High-temperature superconducting coil structure

Abstract

The invention discloses a high-temperature superconducting coil structure, and relates to the technical field of superconducting magnets, and the main points of the technical scheme are that the high-temperature superconducting coil structure comprises a solenoid superconducting coil which is arranged in a layer winding manner and is internally provided with a first cooling channel arranged along the axis direction of a wire; the shunt bypasses are arranged on the solenoid superconducting coil at intervals, and second cooling channels are arranged in the shunt bypasses; wherein the shunt bypass and the solenoid superconducting coil are connected in a lap joint mode to form a connector, and at least one longitudinal cooling hole for communicating the first cooling channel with the second cooling channel is formed in the connector. While the inherent thermal stability and safety of the magnet are improved, the number of coil joints is greatly reduced, and heat generated by the joints is reduced; the superconducting magnet is divided into multiple sections by the shunt bypasses which are connected in parallel, and the shunt bypasses serve as a refrigerant inlet and outlet of the magnet and also serve as a rapid energy release and energy transfer loop during magnet quenching protection, so that the cooling efficiency of the magnet is improved, and the energy release speed of a magnet quenching section is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting magnets, and more particularly to a high-temperature superconducting coil structure. Background Art

[0002] Thanks to the fact that superconducting materials have no DC resistance, they have the advantages of small size, low power consumption, and low operating cost when used in high-field magnets. In particular, the rapid development of high-temperature superconducting materials has made high-temperature superconducting coils more technically suitable and have broader application prospects. REBCO and Bi-based high-temperature superconductors have practical value at temperatures of 77K and below, and the lower the temperature, the higher the current density and practical magnetic field. Since the quench propagation speed of high-temperature superconductors is more than an order of magnitude slower than that of low-temperature superconductors, high-temperature superconducting coils are prone to heat concentration and burning after quenching. Therefore, optimizing the quench detection and thermal stability of the magnet is the core issue to ensure the safe operation of the magnet.

[0003] At present, for insulating superconducting magnets, the main method to improve the thermal stability of the magnet is to increase the conductor current, reduce the number of turns and inductance, which is beneficial to the rapid energy dissipation of the magnet and to improve the cooling efficiency of the magnet. However, the increase in conductor current will increase the heating of the joints, seriously affecting the thermal stability and economy of the magnet; at the same time, the excessive length of a single-stage cooling section will also lead to low cooling efficiency and insufficient thermal stability of the magnet. Therefore, the key to improving the safety of high-temperature supermagnets is to simultaneously meet their rapid quench detection and energy dissipation, as few coil joints as possible, lower joint resistance and efficient cooling. For this reason, existing medium and large high-temperature superconducting coils are mainly composed of non-insulated multi-coil cakes to improve their inherent safety, but the non-insulated characteristics greatly reduce the excitation speed and magnetic field quality of the magnet, increase the coil joints and heat loss, and cannot completely replace the insulating high-temperature superconducting magnet.

[0004] Therefore, how to research and design a high-temperature superconducting coil structure that can overcome the above-mentioned defects is a problem that we urgently need to solve. Summary of the invention

[0005] To address the deficiencies in the prior art, the present invention aims to provide a high-temperature superconducting coil structure, which allows the use of long-length CICC conductors to wind superconducting magnets while improving the inherent thermal stability and safety of the magnet, greatly reducing the number of coil joints and reducing the heat generated by the joints; the superconducting magnet is divided into multiple sections by parallel shunt bypasses, and the shunt bypasses serve as both the refrigerant inlet and outlet of the magnet and the rapid energy dissipation and energy transfer circuit during magnet quench protection, thereby improving the magnet cooling efficiency and increasing the energy dissipation speed of the magnet quench section.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: A high temperature superconducting coil structure, comprising:

[0007] The solenoid superconducting coil is arranged in a layer-wound manner and is provided with a first cooling channel arranged along the axis direction of the conductor;

[0008] At least one shunt bypass is arranged at intervals on the solenoid superconducting coil and is provided with a second cooling channel;

[0009] The shunt bypass is connected to the solenoid superconducting coil in an overlapping manner to form a joint, and at least one longitudinal cooling hole connecting the first cooling channel and the second cooling channel is provided in the joint.

[0010] Furthermore, the solenoid superconducting coil is wound with a high-temperature superconducting armored internally cooled conductor;

[0011] The high-temperature superconducting armored internally cooled conductor comprises a superconducting cable, a wrapped copper tape, a stainless steel cladding and a first insulating layer arranged in sequence from the inside to the outside;

[0012] The superconducting cable is formed by twisting a plurality of high-temperature superconducting strands, and the gaps between the high-temperature superconducting strands and the wrapped copper tapes and the gaps between the high-temperature superconducting strands form a first cooling channel.

[0013] Furthermore, the shunt bypass adopts an armored internally cooled conductor;

[0014] The armored inner cooling conductor comprises a high temperature superconducting stack, a shunt copper matrix, a joint armor and a second insulating layer arranged in sequence from the inside to the outside;

[0015] The gap between the shunt copper substrate and the joint armor forms a second cooling channel.

[0016] Furthermore, when the shunt bypass is overlapped with the solenoid superconducting coil, the shunt copper matrix in the shunt bypass contacts the wrapped copper tape in the solenoid superconducting coil, and the longitudinal cooling hole penetrates the shunt copper matrix and the high-temperature superconducting stack in the shunt bypass.

[0017] Furthermore, the shunt bypass is arranged at a jump turn position at the end of the solenoid superconducting coil.

[0018] Furthermore, the conductor in the shunt bypass is coplanar and parallel to the conductor center line of the solenoid superconducting coil.

[0019] Furthermore, the positive and negative excitation poles of the solenoid superconducting coil and the shunt bypass point in the same direction.

[0020] Furthermore, the overlapping length of the joint is 20-30% of the diameter of the solenoid superconducting coil.

[0021] Furthermore, the two ends of the solenoid superconducting coil are connected to the power feeder as coil excitation positive and negative lead wires; when the number of coil layers of the solenoid superconducting coil is N, each layer of coil is used as a coil segment, and the number of shunt bypasses is set to N-1 at most.

[0022] Furthermore, it is made of low temperature high strength steel, and the low temperature high strength steel includes materials N50 and 316LN;

[0023] The RRR value of the wrapped copper tape (7) and / or the shunt copper matrix (11) is greater than 100 and is in a soft state or a semi-soft state.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. A high-temperature superconducting coil structure provided by the present invention allows the use of long-length CICC conductors to wind superconducting magnets while improving the inherent thermal stability and safety of the magnet, greatly reducing the number of coil joints and reducing the heat generated by the joints; the superconducting magnet is divided into multiple sections by a parallel shunt bypass, and the shunt bypass serves as both a refrigerant inlet and outlet of the magnet and a fast energy dissipation and energy transfer circuit during magnet quench protection, which not only improves the magnet cooling efficiency but also increases the energy dissipation speed of the magnet quench section;

[0026] 2. The shunt bypass joint in the present invention is arranged in the jump turn transposition area between the magnet layers, making full use of the gap in the transposition area, while maintaining the mechanical strength of the magnet without increasing the volume of the magnet, and the influence on the magnetic field quality of the magnet can be ignored;

[0027] 3. The lap-jointed shunt bypass joint of the present invention does not change the high-temperature superconducting cable structure inside the CICC conductor. During normal operation, the shunt parallel joint does not generate heat. The longer lap length ensures that the joint has a lower contact resistance, ensuring that the shunt joint does not overheat and burn during the shunt energy dissipation process.

[0028] 4. The sufficient cooling flow and armor thickness of the shunt bypass in the present invention can ensure that the joint has sufficient mechanical strength, and the welding of the joint armor in the shunt bypass will not cause the high-temperature superconducting tape to overheat and cause the current carrying performance to decline. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0030] Figure 1 is a schematic diagram of the overall structure of an embodiment of the present invention;

[0031] Figure 2 is a cross-sectional view of a high-temperature superconducting armored internally cooled conductor in an embodiment of the present invention;

[0032] Figure 3 is a cross-sectional view of a joint in an embodiment of the present invention, a is a cross-sectional view, and b is an axial cross-sectional view;

[0033] Figure 4 Schematic diagram of the refrigerant passage in an embodiment of the present invention.

[0034] Marks and corresponding parts names in the attached drawings:

[0035] 1. Solenoid superconducting coil; 2. Shunt bypass; 3. Joint; 4. Positive and negative excitation poles; 5. Superconducting cable; 6. First cooling channel; 7. Wrapping copper tape; 8. Stainless steel cladding; 9. First insulating layer; 10. High-temperature superconducting stack; 11. Shunt copper matrix; 12. Joint armor; 13. Second insulating layer; 14. Second cooling channel; 15. Longitudinal cooling hole. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0037] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly on the other component or indirectly on the other component. When a component is referred to as being "connected to" another component, it can be directly or indirectly connected to the other component.

[0038] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] Embodiment: A high temperature superconducting coil structure, such as Figure 1As shown, it includes a solenoid superconducting coil 1, a plurality of shunt bypasses 2 and a joint 3. The solenoid superconducting coil 1 is arranged in a layer-wound manner, and is provided with a first cooling channel 6 arranged along the axial direction of the wire. The shunt bypasses 2 are arranged at intervals on the solenoid superconducting coil 1, and are provided with a second cooling channel 14. The shunt bypasses 2 are connected to the solenoid superconducting coil 1 in an overlapping manner to form a joint 3, and one or more longitudinal cooling holes 15 are provided in the joint 3 to connect the first cooling channel 6 and the second cooling channel 14.

[0041] In this embodiment, the solenoid superconducting coil 1 has 4 layers, each layer has 30 turns, and the total number of turns is 120. The overlapping length of the joint 3 is 20-30% of the diameter of the solenoid superconducting coil 1.

[0042] like Figure 2 As shown, the solenoid superconducting coil 1 is wound with a high-temperature superconducting armored inner cooling conductor; the high-temperature superconducting armored inner cooling conductor includes a superconducting cable 5, a wrapped copper belt 7, a stainless steel cladding 8 and a first insulating layer 9 arranged in sequence from the inside to the outside, the superconducting cable 5 is twisted by a plurality of high-temperature superconducting strands, and the gaps between the high-temperature superconducting strands and the wrapped copper belt 7 and the gaps between the high-temperature superconducting strands constitute a first cooling channel 6, and the first cooling channel 6 is a forced flow cooling channel. In this embodiment, the first insulation can be made of polyimide and glass cloth.

[0043] In this embodiment, taking the following structural dimension parameters as an example, the inner diameter of the stainless steel cladding 8 of the coil conductor is 13 mm, and the outer side length is 20 mm; the inner diameter of the joint armor 12 at the joint 3 is 14 mm, the short side length is 24 mm, the long side is 32 mm, and the overlap length is 200 mm; the stainless steel cladding 8 and / or the joint armor 12 are made of material N50; the RRR value of the wrapped copper tape 7 and / or the shunt joint is greater than 100, and the yield strength is about 80 MPa.

[0044] Among them, the wrapped copper tape 7 absorbs the inward contraction stress of the armor during preparation, preventing the high-temperature superconducting strands from being subjected to excessive strain and losing superconductivity. The wrapped copper tape 7 can increase the shunt capacity between the strands and the conductivity between the strands and the shunt copper matrix 11 at the joint 3, thereby reducing the resistance of the shunt joint.

[0045] like Figure 3 As shown, the shunt bypass 2 adopts another armored internal cooling conductor; the armored internal cooling conductor includes a high-temperature superconducting stack 10, a shunt copper matrix 11, a joint armor 12 and a second insulating layer 13 arranged in sequence from the inside to the outside; the gap between the shunt copper matrix 11 and the joint armor 12 constitutes a second cooling channel 14.

[0046] When the shunt bypass 2 is overlapped with the solenoid superconducting coil 1, the shunt copper matrix 11 in the shunt bypass 2 contacts the wrapped copper tape 7 in the solenoid superconducting coil 1, and the longitudinal cooling hole 15 penetrates the shunt copper matrix 11 in the shunt bypass 2 and the high-temperature superconducting stack 10.

[0047] The shunt bypass 2 is arranged at the jump turn position at the end of the solenoid superconducting coil 1, which is convenient for leading out to make the shunt joint 3 and has sufficient mechanical strength without occupying more space.

[0048] At the joint 3, the upper stainless steel cladding 8 and the first insulating layer 9 of the high-temperature superconducting armored inner cooling conductor of the coil are symmetrically cut off to expose the wrapped copper tape 7, the shunt copper matrix 11 is crimped to the wrapped copper tape 7, and the high-temperature superconducting stack 10 of the shunt bypass 2 is low-temperature brazed into the prefabricated square hole of the shunt copper matrix 11. The gap between the shunt copper matrix 11 and the joint armor 12 constitutes a second cooling channel 14, and the second cooling channel 14 is connected to the first cooling channel 6 in the coil conductor through longitudinal cooling holes 15 distributed in the overlap area of ​​the joint 3. The joint armor 12 is connected to the stainless steel cladding 8 of the coil conductor by laser welding to form a weld. After welding, the weld is leak-checked to ensure that there are no tiny holes, and finally the first insulating layer 9 is wrapped.

[0049] When making the shunt joint 3, a certain length (such as 200 mm) of the upper armor of the stainless steel cladding 8 is removed by pre-sampling precision mechanical cutting, while no obvious damage is caused to the wrapped copper tape 7, and the wrapped copper tape 7 is retained; similarly, a lower armor of the joint armor 12 in the armored internal cooling conductor of the same length (such as 200 mm) is removed by pre-sampling precision mechanical cutting, and it is ensured that the area size of the coil armored internal cooling conductor and the shunt armored internal cooling conductor after part of the armor is removed is consistent, so that overlap can be achieved; then the joint armor 12 and the shunt copper matrix 11 are attached to the partially removed coil conductor at a pressure of 10 to 30 MPa, ensuring that the shunt bypass 2 conductor is always coplanar and parallel to the center line of the coil conductor, and flowing cooling water is introduced into the coil conductor cooling channel during welding to avoid the high temperature of the stainless steel armor being transferred to the high-temperature superconducting strand during welding, causing it to overheat and cause superconductivity degradation. Since the stainless steel armor at the shunt joint 3 is strengthened, the joint 3 can have sufficient mechanical strength to withstand the electromagnetic stress during normal operation and the stress concentration caused by the asymmetric stress at the joint 3 during energy dissipation.

[0050] The head and tail ends of the solenoid superconducting coil 1 are connected to the power feeder as the lead wires of the coil excitation positive and negative electrodes 4. When the number of coil layers is N, a maximum of N coil segments can be set, that is, each layer of coil is a segment, and the maximum number of shunt bypasses 2 set is N-1. The coil excitation positive and negative electrodes 4 and the shunt bypass 2 point in the same direction, which is conducive to the lead-out of the feeder, the shunt and collection of the refrigerant, and the reduction of the magnet volume.

[0051] like Figure 4As shown, the excitation positive and negative poles 4 and the shunt bypass 2 on the same end face serve as the coil refrigerant inlet, and the shunt bypass 2 on the opposite side serves as the coil refrigerant outlet. The refrigerant inlet and outlet flow rates of a single shunt bypass 2 are twice those of the positive and negative poles. Under normal operating conditions, no current passes through the shunt bypass 2, and only the positive and negative current lead joints have obvious heat generation. Each shunt joint 3 has no significant heat generation (because the coil is wound with a long length conductor, there are distributed low-resistance joints 3 inside the conductor, and the heat generation is extremely small compared to the heat generation of the current lead joints and the positions are dispersed), and the cooling flow rate of each coil segment is close. Under the quench protection condition, the abnormal coil segment will generate a large amount of local heat generation, and the current will also generate heat at the shunt joint 3 when it passes through the shunt copper matrix 11 and enters the shunt bypass 2 to quickly discharge energy. Therefore, the cooling flow rate of the abnormal coil segment can be increased to reduce the local temperature rise rate of the coil.

[0052] Compared with the non-segmented parallel shunt structure coil, the present invention divides the coil into four sections for cooling and shunt protection without adding the coil joint 3 and the heat load, thereby increasing the coil cooling capacity by four times. Under the condition of the same energy dissipation resistance, the segmented energy dissipation speed of the protected coil is increased by several times or more, thus greatly improving the effectiveness and reliability of quench protection of high-temperature superconducting magnets.

[0053] Working principle: While improving the inherent thermal stability and safety of the magnet, the present invention allows the use of long-length CICC conductors to wind superconducting magnets, greatly reducing the number of coils (existing high-temperature superconducting coils are assembled using multiple coils, and the coils are connected using resistance joints. During steady-state operation, the heat generated by the joints is the main heat source of the magnet, that is, the main thermal disturbance and low-temperature heating load). Distributed internal joints replace traditional multi-coil joints to improve the thermal stability of the magnet; the superconducting magnet is divided into multiple sections by a parallel shunt bypass 2, which serves as both the refrigerant inlet and outlet of the magnet and a rapid energy dissipation and energy transfer circuit during magnet quench protection, which not only improves the magnet cooling efficiency but also increases the energy dissipation speed of the magnet quench section;

[0054] In addition, the lap-jointed joint 3 of the shunt bypass 2 in the present invention does not change the high-temperature superconducting cable structure inside the CICC conductor. During normal operation, the shunt parallel joint 3 does not generate heat. The longer lap length ensures that the joint 3 has a lower contact resistance, ensuring that the shunt joint 3 does not overheat and burn during the shunt energy release process.

[0055] In addition, the sufficient cooling flow and armor thickness of the shunt bypass 2 in the present invention can ensure that the joint 3 has sufficient mechanical strength, and the welding of the joint armor 12 in the shunt bypass 2 will not cause the high-temperature superconducting tape to overheat and cause the current carrying performance to decline.

[0056] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high temperature superconducting coil structure, characterized in that: include: The solenoid superconducting coil (1) is arranged in a layer-wound manner and is provided with a first cooling channel (6) arranged along the axial direction of the conductor; At least one shunt bypass (2) is arranged at intervals on the solenoid superconducting coil (1) and is provided with a second cooling channel (14); The shunt bypass (2) is connected to the solenoid superconducting coil (1) in an overlapping manner to form a joint (3), and at least one longitudinal cooling hole (15) is provided in the joint (3) for connecting the first cooling channel (6) and the second cooling channel (14).

2. A high temperature superconducting coil structure according to claim 1, characterized in that: The solenoid superconducting coil (1) is wound with a high-temperature superconducting armored internally cooled conductor; The high-temperature superconducting armored internally cooled conductor comprises a superconducting cable (5), a wrapped copper tape (7), a stainless steel cladding (8) and a first insulating layer (9) which are arranged in sequence from the inside to the outside; The superconducting cable (5) is formed by twisting a plurality of high-temperature superconducting strands, and the gaps between the high-temperature superconducting strands and the wrapped copper tape (7) and the gaps between the high-temperature superconducting strands form a first cooling channel (6).

3. A high temperature superconducting coil structure according to claim 1, characterized in that: The current shunt bypass (2) adopts an armored internally cooled conductor; The armored inner cold conductor comprises a high temperature superconducting stack (10), a shunt copper matrix (11), a joint armor (12) and a second insulating layer (13) which are arranged in sequence from the inside to the outside; The gap between the shunt copper substrate (11) and the joint armor (12) forms a second cooling channel (14).

4. A high temperature superconducting coil structure according to claim 1, characterized in that: When the shunt bypass (2) is overlapped with the solenoid superconducting coil (1), the shunt copper matrix (11) in the shunt bypass (2) contacts the wrapped copper tape (7) in the solenoid superconducting coil (1), and the longitudinal cooling hole (15) penetrates the shunt copper matrix (11) in the shunt bypass (2) and the high-temperature superconducting stack (10).

5. A high temperature superconducting coil structure according to claim 1, characterized in that: The shunt bypass (2) is arranged at the jump turn position at the end of the solenoid superconducting coil (1).

6. A high temperature superconducting coil structure according to claim 1, characterized in that: The conductor in the shunt bypass (2) is coplanar and parallel to the conductor center line of the solenoid superconducting coil (1).

7. A high temperature superconducting coil structure according to claim 1, characterized in that: The positive and negative excitation poles (4) of the solenoid superconducting coil (1) and the shunt bypass (2) point in the same direction.

8. A high temperature superconducting coil structure according to claim 1, characterized in that: The overlapping length of the joint (3) is 20-30% of the diameter of the solenoid superconducting coil (1).

9. A high temperature superconducting coil structure according to claim 1, characterized in that: The two ends of the solenoid superconducting coil (1) are connected to the power supply line as the coil excitation positive and negative poles (4) lead wires; when the number of coil layers of the solenoid superconducting coil (1) is N, each coil layer is used as a coil segment, and the number of shunt bypasses (2) is set to N-1 at most.

10. A high temperature superconducting coil structure according to claim 2, characterized in that: The stainless steel cladding (8) and / or the joint armor (12) are made of low-temperature high-strength steel, and the low-temperature high-strength steel includes materials N50 and 316LN; The RRR value of the wrapped copper tape (7) and / or the shunt copper matrix (11) is greater than 100 and is in a soft state or a semi-soft state.

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