Superconducting magnet device

Abstract

To provide a superconducting magnet device that allows tuning of the magnetic field distribution.SOLUTION: A superconducting magnet device 10 includes a group of superconducting coils 12 that generate a synthetic magnetic field 24 in a magnetic field utilization space 20 in a direction perpendicular to the central axis of the magnetic field utilization space 20, and includes at least two superconducting coils 12 arranged on one side of the magnetic field utilization space 20 with respect to the central axis, and at least two further superconducting coils 12 arranged on the other side of the magnetic field utilization space 20 with respect to the central axis, and a plurality of vacuum vessels 14 each housing a corresponding superconducting coil 12 out of the group of superconducting coils 12 and movable in the circumferential direction of the magnetic field utilization space 20.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The MCZ (Magnetic field applied Czochralski) method is known, in which a magnetic field is applied to the melt in the crucible in a single crystal pulling apparatus in order to control the convection of the melt. A superconducting magnet device is used as the magnetic field source for such a single crystal pulling apparatus. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-203106 A Summary of the Invention [Problem to be solved by the invention]

[0004] The applied magnetic field distribution affects the degree of convection suppression in the melt, and as a result, affects the oxygen concentration in the pulled single crystal. The desired oxygen concentration varies depending on the final application of the semiconductor device. However, in superconducting magnet devices for single crystal pulling apparatuses, the arrangement of superconducting coils is generally fixed. Typically, superconducting magnet devices are designed so that the arrangement of superconducting coils generates a magnetic field distribution suitable for realizing a specific oxygen concentration. Therefore, it is often difficult to produce single crystals with different oxygen concentrations by switching from such a designed magnetic field distribution to another magnetic field distribution using a single single crystal pulling apparatus.

[0005] It is an exemplary object of an embodiment of the present invention to provide a superconducting magnet device that allows adjustment of the magnetic field distribution. [Means for solving the problem]

[0006] According to one embodiment of the present invention, a superconducting magnet device includes a group of superconducting coils that generate a resultant magnetic field in a direction perpendicular to a central axis of the magnetic field-utilizing space in the magnetic field-utilizing space, the group including at least two superconducting coils arranged on one side of the magnetic field-utilizing space with respect to the central axis and at least two further superconducting coils arranged on the other side of the magnetic field-utilizing space with respect to the central axis, and a plurality of vacuum containers, each of which houses a corresponding superconducting coil from the group of superconducting coils and is movable in a circumferential direction of the magnetic field-utilizing space. Effect of the Invention

[0007] According to the present invention, it is possible to provide a superconducting magnet device that allows adjustment of the magnetic field distribution. [Brief description of the drawings]

[0008] [Figure 1] 1 is a plan view showing a schematic diagram of a superconducting magnet device according to an embodiment; [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic diagram of the superconducting magnet device shown in FIG. [Diagram 3] FIG. 2 is a plan view showing a schematic diagram of a vacuum vessel of a superconducting magnet device according to an embodiment. [Figure 4] FIG. 11 is a cross-sectional view showing a schematic diagram of a superconducting magnet device according to another embodiment. [Diagram 5] FIG. 11 is a diagram illustrating another example of the support for the superconducting coil according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent components, members, and processes are given the same reference numerals, and duplicated descriptions are omitted as appropriate. The scale and shape of each part shown in the drawings are set for convenience in order to facilitate the description, and are not to be interpreted as being limiting unless otherwise specified. The embodiments are merely examples, and do not limit the scope of the present invention in any way. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0010] Fig. 1 is a plan view showing a schematic diagram of a superconducting magnet device 10 according to an embodiment. Fig. 2 is a cross-sectional view showing a schematic diagram of the superconducting magnet device 10 shown in Fig. 1. Fig. 2 shows a cross section taken along line AA in Fig. 1, and Fig. 1 shows a cross section taken along line BB in Fig. 2. For simplicity, Fig. 1 omits the illustration of some of the components shown in Fig. 2.

[0011] The superconducting magnet device 10 can be used as a magnetic field generating source for a single crystal pulling device using the HMCZ (Horizontal-MCZ; transverse magnetic field type MCZ) method. The single crystal pulling device is, for example, a silicon single crystal pulling device.

[0012] The superconducting magnet device 10 includes a plurality of superconducting coils 12, a plurality of vacuum vessels 14, a guide structure 16, and a magnetic shield 18. These components of the superconducting magnet device 10 are arranged coaxially around the central axis of a magnetic field utilizing space 20 so as to surround the space. In this embodiment, the central axis of the magnetic field utilizing space 20 is parallel to the vertical direction (i.e., a direction perpendicular to a horizontal plane). When the superconducting magnet device 10 is mounted on a single crystal pulling apparatus, a crucible containing a melt of a single crystal material is arranged in the magnetic field utilizing space 20. The magnetic field utilizing space 20 is part of an ambient environment 22 (e.g., a room temperature and atmospheric pressure environment) surrounding the superconducting magnet device 10.

[0013] For ease of explanation, an orthogonal coordinate system is considered below, with the central axis of the magnetic field utilization space 20 as the Z axis, and two axes that are perpendicular to the Z axis and perpendicular to each other as the X axis and Y axis. In the case of a single crystal pulling device, the crystal pulling axis corresponds to the Z axis, and the X axis and Y axis can be defined as 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 defined as the X axis, and the direction perpendicular to this can be defined as the Y axis.

[0014] In this embodiment, the superconducting magnet device 10 is provided with four superconducting coils 12, two of which are arranged on one side of the magnetic field-utilizing space 20 with respect to the Z axis (left side in the figure) and two additional superconducting coils 12 arranged on the other side of the magnetic field-utilizing space 20 with respect to the Z axis (right side in the figure). These four superconducting coils 12 are arranged so as to surround the magnetic field-utilizing space 20 on the radial outside of the magnetic field-utilizing space 20. Each of the superconducting coils 12 is arranged so that the central axis of the coil faces the radial direction of the magnetic field-utilizing space 20 (direction perpendicular to the Z axis). The superconducting coils 12 have the same shape and size, and in this example, are circular coils of the same diameter.

[0015] 1, the two superconducting coils 12 on the left side are arranged adjacent to each other in the circumferential direction (direction around the Z-axis) of the magnetic field-utilizing space 20, and similarly, the two superconducting coils 12 on the right side are also arranged adjacent to each other in the circumferential direction. The left and right superconducting coils 12 (for example, the upper left coil and the upper right coil, or the lower left coil and the lower right coil) are arranged apart in the circumferential direction.

[0016] In the arrangement of FIG. 1, one of the two superconducting coils 12 on the left side and one of the two superconducting coils 12 on the right side (for example, the upper left coil and the lower right coil, or the lower left coil and the upper right coil) have the same coil central axis and face each other across the magnetic field utilization space 20. The coil central axis of such a pair of superconducting coils 12 (for example, the upper left coil and the lower right coil) may coincide with a line that forms +α degrees from the X axis clockwise around the Z axis, and the coil central axis of another pair of superconducting coils 12 (for example, the lower left coil and the upper right coil) may coincide with a line that forms β degrees from the X axis counterclockwise around the Z axis. In many cases, β degrees is equal to -α degrees, and the four superconducting coils 12 are arranged symmetrically with respect to the X axis.

[0017] The superconducting magnet device 10 is provided with a power source 26 disposed in the surrounding environment 22. The power source 26 may be disposed outside the magnetic shield 18. Each of the superconducting coils 12 generates a magnetic field in the radial direction of the magnetic field utilization space 20 by power supply from the power source 26. For example, the two superconducting coils 12 on the left side generate a magnetic field in the radially inward direction (or radially outward direction), and the two superconducting coils 12 on the right side generate a magnetic field in the radially outward direction (or radially inward direction). As a result, the four superconducting coils 12 generate a composite magnetic field 24 in the magnetic field utilization space 20 in a direction perpendicular to the Z axis (in this example, the X-axis direction) as shown in FIG. 1. Therefore, the superconducting coils 12 can be used as a magnetic field generation source of an HMCZ type single crystal pulling device.

[0018] The superconducting magnet device 10 is provided with four vacuum vessels 14 corresponding to the four superconducting coils 12. The vacuum vessels 14 are arranged around the magnetic field utilizing space 20 so as to be movable in the circumferential direction of the magnetic field utilizing space 20. Each of the vacuum vessels 14 houses a corresponding superconducting coil 12, and the superconducting coil 12 is isolated from the surrounding environment 22. The vacuum vessels 14 can also be called coil mounts. Each vacuum vessel 14 is an individual cryostat for each superconducting coil 12, and during operation of the superconducting magnet device 10, a cryogenic vacuum environment suitable for making the superconducting coils 12 superconducting is provided inside the vacuum vessels 14. The vacuum vessels 14 are formed of a non-magnetic material (e.g., a non-magnetic metal material such as stainless steel) so as not to prevent the superconducting coils 12 from generating a magnetic field in the magnetic field utilizing space 20.

[0019] The guide structure 16 is disposed around the magnetic field-utilized space 20 so as to guide the movement of the vacuum vessel 14 in the circumferential direction. The vacuum vessel 14 is provided with a guided portion that fits the guide structure 16. The guide structure 16 moves the vacuum vessel 14 in the circumferential direction of the magnetic field-utilized space 20 by guiding this guided portion along the guide structure 16. In this embodiment, the guide structure 16 is disposed below the vacuum vessel 14, and the guided portion of the vacuum vessel 14 is also provided at the bottom of the vacuum vessel 14. The guide structure 16, like the vacuum vessel 14, is formed of a non-magnetic material (e.g., a non-magnetic metal material such as stainless steel).

[0020] As an example, the guide structure 16 may include a rail surrounding the magnetic field utilizing space 20 as shown in FIG. 1. As shown in FIG. 2, the rail is provided in a circular shape centered on the Z-axis. The rail is installed on a support surface 28. The support surface 28 may be a floor surface on which the superconducting magnet device 10 is installed. Alternatively, it may be a surface of a support that is installed on a floor surface and supports the superconducting magnet device 10. A wheel may be provided as a guided part at the bottom of the vacuum vessel 14. The rail is configured to guide the movement of the wheel along the rail. By the wheel rolling along the rail, the vacuum vessel 14 can move in the circumferential direction of the magnetic field utilizing space 20 along the rail, i.e., the guide structure 16, as shown by the dashed arrow in FIG. 1. Instead of or together with the wheel, the vacuum vessel 14 may include another form of guided part, in which case the guided part may slide or slide along the guide structure 16 to move the vacuum vessel 14 in the circumferential direction.

[0021] As shown in FIG. 1 and FIG. 2, the magnetic shield 18 extends in the circumferential direction of the magnetic field utilization space 20 so as to surround the multiple vacuum vessels 14, and suppresses leakage of the magnetic field generated by the superconducting coil 12 to the outside. The magnetic shield 18 is formed of a magnetic material such as iron. The magnetic shield 18 is installed on the support surface 28 in the same manner as the guide structure 16. The magnetic shield 18 includes a side wall portion that is erected on the support surface 28 and disposed adjacent to the multiple vacuum vessels 14 on the radially outer side of the multiple vacuum vessels 14, and an upper wall portion that extends radially inward from the upper end of the side wall portion. The magnetic shield 18 may include a lower wall portion that extends radially inward (for example, along the support surface 28) from the lower end of the side wall portion. However, the magnetic shield 18 is not provided radially inward with respect to the multiple vacuum vessels 14 so as not to prevent the superconducting coil 12 from generating a magnetic field in the magnetic field utilization space 20.

[0022] 3 is a plan view showing a schematic diagram of the vacuum vessel 14 of the superconducting magnet device 10 according to the embodiment. In FIG. 3, an outer end face of the vacuum vessel 14 as viewed from the direction of the arrow C shown in FIG.

[0023] The vacuum vessel 14 has a cylindrical shape in order to house the superconducting coil 12 having a circular disk shape. The vacuum vessel 14 has two circular flat end faces and a cylindrical side face connecting these end faces, and the diameter of the vacuum vessel 14 (i.e., the diameter of the end faces) is longer than the length of the vacuum vessel 14 (i.e., the length of the side faces). One of the end faces faces outward with respect to the magnetic field utilizing space 20, and the other faces the magnetic field utilizing space 20.

[0024] As shown in Figs. 2 and 3, each of the superconducting coils 12 includes an outer horizontal support 30 extending from the superconducting coil 12 through the vacuum vessel 14 toward the magnetic shield 18. As described below, the outer horizontal support 30 is supported by the magnetic shield 18. The outer horizontal support 30 has a rod-like shape and extends in the radial direction of the magnetic field-utilizing space 20 through the outer end face of the vacuum vessel 14 so as to maintain the airtightness of the vacuum vessel 14. The base end of the outer horizontal support 30 is fixed to the superconducting coil 12. For example, the base end may be fixed to a coil support plate attached to the end face of the superconducting coil 12. The end of the outer horizontal support 30 protrudes outside the vacuum vessel 14 toward the magnetic shield 18.

[0025] In this embodiment, a plurality of outer horizontal supports 30 are provided for one superconducting coil 12. These outer horizontal supports 30 may be arranged at equal angular intervals around the center of the superconducting coil 12. In this example, as shown in FIG. 3, three outer horizontal supports 30 are arranged at 120 degree intervals around the center of the superconducting coil 12. This is just one example, and the number of outer horizontal supports 30 is arbitrary. Alternatively, one outer horizontal support 30 is provided for one superconducting coil 12, and for example, this outer horizontal support 30 may be arranged on the central axis of the coil and fixed to the coil.

[0026] The magnetic shield 18 not only shields against leakage magnetic fields, but also serves as a load-bearing structure that receives the electromagnetic force acting on the superconducting coil 12 during operation of the superconducting magnet device 10. To this end, the magnetic shield 18 includes a support portion 32 that supports an outer horizontal support 30.

[0027] As shown in FIG. 2, the support 32 is provided on the inner peripheral surface of the side wall of the magnetic shield 18 and protrudes toward the vacuum vessel 14. The support 32 may be a separate member attached to the magnetic shield 18, or may be a part of the magnetic shield 18 formed integrally with the magnetic shield 18. The surface of the support 32 is in contact with the end of the outer horizontal support 30. When an outward force acts on the superconducting coil 12 in the radial direction of the magnetic field utilization space 20 during operation of the superconducting magnet device 10, the outer horizontal support 30 can receive this force and support the superconducting coil 12. Such an outward force in the horizontal direction can be generated in the superconducting coil 12, for example, when a quench phenomenon occurs in the superconducting coil 12. For simplicity, the outer horizontal support 30 and the support 32 are not shown in FIG. 1.

[0028] The support parts 32 are provided over the range of circumferential movement of the outer horizontal support 30 caused by movement of the vacuum vessel 14 in the circumferential direction. For example, the support parts 32 may be provided at a plurality of locations on the magnetic shield 18 along the circumferential direction, or may be provided continuously on the magnetic shield 18 along the circumferential direction. In this manner, the outer horizontal support 30 can be supported by the support parts 32 regardless of the circumferential position of the vacuum vessel 14.

[0029] In an embodiment, the support 32 may be configured to penetrate from the outer peripheral surface of the side wall of the magnetic shield 18 and contact the end of the outer horizontal support 30. The support 32 may be operable from outside the magnetic shield 18 to adjust the support force supporting the superconducting coil 12. For example, the support 32 may be a bolt that screws into a bolt hole formed in the magnetic shield 18, the head of the bolt may be provided on the outer peripheral surface of the magnetic shield 18, and the tip of the bolt may contact the end of the outer horizontal support 30. By rotating the bolt, i.e., the support 32, relative to the magnetic shield 18, the support 32 can move in the radial direction of the magnetic field-utilizing space 20, and thereby the force with which the support 32 presses the outer horizontal support 30 in the radial direction (i.e., the force with which the superconducting coil 12 is supported in the radial direction) can be adjusted.

[0030] In one embodiment, the outer horizontal support 30 may be coupled to the support 32 so as to support not only the radially outward force but also the radially inward force. For example, the magnetic shield 18 may be provided with a pin-shaped support 32 extending in the Z direction, and the outer horizontal support 30 may be provided at its end with a pin hole that engages with the pin.

[0031] Each of the superconducting coils 12 includes a vertical support 34 extending from the superconducting coil 12 through the vacuum vessel 14 toward the guide structure 16. The vertical support 34 has a rod-like shape and extends in the Z-axis direction through the side of the vacuum vessel 14 so as to maintain the airtightness of the vacuum vessel 14. The base end of the vertical support 34 is fixed to the superconducting coil 12, and the end of the vertical support 34 protrudes toward the guide structure 16 outside the vacuum vessel 14. The vertical support 34 is supported by the guide structure 16. The end of the vertical support 34 may be provided with a guided part (e.g., the above-mentioned wheel) that is guided along the guide structure 16. The end of the vertical support 34 is guided along the guide structure 16, and the vacuum vessel 14 can be moved in the circumferential direction of the magnetic field-utilizing space 20.

[0032] In this embodiment, a plurality of (e.g., two) vertical supports 34 are provided for one superconducting coil 12. This is just one example, and the number of vertical supports 34 is arbitrary, and only one vertical support 34 may be provided for one superconducting coil 12. The supports (e.g., outer horizontal support 30, vertical support 34) are formed of a nonmagnetic material (e.g., a nonmagnetic metallic material such as stainless steel) similar to the vacuum vessel 14.

[0033] 2, in addition to the outer horizontal support 30 and vertical support 34, each vacuum vessel 14 further includes a cryogenic refrigerator 36, a heat shield 38, and a current input terminal 40. That is, the cryogenic refrigerator 36, the heat shield 38, and the current input terminal 40 are provided for each superconducting coil 12 housed in each vacuum vessel 14.

[0034] The cryocooler 36 is, for example, a two-stage Gifford-McMahon (GM) cryocooler or other types of cryocooler. A first stage cooling section of the cryocooler 36 is thermally coupled to the heat shield 38, and a second stage cooling section of the cryocooler 36 is thermally coupled to the superconducting coil 12. In the illustrated example, the second stage cooling section is thermally coupled to the superconducting coil 12 via a heat transfer plate 42 attached to an end face of the superconducting coil 12 and thermally coupled to the superconducting coil 12. The first stage cooling section cools the heat shield 38 to a first cooling temperature (for example, 30K to 80K), and the second stage cooling section cools the superconducting coil 12 to a second cooling temperature (for example, 3K to 20K) lower than the first cooling temperature.

[0035] The cryogenic refrigerator 36 is installed in the vacuum vessel 14 so as to maintain airtightness within the vacuum vessel 14, with the first stage cooling section and the second stage cooling section inserted into the vacuum vessel 14. In the illustrated example, the cryogenic refrigerator 36 is inserted into the vacuum vessel 14 from an upper portion of the outer end face of the vacuum vessel 14, and installed in the vacuum vessel 14 horizontally (along the radial direction of the magnetic field utilization space 20). Alternatively, the cryogenic refrigerator 36 may be inserted into the vacuum vessel 14 from a side surface (for example, an upper portion) of the vacuum vessel 14, and installed in the vacuum vessel 14 vertically (along the Z-axis direction).

[0036] The heat shield 38 is disposed within the vacuum vessel 14 to surround the superconducting coil 12. The heat shield 38 is formed of a metal material such as copper or other material having high thermal conductivity. The heat shield 38 can thermally protect low-temperature parts, such as the superconducting coil 12, which is disposed inside and cooled to a lower temperature than the heat shield 38, from radiant heat from the vacuum vessel 14. The outer horizontal support 30 and vertical support 34 described above extend from the superconducting coil 12 to the outside of the vacuum vessel 14 through openings provided in the heat shield 38. These supports are not in contact with the heat shield 38.

[0037] The current introduction terminal 40 is an airtight terminal for introducing a current into the vacuum vessel 14, and is provided penetrating the wall of the vacuum vessel 14 while maintaining the airtightness of the vacuum vessel 14. The current introduction terminal 40 includes a positive terminal and a negative terminal. The current introduction terminal 40 is electrically connected to the superconducting coil 12 inside the vacuum vessel 14. Outside the vacuum vessel 14, i.e., in the surrounding environment 22, the current introduction terminal 40 is connected to an electric wiring such as an appropriate power supply cable (not shown), and is connected to the power supply 26 by this power supply cable, or to the power supply 26 via the current introduction terminal 40 and the superconducting coil 12 of another vacuum vessel 14. Thus, an excitation current is supplied from the power supply 26 to each superconducting coil 12 via the power supply cable and the current introduction terminal 40.

[0038] In addition, the superconducting magnet device 10 may be configured to control the direction and / or magnitude of the current supplied from the power source 26 to each superconducting coil 12 in conjunction with or instead of moving the superconducting coils 12, thereby controlling the magnetic field distribution generated by the superconducting coils 12 in the magnetic field-utilizing space 20.

[0039] Each of the multiple vacuum vessels 14 may be installed so as to be individually removable. When an abnormality or failure occurs in a certain vacuum vessel 14 (or components such as the superconducting coil 12 and the cryogenic refrigerator 36 in this vacuum vessel 14) or when the time for maintenance arrives, only the vacuum vessel 14 may be removed from the superconducting magnet device 10 and replaced with a spare vacuum vessel 14 (and superconducting coil 12). In addition, the guide structure 16 and the magnetic shield 18 may be removable from the superconducting magnet device 10. The guide structure 16 and the magnetic shield 18 may each be composed of multiple divided parts (for example, four 90-degree arc-shaped parts), and when removed from the superconducting magnet device 10, they may be disassembled into these divided parts and stored.

[0040] According to the superconducting magnet device 10 of the embodiment, each vacuum vessel 14 can be moved in the circumferential direction of the magnetic field-utilizing space 20, thereby changing the arrangement of the superconducting coils 12 in the circumferential direction and adjusting the magnetic field distribution generated in the magnetic field-utilizing space 20. In the case of the above-mentioned four-coil type, each vacuum vessel 14 and the superconducting coils 12 therein can be moved in an arc shape around the magnetic field-utilizing space 20 in each of the four quadrants of the XY plane, thereby adjusting the magnetic field distribution.

[0041] As described above, by moving each vacuum vessel 14, the coil central axes of a pair of superconducting coils 12 (e.g., the upper left coil and the lower right coil in FIG. 1 ) facing each other across the Z axis can be aligned with a line that forms α degrees from the X axis in a clockwise direction around the Z axis, and the coil central axes of another pair of superconducting coils 12 (e.g., the lower left coil and the upper right coil) can be aligned with a line that forms β degrees from the X axis in a counterclockwise direction around the Z axis. The α and β degrees may be selected, for example, from a range of 30 degrees to 60 degrees, and may be, for example, any of 30 degrees, 45 degrees, or 60 degrees. In many cases, each vacuum vessel 14 is moved so that the β degree is equal to −α degrees, but this is not essential. In some cases, the vacuum vessels 14 may be moved so that the magnitudes of the α and β degrees are different.

[0042] As a result, when the superconducting magnet device 10 is installed in a single crystal pulling apparatus, the single crystal pulling apparatus can switch from a magnetic field distribution suitable for realizing a certain oxygen concentration in the single crystal to another magnetic field distribution suitable for realizing a different oxygen concentration. Thus, single crystals with a plurality of different oxygen concentrations can be produced by a single single crystal pulling apparatus. This improves the operating rate of the single crystal pulling apparatus, which is economical.

[0043] As an alternative to the above-mentioned embodiment, a single huge vacuum vessel may house multiple superconducting coils and a mechanism for moving these coils. During operation of the superconducting magnet device, the inside of the vacuum vessel is cooled to an extremely low temperature, so not only the superconducting coils but also the mechanism for moving them are cooled, and the weight of the cooled object tends to increase. In that case, there is a concern that the time required for initial cooling from room temperature to an extremely low temperature to start up the superconducting magnet device will be considerably long depending on the weight.

[0044] In contrast, according to the embodiment, since the guide structure 16 is disposed outside the vacuum vessel 14, there is no need to cool the guide structure 16. The total weight of the objects to be cooled in the vacuum vessel 14, such as the superconducting coil 12, can be made relatively light, and the initial cooling can be completed in a short time.

[0045] Moreover, in the above-described embodiment, a circular superconducting coil 12 is used. Generally, a circular coil is smaller than coils of other shapes (e.g., saddle-shaped coils), and it is easier to secure space for moving the coil. Therefore, a circular superconducting coil 12 is suitable for the superconducting magnet device 10 according to the embodiment.

[0046] Fig. 4 is a cross-sectional view showing a schematic diagram of a superconducting magnet device 10 according to another embodiment. The embodiment shown in Fig. 4 differs from the previously described embodiments in that a support structure 44 is provided not only on the outside of the vacuum vessel 14 but also on the inside (i.e., on the magnetic field utilization space 20 side), but is otherwise similar. Below, the differences will be mainly described, and similar configurations will not be described in detail and will be omitted as appropriate to avoid redundancy.

[0047] Each of the superconducting coils 12 includes an inner horizontal support 46 extending from the superconducting coil 12 through the vacuum vessel 14 toward the magnetic field-utilizing space 20. The inner horizontal support 46 has a rod-like shape and extends in the radial direction of the magnetic field-utilizing space 20 through the inner end face of the vacuum vessel 14 so as to maintain the airtightness of the vacuum vessel 14. The base end of the inner horizontal support 46 is fixed to the superconducting coil 12. The end end of the inner horizontal support 46 protrudes outside the vacuum vessel 14 toward the magnetic field-utilizing space 20. One or more inner horizontal supports 46 may be provided for one superconducting coil 12.

[0048] The inner horizontal support 46 is supported by a support structure 44. The support structure 44 is arranged so as to be surrounded by a plurality of vacuum vessels 14. The support structure 44 may include a cylindrical wall member arranged so as to surround the magnetic field-utilizing space 20 radially inside the vacuum vessels 14. The support structure 44 is formed of a non-magnetic material (e.g., a non-magnetic metal material such as stainless steel) so as not to impede the superconducting coil 12 from generating a magnetic field in the magnetic field-utilizing space 20.

[0049] An end portion of the inner horizontal support 46 is in contact with the support structure 44. When the superconducting magnet device 10 is in operation (when a magnetic field is being generated by the superconducting coil 12), an electromagnetic force directed radially inward in the magnetic field-utilizing space 20 can act on the superconducting coil 12. The inner horizontal support 46, together with the support structure 44, can receive this electromagnetic force and support the superconducting coil 12.

[0050] In some embodiments, the outer horizontal support 30 may be omitted and only the support structure 44 and the inner horizontal support 46 may be provided. In this case, the inner horizontal support 46 may be coupled to the support structure 44 to support not only radially inward forces but also radially outward forces.

[0051] FIG. 5 is a diagram showing a schematic diagram of another example of the support of the superconducting coil 12 according to the embodiment. As shown in the figure, each of the superconducting coils 12 may include a circumferential support 48 extending from the superconducting coil 12 in the circumferential direction to the vacuum vessel 14. The circumferential support 48 has a rod-like shape, and its base end is fixed to the superconducting coil 12 and its end end is fixed to the vacuum vessel 14 (or abuts against and contacts the inner surface of the vacuum vessel 14). The circumferential support 48 is housed in the vacuum vessel 14. The circumferential support 48 may be provided on both circumferential sides of one superconducting coil 12. Alternatively, the circumferential support 48 may be provided only on one circumferential side of the superconducting coil 12. During the operation of the superconducting magnet device 10, a circumferential force may act on the superconducting coil 12. The circumferential support 48 can receive this force and support the superconducting coil 12.

[0052] The present invention has been described above based on examples. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, that various design changes are possible, that various modifications are possible, and that such modifications are also within the scope of the present invention. Various features described in relation to one embodiment can also be applied to other embodiments. A new embodiment resulting from a combination has the combined effects of each of the combined embodiments.

[0053] In the above embodiment, the guide structure 16 is described as being disposed below the vacuum vessel 14, but the guide structure 16 may be disposed in other locations. For example, the guide structure 16 may be disposed above the vacuum vessel 14. In this case, for example, the guide structure 16 may include a rail attached to the upper wall of the magnetic shield 18 and surrounding the magnetic field-utilizing space 20. Each vacuum vessel 14 may be configured to be movable along the rail and may be supported by being suspended from the rail.

[0054] In the above embodiment, a four-coil superconducting magnet device 10 has been described as an example, but the superconducting magnet device 10 may be a six-coil superconducting magnet device 10 in which three superconducting coils 12 are provided on one side of the magnetic field-utilizing space 20 with respect to the Z axis and another three superconducting coils 12 are provided on the opposite side of the magnetic field-utilizing space 20 with respect to the Z axis. Alternatively, the superconducting magnet device 10 may be provided with more superconducting coils 12.

[0055] In the above embodiment, an example is described in which only one superconducting coil 12 is stored in one vacuum vessel 14, but the present invention is not limited to this. If necessary, one vacuum vessel 14 may further store an additional superconducting coil or an auxiliary superconducting coil.

[0056] In the above embodiment, the superconducting coil 12 is a circular coil, but the superconducting coil 12 may have other shapes. For example, the superconducting coil 12 may be a saddle-shaped coil.

[0057] In the above embodiment, the superconducting magnet device 10 is applied to a single crystal pulling device as an example, but the superconducting magnet device 10 may be applied to other devices. The superconducting magnet device 10 may be mounted in a high magnetic field device as a magnetic field source for, for example, an NMR system, an MRI system, an accelerator such as a cyclotron, a high energy physics system such as a nuclear fusion system, or other high magnetic field device (not shown), and may generate a high magnetic field required for the device.

[0058] The present invention has been described using specific terms based on the embodiments, but the embodiments merely show one aspect of the principles and applications of the present invention, and many modifications and changes in arrangement are permitted to the embodiments without departing from the spirit of the present invention as defined in the claims. [Explanation of symbols]

[0059] 10 superconducting magnet device, 12 superconducting coil, 14 vacuum vessel, 16 guide structure, 18 magnetic shield, 20 magnetic field utilization space, 24 composite magnetic field, 30 outer horizontal support, 34 vertical support, 36 cryogenic refrigerator, 38 heat shield, 40 current introduction terminal, 44 support structure, 46 inner horizontal support, 48 circumferential support.

Claims

1. A group of superconducting coils that generate a composite magnetic field in a direction perpendicular to a central axis of the magnetic field-utilizing space in the magnetic field-utilizing space, the group of superconducting coils including at least two superconducting coils arranged on one side of the magnetic field-utilizing space with respect to the central axis, and at least two additional superconducting coils arranged on the other side of the magnetic field-utilizing space with respect to the central axis; a plurality of vacuum vessels each housing a corresponding one of the group of superconducting coils and movable in a circumferential direction of the magnetic field utilization space;

2. 2. The superconducting magnet apparatus according to claim 1, further comprising a guide structure arranged around the magnetic field utilizing space so as to guide the movement of the vacuum vessel in the circumferential direction.

3. the guide structure is disposed below the plurality of vacuum vessels, 3. The superconducting magnet apparatus of claim 2, wherein each of the group of superconducting coils includes a vertical support extending from the superconducting coil through the vacuum vessel toward the guidance structure and supported by the guidance structure.

4. a magnetic shield extending in the circumferential direction so as to surround the plurality of vacuum vessels; 4. The superconducting magnet apparatus according to claim 1, wherein each of the group of superconducting coils includes an outer horizontal support extending from the superconducting coil through the vacuum vessel toward the magnetic shield and supported by the magnetic shield.

5. Each of the group of superconducting coils includes an inner horizontal support extending from the superconducting coil through the vacuum vessel toward the magnetic field utilizing space; 5. The superconducting magnet apparatus according to claim 1, further comprising a support structure arranged to be surrounded by the plurality of vacuum vessels and supporting the inner horizontal support.

6. 6. The superconducting magnet apparatus according to claim 1, wherein each of the group of superconducting coils includes a circumferential support extending from the superconducting coil in the circumferential direction to the vacuum vessel.

7. 7. The superconducting magnet device according to claim 1, wherein each of the plurality of vacuum vessels comprises a cryogenic refrigerator for cooling a superconducting coil housed in the vacuum vessel, a thermal shield for surrounding the superconducting coil within the vacuum vessel, and a current introduction terminal for supplying power to the superconducting coil.

8. 8. The superconducting magnet apparatus according to claim 1, wherein each of said plurality of vacuum vessels is installed so as to be individually removable.

Images