Lightweight composite superconducting magnet and manufacturing method thereof

Abstract

The invention provides a lightweight composite superconducting magnet and a manufacturing method thereof, and belongs to the technical field of superconducting magnets, the lightweight composite superconducting magnet comprises a solenoid magnet coil formed by winding different superconducting materials on the same skeleton, a low-resistance joint and a magnet coil current lead; the magnet not only can stably operate under the condition of liquid helium soaking, but also has the stable operation characteristic under the condition of a conduction cooling mode, the size scale of a superconducting magnet of 10 T or above can be effectively reduced, the space utilization rate of a superconducting material is improved, the overall mass of the magnet is reduced, and the conduction cooling time of the magnet is shortened; in addition, the magnet of the structure type can reduce the total inductance of the magnet, shorten the excitation time consumption of the magnet and increase the field sweeping rate of the magnet while reducing the development cost of the magnet, and the magnet of the structure type can stably operate under the condition of high load rate; and a feasible implementation scheme is provided for design and preparation of light-weight superconducting magnets with high-parameter steady-state operation of 10T and above.

Description

Technical Field

[0001] This invention relates to the field of superconducting magnet technology, and in particular to a lightweight composite superconducting magnet and its fabrication method. Background Technology

[0002] Large-aperture experimental composite superconducting magnets are key devices designed specifically for the study of superconducting material properties. Their core function is to simulate extreme conditions and test the core parameters of superconducting materials by generating high-intensity steady-state magnetic fields. To achieve this goal and fully leverage the advantages of practical superconducting materials with different performance levels in their respective magnetic field regions, while minimizing the manufacturing cost of the magnet, current technologies generally employ composite coil structures made of Nb3Sn and NbTi superconducting materials.

[0003] However, in existing designs, the coils of the two materials need to be wound independently on discrete frame structures, which leads to the following problems with this type of superconducting magnet: 1. Discrete frames result in repetitive design of support structures and high structural redundancy; 2. Multi-frame layout produces ineffective gaps, resulting in low space utilization and increased magnet volume; 3. The addition of frame material increases the total mass of the system; 4. High manufacturing cost; 5. High inductance, long excitation time, and low sweep rate. Therefore, these problems urgently need to be solved. Summary of the Invention

[0004] To overcome the above-mentioned technical problems, the present invention provides a lightweight composite superconducting magnet and its manufacturing method. The lightweight composite superconducting magnet has the characteristics of large aperture, compact structure, low weight, simple manufacturing and stable performance.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A lightweight composite superconducting magnet includes a solenoid magnet coil wound with different superconducting materials on the same frame, a low-resistance connector, and magnet coil current leads. The solenoid magnet coil is wound with Nb3Sn and NbTi superconducting materials, which are connected in series and wound on the same frame. The low-resistance connector segments the Nb3Sn and NbTi. The magnet coil current leads are used to excite the magnet coil by passing current through it.

[0007] Furthermore: the solenoid magnet coil wound with different superconducting materials on the same frame includes a solenoid magnet coil wound using an odd-even close winding method. From the inside out, the frame contains Nb3Sn superconducting wire and NbTi superconducting wire, connected by a low-resistance connector. The solenoid magnet coil wound with different superconducting materials on the same frame includes a straight cylinder magnet frame made of stainless steel and other high-strength non-magnetic metals, along with matching upper and lower flange structures, a straight cylinder insulation layer, end insulation layers, a superconducting coil, and a pre-tensioned coil. The magnet skeleton cylinder has a wall thickness of 4mm or less. The matching upper and lower flanges of the magnet skeleton have through holes at their centers that match the outer diameter of the cylinder, and are fixedly connected to both ends of the cylinder by welding. Several non-through threaded holes are distributed on the outer circumference of the flanges, with the upper flange of the magnet skeleton having an axial opening to form the inlet and outlet ports of the superconducting coil. Threaded holes are provided at both ends outside this opening area for installing low-resistance connectors and magnet coil current leads. The insulating layer of the cylinder is made of insulating material (such as... The outer surface of the straight cylindrical section of the magnet frame is covered with high-temperature resistant insulating composite materials such as mica and fiberglass cloth. The end insulation layer is used for the Nb3Sn coil end (such as mica, fiberglass, aluminum nitride, etc.) and the NbTi coil end (such as G10, Kapton, Teflon, etc.). The outer diameter of the Nb3Sn coil end insulation layer is the same as the inner diameter of the NbTi superconducting coil. The outer diameter of the NbTi coil end insulation layer is the same as the outer diameter of the upper and lower flanges of the magnet frame. The superconducting wire is made of Nb3Sn and NbTi. The pre-tightening coil is composed of a non-magnetic metal (such as copper, aluminum alloy, stainless steel, etc.) wound circumferentially around the outer surface of the Nb3Sn superconducting coil, with an insulating layer (such as fiberglass tape) between it and the coil body. The outer surface of the NbTi superconducting coil is also wrapped with a non-magnetic metal (such as copper, aluminum alloy, stainless steel, etc.). Multiple insulating layers (such as fiberglass cloth) are wound between the inner diameter of the pre-tightening coil and the outer diameter of the NbTi superconducting coil. The outer diameter of the pre-tightening coil is not greater than the outer diameter of the flange end face of the magnet skeleton.

[0008] Furthermore: the low-resistance connector includes a low-resistance connector bracket and a low-resistance connector insulating gasket, and the low-resistance connector is fixed to the flange on the magnet frame by fastening bolts via the low-resistance connector insulating gasket.

[0009] Furthermore: the magnet coil current lead includes an inlet and outlet end, a mounting base, and a support; the base is fixed to the outer surface of the flange open-loop area on the magnet frame by means of insulating pads and fastening bolts; the support surface is provided with grooves for fixing the superconducting current lead.

[0010] Furthermore: the superconducting magnet comes in two forms: liquid helium immersion type and conductive cooling type; the liquid helium immersion type has upper and lower fixed tooling plates and a first wiring board; the conductive cooling type has upper and lower cooling flanges, clamps, a two-pole cold head cooling flexible connection, a magnet coil current lead wiring support and a second wiring board.

[0011] Furthermore: the upper and lower fixing fixture plates of the liquid helium-immersed superconducting magnet are connected to the solenoid magnet coil by fastening bolts to fix the solenoid magnet coil. The outer ends of the upper and lower fixing fixture plates are provided with threaded holes to facilitate the hoisting of the superconducting magnet coil; the first wiring plate is connected to the magnet upper cover plate by the first screw and is used to arrange and fix the potential lines of the low-resistance connector and the current leads of the magnet coil.

[0012] Furthermore: the upper and lower flanges of the conductive cooling superconducting magnet skeleton are equipped with upper and lower cooling flanges; the superconducting magnet coil is surrounded by a clamp; the upper cooling flange is provided with a first diode cold head cooling flexible connection and a second diode cold head cooling flexible connection; the upper cooling flange is provided with magnet coil current lead routing support, located on both sides of the magnet coil current lead; a cooling plate is provided between the upper and lower cooling flanges, and is flexibly connected to the clamp; the lower cooling flange is provided with a non-through threaded hole for connecting lifting fixtures; the second cable tray is connected to the tray through a second screw, and is used to arrange and fix the potential lines of the low resistance connector and the magnet coil current leads.

[0013] Furthermore: the aforementioned conductive cooling superconducting magnet hoisting fixture includes a second hoisting screw, a tray, and a right-angle support. The superconducting magnet is mounted on the tray via the right-angle support, and the tray is connected to the Dewar flange via the second hoisting screw.

[0014] As another aspect of the present invention, a method for fabricating a lightweight composite superconducting magnet is proposed, specifically including the following steps:

[0015] S1. After insulating the surface of the magnet coil frame, reserve a set length of magnet coil current lead; fix the first end of the superconducting wire to the winding fixture, lead it out through the flange inlet end of the magnet frame, and wind the first layer tightly along the outer wall of the insulation layer of the straight section in a forward spiral trajectory until the first layer winding is completed at the lower flange end of the magnet frame; perform cross-layer transition processing: wind the second layer coil in the opposite direction along the axial groove between adjacent turns of the first layer in a same spiral trajectory until the upper flange end of the magnet frame is fitted into the gap between the first and second turns of the first layer; repeat the cross-layer process: wind the third layer coil along the groove between the turns of the second layer in a forward spiral trajectory, so that the first turn of the third layer is positioned at the gap between the upper flange of the magnet frame and the first turn of the second layer; cycle the operation according to the odd and even layer reverse winding rule until the preset number of layers is reached;

[0016] S2. After completing the specified number of layers of winding of Nb3Sn wire, complete the superconducting wire wiring at the low resistance connector; fully wrap the solenoid magnet coil; use a hose clamp to lock the coil lead end in the winding fixture;

[0017] S3. Fix the beginning of the Nb3Sn pre-tightening material to the winding fixture, introduce it through the inlet end of the upper flange of the magnet frame, and wind the first layer of the pre-tightening coil in a forward spiral trajectory along the outer wall of the magnet coil covered with glass fiber cloth, until the winding is completed at the lower flange end; perform the pre-tightening coil cross-layer processing: wind the second layer of the pre-tightening coil in the forward direction along the groove between the first layer turns to the upper flange end of the magnet frame; repeat the above cross-layer winding process until the preset number of layers is reached, and return the terminal lead to the upper flange end of the magnet frame; use a hose clamp to lock the outlet end of the pre-tightening coil in the positioning groove of the winding fixture;

[0018] S4. Perform high-temperature heat treatment on the wound Nb3Sn superconducting coil; put the magnet coil into the packaging fixture, and inject low-temperature curing resin into the skeleton flange to the preset reference scale line under a certain temperature and vacuum environment, and stop the injection; wait for the low-temperature epoxy resin to be heated and cured.

[0019] S5. Connect the NbTi superconducting wire and the Nb3Sn superconducting coil in series and use them as the input end for winding the NbTi wire. Wind the NbTi superconducting wire tightly and wetly along the outer wall of the pre-tightened coil insulation layer of the Nb3Sn superconducting coil in a clockwise direction. The odd-even winding method is the same as in step S1. When the NbTi superconducting coil reaches the specified number of layers, return the winding end to the flange end on the magnet frame. Use a hose clamp to lock the magnet coil output end and fix the magnet coil output end on the winding fixture.

[0020] S6. Fix one end of the NbTi pre-tightening material to the winding fixture, and wind the NbTi pre-tightening material tightly along the outer wall of the magnet coil through the flange inlet end of the magnet skeleton. The winding method is the same as step S3. After the NbTi pre-tightening material is wound, the lightweight superconducting magnet coil is completed.

[0021] S7. For liquid helium immersion superconducting magnets, connect the superconducting magnet coil to the upper and lower end plates of the magnet; install a wiring board, and extend the current lead of the magnet coil through the wiring board to make a superconducting magnet; for conduction-cooled superconducting magnets, install a clamp on the outer ring of the superconducting magnet coil, install upper and lower cooling flanges on the upper and lower flanges of the frame, install the first and second polarity cold head cooling flexible connection, the second polarity cold head cooling flexible connection, and the magnet coil current lead wiring support on the upper cooling flange. The connection method of each cooling component is flexible connection. Finally, install the hoisting fixture to make a superconducting magnet.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] The lightweight composite superconducting magnet proposed in this invention can generate a central magnetic field of ≥10T under a stable current of 112A in the liquid helium temperature range of 4.2K, and the aperture of the magnet is ≥80mm. This invention uses different superconducting materials to share the same frame, which effectively reduces the size of the composite magnet coil, improves space utilization, reduces the overall mass of the composite superconducting magnet, and makes the structure simpler. This invention can be implemented in two forms: liquid helium immersion type and conduction cooling type. Furthermore, this invention can reduce inductance, shorten excitation time, and improve sweep rate by enhancing coil coupling. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the three-dimensional structure of the coil of the lightweight composite superconducting magnet of the present invention.

[0025] Figure 2 This is a full cross-sectional view of the coil of the lightweight composite superconducting magnet of the present invention.

[0026] Figure 3 This is a schematic diagram of the magnet coil connector and current lead of the lightweight composite superconducting magnet of the present invention.

[0027] Figure 4 This is a schematic diagram of the liquid helium immersion superconducting magnet of the lightweight composite superconducting magnet of the present invention.

[0028] Figure 5 This is a schematic diagram of a conductive cooling superconducting magnet for the lightweight composite superconducting magnet of the present invention.

[0029] In the diagram: 1-Solenoid magnet coils wound on the same frame using different superconducting materials; 2-Low resistance connector; 3-Current lead of the magnet coil; 4-Liquid helium-immersed superconducting magnet; 5-Conductively cooled superconducting magnet; 11-Nb3Sn superconducting coil; 12-NbTi superconducting coil; 13-Straight cylinder of the magnet frame; 14-Upper flange of the magnet frame; 15-Lower flange of the magnet frame; 16-End insulation layer of the Nb3Sn coil; 17-End insulation layer of the NbTi coil; 18-Insulation layer of the straight cylinder of the frame; 19-Insulation layer between the Nb3Sn pre-tightened coil and NbTi; 111-Nb3Sn pre-tightened coil; 121-NbTi pre-tightened coil. 21-Low resistance connector bracket, 22-Low resistance connector insulating gasket, 31-Magnet coil current lead inlet, 32-Magnet coil current lead outlet, 33-Magnet coil current lead insulating gasket, 41-Upper fixed fixture plate, 42-Lower fixed fixture plate, 43-First screw, 44-First cable tray, 51-Upper cooling flange, 52-Lower cooling flange, 53-Clamp, 54-First and second stage cold head cooling flexible connection, 55-Second stage cold head cooling flexible connection, 56-Cooling plate, 57-Right angle support, 58-Pattern, 59-Second screw, 510-Second cable tray, 511-Magnet coil current lead routing support. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] Example:

[0032] According to one embodiment of the present invention, a lightweight composite superconducting magnet is proposed, see appendix. Figure 1 It includes a solenoid magnet coil 1 made of different superconducting materials wound on the same frame, the wires used are Nb3Sn and NbTi, a low resistance connector 2, and magnet coil current leads 3.

[0033] See appendix Figure 2 The solenoid magnet coil 1 includes a magnet skeleton cylinder 13, a magnet skeleton upper flange 14, a magnet skeleton lower flange 15, an Nb3Sn coil end insulation layer 16, an NbTi coil end insulation layer 17, a skeleton cylinder insulation layer 18, an insulation layer 19 between the Nb3Sn pre-tightening coil and the NbTi coil, an Nb3Sn superconducting coil 11, an NbTi superconducting coil 12, an Nb3Sn pre-tightening coil 111, and an NbTi pre-tightening coil 121. The magnet skeleton upper flange 14 and the magnet skeleton lower flange 15 are welded to both ends of the magnet skeleton cylinder 13. The skeleton cylinder insulation layer 18 covers the outer wall of the skeleton cylinder 13. The Nb3Sn coil end insulation layer 16 and the NbTi coil end insulation layer 17 are fixed to the outer wall. Insulation layer 19 between the inner sides of the upper and lower flanges and between the Nb3Sn pre-tightening coil and the NbTi coil; Nb3Sn superconducting coil 11 is tightly wound along the outer surface of the straight cylindrical insulation layer 18 of the skeleton using a positive spiral trajectory. After this process is completed, Nb3Sn pre-tightening coil 111 is immediately coaxially wound on its outer side; after the Nb3Sn pre-tightening coil is wound, insulation layer 19 between the Nb3Sn pre-tightening coil and the NbTi coil is wound. Then, the NbTi superconducting coil 12 is connected to the former in series through the low resistance connector 2. When this coil is wound, the same winding mode is continued along the outer wall of the insulation layer 19 between the Nb3Sn pre-tightening coil and the NbTi coil. Finally, NbTi pre-tightening coil 121 is applied to the outer layer of the NbTi superconducting coil.

[0034] See appendix Figure 3The low-resistance connector 2 includes a low-resistance connector bracket 21 and a low-resistance connector insulating gasket 22. The low-resistance connector is fixed to the upper flange 14 of the magnet frame via the low-resistance connector insulating gasket 22 and fastening bolts. The magnet coil current lead 3 includes a magnet coil current lead inlet 31, a magnet coil current lead outlet 32, and a magnet coil current lead insulating gasket 33. After the superconducting coil is wound to a specified number of layers, the superconducting wire is connected at the open loop of the upper flange 14 of the magnet frame along the magnet coil current lead inlet 31 and the magnet coil current lead outlet 32. The magnet current lead inlet 31 and the magnet current lead outlet 32 ​​are fixed to the upper flange 14 of the magnet frame via the magnet coil current lead insulating gasket 33 and fastening bolts.

[0035] See appendix Figure 4 The upper fixed fixture plate 41 and the lower fixed fixture plate 42 of the liquid helium-immersed superconducting magnet 4 are connected to the upper flange 14 and the lower flange 15 of the magnet skeleton through the first screw 43; the first cable board 44 is connected to the upper fixed fixture plate 41 above the first fixed fixture plate 41 through the first screw 43 and the nut.

[0036] See appendix Figure 5 The upper cooling flange 51 and lower cooling flange 52 of the conductive cooling superconducting magnet 5 are fixed to the upper flange 14 and lower flange 15 of the magnet skeleton by fastening bolts. The clamp 53 is tightly attached to the magnet coil on both sides by fastening bolts. The cooling plate 56 between the upper cooling flange 51 and lower cooling flange 52 is flexibly connected to the clamp 53. The first and second stage cold head cooling flexible connection 54 and the second stage cold head cooling flexible connection 55 are located on the upper cooling flange 51 and fixed by bolts. The magnet coil current lead wire routing support 511 is fixed to the upper cooling flange 51 by fastening bolts and is located on the left and right sides of the opening loop of the magnet coil current lead wire. Then, the magnet is placed on the tray 58 by the right angle support 57 and hoisted to the Dewar by the second screw 59. The second wiring plate 510 is located above the upper cooling flange 51 and is fixed by the second screw 59 and nut.

[0037] According to an embodiment of the present invention, a method for fabricating a lightweight composite superconducting magnet is proposed, which specifically includes the following steps:

[0038] Step 1: After insulating the surface of the magnet coil frame, reserve a set length of magnet coil current lead; fix the first end of the superconducting wire to the winding fixture, lead it out through the flange inlet end of the magnet frame, and wind the first layer tightly along the outer wall of the insulation layer of the straight section in a forward spiral trajectory until the lower flange end completes the first layer winding; perform the cross-layer transition process: wind the second layer coil in the opposite direction along the axial groove between adjacent turns of the first layer in a same spiral trajectory until the flange end of the magnet frame is fitted into the gap between the first and second turns of the first layer; repeat the cross-layer process: wind the third layer coil along the groove between the turns of the second layer in a forward spiral trajectory, so that the first turn of the third layer is positioned at the gap between the flange of the magnet frame and the first turn of the second layer; repeat the operation according to the odd and even layer reverse winding rule until the preset number of layers is reached;

[0039] Step 2: After completing the specified number of layers of Nb3Sn wire winding, complete the superconducting wire wiring on the low-resistance connector bracket; fully wrap the solenoid magnet coil; use a hose clamp to lock the coil lead end to the winding fixture;

[0040] Step 3: Fix the beginning of the Nb3Sn pre-tightening material to the winding fixture, introduce it through the inlet end of the upper flange of the magnet frame, and wind the first layer of the pre-tightening coil in a forward spiral trajectory along the outer wall of the magnet coil covered with glass fiber cloth, until the winding is completed at the lower flange end; perform the pre-tightening coil cross-layer processing: wind the second layer of pre-tightening coil in the forward direction along the groove between the first layer turns to the upper flange end of the magnet frame; repeat the above cross-layer winding process until the preset number of layers is reached, and return the terminal lead to the upper flange end of the magnet frame; use a hose clamp to lock the outlet end of the pre-tightening coil in the positioning groove of the winding fixture;

[0041] Step 4: Perform high-temperature heat treatment on the wound Nb3Sn superconducting coil; then weld the low-resistance connector potential line and the extension line of the magnet coil current lead to the solenoid magnet coil respectively; put the magnet coil into the packaging fixture, and pour low-temperature curing resin into the skeleton flange to the preset reference scale line under a certain temperature and vacuum environment, and stop the injection; wait for the low-temperature epoxy resin to be heated and cured.

[0042] Step 5: Connect the NbTi superconducting wire in series with the Nb3Sn superconducting coil through a low-resistance connector, and use this low-resistance connector as the input end for winding the NbTi wire. Tightly wet-wind the NbTi superconducting wire along the outer wall of the pre-tightened coil insulation layer of the Nb3Sn superconducting coil in a clockwise direction. The odd-even winding method is the same as in Step 1. When the NbTi superconducting coil reaches the specified number of layers, return the winding end to the flange end on the magnet frame, use a hose clamp to lock the magnet coil output end, and fix the magnet coil output end on the winding fixture.

[0043] Step 6: Fix one end of the NbTi preload material to the winding fixture, and wind the NbTi preload material tightly along the outer wall of the magnet coil through the flange inlet end of the magnet frame. The winding method is the same as in Step 3. After the NbTi preload material is wound, the lightweight superconducting magnet coil is completed.

[0044] Step 7: For liquid helium immersion superconducting magnets, connect the superconducting magnet coil to the upper and lower end plates of the magnet; install a wiring board, and extend the current lead of the magnet coil through the wiring board to form a superconducting magnet; for conduction-cooled superconducting magnets, install a clamp on the outer ring of the superconducting magnet coil, install upper and lower cooling flanges on the upper and lower flanges of the frame, install the first and second polarity cold head cooling flexible connection, the second polarity cold head cooling flexible connection, and the magnet coil current lead wiring support on the upper cooling flange. The connection method of each cooling component is flexible connection. Finally, install the hoisting fixture to form a superconducting magnet.

[0045] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes will be obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A lightweight composite superconducting magnet, characterized in that: It includes a solenoid magnet coil wound with different superconducting materials on the same frame, a low-resistance connector, and magnet coil current leads; The solenoid magnet coil, which is made of different superconducting materials wound on the same frame, is made of Nb3Sn and NbTi superconducting materials, and the two superconducting materials are connected in series and wound on the same frame. The low-resistance connector is segmented for Nb3Sn and NbTi; The magnet coil current lead is used to excite the magnet coil by passing current through it. The solenoid magnet coil, which is made of different superconducting materials wound on the same frame, includes a solenoid magnet coil wound using an odd-even close winding method. The frame has Nb3Sn superconducting wire and NbTi superconducting wire from the inside to the outside, and the two types of superconducting wire are connected by a low-resistance connector.

2. The lightweight composite superconducting magnet according to claim 1, characterized in that: The solenoid magnet coil, wound with different superconducting materials on the same frame, includes a magnet frame cylinder made of stainless steel and matching upper and lower flanges of the magnet frame, as well as a cylinder insulation layer, end insulation layers, a superconducting coil, and a pre-tightening coil. The wall thickness of the magnet frame cylinder is less than or equal to 4 mm. The matching upper and lower flanges of the magnet frame have through holes at their center that match the outer diameter of the magnet frame cylinder, and are fixedly connected to both ends of the magnet frame cylinder by welding. The outer circumferential surface of the upper and lower flanges of the magnet frame has several non-through threaded holes, among which the upper flange has an axial opening to form the inlet and outlet of the superconducting coil. Threaded holes are provided at both ends outside the opening area for installing low-resistance connectors and magnet coil current leads.

3. A lightweight composite superconducting magnet according to claim 2, characterized in that: The straight cylindrical insulating layer is made by covering the outer surface of the straight cylindrical section of the magnet skeleton with insulating material; the ends of the Nb3Sn superconducting coil and the ends of the NbTi superconducting coil in the end insulating layer are made of insulating material, the outer diameter of the Nb3Sn coil end insulating layer is the same as the inner diameter of the NbTi superconducting coil, and the outer diameter of the NbTi coil end insulating layer is the same as the outer diameter of the upper flange and the lower flange of the magnet skeleton; the materials of the superconducting coil are Nb3Sn and NbTi; the pre-tightening coil is made by circumferentially winding non-magnetic metal on the outer surface of the Nb3Sn superconducting coil, with an insulating isolation layer between it and the coil body, circumferentially winding non-magnetic metal on the outer surface of the NbTi superconducting coil, and multiple insulating layers are wound between the inner diameter of the pre-tightening coil and the outer diameter of the NbTi superconducting coil, and the outer diameter of the pre-tightening coil is not greater than the outer diameter of the end face of the magnet skeleton flange.

4. A lightweight composite superconducting magnet according to claim 1, characterized in that: The low-resistance connector includes a low-resistance connector bracket and a low-resistance connector insulating gasket. The low-resistance connector is fixed to the flange on the magnet frame by fastening bolts via the low-resistance connector insulating gasket.

5. A lightweight composite superconducting magnet according to claim 1, characterized in that: The magnet coil current lead includes an inlet and outlet end, a base, and a support; the base is fixed to the outer surface of the flange open-loop area on the magnet frame by means of insulating pads and fastening bolts; the support surface is provided with grooves for fixing the superconducting current lead.

6. A lightweight composite superconducting magnet according to claim 1, characterized in that: The superconducting magnet has two forms: liquid helium immersion type and conductive cooling type; the liquid helium immersion type has an upper fixed fixture plate, a lower fixed fixture plate and a first wiring board; the conductive cooling type has an upper cooling flange, a lower cooling flange, a clamp, a two-pole cold head cooling flexible connection, a magnet coil current lead wiring support and a second wiring board.

7. A lightweight composite superconducting magnet according to claim 6, characterized in that: The upper and lower fixing fixture plates of the magnet are made of stainless steel and are connected to the solenoid magnet coil by fastening bolts to fix the solenoid magnet coil. The outer ends of the upper and lower fixing fixture plates are provided with threaded holes to facilitate the hoisting of the superconducting magnet coil. The first wiring plate is connected to the upper fixing fixture plate of the magnet by the first screw and is used to arrange and fix the potential lines of the low resistance connector and the current leads of the magnet coil.

8. A lightweight composite superconducting magnet according to claim 6, characterized in that: The superconducting magnet skeleton has upper and lower flanges with upper and lower cooling flanges installed on its upper and lower flanges; the superconducting magnet coil is surrounded by a clamp; the upper cooling flange is provided with a first diode cooling head flexible connection and a second diode cooling head flexible connection; the upper cooling flange is provided with a magnet coil current lead routing support, located on both sides of the magnet coil current lead; a cooling plate is provided between the upper and lower cooling flanges for connection with the clamp; the lower cooling flange is provided with a non-through threaded hole for connection with lifting fixtures; the second wiring plate is connected to the support plate by a screw and is used to arrange and fix the potential lines of the low-resistance connector and the magnet coil current lead.

9. A lightweight composite superconducting magnet according to claim 8, characterized in that: The hoisting fixture includes a second screw, a tray, and a right-angle support. The superconducting magnet is supported on the tray by the right-angle support, and the tray is connected to the Dewar flange by the second hoisting screw.

10. A method for fabricating a lightweight composite superconducting magnet, used to fabricate any one of the superconducting magnets according to claims 1-9, characterized in that, Includes the following steps: Step 1: After insulating the surface of the magnet coil frame, reserve a set length of magnet coil current lead; fix the first end of the superconducting wire to the winding fixture, lead it out through the flange inlet end of the magnet frame, and wind the first layer tightly along the outer wall of the insulation layer of the straight section in a forward spiral trajectory until the first layer winding is completed at the lower flange end of the magnet frame; perform the cross-layer transition process: wind the second layer coil in the opposite direction along the axial groove between adjacent turns of the first layer in a same spiral trajectory until the upper flange end of the magnet frame is fitted into the gap between the first and second turns of the first layer; repeat the cross-layer process: wind the third layer coil along the groove between the turns of the second layer in a forward spiral trajectory, so that the first turn of the third layer is positioned at the gap between the upper flange of the magnet frame and the first turn of the second layer; repeat the operation according to the odd and even layer reverse winding rule until the preset number of layers is reached; Step 2: After completing the specified number of layers of Nb3Sn wire winding, complete the superconducting wire wiring at the low resistance connector; fully wrap the solenoid magnet coil; use a hose clamp to lock the coil lead end to the winding fixture; Step 3: Fix the beginning of the Nb3Sn pre-tightening material to the winding fixture, introduce it through the inlet end of the upper flange of the magnet frame, and wind the first layer of the pre-tightening coil in a forward spiral trajectory along the outer wall of the magnet coil covered with glass fiber cloth, until the winding is completed at the lower flange end; perform the pre-tightening coil cross-layer processing: wind the second layer of pre-tightening coil in the forward direction along the groove between the first layer turns to the upper flange end of the magnet frame; repeat the above cross-layer winding process until the preset number of layers is reached, and return the terminal lead to the upper flange end of the magnet frame; use a hose clamp to lock the outlet end of the pre-tightening coil in the positioning groove of the winding fixture; Step 4: Perform high-temperature heat treatment on the wound Nb3Sn superconducting coil; The magnet coil is installed in the encapsulation fixture, and low-temperature curing resin is poured into the skeleton flange to the preset reference scale line under a certain temperature and vacuum environment, and then the injection is stopped. Wait for the low-temperature epoxy resin to cure by heating; Step 5: Connect the NbTi superconducting wire and the Nb3Sn superconducting coil in series and use this as the input end for winding the NbTi wire. Wind the NbTi superconducting wire tightly along the outer wall of the pre-tightened coil insulation layer of the Nb3Sn superconducting coil in a clockwise direction. The odd-even winding method is the same as in Step 1. When the NbTi superconducting coil reaches the specified number of layers, return the winding end to the flange end on the magnet frame. Use a hose clamp to lock the magnet coil output end and fix the magnet coil output end on the winding fixture. Step 6: Fix one end of the NbTi preload material to the winding fixture, and wind the NbTi preload material tightly along the outer wall of the magnet coil through the flange inlet end of the magnet frame. The winding method is the same as in Step 3. After the NbTi preload material is wound, the lightweight superconducting magnet coil is completed. Step 7: For liquid helium immersion superconducting magnets, connect the superconducting magnet coil to the upper and lower end plates of the magnet; install a wiring board, and extend the current lead of the magnet coil through the wiring board to form a superconducting magnet; for conduction-cooled superconducting magnets, install a clamp on the outer ring of the superconducting magnet coil, install upper and lower cooling flanges on the upper and lower flanges of the frame, install the first and second polarity cold head cooling flexible connection, the second polarity cold head cooling flexible connection, and the magnet coil current lead wiring support on the upper cooling flange. The connection method of each cooling component is flexible connection. Finally, install the hoisting fixture to form a superconducting magnet.

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