogenic refrigerator 70 is arranged between the first superconducting coil 30b and the second superconducting coil 40c. In this case, some superconducting coils (for example, the second superconducting coils 40a and 40b) are arranged farther away from the cryogenic refrigerator 70 than other superconducting coils adjacent to the cryogenic refrigerator 70. These superconducting coils (40a and 40b) can be connected to the cryogenic refrigerator 70 (or the superconducting coils adjacent to the cryogenic refrigerator 70) via appropriate heat conduction components to be cooled.

[0061] Alternatively, more cryogenic refrigerators 70 may be installed on the cylindrical cryostat 20 as needed. For example, a cryogenic refrigerator 70 may be installed for each superconducting coil. Alternatively, a single superconducting coil may be cooled by multiple cryogenic refrigerators 70 .

[0062] Figure 91 is a cross-sectional view schematically showing the coil support structure 72 of the superconducting magnet apparatus 10. Figure 9 The figure shows the Figure 7 The coil support structure 72 connects the superconducting coils belonging to the first superconducting coil group 30 or the second superconducting coil group 40 (the first superconducting coil 30a in the example shown in the figure) to the cylindrical cryostat 20, and supports the weight of the superconducting coils and the electromagnetic force generated during operation. Figure 9 As shown, coil support structure 72 includes coil support plate 74 and coil support body 76. Coil support plate 74 is provided to connect the superconducting coil and coil support body 76 and is attached to one side of the superconducting coil (e.g., the inner circumference of cylindrical cryostat 20).

[0063] The coil support 76 supports the superconducting coil on the peripheral surface (e.g., the outer peripheral surface) of the cylindrical cryostat 20 and is arranged inside the superconducting coil. One end of the coil support 76 is attached to the coil support plate 74 inside the superconducting coil, while the other end is attached to the outer peripheral surface of the cylindrical cryostat 20. The coil support 76 has a rod-like shape and extends in the horizontal direction. Figure 7 2 shows an end portion of a coil support 76 provided on the outer peripheral surface of the cylindrical cryostat 20. One superconducting coil may be supported on the cylindrical cryostat 20 by a plurality of (eg, two) coil supports 76.

[0064] Figure 10 1 is a perspective view schematically showing another example of the arrangement of superconducting coils in the superconducting magnet apparatus 10 according to the embodiment. Figure 10 As shown, the superconducting magnet apparatus 10 may also use two types of saddle coils of different sizes.

[0065] The first superconducting coil assembly 30 includes a pair of first superconducting coils disposed opposite each other along the X-axis with the central cavity 24 interposed therebetween. The second superconducting coil assembly 40 includes a pair of second superconducting coils disposed opposite each other along the X-axis with the central cavity 24 interposed therebetween. The pair of first superconducting coils is disposed inside the pair of second superconducting coils.

[0066] Even when such a double saddle coil arrangement is used, similar to the six-coil arrangement described above, when the first excitation current I1 is supplied, the first superconducting coil assembly 30 generates a magnetic field distribution in the central cavity 24 that is convex downward on the X-axis and convex upward on the Y-axis. When the second excitation current I2 is supplied, the second superconducting coil assembly 40 generates a magnetic field distribution in the central cavity 24 that is convex upward on the X-axis and convex 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, which results from the superposition of the magnetic fields generated by the first superconducting coil assembly 30 and the second superconducting coil assembly 40, can be controlled.

[0067] The present invention has been described above based on embodiments. Those skilled in the art will appreciate that the present invention is not limited to the aforementioned embodiments. Various design changes and variations are possible, and such variations are also within the scope of the present invention. Various features described in one embodiment may also be applied to other embodiments. New embodiments created through combination have the effects of each of the combined embodiments.

[0068] In the six-coil embodiment described above, all superconducting coils have the same shape and size, but this is not required. For example, the superconducting coils in the first superconducting coil group 30 and the second superconducting coil group 40 may have different shapes and / or sizes.

[0069] In addition to changing the magnitude of the first excitation current I1 and / or the second excitation current I2, the power supply system 50 can also change the direction of the first excitation current I1 and / or the second excitation current I2, or the power supply system 50 can change the direction of the first excitation current I1 and / or the second excitation current I2 instead of changing the magnitude of the first excitation current I1 and / or the second excitation current I2.

[0070] The single crystal pulling apparatus equipped with superconducting magnet apparatus 10 according to the embodiment may be a single crystal pulling apparatus for growing a single crystal of a semiconductor material other than silicon or other materials.

[0071] Superconducting magnet apparatus 10 can be mounted on equipment other than single crystal pulling equipment as long as applicable. Superconducting magnet apparatus 10 can be mounted on high magnetic field utilizing equipment as a magnetic field source for the equipment and generate the high magnetic field required by the equipment.

[0072] The present invention has been described above using specific statements based on the implementation method. However, the implementation method only represents one way of the principle and application of the present invention. Various deformation or configuration changes can be made to the implementation method without departing from the scope of the idea of the present invention as defined by the scope of the technical solution.

Claims

1. A superconducting magnet device, characterized in that: have: A cylindrical cryostat having a central cavity defined on its interior; a first superconducting coil assembly and a second superconducting coil assembly disposed outside the central cavity and inside the cylindrical cryostat; 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; 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.

2. The superconducting magnet device according to claim 1, characterized in that The first superconducting coil assembly includes a pair of first superconducting coils connected in series in the cylindrical cryostat. The power supply system further includes a first circuit connecting the first power supply to the first superconducting coil assembly, the first circuit having a positive feedthrough terminal and a negative feedthrough terminal for introducing the first excitation current into the cylindrical cryostat, the positive feedthrough terminal and the negative feedthrough terminal being arranged to maintain the airtightness of the cylindrical cryostat. The positive electrode of the first power supply is connected to one of the pair of first superconducting coils via the positive electrode feedthrough terminal, and the negative electrode of the first power supply is connected to the other of the pair of first superconducting coils via the negative electrode feedthrough terminal.

3. The superconducting magnet device according to claim 1, wherein: The second superconducting coil assembly includes a first pair of second superconducting coils connected in series in the cylindrical cryostat. The power supply system further includes a second circuit connecting the second power supply and the second superconducting coil assembly, the second circuit having a positive feedthrough terminal for introducing the second excitation current into the cylindrical cryostat, the positive feedthrough terminal being arranged to maintain the airtightness of the cylindrical cryostat. A positive electrode of the second power supply is connected to the first pair of second superconducting coils via the positive electrode feed-through terminal.

4. The superconducting magnet device according to claim 3, characterized in that The second superconducting coil assembly further includes a second pair of second superconducting coils connected in series in the cylindrical cryostat. The second circuit further includes a negative feedthrough terminal for introducing the second excitation current into the cylindrical cryostat, the negative feedthrough terminal being arranged to maintain the airtightness of the cylindrical cryostat. The negative electrode of the second power supply is connected to the second pair of second superconducting coils via the negative electrode feed-through terminal.

5. The superconducting magnet device according to claim 1, wherein When the central axis of the cylindrical cryostat is defined as the Z axis and two axes orthogonal to the Z axis and to each other are defined as the X axis and the Y axis, When the first excitation current is supplied, the first superconducting coil group generates a first magnetic field, wherein a magnetic field distribution of the first magnetic field along the X-axis is strongest at an X position of the first superconducting coil group and weakens as the position approaches the center of the central cavity along the X-axis from the X position, and a magnetic field distribution of the first magnetic field along the Y-axis is strongest at the center of the central cavity and weakens as the position moves outward from the center of the central cavity along the Y-axis. When the second excitation current is supplied, the second superconducting coil group generates a second magnetic field. The magnetic field distribution of the second magnetic field along the X-axis is strongest at the center of the central cavity and weakens as it moves away from the center of the central cavity toward the outside along the X-axis. The magnetic field distribution of the second magnetic field along the Y-axis is weakest at the center of the central cavity and strengthens as it moves away from the center of the central cavity toward the outside along the Y-axis.

6. The superconducting magnet device according to claim 1, wherein: When the central axis of the cylindrical cryostat is defined as the Z axis and two axes orthogonal to the Z axis and to each other are defined as the X axis and the Y axis, The first superconducting coil assembly includes a pair of first superconducting coils disposed opposite to each other on the X-axis with the central cavity interposed therebetween. The second superconducting coil group includes: a pair of second superconducting coils arranged to face each other with the central cavity interposed therebetween, and arranged adjacent to the pair of first superconducting coils in a clockwise direction around the Z-axis; and another pair of second superconducting coils arranged to face each other with the central cavity interposed therebetween, and arranged adjacent to the pair of first superconducting coils in a counterclockwise direction around the Z-axis.

7. The superconducting magnet device according to claim 6, characterized in that The pair of second superconducting coils are arranged on a line rotated 60 degrees clockwise from the X axis around the Z axis, and the other pair of second superconducting coils are arranged on a line rotated 60 degrees counterclockwise from the X axis around the Z axis.

8. The superconducting magnet device according to claim 1, wherein When the central axis of the cylindrical cryostat is set as the Z axis, The superconducting magnet apparatus further includes at least one cryogenic refrigerator for cooling the first superconducting coil group and the second superconducting coil group. When viewed from the Z-axis direction, the at least one cryogenic refrigerator is arranged between two superconducting coils adjacent to each other in the direction around the Z-axis.

9. The superconducting magnet device according to claim 1, 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 field generated by the first superconducting coil group and the second superconducting coil group at a predetermined position in the central cavity does not exceed an upper limit value.

10. The superconducting magnet device according to claim 1, wherein: The invention further includes a coil support plate mounted on the superconducting coil belonging to the first superconducting coil group or the second superconducting coil group.

11. The superconducting magnet device according to claim 10, characterized in that A coil support body is further provided, the coil support body supporting the superconducting coil on the peripheral surface of the cylindrical cryostat and being arranged inside the superconducting coil. One end of the coil support is mounted on the coil support plate, and the other end is mounted on the peripheral surface of the cylindrical cryostat.

12. The superconducting magnet device according to claim 11, characterized in that The coil support has a rod-like shape and extends in the horizontal direction.

13. The superconducting magnet device according to claim 1, wherein When the central axis of the cylindrical cryostat is defined as the Z axis and two axes orthogonal to the Z axis and to each other are defined as the X axis and the Y axis, The first superconducting coil assembly includes a pair of first superconducting coils disposed opposite to each other on the X-axis with the central cavity interposed therebetween. The second superconducting coil group includes a pair of second superconducting coils disposed opposite to each other on the X-axis with the central cavity interposed therebetween. The pair of first superconducting coils is arranged inside the pair of second superconducting coils.

14. A superconducting magnet device, characterized in that: have: A cylindrical cryostat having a central cavity defined on its interior; a first superconducting coil assembly and a second superconducting coil assembly disposed outside the central cavity and inside the cylindrical cryostat; 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 defined as the Z axis and two axes orthogonal to the Z axis and to each other are defined as the X axis and the Y axis, When the first excitation current is supplied, the first superconducting coil group generates a first magnetic field, wherein a magnetic field distribution of the first magnetic field along the X-axis is strongest at an X position of the first superconducting coil group and weakens as the position approaches the center of the central cavity along the X-axis from the X position, and a magnetic field distribution of the first magnetic field along the Y-axis is strongest at the center of the central cavity and weakens as the position moves outward from the center of the central cavity along the Y-axis. When the second excitation current is supplied, the second superconducting coil group generates a second magnetic field. The magnetic field distribution of the second magnetic field along the X-axis is strongest at the center of the central cavity and weakens as it moves away from the center of the central cavity toward the outside along the X-axis. The magnetic field distribution of the second magnetic field along the Y-axis is weakest at the center of the central cavity and strengthens as it moves away from the center of the central cavity toward the outside along the Y-axis.

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