Magnetic control coil and crystal manufacturing device

Abstract

The present invention discloses a magnetic control coil including a coil support and N pairs of coils arranged flat along the surface of the coil support, where N is an integer greater than or equal to 1. By using a multi-layer surface coil instead of the conventional circular, racetrack, or saddle coil with a rectangular cross section, the present invention can improve the efficiency of generating a transverse magnetic field, thereby effectively suppressing the introduction of impurities and the generation of defects during the crystal manufacturing process, and improving the efficiency and quality of crystal manufacturing.

Description

[Technical Field]

[0001] The present invention relates to the technical field of crystal manufacturing, and in particular to a magnetic control coil and a crystal manufacturing apparatus.

[0002] This application claims priority from patent application No. 202310069328.8 filed with the China Patent Office on February 6, 2023, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] In the field of crystal manufacturing, crystals are typically produced by methods such as the Czochralski method and the zone melting method, and then the produced crystals are subjected to post-processing such as cutting and polishing to obtain parts with specific functions. For example, in the process of pulling single-crystal silicon, molten crystal raw material is solidified from the liquid phase to the solid phase according to a predetermined process to form a crystal with a predetermined atomic arrangement structure, which may be polycrystalline or single crystal. During the crystal pulling growth process, thermal convection of the melt often causes various defects, such as point defects or the introduction of impurity elements, at the solid-liquid interface during the growth process.

[0004] Therefore, in the crystal growth process (especially for large crystals), effectively suppressing the influence of thermal convection in the melt on crystal growth is an issue that must be resolved as soon as possible in the field of crystal manufacturing. Summary of the Invention [Problem to be solved by the invention]

[0005] In order to reduce the impact of thermal convection on the quality of crystals during the crystal growth process, the present application provides a magnetic control coil and a crystal manufacturing device that can improve the strength of the transverse magnetic field by using a magnetic control coil arranged flat along the surface of the coil support, effectively suppressing the occurrence of defects and the introduction of impurities during the crystal manufacturing process, and improving the efficiency and quality of crystal manufacturing. [Means for solving the problem]

[0006] According to a first aspect of the present application, there is provided a magnetic control coil including a coil support and N pairs of coils arranged flat along a surface of the coil support, where N is an integer equal to or greater than 1.

[0007] In one embodiment, the coil support is arranged around the central axis, and the i-th pair of coils among the N pairs of coils are distributed symmetrically with respect to the central axis, where i is an integer between 1 and N.

[0008] In one embodiment, the coil support is cylindrical and fabricated from stainless steel or aluminum alloy.

[0009] In one embodiment, the cylindrical side of the coil support includes a coil region and a non-coil region, the coil region being used to position the coils, and the non-coil region being provided in a hollow structure.

[0010] In one embodiment, each coil group includes M layers of coils, where M is an integer greater than or equal to 1, and when M is greater than or equal to 2, the j+1th layer of coils is located above the surface away from the central axis of the ith layer of coils, and j is an integer greater than or equal to 1 and less than or equal to M.

[0011] In one embodiment, each coil group has a planar shape that is a concentric rectangle when expanded along the surface of the coil support, and the concentric rectangle includes a line segment in a first direction, which is a line segment that is parallel to the direction of the central axis.

[0012] In one embodiment, the concentric rectangles include a line segment in the second direction, and the line segment in the second direction is a line segment perpendicular to the direction of the central axis.

[0013] In one embodiment, a transition arc is provided between the line segment in the first direction and the line segment in the second direction, and the radius of curvature of the arc is equal to or greater than a preset threshold.

[0014] In one embodiment, the N pairs of coil groups are formed by winding the same group of conductor wires, and the same group of conductor wires are formed by arranging, twisting, or braiding a plurality of conductor wires.

[0015] In one embodiment, the coils are made of a superconducting material.

[0016] In one embodiment, the magnetic control coil has current leads for connecting the magnetic control coil to a power source.

[0017] In one embodiment, the surface of the coil support is provided with recesses for fixing the coils.

[0018] In one embodiment, a thermally conductive layer is laid on the surface of the coil support, and the thermally conductive layer includes at least one of a pure copper plate, a pure aluminum plate, or a pipe through which a cryogenic fluid flows.

[0019] According to a second aspect of the present application, there is provided a crystal manufacturing apparatus comprising a crystal growth furnace and any one of the magnetic control coils described above, wherein the crystal growth furnace is provided with a heating device and a crucible for containing crystal raw material, the crucible is disposed within a cavity of the crystal growth furnace, and the magnetic control coils are provided around the crystal growth furnace and distributed symmetrically along the central axis of the crystal growth furnace.

[0020] In one embodiment, the crystal manufacturing apparatus further comprises an insulating vacuum chamber, and the magnetic control coil is provided inside the insulating vacuum chamber.

[0021] In one embodiment, the crystal manufacturing apparatus further comprises a cooling device for reducing the temperature within the insulated vacuum chamber.

[0022] In one embodiment, the interior of an insulating vacuum chamber in which the magnetic control coil is located is a vacuum environment, and the magnetic control coil is suspended within the vacuum environment of the insulating vacuum chamber by suspension rods. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic structural diagram of a magnetic control coil according to the present invention; [Figure 2] 1 is a schematic structural diagram of a coil group according to the present invention; [Figure 3] FIG. 1 is a structural schematic diagram of a crystal manufacturing apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0024] In order to better understand the technical solution of the present application, the application scenarios of the magnetic control coil and crystal manufacturing apparatus according to the present application will now be further described. It should be understood that the description of the scenarios here is merely for better understanding of the technical solution of the present application and does not limit the application scenarios of the present application. The magnetic control coil according to the present application can be applied to the field of single crystal silicon manufacturing. In the process of single crystal silicon manufacturing, the pulled and grown crystal is very susceptible to the thermal convection of the melt. In particular, with the rapid development of device manufacturing technologies such as semiconductor microelectronic devices, large scale integrated circuits, and solar panels, the demand for single crystal silicon quality and size is increasing. In the process of manufacturing such large-sized single crystal silicon, the thermal convection of the melt is further strengthened, which further increases the impact of impurity elements (e.g., oxygen) and the uniformity of the melt, often resulting in a deterioration of crystal quality, making it difficult to manufacture large-sized, high-quality single crystal silicon crystals.

[0025] The magnetic control coil provided by the present application to better reduce the impact of thermal convection on crystal quality can well solve this problem, and furthermore, the magnetic control coil of the present application has the characteristics of high magnetic field utilization efficiency, concentrated magnetic force, uniform magnetic field, easy installation and maintenance, and low cost.

[0026] The present application provides a magnetic control coil including a coil support and N pairs of coils arranged flat along a surface of the coil support, where N is an integer greater than or equal to 1.

[0027] 1, in the present application, the coil support may be a coil support framework used to fix the coil groups and support the electromagnetic force. The number of coil groups can be set according to the required magnetic field strength. For example, the number of N pairs of coil groups can be 1 pair, 2 pairs, or 3 pairs, and is not limited here.

[0028] The coil group is made up of multiple coils wound in a spiral shape, and the spacing between each coil can be set as needed, and may be, for example, 2 mm, 3 mm, 4 mm, etc., and is not limited thereto. The coils can be wound spirally from the inside to the outside along the surface of the coil support, or from the outside to the inside, and is not limited thereto.

[0029] In the present application, a group of conducting wires is wound on the surface of a coil support to form multiple coils, and the multiple coils are distributed two-dimensionally and flatly on the surface of the coil support. Here, the surface of the coil support may be flat or curved, and is not limited thereto. Both ends of the group of conducting wires are extended to form current leads for the multiple coils. The magnetic control coil of the present application has higher magnetic field utilization efficiency than the prior art process of tightly winding a single superconducting wire layer by layer to obtain a circular coil or saddle-shaped coil with a rectangular cross section.

[0030] The advantages of the magnetic control coil of the present application will be further explained below with reference to conventional magnetic control coils and winding processes. In the prior art, circular or saddle-shaped magnetic control coils wound around a rectangular cross section experience a decrease in magnetic field generation efficiency as the coil's radial thickness increases during use, due to Biot-Savart's law. This causes more magnetic control energy to concentrate in the coil, resulting in a higher internal magnetic field. This makes it difficult for such coils to generate larger external magnetic fields, such as those required by the crystal manufacturing industry for high-magnetic-field applications. Furthermore, the high internal magnetic field of such coils further weakens the current-carrying capacity of the conductors constituting the coil, reducing the utilization rate of the conductors. Furthermore, the magnetic force is concentrated in the coil, which has a large effect on the coil itself, adversely affecting the coil's fixation and the stability of the internal structure of the coil conductor. With the recent development of superconducting technology, the drawbacks of such magnetic control coils have become even more pronounced in superconducting magnetic coils.

[0031] The magnetic control coil of the present application is wound after being arranged two-dimensionally flat along the surface of a support, and the radial thickness of the coil may be the thickness of the corresponding number of layers of wires / wire groups, specifically the thickness of one or two layers of wires / wire groups. The radial thickness of the coil is significantly reduced, which effectively prevents magnetic flux concentration inside the coil, reduces the influence of magnetic flux on the coil wires, improves magnetic field utilization efficiency, and is advantageous for generating a stronger external magnetic field.

[0032] In some alternative embodiments, the magnetic control coil wires of the present application are made up of multiple groups of conductors; for example, in one scenario, the coil cable of the present application may be made up of 19 conductors, each having a diameter of 0.6 mm.

[0033] In some embodiments, the coil supports are arranged around a central axis, and the i-th coil group of the N coil groups is distributed symmetrically about the central axis, where i is an integer between 1 and N, inclusive.

[0034] Specifically, the coil support may have an integrated structure or a separate structure, but this is not limited thereto. Here, the integrated coil support may be cylindrical, and the separate coil support may be a partial arc shape cut by any two non-parallel planes parallel to the central axis of a cylinder. That is, the cross section of the coil support may be arc-shaped or annular. The coil supports may be arranged around the central axis, and the surface of the coil support may be uniformly arranged around the central axis. Depending on the arrangement of the coil supports, the i-th pair of coils may be symmetrically distributed with respect to the central axis, and the symmetrically distributed i-th pair of coils generates a transverse magnetic field perpendicular to the central axis, where i may be 1, 2, 3, etc., but this is not limited thereto.

[0035] In some embodiments, the coil support is tubular and fabricated from stainless steel or aluminum alloy. Here, the tubular shape may be a cylindrical or polygonal tubular shape. Furthermore, the cross section of the polygonal tubular shape may be any polygon, including, but not limited to, a square, pentagon, hexagon, etc.

[0036] A thermally conductive layer having high thermal conductivity may be laid on the surface of the coil support, and may be, for example, at least one of a pure copper plate, a pure aluminum plate, or a pipe line filled with a cryogenic fluid to enhance heat conduction.

[0037] In some embodiments, the cylindrical side of the coil support includes a coil region and a non-coil region, the coil region being used to wind and arrange the coil groups, and the non-coil region being hollow. Specifically, the non-coil region may be located in the gap between two adjacent coil regions or in the center of a coil group, but this is not limited thereto. By providing a hollow structure in this way, the weight and volume of the coil support can be further reduced, which is particularly significant for some superconducting magnetic control coils. For example, in the cryogenic environment required for the operation of superconducting wires, reducing the weight and volume of the coil support can effectively improve the cooling rate of the coil and the operating efficiency of the equipment.

[0038] In some embodiments, each coil group includes M layers of coils, where M is an integer greater than or equal to 1, and when M is greater than or equal to 2, the j+1th layer of coils is located above a surface away from the central axis of the ith layer of coils, and j is an integer greater than or equal to 1 and less than or equal to M.

[0039] 2, the number of layers M of the coil group can be set according to the required magnetic field strength, for example, M can be 1, 2, 3, etc. The selection of the number of layers is related to the number of conductors wound to form the coil and the thickness of the conductors, and in a specific implementation process, optimal magnetic control coil parameters can be obtained through a limited number of experiments according to actual conditions. Specifically, in the best embodiment of the present application, when the conductors are superconducting wires, the conductor group is composed of 19 conductors, and each conductor is 0.6 mm thick, it is most preferable to configure the magnetic control coil of the best embodiment of the present application with two coil layers.

[0040] When M is 2 or greater, the j+1th coil and the ith coil are arranged two-dimensionally flat in two layers, upper and lower, where j can be 1, 2, 3, etc., and is not limited thereto. Coil groups corresponding to different layers may have the same winding pattern. That is, if the jth coil is wound in a flat rectangular arrangement, the j+1th coil is wound above the jth coil according to the same winding rule. Thus, the two layers of coils have the same planar structure, and there are two layers of coils in a direction perpendicular to the central axis of the coil. Such two-layer magnetic control coils have a stronger magnetic field generation capability.

[0041] In some embodiments, each coil group has a planar shape that is a concentric rectangle when developed along the surface of the coil support, and the concentric rectangle includes a line segment in a first direction that is parallel to the direction of the central axis.

[0042] The surface of the support may be flat or curved. For example, if the support is a polygonal tube, the side surface is flat. In this case, one coil group may be located on the surface of one support, or on the surfaces of multiple adjacent, continuous supports, and this is not limited thereto. If the support is cylindrical, the surface of the support is curved.

[0043] When the coil group is deployed along the surface of the coil support, the planar shape of the coil group is a concentric rectangle. Specifically, the concentric rectangle includes a line segment in a first direction that is parallel to the direction of the central axis.

[0044] In some embodiments, the concentric rectangles include a line segment in a second direction, the line segment in the second direction being a line segment perpendicular to the direction of the central axis.

[0045] In some embodiments, in order to reduce the deterioration of insulation and conductivity performance due to excessive bending of the coil conductor, a transition arc or a spline curve is provided between adjacent line segments in the first direction and line segments in the second direction in the coil group, and the minimum radius of curvature of the transition arc or the spline curve is equal to or greater than a predetermined threshold value. Here, the predetermined threshold value may be determined based on the overall size of the coils in the actual coil group. If the minimum radius of curvature of the transition curve is greater than the predetermined threshold value, the bending strain of the superconducting wire will be too large, which may result in deterioration of the current-carrying ability and affect the generation of the magnetic field of the magnetic control coil.

[0046] In some embodiments, the N pairs of coils are formed by winding the same group of conductor wires, and the same group of conductor wires are formed by arranging, twisting, or braiding multiple conductor wires, which can effectively improve the current density of the process and is more advantageous for implementing the magnetic material manufacturing process of accurate slot wiring.

[0047] In some embodiments, the coils are made of a superconducting material, such as NbTi, Nb3Sn, or Mg2B superconducting wire. When the coils are superconducting coils, the magnetic control coils can generate stronger magnetic flux, thereby meeting the needs of the crystal manufacturing industry for high-strength transverse magnetic fields.

[0048] In some embodiments, the magnetic control coils have current leads for connecting the magnetic control coils to a power source, i.e., the coils in the N pairs of coils have the same current leads, with current flowing in from one end of the lead and out the other end of the lead, forming a closed loop of the magnetic control coils in communication with the power source, and charging currents in the coils generate magnetic fields in the coils.

[0049] In some embodiments, the surface of the coil support is provided with grooves for fixing the coil groups. The grooves can be formed according to the arrangement shape of the coil groups. For example, if the magnetic control coil needs to be wound along a concentric rectangle, loop-shaped grooves can be machined in the coil support according to the concentric rectangle of the coil groups, and then the conductors of the magnetic control coil can be arranged in the grooves according to the groove shape to form the magnetic control coil. Preferably, grooves corresponding to the first and second directional line segments are machined only on the surface of the coil support, so that the coil groups are arranged flatly on the surface of the coil support according to the first and second directional line segments, and transition arcs are naturally formed between adjacent first and second directional line segments in the coil groups due to the restricting effect of the grooves. That is, it is not necessary to machine grooves at the positions corresponding to the transition arcs of the coil groups. It should be understood that the depth of the grooves can be determined according to the number of layers of coil groups in which the magnetic control coils are arranged, for example, if two layers of coil groups are required, it can be determined according to the diameter of the conductor wires in the coil groups. It should also be understood that fixing the magnetic control coils using grooves is only one method according to the present invention, and that various other methods can be implemented, such as ultrasonic-assisted bonding or rapid bonding with photocurable resin, to form the arrangement of the coil groups of the magnetic control coils, and the present invention is not limited thereto.

[0050] FIG. 3 shows a crystal manufacturing apparatus of the present invention, which can be used to manufacture silicon crystals.

[0051] In some embodiments, a crystal manufacturing apparatus includes a crystal growth furnace and any one of the magnetic control coils described above, wherein the crystal growth furnace is provided with a heating device and a crucible for containing crystal raw material, the crucible is disposed within a crystal growth furnace chamber, and the magnetic control coils are disposed around the crystal growth furnace and distributed symmetrically along the central axis of the crystal growth furnace.

[0052] The coil groups can be arranged symmetrically on both sides of the crystal manufacturing apparatus, and the coil groups are arranged flatly along the surface of the coil support. Referring to Figure 3, the magnetic control coil includes a coil support 1 and a coil group 2. The coil support 1 is cylindrical, and the coil group 2 is installed on both sides of the crystal manufacturing apparatus. Specifically, the coil group 2 may exist in pairs, for example, one pair, two pairs, etc., and this is not limited here.

[0053] As shown in FIG. 3 , in some embodiments, the crystal manufacturing apparatus of the present application further includes an insulating vacuum chamber 3, and the magnetic control coil is installed inside the insulating vacuum chamber 3 to ensure that the magnetic control coil operates within an appropriate temperature range. For example, if the magnetic control coil is made of superconducting wire material, it must operate at a very low temperature, and the insulating vacuum chamber 3 can provide a powerful working space for a cryogenic environment. In some alternative embodiments, the insulating vacuum chamber 3 can be configured as a hollow chamber, and a liquid inert gas (e.g., liquid helium) can be injected into the chamber to ensure a cryogenic temperature within the chamber, thereby providing a cryogenic environment for the operation of the superconducting coil. In some cases, a vessel having such an isolated heat-insulating chamber is called a Dewar vessel, and a crystal growing furnace can be installed inside the Dewar vessel to perform crystal pulling.

[0054] The inner wall of the thermal insulation vacuum chamber of the present application may be the same material as the furnace wall of the crystal growth furnace (not shown), in order to further reduce the complexity of the crystal manufacturing equipment and save manufacturing costs. Of course, in some embodiments, the thermal insulation vacuum chamber and the magnetic control coil may be separate components, and a certain distance is maintained between the inner wall of the thermal insulation vacuum chamber and the furnace wall of the crystal growth furnace. In some optional embodiments, the coil support 1 may be installed as a hollow structure, i.e., a support structure may be installed in the coil area and a hollow structure may be installed in the non-coil area, which can significantly reduce the mass of the support, reduce the amount of refrigeration in the low-temperature environment, and improve refrigeration efficiency.

[0055] In a crystal growing apparatus, the crystals grown by pulling are highly susceptible to thermal convection in the melt, which can affect the quality of the crystal, introduce impurities, and cause various defects at the solid-liquid interface. Magnetic control devices are symmetrically arranged around the crystal growing furnace, and the transverse magnetic field generated by the magnetic control devices effectively suppresses the influence of thermal convection on the solid-liquid interface during the crystal growth process, resulting in high-quality crystals. The magnetic control coil provided by the present application can generate a stronger transverse magnetic field and has a good suppression effect on thermal convection when producing large-sized single-crystal silicon. It should be understood that the magnetic control coil of the present application shown in FIG. 3 is merely a simple example in principle, and various forms may be used in actual use, and are not limited thereto.

[0056] In one embodiment, the inside of the insulating vacuum chamber 3 where the magnetic control coil is located is a vacuum environment, and the magnetic control coil is suspended within the vacuum environment of the insulating vacuum chamber 3 by a suspension rod. Here, the suspension rod may be made of a material with high strength but poor thermal conductivity.

[0057] In some embodiments, the crystal manufacturing apparatus according to the present application further includes a cooling device for reducing the temperature within the thermally insulated vacuum chamber 3. The cooling device 4 may include a radiation cold shield 4 and a refrigerator 5. The radiation cold shield 4 completely encases the magnetic control coil. A gap may be formed between the inner wall of the radiation cold shield 4 and the magnetic control coil to prevent solid-state heat conduction. The surface is covered with a multilayer aluminum-plated thin film. The radiation cold shield is maintained at a temperature between 60 K and 100 K by the primary cold head of the refrigerator 5, thereby preventing thermal radiation from the outer wall of the thermally insulated vacuum chamber 3 at room temperature and ensuring a low-temperature operating environment for the internal magnetic control coil assembly. For example, if the coil group 2 in the magnetic control coil is a superconducting coil, the magnetic control coil assembly can be maintained at an extremely low temperature using a liquid inert gas and a refrigerator, providing an appropriate operating temperature for the superconducting coil.

[0058] The crystal manufacturing apparatus of the present invention will be described in detail below. Referring to Fig. 3, the crystal manufacturing apparatus includes a coil support 1, a coil group 2, an insulating vacuum chamber 3, a radiation cold shield 4, a refrigerator 5, and a current lead wire 6.

[0059] The coil support 1 and the coil group 2 together constitute a magnetic control coil. In this embodiment, the magnetic control coils are distributed in pairs on the surface of the coil support. It should be understood that another coil group is provided on the back side visible in FIG. 3, and these two coil groups are wound with the same group of superconducting wire. After the superconducting wire is in an operating state, the magnetic control coils consisting of the symmetrically arranged coil groups will generate a strong transverse magnetic field. This transverse magnetic field can be applied to the molten material inside the vessel, suppressing the thermal convection of the material and stabilizing the crystal growth environment, which is advantageous for obtaining high-quality crystal material.

[0060] In this embodiment, to efficiently generate a horizontal magnetic field, each coil turn in each coil group 2 generally has a rounded, concentric rectangular shape after being unfolded. Aluminum alloy or brass wire is used to provide preload to the exterior of the coil group 2 to control potential displacement of the coil group 2 after it is subjected to electromagnetic force. A low-temperature-resistant insulating material is used between the coil support 1 and the coil group 2 and the external preload structure. For example, insulating with polyimide ensures that no discharge breakdown occurs after magnetic control operation and quenching. In some alternatives, the coil support 1 can be manufactured using a machining method, 3D printing, or injection molding method to form a loop-shaped groove capable of accommodating the superconducting magnetic control coil. The loop-shaped groove can fit two layers of coil groups, securing the magnetic control coil in the groove. In another alternative, the magnetic control coil can be secured to the surface of the coil support 1 using a low-temperature-resistant resin to ensure a two-dimensionally flat arrangement of the magnetic control coil. It should be understood that on the surface of a coil support having multiple coil groups, the coils can be combined based on the above different fixing methods, for example, one coil group uses a loop-shaped groove method and another coil group uses a cryogenic resin method.

[0061] The insulating vacuum chamber 3 has a cylindrical shape, and the chamber formed on the cylindrical inner wall can accommodate the crucible of a crystal growth furnace. The crystal raw material is placed inside the crucible in the crystal growth furnace, and a heat insulating material and a heating element are installed on the outer periphery of the crucible to heat and melt the crystal raw material in the crucible. In this embodiment, the insulating vacuum chamber 3 can function as the furnace wall of the crystal growth furnace. In some cases, the sealed furnace wall of this structure can be called a vacuum outer dewar vessel, and the sealed space inside the vessel can be kept in a vacuum state by evacuating, thereby providing better insulation from the outside, protecting the assemblies inside the sealed chamber, and providing a suitable temperature environment for the operation of the internal assemblies.

[0062] The radiation cold shield 4 is attached to the thermally insulated vacuum chamber 3, completely covering the inner magnetic control coil assembly and maintaining a certain gap between it and the inner wall of the outer thermally insulated vacuum chamber and the outer surface of the inner magnetic control coil to prevent solid-state heat transfer. The magnetic control coil and radiation cold shield 4, consisting of the coil support 1 and the coil group 2, are suspended inside the thermally insulated vacuum chamber 3 by pull rods or a support assembly made of a high-strength, low-thermal-conductivity material. A first temperature zone is formed between the radiation cold shield 4 and the magnetic control coil, and a second temperature zone is formed between the radiation cold shield 4 and the wall of the thermally insulated vacuum chamber 3. The first and second temperature zones are relatively independent. During actual operation, the temperature in the second temperature zone can be maintained between 60 and 100 K in conjunction with the refrigerator, and the temperature in the first temperature zone can be maintained below 10 K, providing a temperature environment suitable for the operation of the superconducting coil. The radiation cold shield 4 may be made of a highly thermally conductive material, but is not limited thereto. The refrigerator 5 is attached to the outer wall of the thermally insulated vacuum chamber 3 and cools the magnetic control coil and radiation cold shield 4 by conduction cooling. The cold heat is transferred from the cold head of the refrigerator to the inside through a cold conduction structure in the insulated vacuum chamber 3. The number of refrigerators 5 may be one, two, three, etc., and can be set as needed.

[0063] The current lead wires 6 connect the magnetic control coil to a power source, and current is sent to the magnetic control coil through the current lead wires to energize it and generate a magnetic field. The current lead wires have the characteristics of high current-carrying capacity and low thermal load, and can transport large currents from the room temperature end to the cryogenically cooled coil. Once the current reaches a set value, it remains stable and does not change, and the magnetic field generated by the magnetic control coil also maintains stable field strength and uniformity.

[0064] Although the embodiments of the present invention have been described above, it should be understood that the above embodiments are illustrative and do not limit the present invention, and that those skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention. [Explanation of symbols]

[0065] 1 Coil support 2 Coil group 3. Insulated vacuum chamber 4 Radiation Cold Shield 5. Freezer 6 Current Leads

Claims

1. A magnetic control coil comprising: a coil support; and a group of N pairs of coils arranged flat along a surface of the coil support, where N is an integer of 1 or greater.

2. 2. The magnetic control coil according to claim 1, wherein the coil support is arranged around a central axis, and the i-th pair of coils among the N pairs of coils is distributed symmetrically with respect to the central axis, where i is an integer greater than or equal to 1 and less than or equal to N.

3. 3. The magnetic control coil according to claim 2, wherein the coil support is cylindrical and made of stainless steel or aluminum alloy.

4. the cylindrical side surface of the coil support includes a coil region and a non-coil region; 4. The magnetic control coil according to claim 3, wherein the coil region is used to arrange the coil group, and the non-coil region is provided in a hollow structure.

5. 3. The magnetic control coil according to claim 2, wherein each of the coil groups includes M layers of coils, where M is an integer of 1 or greater, and when M is 2 or greater, the j+1th layer of coils is located above the surface of the ith layer of coils that is away from the central axis, and j is an integer of 1 or greater and M or less.

6. The magnetic control coil according to claim 5, characterized in that each of the coil groups has a planar shape, developed along the surface of the coil support, of a concentric rectangle, the concentric rectangle including a line segment in a first direction, the line segment in the first direction being a line segment parallel to the direction of the central axis.

7. 7. The magnetic control coil according to claim 6, wherein the concentric rectangles include line segments in a second direction, the line segments in the second direction being perpendicular to the direction of the central axis.

8. 8. The magnetic control coil according to claim 7, wherein a transition arc is provided between the line segment in the first direction and the line segment in the second direction, and the radius of curvature of the arc is equal to or greater than a preset threshold value.

9. 9. The magnetic control coil according to claim 8, wherein the N pairs of coil groups are formed by winding the same group of conductor wires, and the same group of conductor wires are formed by arranging, twisting, or braiding a plurality of conductor wires.

10. 10. The magnetic control coil according to claim 9, wherein the coils are made of a superconducting material.

11. 2. The magnetic control coil of claim 1, wherein the magnetic control coil includes current leads for connecting the magnetic control coil to a power source.

12. 5. The magnetic control coil according to claim 4, wherein a recessed groove for fixing the coil group is provided on the surface of the coil support.

13. 2. The magnetic control coil according to claim 1, wherein a thermally conductive layer is laid on a surface of the coil support, and the thermally conductive layer includes at least one of a pure copper plate, a pure aluminum plate, or a pipe through which a cryogenic fluid flows.

14. A crystal growth furnace and a magnetic control coil according to any one of claims 1 to 12, The crystal growth furnace is provided with a heating device and a crucible for accommodating a crystal raw material, and the crucible is disposed in a cavity of the crystal growth furnace; The magnetic control coils are arranged around the crystal-growing furnace and are symmetrically distributed along the central axis of the crystal-growing furnace.

15. 15. The crystal manufacturing apparatus according to claim 14, further comprising an insulating vacuum chamber, wherein the magnetic control coil is provided inside the insulating vacuum chamber.

16. The crystal manufacturing apparatus according to claim 15, further comprising a cooling device for reducing the temperature inside the thermal insulating vacuum chamber.

17. 17. The crystal manufacturing apparatus of claim 16, wherein the inside of the thermal insulation vacuum chamber is a vacuum environment, and the magnetic control coil is suspended within the vacuum environment of the thermal insulation vacuum chamber by a suspension rod.

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