Superconducting coil optical fiber strain monitoring device and cold assembly method

Abstract

The invention provides a superconducting coil optical fiber strain monitoring device and a cold assembly method, and relates to the technical field of superconducting magnet monitoring. The first optical fiber strain gauge is used for collecting a first dependent variable generated by the coil in real time in the cold assembly process; the second optical fiber strain gauge is used for collecting an initial dependent variable generated when the framework is not assembled and a second dependent variable generated in real time in the cold assembly process; the control unit is used for executing the following steps: acquiring a first coordinate of a first preset reference point calibrated in the framework when the framework is not assembled; correcting the first coordinate according to the initial dependent variable and the second dependent variable to obtain a second coordinate; according to the first dependent variable and the second coordinate, the to-be-assembled body is moved, so that the third coordinate is consistent with the second coordinate; wherein the third coordinate is a real-time coordinate of a second preset reference point calibrated in the coil; and the accuracy and the reliability of the superconducting coil in the installation process are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting magnet monitoring, and particularly to a superconducting coil optical fiber strain monitoring device and a cold assembly method. Background Art

[0002] Superconducting coils play a crucial role in many high-tech fields such as particle accelerators and magnetic resonance imaging (MRI), especially in application scenarios that require high magnetic fields. During their manufacturing process, maintaining structural integrity and performance stability is of utmost importance.

[0003] During the traditional superconducting coil assembly process, physical dimensions need to be strictly controlled and mechanical loads monitored to ensure correct coil assembly and subsequent reliability. Among them, pre-cooling and assembling the coil into the skeleton is a common operation step. However, for the superconducting coil after potting and drying as the component to be assembled, it is often difficult to monitor strain and displacement at its key parts. Currently, only based on experience, the component to be assembled is cooled to a certain low temperature state to estimate the shrinkage displacement, and it is impossible to accurately judge. Only the cooling temperature is used as the pre-cooling target for cold assembly. This method is likely to cause excessive cooling of the component to be assembled, resulting in waste of coolant and increased costs; moreover, environmental temperature changes (such as in high-temperature summers) may make the shrinkage displacement required for cold assembly not achievable with the empirical pre-cooling target (the shrinkage of the component to be assembled is too small and its size is larger than the assembly space of the skeleton), leading to cold assembly failure.

[0004] Strain monitoring during cold assembly is a key step, which is directly related to the success or failure of cold assembly and process costs, and even the performance and lifespan of the coil. Therefore, a strain monitoring method needs to be introduced into the process of cold-assembling a superconducting coil into a skeleton. Traditional strain monitoring methods mostly use resistance strain gauges. Although these strain gauges can provide strain data, in an ultra-low temperature environment, their performance will be affected by the extremely low temperature, and their installation and maintenance processes are cumbersome and vulnerable to environmental factors.

[0005] In recent years, fiber optic strain sensing technology has been proposed for strain monitoring. This technology has advantages such as being immune to electromagnetic interference, high resolution, small size, and light weight. However, applying it to superconducting coil assembly, especially in a low-temperature environment, still faces many challenges. For example, ensuring the reliability and stability of fiber optic strain sensors in extreme low-temperature and high-magnetic-field environments, and how to accurately integrate fiber optic sensors with superconducting coils to achieve the best monitoring effect.

[0006] At present, the research on the cold assembly method of the fiber optic strain monitoring device for superconducting coils is not sufficient. The existing technology does not elaborate in detail on the cold assembly method in a low-temperature environment, especially the precise docking and fixing technology between the optical fiber and the superconducting coil still needs to be improved; for example, how to achieve the efficient and precise integration of the fiber optic strain sensor with the superconducting coil while ensuring its performance in a low-temperature and high-magnetic field environment. In addition, the difficulties often encountered in solving these problems include the selection of low-temperature materials, the optimized design of the optical fiber layout, and the accuracy and reliability issues during the installation process. These challenges have hindered the widespread application of the fiber optic strain monitoring device for superconducting coils, especially in high-performance applications that require extreme environmental stability and high-precision monitoring.

[0007] In summary, although the fiber optic strain sensing technology is an ideal choice for solving the strain monitoring problem of superconducting coils in theory, there are still multiple technical problems to be solved in practical applications of the existing technology. Especially during the cold assembly process of the fiber optic sensor and the superconducting coil, a more refined and efficient technical solution is needed to ensure the performance and reliability of the overall system. Summary of the Invention

[0008] Based on the above problems, the present invention provides a fiber optic strain monitoring device for superconducting coils and its cold assembly method, which can effectively integrate the fiber optic strain monitoring device into the superconducting coil and improve the accuracy and reliability during the installation process.

[0009] In the first aspect, the present invention provides a fiber optic strain monitoring device for superconducting coils, including:

[0010] An object to be assembled, including:

[0011] A multi-layer coil wound by superconducting wire, with at least one first fiber optic strain gauge connected to the surface of each layer of the coil to form a layered composite structure; the object to be assembled is used for cold assembly into the skeleton;

[0012] At least one second fiber optic strain gauge is provided on the inner wall of the skeleton;

[0013] The first fiber optic strain gauge is used to collect the first strain generated by the coil in real time during the cold assembly process;

[0014] The second fiber optic strain gauge is used to collect the initial strain generated by the skeleton when not assembled, and the second strain generated in real time during the cold assembly process;

[0015] A control unit, configured to perform the following steps:

[0016] Obtain the first coordinate of the first preset reference point calibrated in the skeleton when not assembled;

[0017] According to the initial strain and the second strain, correct the first coordinate to obtain the second coordinate;

[0018] Move the assembly to be assembled according to the first strain and the second coordinate so that the third coordinate is consistent with the second coordinate; wherein, the third coordinate is the real-time coordinate of the second preset reference point calibrated in the coil.

[0019] Preferably, the laminated composite structure is formed by alternately winding each layer of coil and the corresponding first fiber optic strain gauge layer by layer, and baking and curing after potting.

[0020] Preferably, the winding method of the assembly to be assembled includes:

[0021] Wind the first layer of superconducting wire, arrange the fiber optic strain gauges along the outer edge of the coil, and fix them by pouring low-temperature glue; the fiber optic strain gauges are embedded in the potted layer;

[0022] Repeat winding the subsequent superconducting wire layers, and synchronously embed fiber optic strain gauges and pot the glue for each layer;

[0023] After winding is completed, bake the coil, and the low-temperature glue is cured to form the assembly to be assembled.

[0024] Preferably, both the assembly to be assembled and the skeleton are hollow cylinders.

[0025] Preferably, there are two assemblies to be assembled, which are symmetrically distributed up and down along the height direction of the cylinder of the skeleton.

[0026] Optionally, the first fiber optic strain gauges are uniformly arranged on each layer of coil.

[0027] Optionally, the number of the first fiber optic strain gauges arranged on each layer of coil is determined according to the strain of the coils in different regions.

[0028] In a second aspect, the present invention provides a cold assembly method, which is implemented by using any superconducting coil fiber optic strain monitoring device of the present invention, and the method includes:

[0029] Collect the initial strain generated by the skeleton when not assembled and the second strain generated in real time during the cold assembly process through the second fiber optic strain gauge;

[0030] Obtain the first coordinate of the first preset reference point calibrated in the skeleton when not assembled;

[0031] Modify the first coordinate according to the initial strain and the second strain to obtain the second coordinate;

[0032] In the cold assembly sealed chamber where the skeleton is located, collect the first strain generated by the coil in real time during the cold assembly process through the first fiber optic strain gauge in the assembly to be assembled; move the assembly to be assembled according to the first strain and the second coordinate so that the third coordinate is consistent with the second coordinate; wherein, the third coordinate is the real-time coordinate of the second preset reference point calibrated in the coil.

[0033] Preferably, the first strain generated in real time by the coil during the cold assembly process is collected by the first fiber optic strain gauge in the to-be-assembled body; according to the first strain and the second coordinate, the to-be-assembled body is moved so that the third coordinate is consistent with the second coordinate; it includes:

[0034] Lift the to-be-assembled body to the cold assembly sealing chamber of the skeleton; collect the first strain generated in real time by the coil during the cold assembly process through the first fiber optic strain gauge;

[0035] Obtain the shrinkage of the coil according to the first strain;

[0036] Generate the third coordinate according to the shrinkage of the coil and in combination with the coil descent height value;

[0037] Compare the third coordinate with the second coordinate to obtain a reference value for the direction and distance of the coil movement; obtain a displacement correction amount;

[0038] Move the position of the to-be-assembled body through the displacement correction amount to complete the assembly of the to-be-assembled body in the skeleton.

[0039] Preferably, moving the position of the to-be-assembled body through the displacement correction amount to complete the assembly of the to-be-assembled body in the skeleton; includes:

[0040] According to the distance reference value in the horizontal direction, move the position of the to-be-assembled body on the horizontal plane to align the second preset reference point with the first preset reference point in the horizontal direction;

[0041] When the position of the second preset reference point in the horizontal direction is aligned with the first preset reference point, perform the cold assembly action, and according to the distance reference value in the vertical direction, slowly lower the height of the superconducting coil to-be-assembled body vertically to complete the assembly of the superconducting coil to-be-assembled body.

[0042] Preferably, the method further includes:

[0043] Adjust the input speed and the amount of coolant of the cold assembly sealing chamber according to the real-time shrinkage of the coil;

[0044] When the shrinkage of the coil reaches the preset target shrinkage value, stop using the coolant;

[0045] Input inert gas into the sealing chamber to gradually increase the temperature, and monitor the coil expansion displacement in real time until the design threshold is reached;

[0046] Record the final temperature, the superconducting coil shrinkage / expansion curve and the assembly parameters to form an empirical database.

[0047] Compared with the prior art, the beneficial effects of the present invention at least include: under the extremely low temperature conditions during the assembly and use of the superconducting coil, compared with other types of strain monitoring elements, the fiber optic strain gauge can maintain stable performance and continuously output reliable monitoring data. Therefore, the monitoring data obtained by the fiber optic strain monitoring device is less interfered by various factors and has extremely high reference value. The operating state of the superconducting coil is closely related to multiple physical fields such as magnetic field, electric field, and temperature field, and the fiber optic strain gauge can sensitively capture the changes in strain data caused by these physical field changes, further improving the accuracy and reliability of the monitoring data; through the analysis of these strain data, the working state of the superconducting coil under different physical field conditions can be intuitively reflected. By flexibly arranging fiber optic strain gauges in the superconducting coil, on the one hand, they can be evenly arranged in the superconducting coil according to the design requirements to achieve comprehensive monitoring of the entire coil and obtain the overall strain distribution of the coil; on the other hand, key parts with larger strain in the superconducting coil can be focused on arranging, increasing the number of strain gauges, so as to more precisely capture the subtle strain changes in these parts; while in the areas with smaller strain, the arrangement quantity can be correspondingly reduced, reasonably optimizing the cost and resource allocation while ensuring the monitoring effect.

[0048] The device of the present application can conveniently convert strain signals into displacement signals for display. The intuitive data display method helps improve work efficiency, enabling relevant personnel to detect problems more promptly and take corresponding measures, enhancing the monitoring and management level of the superconducting coil operation status. By setting an accurate displacement target value, when the actual pre-cooling displacement reaches the target value, the device can automatically send a prompt signal. This function eliminates the need to assign full-time personnel for full-process tracking and monitoring during the assembly process, greatly saving labor costs; automated assembly not only improves assembly efficiency but also reduces the impact of human factors on assembly quality, ensuring the consistency and accuracy of the assembly process, and contributing to improving the overall assembly quality and production efficiency of the superconducting coil. According to the actual displacement value, the input speed of the coolant is adjusted in real time, and when the preset displacement value is reached, the input of the coolant can be timely shut off. This precise control method avoids unnecessary waste of the coolant, effectively reducing production costs. At the same time, reasonable use of the coolant also helps improve the stability and reliability of the assembly process, reducing problems and losses caused by improper use of the coolant. Through real-time monitoring of the displacement value, problems brought about by different basic temperatures due to seasonal changes can be effectively addressed. The method of the present application can, through real-time monitoring of the displacement value, timely adjust the dosage of the coolant and the cooling strategy according to the actual situation, ensuring that the superconducting coil is assembled under appropriate temperature conditions, reducing the risk of assembly failure caused by improper cooling, and improving the success rate and reliability of the assembly. This cold assembly method breaks through the limitations of traditional cold assembly and can achieve precise alignment of the superconducting coil with the skeleton at different temperatures. It not only improves the assembly accuracy of the superconducting coil but also effectively enhances the performance and stability of the superconducting coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a schematic diagram of an object to be assembled according to an embodiment of the present invention;

[0050] Figure 2 is another schematic diagram of an object to be assembled according to an embodiment of the present invention;

[0051] Figure 3 is a third schematic diagram of an object to be assembled according to an embodiment of the present invention;

[0052] Figure 4 is a schematic diagram of the inner side of the skeleton according to an embodiment of the present invention;

[0053] Figure 5 is a schematic diagram of the relative positions of two objects to be assembled in the skeleton according to an embodiment of the present invention;

[0054] Figure 6 is a schematic diagram of the cold assembly method according to an embodiment of the present invention;

[0055] Figure 7It is a schematic diagram after the assembly of the assembly to be assembled and the skeleton in the embodiment of the present invention.

[0056] In the figure: 1. Coil; 2. First fiber optic strain gauge; 3. Glue filling layer; 4. Skeleton; 5. Signal wire; 6. Second fiber optic strain gauge. Detailed implementation manners

[0057] Now, example embodiments will be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this invention will be more complete and comprehensive, and the concept of the example embodiments will be fully conveyed to those skilled in the art.

[0058] Embodiment 1: This embodiment provides a superconducting coil fiber optic strain monitoring device, which is applied to the cold assembly process of a superconducting coil. A fiber optic sensor (fiber optic strain gauge 2) is integrated with the superconducting coil to achieve the best monitoring effect; the monitoring device includes:

[0059] An assembly to be assembled, referring to Figure 1 、 Figure 2 and Figure 3 , including:

[0060] A multi-layer coil 1 wound by superconducting wire, and at least one first fiber optic strain gauge 2 is connected to the surface of each layer of the coil 1 to form a layered composite structure; the assembly to be assembled is used for cold assembly into the skeleton 4; wherein, the first fiber optic strain gauge 2 can be on the outer surface of each layer of the coil or on the inner surface of each layer of the coil 1; through an external device, while the temperature of the cold assembly process of the superconducting coil (referred to as the coil) is displayed in real time, the strain condition of the coil 1 and the converted coil shrinkage or expansion displacement are displayed;

[0061] Referring to Figure 4 , at least one second fiber optic strain gauge 6 is provided on the inner wall of the skeleton 4;

[0062] The first fiber optic strain gauge 2 is configured to: collect the first strain generated by the coil in real time during the cold assembly process;

[0063] The second fiber optic strain gauge 6 is configured to: collect the initial strain generated by the skeleton 4 at room temperature (when not assembled), and the second strain generated by the skeleton in real time during the cold assembly process; when the second fiber optic strain gauge 6 is at room temperature (when not assembled), it collects the initial strain generated by the skeleton 4, and the strain at this time reflects the initial state of the skeleton 4 in the room temperature environment; during the cold assembly process, it collects the second strain generated by the skeleton 4 due to factors such as temperature change and the installation of the assembly to be assembled in real time, and similarly converts these strains into transmissible signals.

[0064] Each fiber optic strain gauge (including the first fiber optic strain gauge 2 and the second fiber optic strain gauge 6) is connected to an external device; it is connected to the external device through the signal line 5, and the signal lines 5 connected to each first fiber optic strain gauge 2 are all led out from the upper surface of the assembly to be assembled; the first fiber optic strain gauge 2 is connected to the external device through the signal line 5 and can sense the strain of the superconducting coil in real time during the assembly process; when the coil is subjected to various forces or the temperature changes during the assembly process, it will cause the coil to generate strain, and the fiber optic strain gauge can convert this strain into corresponding signals, and these signals are transmitted to the external device through the connected lines.

[0065] The external device receives the signals from the first fiber optic strain gauge 2 and the second fiber optic strain gauge 6 and processes them; on the one hand, it displays the temperature during the cold assembly process of the superconducting coil in real time, providing temperature information for the operator to understand the progress and temperature status of the cold assembly; on the other hand, according to the signals received from the first fiber optic strain gauge 2, it displays the strain condition (the first strain amount) of the coil, and through a specific algorithm or model, it converts the strain condition into the shrinkage or expansion displacement of the coil and presents it intuitively to the operator so that they can grasp the deformation condition of the coil in real time; at the same time, the external device displays the strain condition of the skeleton, that is, the second strain amount, according to the signals received from the second fiber optic strain gauge 6.

[0066] A control unit, the control unit is configured to perform the following steps:

[0067] According to the position of the skeleton and the initial strain amount, obtain the first coordinate of the first preset reference point calibrated in the skeleton;

[0068] According to the initial strain amount and the second strain amount, correct the first coordinate to obtain the second coordinate;

[0069] According to the first strain amount and the second coordinate, move the assembly to be assembled so that the third coordinate is consistent with the second coordinate; wherein, the third coordinate is the real-time coordinate of the second preset reference point calibrated in the coil; the first preset reference point and the second preset reference point are the predetermined alignment points before the assembly of the assembly to be assembled and the skeleton; wherein, the coordinate of the first preset reference point in the horizontal direction coincides with the coordinate of the center point of the skeleton in the horizontal direction; the coordinate in the Z-axis direction (height direction) is the Z-axis coordinate of the center point of the installation groove or the Z-axis coordinate of the center point of the skeleton; the second preset reference point is preferably the center point of the coil (i.e., the center point of the assembly to be assembled).

[0070] The second fiber optic strain gauge 6 collects the initial strain amount generated by the skeleton at room temperature (when not assembled), and this data reflects the strain condition of the skeleton in the initial state. At the same time, the position information of the skeleton is also known, which can be determined by means of a mechanical positioning device, a fixed coordinate system of the installation environment, etc.

[0071] Based on the skeleton position and the initial strain, and in combination with the pre-set skeleton geometric model and material mechanics characteristic parameters, the control unit calculates the first coordinate of the first preset reference point calibrated within the skeleton through the built-in algorithm. This first preset reference point usually coincides with the coordinate of the skeleton center point in the horizontal direction, and in the Z-axis direction (height direction), it is the Z-axis coordinate of the center point of the installation groove or the Z-axis coordinate of the center line point of the skeleton. It represents the key position information of the skeleton in the initial state and provides a reference for the subsequent assembly process.

[0072] During the cold assembly process, the second fiber optic strain gauge 6 continuously collects the second strain generated by the skeleton in real time. Since the cold assembly process involves factors such as temperature changes and the interaction force between the assembly body to be assembled and the skeleton, the skeleton will undergo a certain degree of deformation, and the second strain reflects this real-time deformation situation. The control unit compares and analyzes the initial strain and the second strain, and evaluates the degree and direction of the deformation of the skeleton during the cold assembly process according to the difference between the two and the mechanical characteristic model of the skeleton. Then, based on this evaluation result, the first coordinate is corrected to obtain the second coordinate; the second coordinate more accurately reflects the actual position of the skeleton in the current cold assembly stage and can adapt to the dynamic changes of the skeleton during the assembly process.

[0073] The first fiber optic strain gauge 6 collects the first strain generated by the coil in real time during the cold assembly process. The control unit calculates the real-time coordinate of the second preset reference point (preferably the center point of the coil) calibrated within the coil, that is, the third coordinate, according to the first strain and in combination with the geometric structure and material characteristics of the assembly body to be assembled (coil). This coordinate reflects the real-time position of the assembly body to be assembled during the cold assembly process; among them, the strain data of the first fiber optic strain gauges 2 at different positions are used to obtain the first strain of the coil through simulation analysis (such as finite element analysis).

[0074] The control unit compares the third coordinate with the second coordinate, calculates the difference between the two, and generates a displacement correction vector; according to this displacement correction vector, the control unit sends a control instruction to the actuator (such as a robotic arm, an electric slide table, etc.) that moves the assembly body to be assembled to drive the assembly body to move; during the movement, the first fiber optic strain gauges 2 and the second fiber optic strain gauge 6 continuously feedback strain data, and the control unit continuously updates the third coordinate and the second coordinate and adjusts the movement strategy in real time until the third coordinate is consistent with the second coordinate. At this time, the assembly body to be assembled is accurately assembled to the predetermined position within the skeleton, and the precise cold assembly process is completed.

[0075] In a possible implementation, the laminated composite structure is formed by alternately winding each layer of coil and the corresponding first optical fiber strain gauge layer by layer, and then baking and curing after potting. In this process, the optical fiber strain gauge is embedded in the composite structure and tightly bonded to the superconducting wire layer, becoming part of the assembly to be assembled; the outer layer of the assembly to be assembled is wrapped and fixed by the potting layer 3; further ensuring the relative position stability of the optical fiber strain gauge and the superconducting wire layer, so that the optical fiber strain gauge is well protected throughout the process. Compared with the installation method of traditional strain monitoring devices, the survival rate of the optical fiber strain monitoring device is improved, and the monitoring failure problem caused by device damage is reduced.

[0076] In a possible implementation, the winding method of the assembly to be assembled includes:

[0077] Wind the first superconducting coil layer, arrange the optical fiber strain gauge along the outer edge of the coil, and pour and fix the low-temperature adhesive; the optical fiber strain gauge is embedded in the potting layer 3; among them, the low-temperature adhesive can generally complete the curing process in the temperature range from normal temperature to about 150 °C, such as epoxy low-temperature adhesive;

[0078] Repeat winding the subsequent superconducting wire layers, and synchronously embed the optical fiber strain gauge and pot the glue for each layer;

[0079] After completion of winding, place the coil in an oven for baking, and the low-temperature adhesive cures to form a coil assembly to be assembled with strain monitoring function.

[0080] By the above method, the optical fiber strain gauges are distributed in each layer of the superconducting coil, and can more comprehensively and accurately sense the strain conditions at different positions of the superconducting coil. Compared with the method of only arranging strain gauges on the surface or at local positions, the above method can greatly improve the accuracy of strain monitoring, timely detect the small strain changes of the superconducting coil during operation, and provide more reliable guarantee for the safe operation of the superconducting coil. By pouring the low-temperature adhesive and baking and curing, the optical fiber strain gauge is tightly bonded to the superconducting coil layer to form a stable overall structure. This structure can enhance the mechanical strength and stability of the superconducting coil, and reduce the structural deformation and damage caused by external factors such as vibration and impact. At the same time, the curing process of the low-temperature adhesive will not have an obvious impact on the electrical performance of the superconducting coil, ensuring the normal operation of the superconducting coil.

[0081] In a possible implementation, the assembly body and the skeleton are both hollow cylinders; the assembly body is adapted to the size of the skeleton; a mounting groove is provided in the skeleton; used to mount the assembly body; the cylindrical structure has a high degree of symmetry. Compared with other irregular shapes, the cylinder can effectively avoid stress concentration and reduce the risk of structural damage due to excessive local stress, thereby improving the mechanical stability and reliability of the superconducting coil and the skeleton and extending their service life; in superconducting applications, uniform magnetic field distribution is a key requirement for many application scenarios, such as magnetic resonance imaging (MRI), particle accelerators, etc.; the cylindrical structure helps to produce a more uniform magnetic field distribution; the hollow cylindrical structure provides a good channel for the flow of coolant. The coolant can flow in the hollow part, take away the heat generated by the superconducting coil, effectively reduce the temperature of the coil, and ensure its stable operation in the superconducting state; the circumferential shape of the cylinder enables the coolant to evenly contact the coil surface, improve the heat dissipation efficiency, and avoid the occurrence of local overheating. The cylinder is relatively easy to realize in the manufacturing process; the manufacturing difficulty and cost are reduced.

[0082] Reference Figure 5 In a possible implementation, there are two bodies to be assembled, which are distributed up and down along the height direction of the cylinder of the skeleton, preferably symmetrically distributed up and down, and installation grooves are provided in the upper and lower parts along the height direction of the cylinder of the skeleton, which are not shown in the figure. If there is only one body to be assembled, the first preset reference point is preferably the center point of the skeleton; if there are two bodies to be assembled, the first preset reference point preferably coincides with the coordinates of the center point of the skeleton in the horizontal direction, and the Z-axis direction is the Z-axis coordinate of the center point of the installation groove.

[0083] The two bodies to be assembled are symmetrically distributed up and down along the height direction of the skeleton cylinder. This symmetrical structure can make the magnetic field generated by the superconducting coil more uniform and symmetrical; in many superconducting application scenarios, such as magnetic resonance imaging (MRI) equipment and particle accelerators, a uniform and symmetrical magnetic field is crucial. A uniform magnetic field can improve the clarity and accuracy of imaging, reduce image distortion and artifacts, and also help particles to run stably in the accelerator, improving acceleration efficiency and beam quality.

[0084] Symmetrical distribution of the assembly parts can make the skeleton more balanced in terms of force; during the cold assembly process and when the superconducting coil is working, the assembly parts and the skeleton will be subjected to various stresses due to temperature changes and electromagnetic forces. The symmetrical structure can evenly distribute these stresses on the skeleton, reduce local stress concentration, reduce the risk of structural damage, and improve the mechanical stability and service life of the entire device.

[0085] The two assemblies to be assembled are symmetrically distributed up and down, and mounting grooves are provided in both the upper and lower parts of the skeleton. This design makes the installation and positioning of the assemblies to be assembled more convenient and accurate; the mounting grooves provide a clear installation position and guidance for the assemblies to be assembled. Operators can complete the assembly work more quickly and accurately according to the characteristics of the symmetrical structure, improving the assembly efficiency and quality.

[0086] In a possible implementation, the first fiber optic strain gauges are evenly distributed on each layer of the coil; evenly distributing the first fiber optic strain gauges can ensure comprehensive coverage monitoring of the strain conditions of each part of the superconducting coil; during the operation of the superconducting coil, different positions may be subjected to stress to varying degrees. The evenly distributed strain gauges can obtain the strain information of each area in real time and synchronously, without monitoring blind spots; it provides operators with a complete picture of the overall strain state of the superconducting coil, helping to detect potential problems in a timely manner, such as local stress concentration, etc., and avoiding damage or performance degradation of the superconducting coil caused by the failure to detect local problems in a timely manner. The method of evenly distributing the strain gauges is simpler and more standardized in system design. Whether it is wiring, connecting external devices, or performing data acquisition and processing, a unified standard and mode can be adopted, reducing the complexity and cost of system design; in terms of maintenance, the evenly distributed strain gauges are also convenient for inspection, replacement, and calibration.

[0087] In another possible implementation, the number of the first fiber optic strain gauges on each layer of the coil is arranged according to the strain of the coils in different regions. In a superconducting coil, certain regions may be more likely to generate larger strains due to factors such as structural design, stress conditions, or operating conditions. These regions are key parts that need to be focused on; the stress distribution of different regions can be obtained through simulation data and historical monitoring data. For example, the closer to the center of the coil, the greater the strain, so more first fiber optic strain gauges are arranged, and the farther away from the center, the smaller the strain, so fewer first fiber optic strain gauges are arranged; by increasing the number of strain gauges in these high-strain regions, smaller strain changes can be captured more precisely, and potential fault hazards can be detected in a timely manner; at the same time, for regions with relatively small and insignificant strain changes, the number of strain gauges can be appropriately reduced to avoid waste of resources and achieve optimal allocation of monitoring resources.

[0088] Embodiment 2: Refer to Figure 6 , this embodiment provides a cold assembly method implemented by a superconducting coil fiber optic strain monitoring device. The method includes:

[0089] Collect the initial strain generated by the skeleton at room temperature (when not assembled) and the second strain generated by the skeleton in real time during the cold assembly process through the second fiber optic strain gauges;

[0090] Obtain the first coordinate of the first preset reference point calibrated within the skeleton according to the skeleton position and the initial strain;

[0091] Correct the first coordinate according to the initial strain and the second strain to obtain the second coordinate;

[0092] In the cold assembly sealed chamber where the skeleton is located, collect the first strain generated by the coil in real time during the cold assembly process through the first fiber optic strain gauge in the to-be-assembled body; move the to-be-assembled body according to the first strain and the second coordinate so that the third coordinate is consistent with the second coordinate; wherein, the third coordinate is the real-time coordinate of the second preset reference point calibrated within the coil; the first preset reference point and the second preset reference point are the predetermined alignment points before the to-be-assembled body and the skeleton are assembled.

[0093] In a possible implementation manner, the collecting the first strain generated by the coil in real time during the cold assembly process through the first fiber optic strain gauge in the to-be-assembled body; moving the to-be-assembled body according to the first strain and the second coordinate so that the third coordinate is consistent with the second coordinate includes:

[0094] Lift the to-be-assembled body to the cold assembly sealed chamber of the skeleton; pre-cool the coil and the skeleton with coolant;

[0095] Collect the first strain generated by the coil in real time during the cold assembly process through the first fiber optic strain gauge;

[0096] Obtain the shrinkage of the coil according to the first strain at different temperatures;

[0097] Generate the third coordinate according to the shrinkage of the coil in combination with the coil descent height value;

[0098] Compare the third coordinate with the second coordinate to obtain the reference value of the direction and distance of the coil movement; obtain the displacement correction amount.

[0099] The principle of the above solution is that the sealed chamber provides a relatively stable and controllable environment for cold assembly, facilitating precise temperature control and subsequent operations; during cold assembly, due to factors such as temperature changes, the superconducting coil will generate strain, and the first fiber optic strain gauge can sense this strain in real time and convert it into measurable physical quantities such as electrical signals or optical signals, which are transmitted to the data acquisition system through the connected lines, so as to obtain the first strain generated by the coil in real time during the cold assembly process.

[0100] The material properties of the superconducting coil will change at different temperatures, resulting in different degrees of shrinkage or expansion of the coil; according to the principles of material mechanics and the characteristics of superconducting materials, establish a mathematical model (such as the thermoelastic constitutive equation) between temperature, strain and shrinkage.

[0101] Using the collected first strain variable and combining with the above mathematical model, calculate the shrinkage of the coil at the current temperature. This shrinkage reflects the dimensional change of the superconducting coil due to temperature change; the coil descent height value is a parameter measured in real time during hoisting and assembly, representing the moving distance of the assembly to be assembled relative to the initial position in the vertical direction.

[0102] Combine the calculated coil shrinkage with the coil descent height value, and through the preset coordinate system and geometric relationship, calculate the real-time coordinates of the second preset reference point calibrated in the current state of the assembly to be assembled, that is, the third coordinate, which accurately reflects the actual position of the assembly to be assembled in the cold assembly sealing chamber.

[0103] Compare the calculated third coordinate with the second coordinate obtained by monitoring and correcting the skeleton strain before. The second coordinate represents the accurate position information of the skeleton during cold assembly and is the target position that the assembly to be assembled needs to align with.

[0104] By comparing the third coordinate and the second coordinate, calculate the difference between the two. This difference is presented in the form of the direction and distance of the coil movement and serves as a reference value for the movement of the assembly to be assembled; according to this reference value, the displacement correction amount that the assembly to be assembled needs to perform can be further determined to ensure that the assembly to be assembled can accurately move to the target position matching the skeleton and complete the precise cold assembly process.

[0105] In a possible implementation manner, the method for determining the first strain variable of the coil includes:

[0106] Establish a finite element model of the coil, and determine the geometric shape, material properties, boundary conditions, etc. of the model;

[0107] Through finite element analysis, obtain the strain values of each node in the model;

[0108] Compare the strain variable of the actual measured first strain gauge with the calculation result of the finite element model, and calculate the error;

[0109] Use an optimization algorithm (such as genetic algorithm, particle swarm algorithm, etc.) to adjust the parameters of the finite element model to minimize the error;

[0110] According to the corrected finite element model, recalculate the strain distribution of the coil, and select a suitable index (such as average strain, maximum strain, etc.) as the first strain variable of the coil;

[0111] The finite element model can consider in detail factors such as the geometry of the coil, material properties, and boundary conditions, and accurately simulate the strain distribution of the coil. By comparing the actually measured strain of the first strain gauge with the model calculation results and correcting the errors, the model can be made closer to the actual situation, so as to obtain a more accurate strain distribution of the coil, and the finally determined first strain can better reflect the true state of the coil. For example, in a superconducting coil with a complex shape, finite element analysis can accurately simulate the stress concentration and strain changes in different parts, and can significantly improve the accuracy of strain calculation compared with simple empirical formulas or estimation methods.

[0112] In another possible implementation, the method for determining the first strain of the coil includes:

[0113] Divide multiple regions according to the distance between the first strain gauge and the center of the coil, and each region;

[0114] Calculate the mean value of the strains of multiple first strain gauge nodes in the same region under the same conditions to obtain the first mean value;

[0115] Obtain the first weight according to the distance between the region and the center of the coil; the smaller the distance between the region and the center of the coil, the greater the weight;

[0116] Weight and average multiple first mean values according to the first weight to obtain the first strain of the coil.

[0117] Dividing regions according to the distance between the first strain gauge and the center of the coil and assigning different weights fully considers the differences in the contributions of different regions of the coil to the strain; generally speaking, the regions closer to the center of the coil are more sensitive to strain and have a greater impact on the overall performance. Giving a greater weight can more accurately reflect the overall strain situation of the coil. For example, in a circular superconducting coil, the magnetic field distribution and force conditions in the central region are very different from those in the edge region. This method can better capture this difference and make the calculation results more in line with the actual situation; calculating the mean value of the strains of multiple first strain gauges in each region can effectively reduce the influence of the measurement error of a single strain gauge. Since there may be certain errors and fluctuations in the measurement of the strain, taking the mean value can make the data more stable and reliable, and improve the accuracy of the calculation of the first strain.

[0118] In a possible implementation, moving the position of the to-be-assembled body by the displacement correction amount to complete the assembly of the to-be-assembled body in the skeleton; includes:

[0119] According to the distance reference value in the horizontal direction, move the position of the to-be-assembled body on the horizontal plane to align the second preset reference point with the first preset reference point in the horizontal direction;

[0120] After the position of the second preset reference point in the horizontal direction is aligned with the first preset reference point, perform the cold assembly action. According to the distance reference value in the vertical direction, slowly lower the height of the superconducting coil to-be-assembled body vertically to complete the assembly of the superconducting coil to-be-assembled body. The assembly completion diagram is referred to Figure 7 。

[0121] In the horizontal direction, moving the to-be-assembled body according to the distance reference value can accurately align the second preset reference point with the first preset reference point. For components such as superconducting coils that require extremely high assembly accuracy, precise alignment in the horizontal direction is crucial. For example, in the application of superconducting magnets, a small horizontal deviation may lead to uneven magnetic field distribution, thereby affecting the performance and stability of the magnet. Through precise horizontal positioning, it can be ensured that the position of the superconducting coil in the framework meets the design requirements, thus ensuring that the performance of the entire superconducting device reaches the optimal state.

[0122] After the horizontal position is aligned, slowly lowering the to-be-assembled body vertically according to the distance reference value in the vertical direction can avoid assembly problems caused by height errors, such as excessive extrusion or too large a gap between the coil and the framework. Precise vertical assembly helps to maintain the mechanical stability and electrical performance of the superconducting coil, ensuring that it will not malfunction due to improper assembly during operation.

[0123] First perform horizontal alignment and then perform vertical slow descent. This orderly assembly process helps to improve the stability of the assembly process; horizontal alignment provides a stable foundation for vertical slow descent, enabling the to-be-assembled body to maintain the correct posture and position during the descent process, reducing assembly errors caused by shaking or deviation. A stable assembly process can reduce the risk of damage to the superconducting coil and the framework and extend their service life.

[0124] The precise assembly position can make the superconducting coil evenly stressed in the framework, reducing the phenomenon of stress concentration. During the operation of the superconducting device, stress concentration may lead to a decline in the performance of the superconducting material and even cause the destruction of the superconducting state. By ensuring precise assembly in the horizontal and vertical directions, the stress distribution can be optimized, improving the stability and reliability of the superconducting coil.

[0125] In a possible implementation manner, the method further includes:

[0126] Adjust the input speed of the coolant in the cold assembly sealed chamber according to the real-time shrinkage amount of the coil;

[0127] When the shrinkage amount of the coil reaches the preset target shrinkage value, stop using the coolant;

[0128] Input inert gas into the sealed chamber to gradually increase the temperature, and monitor the expansion displacement of the coil in real time until it reaches the design threshold;

[0129] Record the final temperature, the contraction / expansion curve of the superconducting coil, and the assembly parameters to form an empirical database.

[0130] The contraction amount of the superconducting material is closely related to the temperature. During the cold assembly process, the input speed and amount of the coolant will directly affect the temperature of the sealed chamber, and thus affect the contraction amount of the superconducting coil. By monitoring the contraction amount of the coil in real time, the input of the coolant can be feedback-regulated. When the contraction amount of the coil is too fast, reduce the input speed of the coolant to avoid excessive contraction. When the contraction amount is too slow, increase the input speed of the coolant to accelerate the contraction process, so as to ensure that the contraction process meets the expectations and achieve precise control.

[0131] The preset target contraction value is determined according to the assembly requirements of the superconducting coil and the skeleton. According to the interference amount of the superconducting coil in the superconducting coil skeleton at the initial design stage (determined according to the value of the electromagnetic prestress during use), set the target contraction value of the superconducting coil. When the contraction amount of the coil reaches this target value, it means that the superconducting coil has shrunk to a suitable size and can be successfully assembled into the skeleton. At this time, stop using the coolant to prevent uncontrollable changes in the performance of the superconducting material caused by excessive cooling, and at the same time save coolant resources.

[0132] After the cold assembly is completed, it is necessary to restore the superconducting coil to the normal operating temperature range. Inputting inert gas can provide a stable and non-oxidizing environment to prevent the superconducting material from being oxidized during the heating process. During the gradual heating process, the superconducting coil will expand. Real-time monitoring of the expansion displacement can ensure that the expansion process is within a controllable range, avoiding damage to the assembly structure due to excessive or too fast expansion until the design threshold is reached, so that the superconducting coil reaches a suitable working state.

[0133] Recording the final temperature, the contraction / expansion curve of the superconducting coil, and the assembly parameters is to accumulate various data during the assembly process. These data include the contraction and expansion characteristics of the superconducting material under different temperature conditions, as well as various parameter settings during the assembly process. By analyzing and summarizing these data, an empirical database can be formed to provide reference for subsequent assembly work, optimize the assembly process, and improve the assembly quality and efficiency. For example, in what temperature change range and how much coolant is used.

[0134] In a possible implementation, adjust the input speed of the coolant in the cold assembly sealed chamber according to the real-time contraction amount of the coil, including:

[0135] Based on historical data, establish a first model of the coolant flow rate and temperature change, and a second model of the relationship between temperature change and contraction amount change. Linear regression, non-linear regression, machine learning algorithms (such as neural networks, decision trees, etc.) can be used to construct the models.

[0136] The real-time shrinkage amount and flow rate mapping relationship is obtained through the first model and the second model; a function directly describing the relationship between the shrinkage amount and the flow rate can be obtained by combining and deriving the two models; for example, substituting the temperature change expression obtained by the first model into the second model to eliminate the temperature change variable, and obtaining the functional relationship between the shrinkage amount and the flow rate.

[0137] The deviation between the target shrinkage amount and the actual shrinkage amount is used as the input of the PID controller, and the input speed of the coolant is adjusted according to the control amount calculated by the PID controller; at the same time, the deviation between the target shrinkage amount and the actual shrinkage amount is continuously compared, and the parameters of the PID controller are adjusted in real time according to the change of the deviation to adapt to the dynamic changes of the system.

[0138] In a possible implementation manner, there are two to-be-assembled bodies, which are symmetrically distributed up and down along the height direction of the skeleton; mounting grooves and first preset reference points are provided in both the upper and lower parts along the height direction of the skeleton; the coordinates of the first preset reference point in the horizontal direction coincide with the coordinates of the center point of the skeleton in the horizontal direction, and the coordinates in the Z-axis direction are the height coordinates of the center points of the upper and lower mounting grooves.

[0139] After completing the cold assembly of the first to-be-assembled body in the corresponding mounting groove of the skeleton through the cold assembly step; the skeleton is axially flipped by 180°, so that the upper mounting groove of the original skeleton is switched to the lower part; the cold assembly step is repeated to complete the cold assembly of the second superconducting coil to-be-assembled body in the corresponding mounting groove of the flipped skeleton.

[0140] The embodiment of the present invention also provides a superconducting magnet, and the superconducting magnet includes the aforementioned skeleton and a superconducting coil optical fiber strain monitoring device.

[0141] The embodiment of the present invention also provides an electronic device, and the electronic device includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of any method described in the embodiments of the present application or the functions of any device described in the embodiments of the present application.

[0142] The embodiment of the present application also provides a computer-readable storage medium, which is used to store a computer program. When the computer program is executed, it implements the steps of the method described in the embodiments of the present application or the functions of any device described in the embodiments of the present application. Its specific implementation manner is consistent with the implementation manner and the achieved technical effects described in the above method embodiments, and some contents will not be repeated.

[0143] In this application, the readable storage medium can be any tangible medium that contains or stores a program, which can be used by or in conjunction with an instruction execution system, apparatus, or device. The program product can adopt any combination of one or more readable media. The readable media can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the readable storage medium include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0144] The computer-readable storage medium can include a data signal propagated in a baseband or as part of a carrier wave, which carries the readable program code. Such a propagated data signal can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The readable storage medium can also be any readable medium that can send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code contained on the readable storage medium can be transmitted using any appropriate medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination of the above. The program code for performing the operations of the present invention can be written in any combination of one or more programming languages, including object-oriented programming languages such as Java, C++, etc., and also including conventional procedural programming languages such as the C language or similar programming languages. The program code can be executed entirely on the user computing device, partially on an associated device, executed as a stand-alone software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (for example, by using an Internet service provider to connect through the Internet).

[0145] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes of the present invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A superconducting coil optical fiber strain monitoring device, characterized in that: include: The assembly to be made includes: A multi-layer coil wound by a superconducting wire, the surface of each layer of the coil is connected to at least one first optical fiber strain gauge to form a layered composite structure; the assembly to be assembled is used for cold assembly into the frame; At least one second optical fiber strain gauge is disposed on the inner wall of the frame; The first optical fiber strain gauge is used to collect the first strain amount generated by the coil in real time during the cold assembly process; The second optical fiber strain gauge is used to collect the initial strain amount generated by the skeleton when it is not assembled, and the second strain amount generated in real time during the cold assembly process; A control unit for performing the following steps: Obtaining a first coordinate of a first preset reference point calibrated in the skeleton when not assembled; According to the initial strain and the second strain, the first coordinate is corrected to obtain a second coordinate; According to the first strain and the second coordinate, the assembly body is moved so that the third coordinate is consistent with the second coordinate; wherein the third coordinate is the real-time coordinate of the second preset reference point calibrated in the coil.

2. The superconducting coil optical fiber strain monitoring device according to claim 1, characterized in that: The layered composite structure is formed by alternately winding each layer of coils with the corresponding first optical fiber strain gauge layer by layer, and then baking and curing after glue filling.

3. The superconducting coil optical fiber strain monitoring device according to claim 1, characterized in that: The winding method of the assembly includes: Winding the first layer of superconducting wire, arranging the optical fiber strain gauge along the outer edge of the coil, and injecting low-temperature glue to fix it; the optical fiber strain gauge is embedded in the glue injection layer; Repeatedly wind the subsequent superconducting wire layers, and embed the optical fiber strain gauges and glue each layer simultaneously; After winding is completed, the coil is baked and the low-temperature glue is cured to form the assembly.

4. The superconducting coil optical fiber strain monitoring device according to claim 1, characterized in that: The object to be assembled and the skeleton are both hollow cylinders.

5. The superconducting coil optical fiber strain monitoring device according to claim 4, characterized in that: There are two bodies to be assembled, which are symmetrically distributed up and down along the height direction of the cylinder of the skeleton.

6. The superconducting coil optical fiber strain monitoring device according to claim 1, characterized in that: The first optical fiber strain gauges are evenly arranged on each layer of coils.

7. The superconducting coil optical fiber strain monitoring device according to claim 1, characterized in that: The number of first optical fiber strain gauges on each layer of coils is arranged according to the strain amounts of coils in different regions.

8. A cold assembly method, implemented by using the superconducting coil optical fiber strain monitoring device according to any one of claims 1 to 7, the method comprising: The initial strain amount generated by the skeleton when it is not assembled and the second strain amount generated in real time during the cold assembly process are collected by a second optical fiber strain gauge; Obtaining a first coordinate of a first preset reference point calibrated in the skeleton when not assembled; According to the initial strain and the second strain, the first coordinate is corrected to obtain a second coordinate; In the cold assembly sealed chamber where the skeleton is located, the first strain value generated by the coil in real time during the cold assembly process is collected through the first optical fiber strain gauge in the body to be assembled; according to the first strain value and the second coordinate, the body to be assembled is moved to make the third coordinate consistent with the second coordinate; wherein the third coordinate is the real-time coordinate of the second preset reference point calibrated in the coil.

9. The cold assembly method according to claim 8, characterized in that: The first optical fiber strain gauge in the assembly object is used to collect the first strain generated by the coil in real time during the cold assembly process; According to the first strain and the second coordinate, the assembly body is moved so that the third coordinate is consistent with the second coordinate; including: The object to be assembled is hoisted into the cold assembly sealed chamber of the frame; a first strain value generated by the coil in real time during the cold assembly process is collected by a first optical fiber strain gauge; According to the first strain, obtaining the contraction amount of the coil; The third coordinate is generated according to the contraction amount of the coil and the descending height value of the coil; Comparing the third coordinate with the second coordinate to obtain reference values ​​of the direction and distance of coil movement; obtaining a displacement correction amount; The position of the body to be assembled is moved by the displacement correction amount to complete the assembly of the body to be assembled in the skeleton.

10. The cold assembly method according to claim 9, characterized in that: The method of moving the position of the body to be assembled by the displacement correction amount to complete the assembly of the body to be assembled in the skeleton comprises: According to the distance reference value in the horizontal direction, move the position of the assembly to be assembled on the horizontal plane, and align the second preset reference point with the first preset reference point in the horizontal direction; When the second preset reference point is aligned with the first preset reference point in the horizontal direction, the cold assembly action is implemented, and the height of the superconducting coil assembly body is vertically lowered according to the vertical distance reference value to complete the assembly of the superconducting coil assembly body.

11. The cold assembly method according to claim 9, characterized in that: The method further comprises: Adjust the input speed and amount of coolant in the cold assembly sealing chamber according to the real-time contraction amount of the coil; When the coil shrinkage reaches the preset target shrinkage value, stop using the coolant; Inert gas is introduced into the sealed chamber to gradually increase the temperature, and the expansion displacement of the coil is monitored in real time until the designed threshold is reached; The final temperature, superconducting coil shrinkage / expansion curve and assembly parameters are recorded to form an experience database.

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