A niobium tri-tin superconducting magnet joint

Abstract

The application discloses a Nb3Sn superconducting magnet joint, which comprises a superconducting magnet framework, an incoming line joint positioning block and an outgoing line joint positioning block, the superconducting magnet framework is provided with an incoming line groove and an outgoing line groove, the upper and lower groove openings of the incoming line groove and the outgoing line groove are in the shape of an outwardly expanding arc, the incoming line joint positioning block is arranged above the incoming line groove, and the outgoing line joint positioning block is arranged above the outgoing line groove; the incoming line joint positioning block is provided with a first welding groove in communication with the incoming line groove, and the outgoing line joint positioning block is provided with a second welding groove in communication with the outgoing line groove. The Nb3Sn superconducting joint has the advantages that the lower energy loss of the Nb3Sn superconducting joint under a high field can be effectively realized, the joint structure is simple, the joint can be integrally filled and formed in the groove body, the installation is convenient, the brittle fracture of the Nb3Sn superconducting wire caused by the disassembly of the traditional joint before and after heat treatment is avoided, the manufacturing and use costs of the joint are lower, and the installation and welding operation risks are also lower.

Description

Technical Field

[0001] This invention relates to the field of superconducting magnet technology, specifically to a niobium-tin superconducting magnet connector. Background Technology

[0002] Highly efficient superconducting magnet technology and cryogenic refrigeration technology have been widely applied in national economy, scientific experiments, national defense, nuclear magnetic resonance, magnetic levitation, and other scientific and technological fields. As a technology with near-zero resistance and zero energy consumption, superconducting magnets can achieve high current and strong magnetic fields at relatively low voltages, making them widely applicable and valuable for scientific research in fields such as integrated circuits, semiconductors, biomedicine, and new materials. The main reason why superconducting magnets cannot achieve completely zero resistance is that the superconducting joint itself is an open-circuit connection structure. Currently, no superconducting welding materials have been found internationally, therefore, the superconducting joint cannot achieve a zero-resistance superconducting state at 4K (-269℃). This situation results in a constant low-resistance heat loss in the entire current loop, causing the current in the loop to continuously decrease over time.

[0003] A superconducting connector is a fixed device that connects the two ends of a superconducting wire, or a fixed lead-out device in the transition section between the inlet / outlet connectors of a superconducting magnet and a higher external temperature region. This device has ultra-low resistance and can meet the requirements of high-temperature heat treatment of 640℃ and deep-temperature operation of superconducting magnets at 4K (-269℃). In a typical superconducting coil, the heat loss of the superconducting connector accounts for more than half of the total heat loss of the superconducting magnet, especially in closed-loop superconducting magnet systems (such as nuclear magnetic resonance imaging, nuclear magnetic resonance spectrometers, proton accelerators, etc.). However, due to the continuous decay of the current, it is impossible to achieve stable magnetic field operation for a long time, and it is necessary to perform a replenishment operation after the decay reaches a certain value.

[0004] Niobium-tin (Nb3Sn) superconducting magnets are generally used in technical fields with high magnetic fields. Compared with conventional niobium-titanium superconducting magnets, which are widely used in magnetic field strengths of 7T and below, Nb3Sn superconducting magnets are generally used in high magnetic field fields of 7T~20T. At a temperature of 4.2 K, its critical magnetic field can reach 24.5 T. Nb3Sn superconducting joints typically require complex tooling. After the Nb3Sn coil is wound, it must undergo high-temperature heat treatment in a vacuum heat treatment furnace to allow the niobium and tin inside the wire to react chemically and form the Nb3Sn superconducting phase, thus acquiring superconducting properties. However, the heat-treated Nb3Sn wire is a ceramic structure, prone to bending and brittle fracture, posing a significant risk to the manufacturing and transmission performance of the magnet. To achieve a large critical current and a high magnetic field, the transmission bottleneck of Nb3Sn superconducting magnets lies at the location of the brittle superconducting joint. The quality of the superconducting joint design directly affects the performance of Nb3Sn superconducting magnets, becoming a bottleneck restricting their development and application. Therefore, design optimization of the superconducting joint is necessary to improve the safety and stability of the magnet.

[0005] The traditional installation process of Nb3Sn superconducting connectors generally involves two steps. Before heat treatment at 640℃, a stainless steel armor sleeve is used to protect the electrical lead taps outside the magnet. After heat treatment, the stainless steel armor is removed and replaced with an oxygen-free copper armor sleeve, which has lower resistivity and higher thermal conductivity. However, due to the risk of brittle fracture of the wire after heat treatment, repeated installation, disassembly, and welding position adjustments during manual operation can easily cause the ceramic core of the Nb3Sn superconducting wire taps to crack, resulting in a significant reduction in current per unit area, high energy loss, and even loss of superconducting properties. Furthermore, to achieve lower resistance and protect the connector as much as possible, the height of the oxygen-free copper armor sleeve is usually 100mm-150mm or more. After the superconducting coil is wound, it is pulled out from the end of the toroidal coil. Because the pulled-out wire is relatively long, to avoid electromagnetic forces on the superconducting wire, its direction must be parallel to the axial magnetic field direction. Therefore, the superconducting wire needs to be bent vertically after being pulled out before large-area welding. Because the superconducting wire is subjected to bending stress, the internal stress of the wire will be released after heat treatment at 640℃, resulting in bending deformation in some areas, which increases the difficulty of manual welding and disassembly operations. Summary of the Invention

[0006] The technical problem to be solved by this invention is how to provide a low-loss, easy-to-install superconducting magnet connector.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A niobium-tin superconducting magnet connector includes a superconducting magnet skeleton, an inlet connector positioning block, and an outlet connector positioning block. The superconducting magnet skeleton is provided with an inlet slot and an outlet slot. The upper and lower openings of the inlet slot and the outlet slot are in an outwardly expanding arc shape. An inlet connector positioning block is provided above the inlet slot, and an outlet connector positioning block is provided above the outlet slot. The inlet connector positioning block is provided with a first welding groove that communicates with the inlet slot. The first welding groove is inclined toward the tangent direction of the groove opening on the arc shape of the inlet slot, so that the niobium-tin superconducting tap can be smoothly led out from the inlet slot and the first welding groove. The outlet connector positioning block is provided with a second welding groove that communicates with the outlet groove. The second welding groove is inclined toward the tangent direction of the groove opening on the arc shape of the outlet groove, so that the niobium-tin superconducting tap can be smoothly led out from the outlet groove and the second welding groove.

[0008] By designing this connector, the niobium-tin superconducting tap does not change direction after being led out, adopting a straight-in, straight-out method. The entire path requires no bending or angle adjustment, reducing internal bending stress in the wire and better preserving performance after heat treatment. Simultaneously, the connector extends in the planar direction, increasing the cross-sectional area of ​​the positioning block and reducing the transmission path length. This method lowers the resistance of the superconducting connector, yielding good results in experiments, with a connector resistance reaching 10 Ω. -9 ~10 -10 The size of the connector is reduced to the order of magnitude, avoiding large connector dimensions. The overall height of the connector is only about 15mm, which makes it possible to design and install in small spaces in superconducting magnet systems. It is better adapted to the design of superconducting connectors in limited and narrow spaces. Under the premise of meeting parameter requirements, different shapes can be used to adapt to the limited space in cryogenic systems, which can effectively achieve low energy loss of niobium-tin superconducting connectors under high fields.

[0009] In addition, the connector has a simple structure and can be integrally molded in the tank, making it easy to install. It avoids the brittle fracture of the niobium-tin superconducting wire caused by disassembly and assembly before and after heat treatment, which is a common problem with traditional connectors. Furthermore, the connector has lower manufacturing and usage costs, as well as lower installation and welding operation risks.

[0010] Preferably, the surface of the superconducting magnet skeleton is coated with an insulating layer.

[0011] Preferably, insulating sheets are provided between the inlet connector positioning block and the outlet connector positioning block and the superconducting magnet frame.

[0012] Preferably, insulating cloth is provided on the walls of both the first welding tank and the second welding tank.

[0013] Preferably, both the inlet connector positioning block and the outlet connector positioning block are fixed to the superconducting magnet frame by fixing bolts, and an electrical insulating sleeve is fitted on the fixing bolts.

[0014] Preferably, the niobium-tin superconducting tap and the superconducting wire are integrally molded in the first welding groove and the second welding groove.

[0015] Preferably, the first and second welding tanks are filled with alloy solder with high thermal conductivity and low melting point.

[0016] Preferably, the superconducting magnet skeleton, the inlet connector positioning block, and the outlet connector positioning block are all made of non-magnetic metal materials.

[0017] Preferably, the system further includes an intermediate transition joint positioning block, which has an X-shaped cross third welding groove. The superconducting magnet skeleton also has a transition inlet groove and a transition outlet groove, which are arranged in a figure-eight shape. The upper and lower openings of the transition inlet groove and the transition outlet groove are arc-shaped and expand outwards. The transition inlet groove is connected to one of the bottom openings of the third welding groove, and the transition outlet groove is connected to the other bottom opening of the third welding groove. The two bottom openings of the third welding groove are inclined towards the tangent direction of the upper opening of the arc-shaped transition inlet groove and the transition outlet groove, so that the niobium-tin superconducting transition tap can be smoothly led out from the two openings of the third welding groove.

[0018] Preferably, an insulating cover base is also provided on the superconducting magnet skeleton at both ends of the intermediate transition joint positioning block.

[0019] Compared with the prior art, the beneficial effects of the present invention are: By designing this connector, the niobium-tin superconducting tap does not change direction after being led out, adopting a straight-in, straight-out method. The entire path requires no bending or angle adjustment, reducing internal bending stress in the wire and better preserving performance after heat treatment. Simultaneously, the connector extends in the planar direction, increasing the cross-sectional area of ​​the positioning block and reducing the transmission path length. This method lowers the resistance of the superconducting connector, yielding good results in experiments, with a connector resistance reaching 10 Ω. -9 ~10 -10 The size of the connector is reduced to the order of magnitude, avoiding large connector dimensions. The overall height of the connector is only about 15mm, which makes it possible to design and install in small spaces in superconducting magnet systems. It is better adapted to the design of superconducting connectors in limited and narrow spaces. Under the premise of meeting parameter requirements, different shapes can be used to adapt to the limited space in cryogenic systems, which can effectively achieve low energy loss of niobium-tin superconducting connectors under high fields.

[0020] In addition, the connector has a simple structure and can be integrally molded in the tank, making it easy to install. It avoids the brittle fracture of the niobium-tin superconducting wire caused by disassembly and assembly before and after heat treatment, which is a common problem with traditional connectors. Furthermore, the connector has lower manufacturing and usage costs, as well as lower installation and welding operation risks. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is another structural schematic diagram of an embodiment of the present invention. Detailed Implementation

[0022] To facilitate understanding of the technical solution of the present invention by those skilled in the art, the technical solution of the present invention will now be further described in conjunction with the accompanying drawings.

[0023] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] In this application, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly and specifically limited.

[0025] See Figure 1 and Figure 2 This embodiment discloses a niobium-tritin superconducting magnet connector, which is fixed on the niobium-tritin superconducting winding 5. The connector includes a superconducting magnet skeleton 1, an inlet connector positioning block 2, an outlet connector positioning block 3, and an intermediate transition connector positioning block 4. The surface of the superconducting magnet skeleton 1 is coated with an insulating layer, which electrically insulates the niobium-tritin superconducting wire from the superconducting magnet skeleton 1. The superconducting magnet skeleton 1 is provided with an inlet slot 101, an outlet slot 102, a transition inlet slot 103, and a transition outlet slot 104. The cable outlet groove 104, the transition cable inlet groove 103 and the transition cable outlet groove 104 are arranged in a figure-eight shape, the upper and lower openings of the cable inlet groove 101, the cable outlet groove 102, the transition cable inlet groove 103 and the transition cable outlet groove 104 are in an outwardly expanding arc shape, the cable inlet connector positioning block 2 is fixed above the cable inlet groove 101, the cable outlet connector positioning block 3 is fixed above the cable outlet groove 102, and the intermediate transition connector positioning block 4 is fixed above the transition cable inlet groove 103 and the transition cable outlet groove 104.

[0026] Furthermore, the material of the insulating layer includes, but is not limited to, silica ceramic particles, mica sheets, or other types of insulating spraying materials or electrical insulating materials, in order to achieve high temperature resistance of 640℃ and meet the requirements of electrical insulation with the superconducting magnet skeleton 1.

[0027] The materials used for the inlet connector positioning block 2, outlet connector positioning block 3, and intermediate transition connector positioning block 4 have high heat resistance and structural strength, and their coefficient of thermal expansion is close to that of niobium-tin superconducting wire. Furthermore, their RRR value at low temperatures is between 60 and 800, their heat resistance temperature is not lower than 640℃, and they possess high 4K low-temperature thermal conductivity (-269℃), with a thermal conductivity not lower than 350 W / (m·K). The inlet connector positioning block 2, outlet connector positioning block 3, and intermediate transition connector positioning block 4 have low resistivity within the 4K temperature range (-269℃), and their length in the current transmission direction is not greater than 30 mm, while their cross-sectional area in the current transmission direction is not less than 5000 mm². 2 By adjusting the appropriate height and cross-sectional area, the theoretical resistance at low temperatures can be ≤10. -10 Or the lower resistance value below, with an actual assembled resistance value ≤10. -9 Or a lower resistance value. This ensures that the superconducting magnet has low heat loss per unit time, allowing for stable operation with low current loss for more than 10 days.

[0028] Furthermore, the materials of the superconducting magnet skeleton 1 include, but are not limited to, 304L non-magnetic stainless steel, 316L non-magnetic stainless steel, T2 copper, TU0 / TU1 high-conductivity oxygen-free copper, or other non-magnetic metal materials, high-strength alloy materials, and thermally conductive composite materials with high heat transfer efficiency.

[0029] The materials of the inlet connector positioning block 2, outlet connector positioning block 3, and intermediate transition connector positioning block 4 include, but are not limited to, TU00 high-conductivity oxygen-free copper, TU0 high-conductivity oxygen-free copper, TU1 high-conductivity oxygen-free copper, or other non-magnetic metal materials and thermally conductive composite materials with high heat transfer efficiency.

[0030] Insulating sheets 6 are provided between the inlet connector positioning block 2, the outlet connector positioning block 3, the intermediate transition connector positioning block 4 and the superconducting magnet skeleton 1. Furthermore, the insulating sheet 6 has an insulation withstand voltage of not less than 12 kV / mm, and its electrical insulation performance does not change significantly when subjected to heat treatment at 640℃ and deep low temperature 4K (-269℃). Specifically, the insulating sheet 6 may include, but is not limited to, mica sheets, Mylar sheets, aluminum oxide nano-pads, aluminum nitride nano-pads, polyimide films, polyester films or other types of insulating spray materials or electrical insulating films.

[0031] Furthermore, the size of the insulating sheet 6 should be slightly larger than the outer dimensions of the inlet connector positioning block 2, the outlet connector positioning block 3, and the intermediate transition connector positioning block 4, preferably not less than 2mm on each side. It should also be free from cracks or damage during the processing and forming process to avoid electrical insulation breakdown. The maximum number of insulating sheets 6 during installation is 2 to ensure that the superconducting connector receives effective low-temperature cooling, reduce the thermal resistance of the contact surface on the heat transfer path, and ensure that the overall temperature difference of the connector is not greater than 0.02K.

[0032] The inlet connector positioning block 2 and outlet connector positioning block 3 can be made into different shapes according to the space constraints inside the cavity of the superconducting magnet system, and the RRR value at low temperature is between 60 and 800, including but not limited to cube blocks, cuboid blocks, triangular blocks, trapezoidal blocks, cylindrical blocks, etc.

[0033] Furthermore, the inlet connector positioning block 2, the outlet connector positioning block 3, and the intermediate transition connector positioning block 4 are all fixed to the superconducting magnet frame 1 by fixing bolts 7, and an electrical insulating sleeve (not shown in the figure) is fitted on the fixing bolts 7.

[0034] The inlet connector positioning block 2 is provided with a first welding groove 201 that communicates with the inlet groove 101. The first welding groove 201 is inclined toward the tangent direction of the arc-shaped groove opening of the inlet groove 101, so that the niobium-tin superconducting tap 8 can be smoothly led out from the inlet groove 101 and the first welding groove 201.

[0035] The outlet connector positioning block 3 is provided with a second welding groove 301 that communicates with the outlet groove 102. The second welding groove 301 is inclined toward the tangent direction of the arc-shaped groove opening of the outlet groove 102, so that the niobium-tin superconducting tap 8 can be smoothly led out from the outlet groove 102 and the second welding groove 301.

[0036] The intermediate transition joint positioning block 4 is provided with a third welding groove 401 in an X-shaped cross shape. The transition inlet groove 103 is connected to one of the bottom openings of the third welding groove 401, and the transition outlet groove 104 is connected to the other bottom opening of the third welding groove 401. The two bottom openings of the third welding groove 401 are respectively inclined towards the tangent direction of the arc-shaped upper opening of the transition inlet groove 103 and the transition outlet groove 104, so that the niobium-tin superconducting transition tap can be smoothly led out from the two openings of the third welding groove 401.

[0037] The niobium-tin superconducting tap 8 and the external superconducting wire 10 are integrally molded in the first welding groove 201 and the second welding groove 301. The niobium-tin superconducting transition tap and the external superconducting wire 10 are integrally molded in the third welding groove 401. Specifically, a high thermal conductivity, low melting point alloy solder is melted and poured into the first welding groove 201, the second welding groove 301 and the third welding groove 401 for integral molding. During the filling process, the temperature of the positioning block is not lower than 100°C to ensure that the high thermal conductivity, low melting point alloy solder completely fills the welding groove without the appearance of air bubbles. Then, it is naturally cooled to room temperature for curing.

[0038] In this embodiment, after the niobium-tin superconducting winding 5 is wound, the niobium-tin superconducting tap 8 enters the first welding groove 201 smoothly along the tangent direction of the upper arc-shaped slot of the inlet groove 101 and is then smoothly led out. The niobium-tin superconducting tap 8 enters the second welding groove 301 smoothly along the tangent direction of the upper arc-shaped slot of the outlet groove 102 and is then smoothly led out. The niobium-tin superconducting transition tap is also smoothly led out from the third welding groove 401 in the same manner as described above. After being led out, the tap direction is not changed. A straight-in and straight-out method is adopted, and no bending or angle adjustment is required throughout the entire path, which reduces the internal bending stress of the wire and better preserves the performance after heat treatment. At the same time, the joint extends in the planar direction, increasing the cross-sectional area of ​​the positioning block and reducing the length of the transmission path. This method reduces the resistance of the superconducting joint, and good results were obtained in the experiment. The joint resistance can reach 10. -9 ~10 -10 The size of the connector is reduced to the order of magnitude, avoiding large connector dimensions. The overall height of the connector is only about 15mm, which makes it possible to design and install in small spaces in superconducting magnet systems. It is better adapted to the design of superconducting connectors in limited and narrow spaces. Under the premise of meeting parameter requirements, different shapes can be used to adapt to the limited space in cryogenic systems, which can effectively achieve low energy loss of niobium-tin superconducting connectors under high fields.

[0039] It should be noted that although the joint will receive a certain electromagnetic force, its length is five times or more shorter than the original length. According to the electromagnetic force formula F=BIL(magnetic field × current × length), when the magnetic field and current are constant, a decrease in length results in a corresponding decrease in electromagnetic force. Furthermore, due to the short length of the niobium-tin superconducting tap 8 led from the superconducting wire, the electromagnetic field gradient along its path becomes very small. Therefore, when the overlap length of the joint is not less than 40 mm, the vertical projection length along the radial gradient direction of the magnetic field lines is less than 3 cm. Under a normal magnetic field of 10.0 T@150 A, the transverse electromagnetic force it experiences is only 45 N. After welding and fixing in the welding tank, the effect on the critical current can be ignored. In addition, the connector has a simple structure, is integrally molded, and is easy to install. It avoids the brittle fracture of the niobium-tin superconducting wire caused by disassembly and assembly before and after heat treatment of traditional connectors. Furthermore, the connector has lower manufacturing and usage costs, as well as lower installation and welding operation risks.

[0040] Furthermore, the superconducting wire 10 consists of two high copper-to-superconducting ratio wires with a diameter of 0.5~1.5mm after removing the surface insulating acetal varnish, connected in parallel. Specifically, the two high copper-to-superconducting ratio wires are bound together with 0.05mm ultrafine high-purity copper wire to form the superconducting wire 10, which is then embedded in the first welding groove 201, the second welding groove 301, and the third welding groove 401, and locally spot-welded with the niobium-tin superconducting tap 8 and the niobium-tin superconducting transition tap.

[0041] Furthermore, the high thermal conductivity, low melting point alloy solder has a thermal conductivity of not less than 10 W / (m·K) at a deep cryogenic temperature of 4K, and its bond strength with oxygen-free copper is 10 kg or less without peeling at the contact surface. The alloy solder includes, but is not limited to, indium-based solders, bismuth-based solders, silver-copper-based solders, palladium-based solders, and gold-based solders. The superconducting wire 10 has a thermal conductivity of not less than 500 W / (m·K) at a deep cryogenic temperature of 4K, and an RRR value of not less than 70. The materials of the superconducting wire 10 include, but are not limited to, NbTi / Cu superconducting wires, iron-based superconducting wires, MgB2 superconducting wires, yttrium-based tapes, iron-based tapes, and Bi-based tapes.

[0042] Insulating cloth (not shown in the figure) is provided on the walls of the first welding groove 201, the second welding groove 301 and the third welding groove 401 to prevent the niobium triple tin superconducting tap 8 and the niobium triple tin superconducting transition tap from sticking to the groove wall when the alloy solder is filled. In this embodiment, the insulating cloth is ceramic insulating cloth.

[0043] Furthermore, an insulating cover base 11 is also provided on the superconducting magnet skeleton 1 at both ends of the intermediate transition joint positioning block 4 for installing an insulating cover to protect the intermediate transition joint positioning block 4 and form electrical insulation with external components, meeting the structural requirements for easy disassembly and assembly, and allowing for inspection and maintenance of the superconducting joint; the electrical insulation withstand voltage of the insulating cover base 11 at low temperature is not less than 12kV / mm, and the material of the insulating cover base 11 includes, but is not limited to, aluminum nitride blocks / sheets, aluminum oxide blocks / sheets, epoxy resin blocks / sheets, Mylar blocks / sheets, polyester blocks / sheets, polyimide blocks / sheets, etc. There are no fixed requirements for the specific structure, and it can be adapted according to the joint type as long as the insulation requirements are met.

[0044] Furthermore, before installing the connector, the superconducting magnet skeleton 1, the inlet connector positioning block 2, the outlet connector positioning block 3, the intermediate transition connector positioning block 4, the niobium-tin superconducting tap 8, and the niobium-tin superconducting transition tap need to be acid-washed and cleaned to prevent acid from penetrating into the magnet.

[0045] The installation process in this embodiment is as follows: First, the inlet connector positioning block 2, outlet connector positioning block 3, and intermediate transition connector positioning block 4 are fixed to the superconducting magnet frame 1 using fixing bolts 7. Then, the niobium-tin superconducting tap 8 is smoothly led out after entering the first welding groove 201 along the tangent direction of the arc-shaped upper groove opening of the inlet groove 101. The niobium-tin superconducting tap 8 is smoothly led out after entering the second welding groove 301 along the tangent direction of the arc-shaped upper groove opening of the outlet groove 102. The niobium-tin superconducting transition tap is also smoothly led out after exiting from the third welding groove 401 in the same manner as described above. After exiting, the tap direction is not changed, and a straight-in and straight-out method is adopted. Then, ceramic insulating cloth is installed on the groove walls of the first welding groove 201, the second welding groove 301, and the third welding groove 401 to prevent the niobium-tin superconducting tap 8 and the niobium-tin superconducting transition tap from sticking to the groove walls. Finally, the superconducting wire 10 is embedded in the first welding groove. In the first welding tank 201, the second welding tank 301, and the third welding tank 401, local spot welding is performed with the niobium-tin superconducting tap 8 and the niobium-tin superconducting transition tap. After welding, high thermal conductivity and low melting point alloy solder is melted and poured into the first welding tank 201, the second welding tank 301, and the third welding tank 401 for integral filling and molding. During the filling process, the temperature of the positioning block is not lower than 100℃ to ensure that the high thermal conductivity and low melting point alloy solder completely fills the welding tank without any air bubbles. Then, it is naturally cooled to room temperature for curing. The insulation performance of the coil is then tested using a withstand voltage tester, and the overall resistance of the superconducting magnet is measured, checked, and recorded. Finally, the insulating cover base 11 is installed and fixed, and the insulating cover is installed to protect the intermediate transition joint positioning block 4 and form electrical insulation with the external components. This completes the fabrication and installation of the low-loss Nb3Sn superconducting joint.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0047] The above embodiments are merely examples of implementation methods of the invention. The scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A niobium-tin superconducting magnet connector, characterized in that: It includes a superconducting magnet skeleton, an inlet connector positioning block, and an outlet connector positioning block. The superconducting magnet skeleton is provided with an inlet slot and an outlet slot. The upper and lower openings of the inlet slot and the outlet slot are in an outwardly expanding arc shape. An inlet connector positioning block is provided above the inlet slot, and an outlet connector positioning block is provided above the outlet slot. The inlet connector positioning block is provided with a first welding groove that communicates with the inlet slot. The first welding groove is inclined toward the tangent direction of the groove opening on the arc shape of the inlet slot, so that the niobium-tin superconducting tap can be smoothly led out from the inlet slot and the first welding groove. The outlet connector positioning block is provided with a second welding groove that communicates with the outlet groove. The second welding groove is inclined toward the tangent direction of the groove opening on the arc shape of the outlet groove, so that the niobium-tin superconducting tap can be smoothly led out from the outlet groove and the second welding groove.

2. The niobium-tin superconducting magnet connector according to claim 1, characterized in that: The surface of the superconducting magnet skeleton is coated with an insulating layer.

3. The niobium-tin superconducting magnet connector according to claim 1, characterized in that: Insulating sheets are provided between the inlet connector positioning block and the outlet connector positioning block and the superconducting magnet frame.

4. The niobium-tin superconducting magnet connector according to claim 1, characterized in that: Insulating cloth is provided on the walls of both the first and second welding tanks.

5. A niobium-tin superconducting magnet connector according to claim 1, characterized in that: Both the inlet connector positioning block and the outlet connector positioning block are fixed to the superconducting magnet frame by fixing bolts, and an electrical insulating sleeve is fitted on the fixing bolts.

6. A niobium-tin superconducting magnet connector according to claim 1, characterized in that: The niobium-tin superconducting tap and the superconducting wire are integrally molded in the first and second welding grooves.

7. A niobium-tin superconducting magnet connector according to claim 6, characterized in that: The first and second welding tanks are filled with alloy solder with high thermal conductivity and low melting point.

8. A niobium-tin superconducting magnet connector according to claim 1, characterized in that: The superconducting magnet skeleton, the inlet connector positioning block, and the outlet connector positioning block are all made of non-magnetic metal materials.

9. A niobium-tin superconducting magnet connector according to claim 1, characterized in that: It also includes an intermediate transition joint positioning block, which has a third welding groove in an X-shaped cross shape. The superconducting magnet skeleton is also provided with a transition inlet groove and a transition outlet groove. The transition inlet groove and the transition outlet groove are arranged in a figure-eight shape. The upper and lower openings of the transition inlet groove and the transition outlet groove are in an outwardly expanding arc shape. The transition inlet groove is connected to one of the bottom openings of the third welding groove, and the transition outlet groove is connected to the other bottom opening of the third welding groove. The two bottom openings of the third welding groove are respectively inclined towards the tangent direction of the upper opening of the arc shape of the transition inlet groove and the transition outlet groove, so that the niobium-tin superconducting transition tap can be smoothly led out from the two openings of the third welding groove.

10. A niobium-tin superconducting magnet connector according to claim 9, characterized in that: An insulating cover base is also provided on the superconducting magnet skeleton at both ends of the intermediate transition joint positioning block.

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