Material residual magnetism detection method and environmental residual magnetism true value detection method

Abstract

This application relates to a method for detecting the remanence of materials and a method for detecting the true value of environmental remanence. The method for detecting the remanence of materials includes the following steps: S11, placing the probe inside the magnetic shielding cylinder and keeping the probe position unchanged; S12, moving the empty stage to the material remanence measurement position inside the magnetic shielding cylinder, and calculating the triaxial magnetic compensation values ​​Bx0, By0, and Bz0 of the SERF atomic magnetometer; S13, moving the stage containing the material to be measured to the material remanence measurement position inside the magnetic shielding cylinder, and calculating the triaxial magnetic compensation values ​​Bx1, By1, and Bz1 of the SERF atomic magnetometer; S14, according to B=[(Bx1-Bx0)]... 2 +(By 1‑ By0) 2 +(Bz1-Bz0) 2 ] 1 / 2 Calculate the remanence B of the material under test. The method for detecting remanence of materials is highly accurate and easy to deploy.

Description

Technical Field

[0001] This application relates to the field of residual magnetism detection technology, and in particular to methods for detecting residual magnetism in materials and methods for detecting the true value of residual magnetism in the environment. Background Technology

[0002] The precise quantitative detection of remanence is crucial for modern industrial quality control and scientific research. In the aerospace field, weak remanence in processed titanium alloy components can induce fatigue crack propagation, threatening flight safety. In precision bearing manufacturing, remanence attracts wear debris, accelerating wear. In the medical device field, residual magnetism in surgical instruments can interfere with the operation of precision imaging equipment. Currently, remanence can be measured using devices such as Hall sensors, fluxgate magnetometers, and superconducting quantum interference devices (SQUIDs). However, Hall sensors and fluxgate magnetometers have limited sensitivity, typically only reaching the μT level, making it difficult to capture weak remanence below the nT level. They are also susceptible to interference from environmental magnetic fields, resulting in poor measurement stability. While SQUIDs possess high sensitivity at the fT level, they rely on liquid helium temperatures or complex refrigeration systems, leading to a bulky and inconveniently deployed system. This makes them virtually unsuitable for production line or outdoor field testing, and their operation and maintenance are complex and costly. Summary of the Invention

[0003] Therefore, it is necessary to provide a method for detecting the residual magnetism of materials and a method for detecting the true value of residual magnetism in the environment to address the above problems.

[0004] To address the above problems, this application provides the following technical solution: A method for detecting remanence of materials, based on a detection system comprising a magnetic shielding system and a SERF atomic magnetometer, wherein the magnetic shielding system includes a magnetic shielding cylinder and a stage, the stage being movable relative to the magnetic shielding cylinder, and the SERF atomic magnetometer having a probe, the method comprising the following steps: S11. Place the probe inside the magnetic shielding cylinder and keep the probe in the same position, then open the magnetic shielding cylinder to shield the external magnetic field; wherein, the probe has a triaxial magnetic compensation coil; S12. Move the empty stage to the material remanence measurement position inside the magnetic shielding cylinder. With the SERF atomic magnetometer stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state. Record the voltages Ux0, Uy0, and Uz0 of each coil in the triaxial magnetic compensation coil when the atomic gas cell inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state. Calculate the triaxial magnetic compensation values ​​Bx0, By0, and Bz0 of the SERF atomic magnetometer based on Ux0, Uy0, and Uz0. S13. Move the stage carrying the material to be tested to the material remanence measurement position inside the magnetic shielding cylinder. When the SERF atomic magnetometer is stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell inside the magnetic shielding cylinder reaches a state of no spin exchange relaxation. Record the voltages Ux1, Uy1, and Uz1 of each coil in the triaxial magnetic compensation coil when the atomic gas cell inside the magnetic shielding cylinder reaches a state of no spin exchange relaxation. Calculate the triaxial magnetic compensation values ​​Bx1, By1, and Bz1 of the SERF atomic magnetometer based on Ux1, Uy1, and Uz1. S14. According to B=[(Bx1-Bx0)] 2 +(By 1- By0) 2 +(Bz1-Bz0) 2 ] 1 / 2 Calculate the remanence B of the material to be tested.

[0005] The method for detecting the remanence of this material has at least the following beneficial effects: The material remanence detection method provided in this application can calculate the remanence of the material under test with high precision and stability by comparing triaxial magnetic compensation values ​​with and without the material under test. It can detect weak remanence of materials on the order of nT and improve the detection accuracy to the order of pT, while also achieving 1 fT / Hz. 1 / 2 The ultra-high detection sensitivity significantly overcomes the shortcomings of traditional Hall sensors and fluxgate magnetometers, such as their inability to measure weak remanence below the nT level and their poor measurement stability. Moreover, the detection system relied upon by this material remanence detection method is much smaller than that of a superconducting quantum interference device, thus avoiding problems such as large size, inconvenient deployment, complex operation and maintenance, and high cost.

[0006] In one embodiment, the step S11 is further included before the following step: S15. Detect the true value of the residual magnetism Br0 inside the magnetic shielding cylinder. If -4nT≤Br0≤4nT, then use the magnetic shielding cylinder to complete step S11. If Br0≤-4nT or Br0≥4nT, then replace or repair the magnetic shielding cylinder until the true value of the residual magnetism Br0 inside the magnetic shielding cylinder satisfies -4nT≤Br0≤4nT, then use the magnetic shielding cylinder to complete step S11.

[0007] This setup ensures the good magnetic shielding performance of the magnetic shielding cylinder, thereby guaranteeing the accuracy and reliability of subsequent material remanence measurement results from the source and avoiding systematic errors caused by substandard testing environments.

[0008] In one embodiment, in step S15, the true value of the environmental remanent magnetization Br0 of the internal space of the magnetic shielding cylinder is detected according to the following steps: S21. Open the magnetic shielding cylinder to shield against external magnetic fields; S22. Place the probe inside the magnetic shielding cylinder and define the probe's current position as the first position. With the SERF atomic magnetometer stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas chamber inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state. Record the voltages Uxo, Uyo, and Uzo of each coil in the triaxial magnetic compensation coil when the atomic gas chamber inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state. Calculate the triaxial magnetic compensation values ​​Bxo, Byo, and Bzo of the SERF atomic magnetometer in the first position based on Uxo, Uyo, and Uzo. S23. Place the probe in the internal space of the magnetic shielding cylinder in a second posture, wherein the second posture can be obtained by rotating the first posture 180° along the x-axis of the probe; in the stable and initialized state of the SERF atomic magnetometer, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and record the voltages Uxx, Uyx, and Uzx of each coil in the triaxial magnetic compensation coil when the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and calculate the triaxial magnetic compensation values ​​Bxx, Byx, and Bzx of the SERF atomic magnetometer in the second posture based on Uxx, Uyx, and Uzx; S24. Place the probe in the internal space of the magnetic shielding cylinder in a third posture, wherein the third posture can be obtained by rotating the first posture 180° along the y-axis of the probe; in the stable and initialized state of the SERF atomic magnetometer, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and record the voltages Uxy, Uyy, and Uzy of each coil in the triaxial magnetic compensation coil when the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and calculate the triaxial magnetic compensation values ​​Bxy, Byy, and Bzy of the SERF atomic magnetometer in the third posture based on Uxy, Uyy, and Uzy; S25. Calculate Bx0 according to Bx0=(Bxo-Bxy) / 2; Calculate By0 based on By0 = (Byo - Byx) / 2; Calculate Bz0 based on Bz0 = (Bzo - Bzx) / 2; According to Br0=[Bx0 2+By0 2 +Bz0 2 ] 1 / 2 Calculate the true value of the residual magnetism Br0 inside the magnetic shielding cylinder.

[0009] With this setup, steps S21 to S25 provide a specific and operable method for detecting the true value of environmental residual magnetism. This method can separate the environmental residual magnetism from the probe's own inherent residual magnetism, thereby obtaining the true value Br0 of the environmental residual magnetism inside the magnetic shielding cylinder. The detection accuracy can reach the pT level, enabling precise detection of the magnetic shielding performance of the magnetic shielding cylinder.

[0010] In one embodiment, the magnetic shielding cylinder has a permalloy layer and a ferrite layer, the permalloy layer covering the ferrite layer, and the internal space of the magnetic shielding cylinder is the space enclosed by the ferrite layer.

[0011] With this configuration, the permalloy layer can effectively shield external magnetic fields, while the ferrite layer further shields external magnetic fields and provides an internal environment with extremely low magnetic noise. The combination of the permalloy layer and the ferrite layer creates favorable conditions for the SERF atomic magnetometer to work normally and exert its measurement sensitivity.

[0012] In one embodiment, multiple permalloy layers are provided, and the multiple permalloy layers are nested sequentially, with the ferrite layer located within the innermost permalloy layer.

[0013] This setup significantly improves the shielding effectiveness against external magnetic fields, further reduces external interference, and creates a near-ideal zero-magnetic working environment for the SERF atomic magnetometer.

[0014] In one embodiment, both the ferrite layer and each of the permalloy layers are cylindrical structures, and each of the permalloy layers is coaxially arranged with the ferrite layer.

[0015] This setup helps to create a uniform and symmetrical magnetic shielding space, reducing the gradient changes of the magnetic field inside the magnetic shielding cylinder, thereby improving the stability and consistency of the magnetic field environment within the measurement area and enhancing the repeatability of the measurement.

[0016] In one embodiment, in step S11, the sensitive center of the probe is positioned at the axial position of the ferrite layer.

[0017] This setup ensures that the probe is positioned in the area with the most uniform and stable magnetic field, minimizing measurement errors caused by positional deviations and guaranteeing the accuracy of the test results.

[0018] In one embodiment, the magnetic shielding system further includes a slide rail connected to the magnetic shielding cylinder, the stage being slidably connected to the slide rail, and the material residual magnetism measurement position in the internal space of the magnetic shielding cylinder being located on the sliding path of the stage.

[0019] With this setup, the stage can easily and smoothly reach and leave the material remanence measurement position, facilitating rapid switching and comparative measurement between the two states of "empty" and "carrying the material to be tested", making it easier to complete steps S12 and S13 and improving detection efficiency.

[0020] In one embodiment, the magnetic shielding system further includes a limiting member, which is fixedly connected to the slide rail and located on the sliding path of the stage. The limiting member is located in the internal space of the magnetic shielding cylinder. When the stage contacts the limiting member, the stage is at the material residual magnetism measurement position in the internal space of the magnetic shielding cylinder.

[0021] With this configuration, the limiting component can accurately limit the stage to the material remanence measurement position, facilitating the completion of steps S12 and S13, improving detection efficiency, and greatly enhancing the repeatability of the measurement.

[0022] This application also provides a method for detecting the true value of environmental remanent magnetization, used to detect the true value of environmental remanent magnetization inside a magnetically shielded cylinder, based on a SERF atomic magnetometer, wherein the SERF atomic magnetometer has a probe, and the method for detecting the true value of environmental remanent magnetization includes the following steps: S21. Open the magnetic shielding cylinder to shield against external magnetic fields; S22. Place the probe inside the magnetic shielding cylinder and define the probe's current position as the first position; wherein, the probe has a triaxial magnetic compensation coil; in the stable and initialized state of the SERF atomic magnetometer, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and record the voltages Uxo, Uyo, and Uzo of each coil in the triaxial magnetic compensation coil when the atomic gas cell inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and calculate the triaxial magnetic compensation values ​​Bxo, Byo, and Bzo of the SERF atomic magnetometer in the first position based on Uxo, Uyo, and Uzo; S23. Place the probe in the internal space of the magnetic shielding cylinder in a second posture, wherein the second posture can be obtained by rotating the first posture 180° along the x-axis of the probe; in the stable and initialized state of the SERF atomic magnetometer, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and record the voltages Uxx, Uyx, and Uzx of each coil in the triaxial magnetic compensation coil when the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and calculate the triaxial magnetic compensation values ​​Bxx, Byx, and Bzx of the SERF atomic magnetometer in the second posture based on Uxx, Uyx, and Uzx; S24. Place the probe in the internal space of the magnetic shielding cylinder in a third posture, wherein the third posture can be obtained by rotating the first posture 180° along the y-axis of the probe; in the stable and initialized state of the SERF atomic magnetometer, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and record the voltages Uxy, Uyy, and Uzy of each coil in the triaxial magnetic compensation coil when the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and calculate the triaxial magnetic compensation values ​​Bxy, Byy, and Bzy of the SERF atomic magnetometer in the third posture based on Uxy, Uyy, and Uzy; S25. Calculate Bx0 according to Bx0=(Bxo-Bxy) / 2; Calculate By0 based on By0 = (Byo - Byx) / 2; Calculate Bz0 based on Bz0 = (Bzo - Bzx) / 2; According to Br0=[Bx0 2 +By0 2 +Bz0 2 ] 1 / 2 Calculate the true value of the residual magnetism Br0 inside the magnetic shielding cylinder.

[0023] This method for detecting the true value of residual magnetism in an environment has at least the following beneficial effects: This method for detecting the true value of environmental remanent magnetization separates the environmental remanent magnetization from the probe's own inherent remanent magnetization by rotating the probe along different axes and performing combined measurements. This yields the true value Br0 of the environmental remanent magnetization inside the magnetic shielding cylinder. The detection accuracy can reach the pT level, enabling precise detection of the magnetic shielding performance of the magnetic shielding cylinder. It can also serve as a high-precision environmental remanent magnetization calibration technique. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of a detection system according to an embodiment of this application; Figure 2 for Figure 1 Another cross-sectional view of the detection system shown.

[0025] Figure label: 1. Magnetic shielding system; 11. Magnetic shielding cylinder; 111. Permalloy layer; 112. Ferrite layer; 113. Material remanence measurement position; 12. Stage; 13. Slide rail; 14. Limiting component; 15. Fixing block; 16. Ferrite support component; 17. Magnetometer support component; 2. SERF atomic magnetometer; 21. Probe; 22. Electrical control unit. Detailed Implementation

[0026] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0027] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0030] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0032] This application first provides a method for detecting the remanence of materials, which is based on a detection system. (See reference...) Figure 1 and Figure 2 The detection system includes a magnetic shielding system 1 and a SERF (Spin-Exchange Relaxation-Free) atomic magnetometer. The magnetic shielding system 1 includes a magnetic shielding cylinder 11 and a stage 12, the stage 12 being movable relative to the magnetic shielding cylinder 11. The SERF atomic magnetometer 2 has a probe 21. The method for detecting the remanence of this material includes the following steps: S11. Place the probe 21 inside the magnetic shielding cylinder 11 and keep the position of the probe 21 unchanged. Turn on the magnetic shielding cylinder 11 to shield the external magnetic field. The probe 21 has a triaxial magnetic compensation coil. S12. Move the empty stage 12 to the material remanence measurement position 113 inside the magnetic shielding cylinder 11. With the SERF atomic magnetometer 2 stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell inside the magnetic shielding cylinder 11 reaches a spin-free exchange relaxation state. Record the voltages Ux0, Uy0, and Uz0 of each coil in the triaxial magnetic compensation coil when the atomic gas cell inside the magnetic shielding cylinder 11 reaches a spin-free exchange relaxation state. Calculate the triaxial magnetic compensation values ​​Bx0, By0, and Bz0 of the SERF atomic magnetometer 2 based on Ux0, Uy0, and Uz0. S13. Move the stage 12 carrying the material to be tested to the material remanence measurement position 113 inside the magnetic shielding cylinder 11. With the SERF atomic magnetometer 2 stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell inside the magnetic shielding cylinder 11 reaches a state of no spin exchange relaxation. Record the voltages Ux1, Uy1, and Uz1 of each coil in the triaxial magnetic compensation coil when the atomic gas cell inside the magnetic shielding cylinder 11 reaches a state of no spin exchange relaxation. Calculate the triaxial magnetic compensation values ​​Bx1, By1, and Bz1 of the SERF atomic magnetometer 2 based on Ux1, Uy1, and Uz1. S14. According to B=[(Bx1-Bx0)] 2 +(By 1- By0) 2 +(Bz1-Bz0) 2 ] 1 / 2 Calculate the remanence B of the material to be tested.

[0033] The material remanence detection method provided in this application can calculate the remanence of the material under test with high precision and stability by comparing triaxial magnetic compensation values ​​with and without the material under test. It can detect weak remanence of materials on the order of nT and improve the detection accuracy to the order of pT, while also achieving 1 fT / Hz. 1 / 2 The ultra-high detection sensitivity significantly overcomes the shortcomings of traditional Hall sensors and fluxgate magnetometers, such as their inability to measure weak remanence below the nT level and their poor measurement stability. Moreover, the detection system relied upon by this material remanence detection method is much smaller than that of a superconducting quantum interference device, thus avoiding problems such as large size, inconvenient deployment, complex operation and maintenance, and high cost.

[0034] The calculation of the triaxial magnetic compensation value of the SERF atomic magnetometer 2 based on the voltage of each coil in the triaxial magnetic compensation coil is prior art and will not be elaborated upon in this application.

[0035] Preferably, before step S11, the following step is included: S15, detecting the true value of the environmental remanent magnetization Br0 inside the magnetic shielding cylinder 11. If -4nT ≤ Br0 ≤ 4nT, then step S11 is completed using the magnetic shielding cylinder 11; if Br0 ≤ -4nT or Br0 ≥ 4nT, then the magnetic shielding cylinder 11 is replaced or repaired until the true value of the environmental remanent magnetization Br0 inside the magnetic shielding cylinder 11 satisfies -4nT ≤ Br0 ≤ 4nT, and then step S11 is completed using the magnetic shielding cylinder 11. This ensures good magnetic shielding performance of the magnetic shielding cylinder 11, thereby guaranteeing the accuracy and reliability of subsequent material remanent magnetization measurement results from the source, and avoiding systematic errors caused by substandard detection environment.

[0036] Preferably, in step S15, the true value of the residual magnetism Br0 of the internal space of the magnetic shielding cylinder 11 is detected according to the following steps S21 to S25: S21. Open the magnetic shielding cylinder 11 to shield the external magnetic field; S22. Place the probe 21 inside the magnetic shielding cylinder 11 and define the current position of the probe 21 as the first position. With the SERF atomic magnetometer 2 stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell inside the magnetic shielding cylinder 11 reaches a spin-free exchange relaxation state. Record the voltages Uxo, Uyo, and Uzo of each coil in the triaxial magnetic compensation coil when the atomic gas cell inside the magnetic shielding cylinder 11 reaches a spin-free exchange relaxation state. Calculate the triaxial magnetic compensation values ​​Bxo, Byo, and Bzo of the SERF atomic magnetometer 2 in the first position based on Uxo, Uyo, and Uzo. S23. Place the probe 21 in the internal space of the magnetic shielding cylinder 11 in a second posture. The second posture can be obtained by rotating the first posture 180° along the x-axis of the probe 21. With the SERF atomic magnetometer 2 stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas chamber in the internal space of the magnetic shielding cylinder 11 reaches a state of no spin exchange relaxation. Record the voltages Uxx, Uyx, and Uzx of each coil in the triaxial magnetic compensation coil when the atomic gas chamber in the internal space of the magnetic shielding cylinder 11 reaches a state of no spin exchange relaxation. Calculate the triaxial magnetic compensation values ​​Bxx, Byx, and Bzx of the SERF atomic magnetometer 2 in the second posture based on Uxx, Uyx, and Uzx. S24. Place the probe 21 in the internal space of the magnetic shielding cylinder 11 in a third posture. The third posture can be obtained by rotating the first posture 180° along the y-axis of the probe 21. With the SERF atomic magnetometer 2 stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas chamber in the internal space of the magnetic shielding cylinder 11 reaches a spin-free exchange relaxation state. Record the voltages Uxy, Uyy, and Uzy of each coil in the triaxial magnetic compensation coil when the atomic gas chamber in the internal space of the magnetic shielding cylinder 11 reaches a spin-free exchange relaxation state. Calculate the triaxial magnetic compensation values ​​Bxy, Byy, and Bzy of the SERF atomic magnetometer 2 in the third posture based on Uxy, Uyy, and Uzy. S25. Calculate Bx0 based on Bx0=(Bxo-Bxy) / 2; calculate By0 based on By0=(Byo-Byx) / 2; calculate Bz0 based on Bz0=(Bzo-Bzx) / 2; calculate Bz0 based on Br0=[Bx0 2 +By0 2 +Bz0 2 ] 1 / 2 Calculate the true value of the residual magnetism Br0 inside the magnetic shielding cylinder 11.

[0037] Steps S21 to S25 provide a specific and operable method for detecting the true value of environmental residual magnetism. This method can separate the environmental residual magnetism from the inherent residual magnetism of the probe 21 itself, thereby obtaining the true value Br0 of the environmental residual magnetism inside the magnetic shielding cylinder 11. The detection accuracy can reach the pT level, and it can accurately detect the magnetic shielding performance of the magnetic shielding cylinder 11.

[0038] The definitions of the x-axis, y-axis, and z-axis of probe 21 are well known to those skilled in the field of residual magnetism detection technology, and will not be elaborated upon in this application.

[0039] It should be noted that Bxo, Byo, and Bzo all represent the sum of the remanent magnetism of the environment sensed by probe 21 in the first posture and the remanent magnetism of probe 21 itself. Let Bxo represent the remanent magnetism of the environment sensed by probe 21 in its x-axis direction and the remanent magnetism of probe 21 itself. 探头 And Bx0, define the environmental remanence sensed by probe 21 in its own y-axis direction and the remanence of probe 21 itself as By and Bx0, respectively. 探头 And By0, define the environmental remanence sensed by probe 21 in its own z-axis direction and the remanence of probe 21 itself as Bz. 探头 And Bz0, then: Bxo=Bx 探头 +Bx0; Byo=By 探头 +By0; Bzo=Bz 探头 +Bz0.

[0040] Bxx, Byx, and Bzx represent the sum of the remanent magnetism of the environment sensed by probe 21 in the second posture and the remanent magnetism of probe 21 itself. Since the second posture can be obtained by rotating the first posture 180° along the x-axis of probe 21, compared to probe 21 in the first posture, the remanent magnetism of the environment sensed by probe 21 in the second posture remains unchanged in its x-axis direction, while the remanent magnetism sensed by probe 21 in its y-axis and z-axis directions is opposite. Furthermore, the remanent magnetism of probe 21 itself sensed in the x, y, and z-axis directions remains unchanged. That is: Bxx=Bx 探头 +Bx0; Byx=By 探头 -By0; Bzx=Bz 探头 -Bz0.

[0041] Bxy, Byy, and Bzy all represent the sum of the remanent magnetism of the environment sensed by probe 21 in the third attitude and the remanent magnetism of probe 21 itself. Since the third attitude can be obtained by rotating the first attitude 180° along the y-axis of probe 21, compared to probe 21 in the first attitude, the remanent magnetism of the environment sensed by probe 21 in the third attitude remains unchanged in its y-axis direction, while the remanent magnetism sensed by probe 21 in its x-axis and z-axis directions is opposite. Furthermore, the remanent magnetism of probe 21 itself sensed in the x-axis, y-axis, and z-axis directions remains unchanged. That is: Bxy=Bx 探头 -Bx0; Byy=By 探头 +By0; Bzy=Bz 探头 -Bz0.

[0042] Combining the above formulas and performing mathematical operations, we can obtain: Bx0 = (Bxo - Bxy) / 2; By0=(Byo-Byx) / 2; Bz0 = (Bzo - Bzx) / 2.

[0043] See Figure 1 and Figure 2 The magnetic shielding cylinder 11 has a permalloy layer 111 and a ferrite layer 112. The permalloy layer 111 covers the ferrite layer 112, and the internal space of the magnetic shielding cylinder 11 is the space enclosed by the ferrite layer 112. The permalloy layer 111 can efficiently shield external magnetic fields, while the ferrite layer 112 further shields external magnetic fields and provides an internal environment with extremely low magnetic noise. The combination of the permalloy layer 111 and the ferrite layer 112 creates favorable conditions for the normal operation of the SERF atomic magnetometer 2 and for it to exert its measurement sensitivity.

[0044] See Figure 1 and Figure 2 Multiple permalloy layers 111 are provided, and the multiple permalloy layers 111 are nested in sequence, with the ferrite layer 112 located inside the innermost permalloy layer 111. This can significantly improve the shielding effectiveness against external magnetic fields, further reduce external interference, and create a near-ideal zero-magnetic working environment for the SERF atomic magnetometer 2.

[0045] For example, the permalloy layer 111 has 2, 3, 4, 5, 6, 7, 8, 9 or 10 layers.

[0046] See Figure 1 and Figure 2 Both the ferrite layer 112 and each permalloy layer 111 are cylindrical structures, and each permalloy layer 111 is coaxially arranged with the ferrite layer 112. This helps to form a uniform and symmetrical magnetic shielding space, reduce the gradient change of the magnetic field in the internal space of the magnetic shielding cylinder 11, thereby improving the stability and consistency of the magnetic field environment in the measurement area and improving the repeatability accuracy of the measurement.

[0047] Preferably, in step S11, the sensitive center of the probe 21 is located on the axis of the ferrite layer 112. This ensures that the probe 21 is in the region with the most uniform and stable magnetic field, minimizing measurement errors caused by positional deviations and guaranteeing the accuracy of the detection results.

[0048] See Figure 1 and Figure 2 The magnetic shielding system 1 also includes a slide rail 13 connected to the magnetic shielding cylinder 11. The stage 12 is slidably connected to the slide rail 13, and the material remanence measurement position 113 inside the magnetic shielding cylinder 11 is located on the sliding path of the stage 12. In this way, the stage 12 can conveniently and smoothly reach and leave the material remanence measurement position 113, facilitating the rapid switching and comparison measurement between the two states of "empty" and "carrying the material to be tested", making it easier to complete steps S12 and S13 and improving the detection efficiency.

[0049] See Figure 1 and Figure 2 The magnetic shielding system 1 also includes a limiting member 14, which is fixedly connected to the slide rail 13 and located on the sliding path of the stage 12. The limiting member 14 is located inside the magnetic shielding cylinder 11. When the stage 12 contacts the limiting member 14, the stage 12 is positioned at the material remanent magnetization measurement position 113 inside the magnetic shielding cylinder 11. The limiting member 14 can accurately limit the stage 12 to the material remanent magnetization measurement position 113, facilitating the completion of steps S12 and S13, improving detection efficiency, and greatly improving the repeatability of the measurement.

[0050] The magnetic shielding system 1 also includes a fixing block 15, a ferrite support 16, and a magnetometer support 17. The fixing block 15 is movably connected to the stage 12 and is used to fix the material to be tested. Exemplarily, a screw is fixed on the stage 12, and the fixing block 15 is threadedly connected to the screw. The ferrite support 16 is fixed to the innermost permalloy layer 111, and the ferrite layer 112 is fixed to the ferrite support 16. The magnetometer support 17 is fixed to the ferrite support 16 and is used to support the SERF atomic magnetometer 2. The slide rail 13 is fixed to the magnetometer support 17.

[0051] To facilitate the transfer of the material to be tested, both the ferrite layer 112 and each permalloy layer 111 are semi-open structures.

[0052] The structures in the magnetic shielding system 1 that need to be free of magnetism can be made of plastics such as PEEK (polyether ether ketone) and epoxy resin. On the one hand, this can effectively reduce the residual magnetism and magnetic noise in the zero-magnetic shielding system 1; on the other hand, this is beneficial for these structures to have extremely high strength, and is also easy to machine, which helps to ensure the accuracy of the entire magnetic shielding system 1.

[0053] See Figure 1 and Figure 2 The SERF atomic magnetometer 2 system includes an electronic control unit 22, which is used to drive the probe 21 to work normally. The electronic control unit 22 and the probe 21 are connected by optical fiber and cable.

[0054] This application also provides a method for detecting the true value of environmental remanent magnetization, used to detect the true value of environmental remanent magnetization inside a magnetically shielded cylinder. This method is based on a SERF atomic magnetometer, which has a probe. The method includes the following steps: S21. Open the magnetic shielding cylinder 11 to shield the external magnetic field; S22. Place the probe 21 inside the magnetic shielding cylinder 11 and define the current position of the probe 21 as the first position. The probe 21 has a triaxial magnetic compensation coil. When the SERF atomic magnetometer 2 is stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell inside the magnetic shielding cylinder 11 reaches a spin-free exchange relaxation state. Record the voltages Uxo, Uyo, and Uzo of each coil in the triaxial magnetic compensation coil when the atomic gas cell inside the magnetic shielding cylinder 11 reaches a spin-free exchange relaxation state. Calculate the triaxial magnetic compensation values ​​Bxo, Byo, and Bzo of the SERF atomic magnetometer 2 in the first position based on Uxo, Uyo, and Uzo. S23. Place the probe 21 in the internal space of the magnetic shielding cylinder 11 in a second posture. The second posture can be obtained by rotating the first posture 180° along the x-axis of the probe 21. With the SERF atomic magnetometer 2 stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas chamber in the internal space of the magnetic shielding cylinder 11 reaches a state of no spin exchange relaxation. Record the voltages Uxx, Uyx, and Uzx of each coil in the triaxial magnetic compensation coil when the atomic gas chamber in the internal space of the magnetic shielding cylinder 11 reaches a state of no spin exchange relaxation. Calculate the triaxial magnetic compensation values ​​Bxx, Byx, and Bzx of the SERF atomic magnetometer 2 in the second posture based on Uxx, Uyx, and Uzx. S24. Place the probe 21 in the internal space of the magnetic shielding cylinder 11 in a third posture. The third posture can be obtained by rotating the first posture 180° along the y-axis of the probe 21. With the SERF atomic magnetometer 2 stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas chamber in the internal space of the magnetic shielding cylinder 11 reaches a spin-free exchange relaxation state. Record the voltages Uxy, Uyy, and Uzy of each coil in the triaxial magnetic compensation coil when the atomic gas chamber in the internal space of the magnetic shielding cylinder 11 reaches a spin-free exchange relaxation state. Calculate the triaxial magnetic compensation values ​​Bxy, Byy, and Bzy of the SERF atomic magnetometer 2 in the third posture based on Uxy, Uyy, and Uzy. S25. Calculate Bx0 based on Bx0=(Bxo-Bxy) / 2; calculate By0 based on By0=(Byo-Byx) / 2; calculate Bz0 based on Bz0=(Bzo-Bzx) / 2; calculate Bz0 based on Br0=[Bx0 2 +By0 2 +Bz0 2 ] 1 / 2 Calculate the true value of the residual magnetism Br0 inside the magnetic shielding cylinder 11.

[0055] This method for detecting the true value of environmental residual magnetism involves rotating the probe 21 along different axes and performing combined measurements to separate the environmental residual magnetism from the inherent residual magnetism of the probe 21 itself, thereby obtaining the true value Br0 of the environmental residual magnetism inside the magnetic shielding cylinder 11. The detection accuracy can reach the pT level, accurately detecting the magnetic shielding performance of the magnetic shielding cylinder 11, and can also serve as a high-precision environmental residual magnetism calibration technique.

[0056] In step S22, after the probe 21 is placed inside the magnetic shielding cylinder 11, the posture of the probe 21 is the first posture. This application does not limit the first posture; the first posture can be any posture.

[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A method for detecting residual magnetism in materials, characterized in that, Based on the detection system, the detection system includes a magnetic shielding system and a SERF atomic magnetometer. The magnetic shielding system includes a magnetic shielding cylinder and a stage, the stage being movable relative to the magnetic shielding cylinder. The SERF atomic magnetometer has a probe. The material remanence detection method includes the following steps: S11. Place the probe inside the magnetic shielding cylinder and keep the probe in the same position, then open the magnetic shielding cylinder to shield the external magnetic field; wherein, the probe has a triaxial magnetic compensation coil; S12. Move the empty stage to the material remanence measurement position inside the magnetic shielding cylinder. With the SERF atomic magnetometer stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state. Record the voltages Ux0, Uy0, and Uz0 of each coil in the triaxial magnetic compensation coil when the atomic gas cell inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state. Calculate the triaxial magnetic compensation values ​​Bx0, By0, and Bz0 of the SERF atomic magnetometer based on Ux0, Uy0, and Uz0. S13. Move the stage carrying the material to be tested to the material remanence measurement position inside the magnetic shielding cylinder. When the SERF atomic magnetometer is stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell inside the magnetic shielding cylinder reaches a state of no spin exchange relaxation. Record the voltages Ux1, Uy1, and Uz1 of each coil in the triaxial magnetic compensation coil when the atomic gas cell inside the magnetic shielding cylinder reaches a state of no spin exchange relaxation. Calculate the triaxial magnetic compensation values ​​Bx1, By1, and Bz1 of the SERF atomic magnetometer based on Ux1, Uy1, and Uz1. S14. According to B=[(Bx1-Bx0)] 2 +(By 1- By0) 2 +(Bz1-Bz0) 2 ] 1 / 2 Calculate the remanence B of the material to be tested.

2. The method for detecting residual magnetism in materials according to claim 1, characterized in that, The steps preceding step S11 include: S15. Detect the true value of the residual magnetism Br0 inside the magnetic shielding cylinder. If -4nT≤Br0≤4nT, then use the magnetic shielding cylinder to complete step S11. If Br0≤-4nT or Br0≥4nT, then replace or repair the magnetic shielding cylinder until the true value of the residual magnetism Br0 inside the magnetic shielding cylinder satisfies -4nT≤Br0≤4nT, then use the magnetic shielding cylinder to complete step S11.

3. The method for detecting residual magnetism in materials according to claim 2, characterized in that, In step S15, the true value of the residual magnetism Br0 of the internal space of the magnetic shielding cylinder is detected according to the following steps: S21. Open the magnetic shielding cylinder to shield against external magnetic fields; S22. Place the probe inside the magnetic shielding cylinder and define the probe's current position as the first position. With the SERF atomic magnetometer stable and initialized, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas chamber inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state. Record the voltages Uxo, Uyo, and Uzo of each coil in the triaxial magnetic compensation coil when the atomic gas chamber inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state. Calculate the triaxial magnetic compensation values ​​Bxo, Byo, and Bzo of the SERF atomic magnetometer in the first position based on Uxo, Uyo, and Uzo. S23. Place the probe in the internal space of the magnetic shielding cylinder in a second posture, wherein the second posture can be obtained by rotating the first posture 180° along the x-axis of the probe; in the stable and initialized state of the SERF atomic magnetometer, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and record the voltages Uxx, Uyx, and Uzx of each coil in the triaxial magnetic compensation coil when the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and calculate the triaxial magnetic compensation values ​​Bxx, Byx, and Bzx of the SERF atomic magnetometer in the second posture based on Uxx, Uyx, and Uzx; S24. Place the probe in the internal space of the magnetic shielding cylinder in a third posture, wherein the third posture can be obtained by rotating the first posture 180° along the y-axis of the probe; in the stable and initialized state of the SERF atomic magnetometer, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and record the voltages Uxy, Uyy, and Uzy of each coil in the triaxial magnetic compensation coil when the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and calculate the triaxial magnetic compensation values ​​Bxy, Byy, and Bzy of the SERF atomic magnetometer in the third posture based on Uxy, Uyy, and Uzy; S25. Calculate Bx0 according to Bx0=(Bxo-Bxy) / 2; Calculate By0 based on By0 = (Byo - Byx) / 2; Calculate Bz0 based on Bz0 = (Bzo - Bzx) / 2; According to Br0=[Bx0 2 +By0 2 +Bz0 2 ] 1 / 2 Calculate the true value of the residual magnetism Br0 inside the magnetic shielding cylinder.

4. The method for detecting residual magnetism in materials according to claim 1, characterized in that, The magnetic shielding cylinder has a permalloy layer and a ferrite layer, the permalloy layer covering the ferrite layer, and the internal space of the magnetic shielding cylinder is the space enclosed by the ferrite layer.

5. The method for detecting residual magnetism in materials according to claim 4, characterized in that, The permalloy layer is provided in multiple layers, and the multiple permalloy layers are nested in sequence, with the ferrite layer located in the innermost permalloy layer.

6. The method for detecting residual magnetism in materials according to claim 5, characterized in that, Both the ferrite layer and each of the permalloy layers are cylindrical structures, and each of the permalloy layers is coaxially arranged with the ferrite layer.

7. The method for detecting residual magnetism in materials according to claim 6, characterized in that, In step S11, the sensitive center of the probe is positioned at the axial position of the ferrite layer.

8. The method for detecting residual magnetism in materials according to claim 1, characterized in that, The magnetic shielding system also includes a slide rail connected to the magnetic shielding cylinder, the stage being slidably connected to the slide rail, and the material residual magnetism measurement position in the internal space of the magnetic shielding cylinder being located on the sliding path of the stage.

9. The method for detecting residual magnetism in materials according to claim 8, characterized in that, The magnetic shielding system also includes a limiting member, which is fixedly connected to the slide rail and located on the sliding path of the stage. The limiting member is located in the internal space of the magnetic shielding cylinder. When the stage contacts the limiting member, the stage is at the material residual magnetism measurement position in the internal space of the magnetic shielding cylinder.

10. A method for detecting the true value of environmental residual magnetism, used to detect the true value of environmental residual magnetism inside a magnetically shielded cylinder, characterized in that, Based on a SERF atomic magnetometer, which has a probe, the method for detecting the true value of environmental remanence includes the following steps: S21. Open the magnetic shielding cylinder to shield against external magnetic fields; S22. Place the probe inside the magnetic shielding cylinder and define the probe's current position as the first position; wherein, the probe has a triaxial magnetic compensation coil; in the stable and initialized state of the SERF atomic magnetometer, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and record the voltages Uxo, Uyo, and Uzo of each coil in the triaxial magnetic compensation coil when the atomic gas cell inside the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and calculate the triaxial magnetic compensation values ​​Bxo, Byo, and Bzo of the SERF atomic magnetometer in the first position based on Uxo, Uyo, and Uzo; S23. Place the probe in the internal space of the magnetic shielding cylinder in a second posture, wherein the second posture can be obtained by rotating the first posture 180° along the x-axis of the probe; in the stable and initialized state of the SERF atomic magnetometer, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and record the voltages Uxx, Uyx, and Uzx of each coil in the triaxial magnetic compensation coil when the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and calculate the triaxial magnetic compensation values ​​Bxx, Byx, and Bzx of the SERF atomic magnetometer in the second posture based on Uxx, Uyx, and Uzx; S24. Place the probe in the internal space of the magnetic shielding cylinder in a third posture, wherein the third posture can be obtained by rotating the first posture 180° along the y-axis of the probe; in the stable and initialized state of the SERF atomic magnetometer, adjust the voltage of each coil in the triaxial magnetic compensation coil until the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and record the voltages Uxy, Uyy, and Uzy of each coil in the triaxial magnetic compensation coil when the atomic gas cell in the internal space of the magnetic shielding cylinder reaches a spin-free exchange relaxation state, and calculate the triaxial magnetic compensation values ​​Bxy, Byy, and Bzy of the SERF atomic magnetometer in the third posture based on Uxy, Uyy, and Uzy; S25. Calculate Bx0 according to Bx0=(Bxo-Bxy) / 2; Calculate By0 based on By0 = (Byo - Byx) / 2; Calculate Bz0 based on Bz0 = (Bzo - Bzx) / 2; According to Br0=[Bx0 2 +By0 2 +Bz0 2 ] 1 / 2 Calculate the true value of the residual magnetism Br0 inside the magnetic shielding cylinder.

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