Segmented temperature detection and quenching detection system and method for high-temperature superconducting magnet

Abstract

The invention belongs to the field of superconducting magnet application, and discloses a segmented temperature detection and quench detection system and method for a high-temperature superconducting magnet, the system adopts an optical fiber interference technology, and temperature change is detected by accurately calculating an optical path difference. Because the optical fiber has high stability and a measurement signal is not easily influenced by external electromagnetic interference, compared with a traditional resistance temperature sensor and other modes, the measurement precision is higher, and the temperature of each segment of the high-temperature superconducting magnet can be monitored more accurately in a segmented manner. The system transmits and detects the temperature change by using the optical fiber, and the transmission speed of an optical fiber signal is far higher than that of a traditional electric signal, so that the response speed of the system is remarkably improved. The method is particularly important for quench detection of the high-temperature superconducting magnet, temperature change analysis can be rapidly carried out at the initial stage of the quench phenomenon, and measures can be taken in time.

Description

Technical Field

[0001] The invention belongs to the field of superconducting magnet applications, and in particular relates to a high-temperature superconducting magnet segmented temperature detection and quench detection system and method. Background Art

[0002] In the field of superconducting applications, high-temperature superconducting magnets have excellent electromagnetic properties and low energy consumption characteristics, and have development potential in many fields such as power transmission, maglev trains, nuclear magnetic resonance imaging, and controlled nuclear fusion. However, the operating stability of high-temperature superconducting magnets is greatly affected by temperature. Slight fluctuations in the temperature of various parts of the magnet will cause changes in the operating state of the magnet. In severe cases, it will cause quenching, which will generate a lot of heat and damage the equipment. Therefore, it is very necessary to detect the temperature of various parts of the high-temperature superconducting magnet during operation.

[0003] Traditional temperature detection methods such as thermocouples and infrared temperature measurement have limited measurement accuracy, slow response speed and susceptibility to interference in high magnetic field and low temperature environments, and it is difficult to accurately detect the temperature of various parts of the magnet. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned problems of limited measurement accuracy, slow response speed and susceptibility to interference, and to provide a high-temperature superconducting magnet segmented temperature detection and quench detection system and method.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: In a first aspect, the present invention provides a high-temperature superconducting magnet segmented temperature detection and quench detection system, comprising a light source, wherein the light source is divided into at least two paths, one light source is respectively connected to a reference optical fiber, and the other light sources are connected to a measuring optical fiber group, the measuring optical fiber group and the reference optical fiber have the same length and shape, the measuring optical fiber group is wound into a high-temperature superconducting magnet, the measuring optical fiber group is connected to a corresponding optical fiber coupler, the reference optical fiber is divided into at least one path, at least one reference optical fiber is connected to a corresponding optical fiber coupler, each optical fiber coupler is connected to one measuring optical fiber and one reference optical fiber, and the optical fiber coupler is connected to a data processing unit; The processing unit is used to analyze the data output by the second optical fiber coupler to obtain an interference image, obtain an optical path difference according to changes in a number of bright fringes and dark fringes in the interference image, calculate the temperature change of each section of the high-temperature superconducting magnet according to the obtained optical path difference, and obtain the temperature of each section of the high-temperature superconducting magnet according to the temperature change of each section of the high-temperature superconducting magnet.

[0006] A further improvement of the present invention is that the light source is connected to the input end of the first fiber coupler, the first fiber coupler is used to divide the light source into at least two paths, and the output end of the first fiber coupler is connected to the input end of the measurement fiber group and the input end of the reference fiber.

[0007] A further improvement of the present invention is that the output end of the measuring optical fiber group and the output end of the reference optical fiber are both connected to the input end of the corresponding second optical fiber coupler, and the output end of the second optical fiber coupler is connected to the data processing unit.

[0008] A further improvement of the present invention is that the output end of the reference optical fiber is connected to the input end of the third optical fiber coupler, and the output end of the third optical fiber coupler is connected to the corresponding second optical fiber coupler.

[0009] A further improvement of the present invention is that the measuring optical fiber group includes several measuring optical fibers and one superconducting tape, the superconducting tape is in a solenoid shape, each measuring optical fiber is segmented and fixed in the middle of the inner side of the superconducting tape, and the superconducting tape and all the measuring optical fibers form a high-temperature superconducting magnet.

[0010] A further improvement of the present invention is that the reference optical fiber is in a solenoid shape.

[0011] A further improvement of the present invention is that the processing unit comprises: a photoelectric detector, used for converting the optical signal output by the second optical fiber coupler into an electrical signal; Amplifier, used to amplify the electrical signal; A data acquisition card, used to collect the amplified electrical signal; The data processor is used for real-time display based on the collected electrical signals.

[0012] A further improvement of the present invention is that the light source adopts a distributed feedback laser.

[0013] A further improvement of the present invention is that both the first optical fiber coupler and the second optical fiber coupler are single-mode optical fiber couplers.

[0014] In a second aspect, the present invention provides a method for segmented temperature detection and quench detection of a high-temperature superconducting magnet, comprising the following steps: When the high temperature superconducting magnet is working, the outgoing light of the measuring optical fiber group and the outgoing light of the reference optical fiber are collected; Interfere the outgoing light of the measuring optical fiber group with the outgoing light of the reference optical fiber to form an interference light signal, wherein the interference light signal includes a plurality of bright fringes and dark fringes; The interference light signal is analyzed to obtain an interference image, and the optical path difference is obtained according to the changes of a number of bright fringes and dark fringes in the interference image; Based on the obtained optical path difference, the temperature change of each section of the high-temperature superconducting magnet is calculated; According to the temperature change of each section of the high temperature superconducting magnet, the temperature of each section of the high temperature superconducting magnet is obtained.

[0015] A further improvement of the present invention is that when the high temperature superconducting magnet is working, the specific steps of collecting the outgoing light of the measurement optical fiber group and the outgoing light of the reference optical fiber are as follows: Start the light source and the high-temperature superconducting magnet will continue to work; The light source is divided into at least two paths, one path of the light source is sent into the reference optical fiber, and the other path of the light source is sent into the measurement optical fiber group; The outgoing light of the measuring optical fiber group is sent into the corresponding optical fiber coupler; The outgoing light of the reference optical fiber is divided into at least one path and sent to the corresponding optical fiber coupler, so that each optical fiber coupler is connected to one measuring optical fiber and one reference optical fiber.

[0016] A further improvement of the present invention is that the specific method of interfering the outgoing light of the measuring optical fiber group with the outgoing light of the reference optical fiber to form an interference light signal is as follows: The heat generated by the high-temperature superconducting magnet causes changes in the bright and dark fringes in the interference image, forming an interference light signal.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The system of the present invention adopts optical fiber interference technology to detect temperature changes by accurately calculating the optical path difference. Since the optical fiber itself has high stability and the measurement signal is not easily affected by external electromagnetic interference, compared with traditional resistance temperature sensors and other methods, its measurement accuracy is higher, and the temperature of each section of the high-temperature superconducting magnet can be more accurately monitored in sections. Since the system uses optical fiber to transmit and detect temperature changes, the transmission speed of optical fiber signals is much faster than traditional electrical signals, thereby significantly improving the response speed of the system. This is particularly important for quench detection of high-temperature superconducting magnets, and it can quickly analyze temperature changes at the early stage of quench phenomenon and take timely measures. Optical fiber is not subject to electromagnetic interference, so it is more suitable for high-voltage or strong magnetic field environments such as high-temperature superconducting magnets than electrical sensors. Temperature monitoring through optical fiber can effectively avoid the interference that traditional metal wire sensors may encounter under high magnetic field and high temperature conditions, and improve the reliability of data. The measuring optical fiber group is wound around the high-temperature superconducting magnet, and data is transmitted through multiple optical fiber couplers, which can realize independent detection of the temperature of different regions (segments) of the superconducting magnet. This high-precision segmented temperature monitoring can provide information about the temperature changes in different parts of the magnet, help analyze the temperature gradient and the thermal effects of different areas, and thus improve the understanding of the overall state of the superconducting magnet and the prediction of the risk of quenching. The system adopts multiple redundant designs (such as redundant configuration of at least two light sources, reference optical fibers, and measurement optical fibers), which can effectively enhance the reliability of the system in operation. Even if a certain channel fails, the system can still rely on the backup channel to work normally, avoiding system failure caused by single-point failure. In summary, the system of the present invention can provide higher accuracy, speed and reliability while overcoming problems such as limited measurement accuracy, slow response speed, and susceptibility to interference, and effectively improve the operation monitoring capability of high-temperature superconducting magnets.

[0018] Compared with the method of the present invention, the fiber optic interferometry technology provides higher resolution and more accurate temperature measurement, especially in high temperature and strong magnetic field environment, and has significant advantages. The fiber optic interferometry measurement adopted by the present invention has a very fast response speed to temperature changes, and can reflect the temperature fluctuations of the high-temperature superconducting magnet in the working process in real time. This enables the method to quickly capture abnormal temperature changes before the superconducting magnet quenches, and provide data support for timely countermeasures (such as adjusting cooling, reducing load, etc.). The high-speed transmission performance of the fiber optic signal further speeds up the overall response time of the system. The present invention can realize independent temperature monitoring of different sections of the high-temperature superconducting magnet through the configuration of multi-channel optical fiber (measurement optical fiber group and reference optical fiber) and optical fiber coupler. By using the change of interference fringes, the temperature change of each section can be accurately obtained. Especially for large-scale or complex structure magnet systems, this segmented temperature monitoring is particularly important, which helps to identify which parts may have the risk of overheating or quenching. The fiber optic interferometry method used in the present invention is a non-contact temperature measurement method, which enables it to monitor temperature changes in real time without interfering with the normal operation of the magnet. For equipment such as high-temperature superconducting magnets, traditional contact temperature sensors may be worn or damaged due to long-term operation or excessive contact, while the optical fiber method avoids this problem and improves the stability and safety of the system. In summary, the present invention, by utilizing optical fiber interference technology, can provide high-precision, fast-response, and anti-interference temperature monitoring capabilities, solving the problems of limited accuracy, slow response, and susceptibility to interference in traditional technologies, and improving the accuracy of monitoring the state of high-temperature superconducting magnets and predicting quench risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a system diagram of the present invention; Figure 2 is a schematic diagram of a measuring optical fiber group in the present invention; Figure 3 is a schematic diagram of a reference optical fiber in the present invention; Figure 4 It is a flow chart of the present invention.

[0020] Among them, 101, measuring optical fiber; 102, superconducting tape; 301, light source; 302, first optical fiber coupler; 303, measuring optical fiber group; 304, second optical fiber coupler; 305, reference optical fiber; 306, third optical fiber coupler; 307, photodetector; 308, amplifier; 309, data acquisition card; 310, data processor; 311, high-temperature superconducting magnet. DETAILED DESCRIPTION

[0021] In order to further understand the content of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely explanations of the present invention and are not intended to be limiting. In addition, the terms "first" and "second" are used only for descriptive purposes and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0022] Embodiment 1: See also Figure 1 , A high-temperature superconducting magnet segmented temperature detection and quench detection system, characterized in that it includes a light source 301, the light source 301 is divided into at least two paths, one light source 301 is connected to a reference optical fiber 305, and the other light sources 301 are connected to a measuring optical fiber group 303, the measuring optical fiber group 303 and the reference optical fiber 305 have the same length and shape, the measuring optical fiber group 303 is wound into a high-temperature superconducting magnet 311, the measuring optical fiber group 303 is connected to a corresponding optical fiber coupler, the reference optical fiber 305 is divided into at least one path, at least one reference optical fiber 305 is connected to a corresponding optical fiber coupler, each optical fiber coupler is connected to a measuring optical fiber 101 and a reference optical fiber 305, and the optical fiber coupler is connected to a data processing unit; The processing unit is used to analyze the data output by the second optical fiber coupler 304 to obtain an interference image, obtain an optical path difference according to changes in a number of bright fringes and dark fringes in the interference image, calculate the temperature change of each section of the high-temperature superconducting magnet 311 according to the obtained optical path difference, and obtain the temperature of each section of the high-temperature superconducting magnet 311 according to the temperature change of each section of the high-temperature superconducting magnet 311.

[0023] Embodiment 2: See also Figure 1 , the light source 301 is connected to the input end of the first fiber coupler 302, the first fiber coupler 302 is used to divide the light source 301 into at least two paths, and the output end of the first fiber coupler 302 is connected to the input end of the measuring fiber group 303 and the input end of the reference fiber 305. The output end of the measuring fiber group 303 and the output end of the reference fiber 305 are both connected to the input end of the corresponding second fiber coupler 304, and the output end of the second fiber coupler 304 is connected to the data processing unit. The output end of the reference fiber 305 is connected to the input end of the third fiber coupler 306, and the output end of the third fiber coupler 306 is connected to the corresponding second fiber coupler 304.

[0024] The first fiber coupler 302 of this embodiment distributes the light source 301 into at least two paths, ensuring that the measuring fiber group 303 and the reference fiber 305 receive light signals of sufficient intensity respectively. This can achieve balanced signal distribution, avoid data acquisition errors or instability caused by intensity attenuation of a certain signal, and enhance the robustness and reliability of the system. In addition, the redundant design of light source distribution can improve the fault tolerance of the system and reduce the risk of single point failure. By setting the second fiber coupler 304 between the measuring fiber group 303 and the reference fiber 305, the system can effectively synthesize and process signals from different optical fibers, thereby accurately obtaining interference images. The second fiber coupler 304 not only synthesizes the optical signals from the measuring fiber group 303 and the reference fiber 305, but also ensures synchronous transmission of signals, reducing delays and deviations between different channels. Through precise signal processing, the system can more accurately extract the changes in interference fringes, and then accurately calculate the changes in temperature of each section, thereby improving the accuracy and real-time performance of temperature monitoring. The third fiber coupler 306 connects the reference fiber 305 to the second fiber coupler 304, allowing the reference signal to be processed independently of the measurement signal. In this way, the optical signal between the reference optical fiber 305 and the measuring optical fiber 101 can be more accurately interfered with and analyzed. By independently processing the reference optical signal and the measuring signal, the sensitivity of the system to the change of the optical path difference can be improved, thereby improving the resolution of the optical fiber interferometry technology.

[0025] Embodiment 3: See also Figure 2 and Figure 3 The measuring optical fiber group 303 includes a plurality of measuring optical fibers 101 and a superconducting tape 102. The superconducting tape 102 is in a solenoid shape. Each measuring optical fiber 101 is fixed in sections in the middle of the inner side of the superconducting tape 102. The superconducting tape 102 and all the measuring optical fibers 101 form a high-temperature superconducting magnet 311. The reference optical fiber 305 is in a solenoid shape.

[0026] The measuring optical fiber 101 is fixed in the middle of the inner side of the superconducting tape 102, so that the measuring optical fiber can be more closely coupled with the temperature change of the superconducting tape. As a key part of the temperature change, the superconducting tape 102 can directly reflect the thermal effect and temperature gradient in the high-temperature superconducting magnet 311. Through this fixing method, the optical fiber responds to the temperature change more directly and sensitively, thereby improving the accuracy of temperature detection. Since each measuring optical fiber 101 is fixed in sections on the inner side of the superconducting tape 102, each section of the measuring optical fiber can accurately monitor the temperature change of a specific area. This segmented arrangement can accurately obtain the temperature information of each part of the high-temperature superconducting magnet, especially for areas with large temperature changes, the optical fiber can better reflect the local temperature changes, which helps to achieve high-precision temperature distribution monitoring of the entire superconducting magnet.

[0027] Embodiment 4: The processing unit includes: A photodetector 307, used to convert the optical signal output by the second optical fiber coupler 304 into an electrical signal; Amplifier 308, used to amplify the electrical signal; A data acquisition card 309 is used to collect the amplified electrical signal; The data processor 310 is used to analyze the amplified electrical signal to obtain an interference image, obtain an optical path difference based on changes in a number of bright fringes and dark fringes in the interference image, calculate the temperature change of each section of the high-temperature superconducting magnet 311 based on the obtained optical path difference, and obtain the temperature of each section of the high-temperature superconducting magnet 311 based on the temperature change of each section of the high-temperature superconducting magnet 311.

[0028] The introduction of the photodetector 307 enables the system to convert optical signals into electrical signals, which is convenient for subsequent electronic equipment to process. By converting optical signals into electrical signals, the system can use existing electronic processing technology for efficient analysis, which improves the compatibility and ease of use of the system. The signal is usually weak after passing through the photodetector, especially in long-term operation or high-temperature environment. The addition of the amplifier 308 can effectively amplify the electrical signal to ensure that the signal strength is sufficient for accurate processing and avoid distortion or measurement errors caused by signal attenuation. The amplified signal can improve the detection accuracy of the interference fringe changes, thereby enhancing the sensitivity and reliability of the system. The introduction of the data acquisition card 309 can ensure that the amplified signal is collected at high speed and high precision. The data acquisition card has the advantages of high-speed sampling and high-precision quantization, and can monitor the changes in the signal in real time, supporting the system's rapid response to temperature changes in high-temperature superconducting magnets. This device effectively improves the real-time nature of data acquisition and ensures timely monitoring and feedback of temperature changes. Real-time data acquisition can also quickly detect temperature changes, especially in the case of abnormalities or quenching of the magnet, the system can respond in time and provide real-time data support for decision-making. Embodiment 5: See also Figure 4 , a high-temperature superconducting magnet segmented temperature detection and quench detection method, comprising the following steps: Step 1: When the high temperature superconducting magnet 311 is working, the outgoing light of the measuring optical fiber group 303 and the outgoing light of the reference optical fiber 305 are collected.

[0029] Step 2: interfere the outgoing light of the measuring optical fiber group 303 with the outgoing light of the reference optical fiber 305 to form an interference light signal, which includes a plurality of bright fringes and dark fringes.

[0030] Step three, analyzing the interference light signal to obtain an interference image, and obtaining the optical path difference according to the changes of a number of bright fringes and dark fringes in the interference image.

[0031] Step 4: Calculate the temperature change of each section of the high temperature superconducting magnet 311 according to the obtained optical path difference.

[0032] Step five: obtaining the temperature of each section of the high temperature superconducting magnet 311 according to the temperature change of each section of the high temperature superconducting magnet 311 .

[0033] Embodiment 6: The output end of the light source 301 is connected to the input end of the first fiber coupler 302, and the N+1 output ends of the first fiber coupler 302 are respectively connected to the input ends of N+1 optical fibers, wherein the N measuring optical fibers 101 are segmentedly wound along with the superconducting tape and are respectively connected to the input ends of N second fiber couplers 304 at the output ends, and the output end of another reference optical fiber 305 is connected to the input end of the third fiber coupler 306, and the output end of the third fiber coupler 306 is respectively connected to the input ends of N second fiber couplers 304, and the output ends of the N second fiber couplers 304 are connected to the photodetector 307 to convert the optical signal into an electrical signal, which is then connected to the data processor 310 via the amplifier 308 and the data acquisition card 309.

[0034] Wherein, N is a positive integer, and the lengths of N+1 optical fibers are the same, wherein N optical fibers are used as measurement optical fibers 101 and are wound into high-temperature superconducting magnets 311 along with superconducting tape segments, and the N measurement optical fibers 101 have the same bending shapes and divide the high-temperature superconducting magnet 311 into N equal parts; another optical fiber is used as a reference optical fiber 305 and is wound into the same structure as the measurement optical fiber 101 and is in the same ambient temperature as the high-temperature superconducting magnet 311.

[0035] The outgoing light of the N measuring optical fibers 101 and the outgoing light of the reference optical fiber 305 meet in the second optical fiber coupler 304, interfere with each other and generate light and dark stripes. The corresponding optical path difference is obtained by detecting the change in the number of light and dark stripes in the interference image. The optical path difference has a definite relationship with the temperature of the superconducting magnet, thereby obtaining the actual temperature of each part of the superconducting magnet.

[0036] Preferably, the light source 301 is a fiber laser, a distributed feedback laser or other light emitting device, such as a light emitting diode.

[0037] The first fiber coupler 302 is of 1×(N+1) type, with a splitting ratio of 1:1. The second fiber coupler 304 is of 2×1 type. The third fiber coupler 306 is of 1×N type, with a splitting ratio of 1:1.

[0038] The high temperature superconducting magnet 311 is wound from a superconducting tape 102 and is cooled by immersion cooling, gas cooling, conduction cooling or other cooling methods.

[0039] Embodiment 7: The light source 301 is started, and the incident light is split into N+1 beams by the first fiber coupler 302 and respectively emitted into N measuring optical fibers 101 and reference optical fibers 305. The emitted light of the N measuring optical fibers 101 respectively enters the N second fiber couplers 304. The emitted light of the reference optical fiber 305 is split into N beams by the third fiber coupler 306 and emitted into the N second fiber couplers 304 and interferes with the emitted light of the measuring optical fiber 101. The optical signal is converted into an electrical signal by the photoelectric detector 307 and input into the data processor 310 to obtain the optical path difference between each measuring light beam and the reference light beam.

[0040] The high temperature superconducting magnet 311 is started and operated in a superconducting state for a long time. The heat generated at this time will cause the temperature of the environment in which the N measuring optical fibers 101 and the reference optical fiber 305 are located to be different. Therefore, the optical path of the light therein also changes, resulting in a change in the number of light and dark fringes in the interference image. The specific principle is as follows: In the interference image, if the optical path difference △x=mλ, the interference image is bright fringes; if the optical path difference △x=(m+1 / 2)λ, the interference image is dark fringes; where m is a positive integer and λ is the wavelength of the refracted light.

[0041] The optical path difference of the refracted light of N measuring optical fibers and the reference optical fiber can be expressed as △x (1-N) =x (1-N) -x0=n (1-N) (T (1-N) )L (1-N) -n0(T0)L0=△n (1-N) △L (1-N) , where n (1-N) (T (1-N) ) represents the temperature of each measuring fiber at T (1-N) The refractive index of the reference fiber at the cooling environment temperature T0 is n0(T0), L (1-N) Indicates the length of each measured optical fiber, L0 indicates the length of the reference optical fiber, △L (1-N) Indicates the length of the temperature change section of each measuring optical fiber.

[0042] At the beginning, the temperature of the N measurement fibers and the reference fiber is equal, T (1-N) =T0, and the length of each optical fiber is the same, L (1-N) =L0, so △x=0. When the superconducting magnet is in operation or fails, the heat generated will cause a certain length of N measuring optical fibers to be △L (1-N) Temperature T (1-N) The change in refractive index n (1-N) changes, at this time the optical path difference △x (1-N) This causes changes in the light and dark fringes in the interference image. By recording the number of changes in the light and dark fringes to obtain the m value, the corresponding optical path differences △x1, △x2, ...△xN .

[0043] The temperature changes of each section of the magnet are obtained by the following formula: △T1, △T2, ...△T N Then we can get the temperature of each section of the magnet, T1, T2, ...T N :

[0044]

[0045] Where: L(T0) represents the length of the measured optical fiber at temperature T0, n(T0) represents the refractive index of the measured optical fiber at temperature T0, α T Indicates the thermal expansion coefficient of the measured optical fiber, C T It indicates the temperature coefficient of the measured optical fiber. The above data can be obtained through calibration measurement or from the manufacturer. T0 indicates the temperature of the environment where the superconducting magnet is located.

[0046] Embodiment 8: The present invention includes a light source 301, wherein the output end of the light source 301 is connected to the input end of a first optical fiber coupler 302, and the four output ends of the first optical fiber coupler 302 are respectively connected to the input ends of four optical fibers, wherein three measuring optical fibers 303 are segmentedly wound along with superconducting tapes and are respectively connected to the input ends of three second optical fiber couplers 304 at the output ends, and the output end of another reference optical fiber 305 is connected to the input end of a third optical fiber coupler 306, and the output end of the third optical fiber coupler 306 is respectively connected to the input ends of three second optical fiber couplers 304, and the output ends of the three second optical fiber couplers 304 are connected to a photoelectric detector 307 to convert optical signals into electrical signals, and then connected to a data processor 310 via an amplifier 308 and a data acquisition card 309.

[0047] The four optical fibers have the same length, three of which are used as measurement optical fibers 101 and are wound along with the superconducting tape into a high-temperature superconducting magnet 311. The three measurement optical fibers 101 have the same bending shape and divide the superconducting magnet into three equal parts. The other optical fiber is used as a reference optical fiber 305 and is wound into the same structure as the measurement optical fiber 303 and is placed in the same ambient temperature as the superconducting magnet.

[0048] The light source 301 is a self-made 1500nm band fiber laser with an output light intensity of 60mW and a line width of 7kHz. Other distributed feedback lasers or other light-emitting devices may also be used.

[0049] The first fiber coupler 302 is a 1×4 type common single mode fiber coupler with a splitting ratio of 1:1. The second fiber coupler 304 is a 2×1 type common single mode fiber coupler. The third fiber coupler 306 is a 1×3 type common single mode fiber coupler with a splitting ratio of 1:1.

[0050] The photodetector 307 is a high-speed detector that converts optical signals into electrical signals. The bandwidth of the photodetector used in the present invention is 800 MHz, which can realize high-speed optical pulse signal detection. Other types of high-speed photodetectors can also be used.

[0051] Amplifier 308 is a device for amplifying electrical signals. Other types of microwave amplifying elements may also be used.

[0052] The data acquisition card 309 is a device for triggering data acquisition, and the sampling rate is 3GS / s. Other types of high-speed acquisition cards can also be used.

[0053] The data processor 310 is mainly used to process and display in real time the data collected by the data acquisition card 309. The system software written in the example of the present invention is based on the data acquisition card for processing.

[0054] The refractive index of the optical fiber of this embodiment is affected by temperature. In the interference system, there is a quantitative relationship between the optical path difference of each measuring optical fiber and the reference optical fiber and the temperature. The optical path difference is obtained by detecting the change in the number of light and dark fringes in the interference image before and after the temperature change, so as to obtain the temperature of each section of the magnet. A 1×(N+1) type fiber coupler is used to divide the incident light into N+1 beams and inject them into each measuring optical fiber and the reference optical fiber. Then, a 1×N type fiber coupler is used to divide the outgoing light of the reference optical fiber into N beams and inject them into N fiber couplers respectively to interfere with the outgoing light of the N measuring optical fibers. When the magnet starts to run or fails, the heat generated by the heat generation will increase the temperature of each measuring optical fiber, thereby causing the refractive index of the optical fiber to change. Therefore, it is only necessary to detect the interference image of each measuring optical fiber and the reference optical fiber to obtain the corresponding optical path difference, so that the temperature of each section of the magnet can be accurately obtained.

[0055] Embodiment 9: This embodiment presets the following data: Light source wavelength: λ = 1.55 µm (common fiber optic communication wavelength) Reference fiber length: = 1000 m Measuring fiber length: = = ... = = 1000 m Superconducting magnet working environment temperature: = 300 K (room temperature) Refractive index of optical fiber (at room temperature): ( ) = 1.468 Thermal expansion coefficient of optical fiber: α T = 0.00001 / K Temperature coefficient of optical fiber: = 0.0002 / K Temperature change caused by heating of superconducting magnet: The temperature change of the Nth segment of the magnet at a certain moment is △ = 5 K The relationship between optical path difference and fringe change: optical path difference △ Corresponding to the change of light and dark fringes m (the measurement system can accurately capture the light and dark fringes and accurately calculate the change of optical path difference by the number of fringes) Step 1: Calculate the optical path difference ; According to the principle, the optical path difference is caused by the change of refractive index and the change of fiber length. Specifically, the optical path difference △ It can be calculated by the following formula:

[0056] Temperature variation of N-segment measuring fiber leads to refractive index variation , the change of optical path difference can be expressed by the following simplified formula:

[0057] The change in refractive index is It is expressed as:

[0058] The change in refractive index is usually linear with the change in temperature, that is:

[0059] Therefore, the refractive index change is:

[0060] Temperature changes = 5 K, and CT = 0.0002 / K, then:

[0061] Therefore, the optical path difference is:

[0062] Step 2: Calculate the temperature change based on the optical path difference ; According to the formula:

[0063] Substitute the known values:

[0064] The calculation results are:

[0065] Step 3: Calculate the actual temperature ; Calculate the temperature change Then, the actual temperature of the Nth section of the measured optical fiber is obtained. :

[0066] Step 4: Calculate the temperature change of each measuring optical fiber segment and obtain the temperature of each measuring optical fiber segment.

[0067] In this embodiment, only the measurement of the Nth segment is considered, but there may be N optical fiber segments in an actual system, and the temperature of each measured optical fiber segment can be analyzed one by one through the same calculation steps.

[0068] The present invention realizes the segmented and precise measurement of the temperature of the superconducting magnet. The present invention uses the relationship between the refractive index of the optical fiber and its temperature, and winds N optical fibers as measuring optical fibers along with the superconducting tape to form a superconducting magnet in segments, and another optical fiber is used as a reference optical fiber. The outgoing light of the N measuring optical fibers interferes with the outgoing light of the reference optical fiber, and the coupled light is converted into an electrical signal by a photoelectric converter. After the data acquisition card collects the data, the data processor analyzes it to obtain the optical path difference, and the optical path difference is used to reflect the temperature changes of each segment of the magnet. In the above technical scheme, a high-speed acquisition card is used to collect signals at a higher sampling rate, which can more accurately capture the changes in optical path difference. At the same time, higher resolution can reduce quantization errors, improve the digitization accuracy of signals, and achieve the beneficial effect of improving measurement accuracy. The present invention utilizes the characteristics of fast thermal response speed of optical fiber and extremely high optical signal transmission speed, combined with the faster data transmission speed of the data acquisition card, to achieve the beneficial effects of improving response speed and reducing data delay. The present invention adopts non-contact optical interference temperature measurement, which can work stably in a high magnetic field and low temperature environment, and achieves the beneficial effect of being not easily interfered with. The present invention uses N optical fibers as measuring optical fibers and winds them into superconducting magnets in sections with superconducting tapes, which interfere with reference optical fibers respectively, and can measure the temperature of various parts of the superconducting magnet during the operation of the high-temperature superconducting magnet, with the beneficial effects of simple operation, high detection accuracy, high sensitivity, and strong anti-interference ability.

[0069] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0070] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A high-temperature superconducting magnet segmented temperature detection and quench detection system, characterized in that: The invention comprises a light source (301), wherein the light source (301) is divided into at least two paths, one path of the light source (301) is respectively connected to a reference optical fiber (305), and the other path of the light source (301) is connected to a measuring optical fiber group (303), the measuring optical fiber group (303) and the reference optical fiber (305) have the same length and shape, the measuring optical fiber group (303) is wound into a high-temperature superconducting magnet (311), the measuring optical fiber group (303) is connected to a corresponding optical fiber coupler, the reference optical fiber (305) is divided into at least one path, at least one reference optical fiber (305) is connected to a corresponding optical fiber coupler, each optical fiber coupler is connected to a measuring optical fiber (101) and a reference optical fiber (305), and the optical fiber coupler is connected to a data processing unit; The processing unit is used to analyze the data output by the second optical fiber coupler (304) to obtain an interference image, obtain an optical path difference based on changes in a plurality of bright fringes and dark fringes in the interference image, calculate the temperature change of each section of the high-temperature superconducting magnet (311) based on the obtained optical path difference, and obtain the temperature of each section of the high-temperature superconducting magnet (311) based on the temperature change of each section of the high-temperature superconducting magnet (311).

2. A high-temperature superconducting magnet segmented temperature detection and quench detection system according to claim 1, characterized in that: The light source (301) is connected to the input end of a first optical fiber coupler (302), the first optical fiber coupler (302) is used to divide the light source (301) into at least two paths, and the output end of the first optical fiber coupler (302) is connected to the input end of a measurement optical fiber group (303) and the input end of a reference optical fiber (305).

3. A high-temperature superconducting magnet segmented temperature detection and quench detection system according to claim 1, characterized in that: The output end of the measuring optical fiber group (303) and the output end of the reference optical fiber (305) are both connected to the input end of the corresponding second optical fiber coupler (304), and the output end of the second optical fiber coupler (304) is connected to the data processing unit.

4. A high-temperature superconducting magnet segmented temperature detection and quench detection system according to claim 3, characterized in that: The output end of the reference optical fiber (305) is connected to the input end of the third optical fiber coupler (306), and the output end of the third optical fiber coupler (306) is connected to the corresponding second optical fiber coupler (304).

5. A high-temperature superconducting magnet segmented temperature detection and quench detection system according to claim 1, characterized in that: The measuring optical fiber group (303) includes a plurality of measuring optical fibers (101) and a superconducting tape (102). The superconducting tape (102) is in a solenoid shape. Each measuring optical fiber (101) is fixed in sections at the middle of the inner side of the superconducting tape (102). The superconducting tape (102) and all the measuring optical fibers (101) form a high-temperature superconducting magnet (311).

6. A high-temperature superconducting magnet segmented temperature detection and quench detection system according to claim 1, characterized in that: The reference optical fiber (305) is in the shape of a solenoid.

7. A high-temperature superconducting magnet segmented temperature detection and quench detection system according to claim 1, characterized in that: The processing unit includes: A photoelectric detector (307), used for converting the optical signal output by the second optical fiber coupler (304) into an electrical signal; An amplifier (308), used to amplify the electrical signal; A data acquisition card (309), used for collecting the amplified electrical signal; The data processor (310) is used to perform real-time display based on the collected electrical signals.

8. A high-temperature superconducting magnet segmented temperature detection and quench detection system according to claim 1, characterized in that: The light source (301) adopts a distributed feedback laser.

9. A high-temperature superconducting magnet segmented temperature detection and quench detection system according to claim 1, characterized in that: The first optical fiber coupler (302) and the second optical fiber coupler (304) are both single-mode optical fiber couplers.

10. A method for detecting segmented temperature and quenching of a high-temperature superconducting magnet, characterized in that: A high-temperature superconducting magnet segmented temperature detection and quench detection system according to any one of claims 1 to 9, comprising the following steps: When the high-temperature superconducting magnet (311) is in operation, the emitted light of the measuring optical fiber group (303) and the emitted light of the reference optical fiber (305) are collected; Interfering the outgoing light of the measuring optical fiber group (303) with the outgoing light of the reference optical fiber (305) to form an interference light signal, wherein the interference light signal includes a plurality of bright fringes and dark fringes; The interference light signal is analyzed to obtain an interference image, and the optical path difference is obtained according to the changes of a number of bright fringes and dark fringes in the interference image; Calculating the temperature change of each section of the high temperature superconducting magnet (311) based on the obtained optical path difference; The temperature of each section of the high-temperature superconducting magnet (311) is obtained according to the temperature change of each section of the high-temperature superconducting magnet (311).

11. A method for detecting segmented temperature and quenching of a high-temperature superconducting magnet according to claim 10, characterized in that: When the high-temperature superconducting magnet (311) is working, the specific steps of collecting the output light of the measurement optical fiber group (303) and the output light of the reference optical fiber (305) are as follows: The light source (301) is started, and the high temperature superconducting magnet (311) continues to work; The light source (301) is divided into at least two paths, one path of the light source (301) is sent into the reference optical fiber (305), and the other path of the light source (301) is sent into the measurement optical fiber group (303); The output light of the measuring optical fiber group (303) is sent to the corresponding optical fiber coupler; The output light of the reference optical fiber (305) is divided into at least one path and sent to corresponding optical fiber couplers, so that each optical fiber coupler is connected to one measurement optical fiber (101) and one reference optical fiber (305).

12. A method for detecting segmented temperature and quenching of a high-temperature superconducting magnet according to claim 10, characterized in that: The specific method of interfering the outgoing light of the measuring optical fiber group (303) with the outgoing light of the reference optical fiber (305) to form an interference light signal is as follows: The heat generated by the high-temperature superconducting magnet (311) causes changes in the bright fringes and dark fringes in the interference image, thereby forming an interference light signal.

Images