Superconducting magnetic shielding structure based on step splicing synergistic effect and testing device thereof

Abstract

The invention discloses a superconductive magnetic shielding structure based on a stepped splicing synergistic effect and a testing device thereof, and provides a composite configuration design of convex splicing and oblique splicing aiming at the technical bottlenecks of residual magnetism, concentrated magnetic flux at a seam, complex processing and the like in the existing direct splicing type superconductive magnetic shielding. The high-temperature superconducting blocks are spliced to form the large-size shielding plate, the magnetic flux density gradient of a vertical magnetic field at the seam can be effectively restrained through the synergistic effect of the two-dimensional special-shaped seam, the magnetic flux pinning effect is reduced, and the magnetic shielding performance is tested and characterized, so that compared with a linear splicing structure, the magnetic shielding performance of the large-size shielding plate is greatly improved. The residual magnetism shielding performance of the two-dimensional special-shaped seam structure in a geomagnetic field is improved by times.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic shielding, and in particular to a superconducting magnetic shielding structure based on the stepped splicing synergy effect and its testing device. Background Art

[0002] In a quantum precision magnetic field measurement system based on the Spin-Exchange Relaxation-Free (SERF) effect, constructing an extremely weak magnetic field environment is a prerequisite for achieving ultra-high sensitivity magnetic field measurement. The traditional magnetic shielding system generally adopts a nested configuration of multiple layers of high magnetic permeability nickel-iron alloys (such as permalloy) to attenuate the Earth's background magnetic field (typical value 30 - 50 μT) by at least 7 orders of magnitude to the sub-nT or even pT level. However, the eddy current effect caused by its good conductor characteristics will significantly increase the dynamic magnetic field noise base, resulting in limited comprehensive sensitivity of the magnetic field measurement unit and making it difficult to break through the sensitivity index of the existing quantum precision measurement technology.

[0003] In recent years, low-conductivity ferrite materials have been introduced into the magnetic shielding field due to their excellent electromagnetic properties, and can effectively suppress eddy current noise compared with metal magnetic materials. However, ferrite soft magnetic materials have intrinsic magnetic hysteresis losses, and their residual magnetic noise has approached the physical limit value of the material, which cannot meet the requirements of the next-generation ultra-high sensitivity magnetic field detection system. High-temperature superconducting bulk materials have the property of zero resistance. In theory, a magnetic shielding system prepared with superconducting materials has zero magnetic noise. However, in practical applications, it is limited by two major technical bottlenecks: First, it is difficult to prepare a large-size integral structure for conventional high-temperature superconducting bulk materials due to crystal growth process limitations; second, a magnetic flux penetration effect will occur at the splicing joints of multiple superconducting materials, resulting in magnetic field distortion inside the magnetic shielding. Therefore, there is an urgent need to develop a new design method for superconducting magnetic shielding structures and a magnetic shielding performance testing device for spliced superconducting plates, optimize the magnetic flux distribution control mechanism at the joints and evaluate the splicing method, so that the high-temperature superconducting magnetic shielding technology can adapt to the space constraints and performance indicators of SERF measurement devices. Summary of the Invention

[0004] Aiming at the defects or deficiencies existing in the prior art, the present invention provides a superconducting magnetic shielding structure based on the stepped splicing synergy effect and its testing device.

[0005] The technical solution of the present invention is as follows:

[0006] Superconducting magnetic shielding structure based on stepped splicing synergy, characterized in that it includes a superconducting magnetic shielding cavity enclosed by superconducting block combination surfaces. Each superconducting block in each superconducting block combination surface has a convex splicing structure forming a lateral side and an inclined splicing structure forming a longitudinal side. Between adjacent superconducting blocks spliced horizontally, a low-temperature adhesive resistant to liquid nitrogen temperature is used to bond the convex splicing gap, and between adjacent superconducting blocks spliced longitudinally, a low-temperature adhesive resistant to liquid nitrogen temperature is used to bond the inclined splicing gap. Through the synergy of the two-dimensional special-shaped stepped splicing joints, the magnetic flux density gradient of the vertical magnetic field at the joints is effectively suppressed, and the flux pinning effect is reduced.

[0007] The superconducting block is a YBCO yttrium barium copper oxide high-temperature superconductor.

[0008] The inclined splicing gaps are arranged in a staggered manner at an angle of 30° to 60°, and the inclined splicing structure forms a Z-shaped magnetic field attenuation path.

[0009] The step height of the convex splicing gap is 2 to 4 mm, the step width is 3 to 6 mm, and the step joint fold angle is 90° ± 2°. The convex splicing structure utilizes the characteristic that magnetic flux lines cannot mutate to suppress magnetic flux concentration.

[0010] A test device for a superconducting magnetic shielding structure, characterized in that it includes a liquid nitrogen container. Inside the liquid nitrogen container, the superconducting block combination surface used in the above-mentioned superconducting magnetic shielding structure based on stepped splicing synergy is placed. An inlet for liquid nitrogen is provided above the liquid nitrogen container. The liquid nitrogen container is located inside a uniform magnetic field coil, and the uniform magnetic field coil is located inside a low-temperature permalloy magnetic shielding barrel. Above the superconducting block combination surface, a tetrafluoroethylene elbow joint is provided. The lower port of the tetrafluoroethylene elbow joint is connected to a low-temperature magnetic field sensitive probe extending towards the superconducting block combination surface. The left port of the tetrafluoroethylene elbow joint is connected to a three-axis displacement stage through a support rod. The three-axis displacement stage is connected to a host computer, and a platinum resistance is attached to the low-temperature magnetic field sensitive probe.

[0011] The outer bottom surface of the liquid nitrogen container is connected to a liquid nitrogen container support block.

[0012] The uniform magnetic field coil is used to generate a three-axis uniform magnetic field of 5 nT to 60000 nT, and the magnetic field uniform area formed by the uniform magnetic field coil is 150 × 150 × 150 mm.

[0013] The inlet for liquid nitrogen is used to add liquid nitrogen to cool the superconducting block combination surface. The platinum resistance is used to indicate the position of the liquid nitrogen, indicating that the liquid nitrogen has covered the low-temperature magnetic field sensitive probe at a temperature of 77 K, and liquid nitrogen is supplemented at any time by observing the temperature change during the test. The three-axis displacement stage scans the magnetic field on the entire surface of the superconducting plate by moving in the X, Y, and Z directions. The host computer is used to record experimental data.

[0014] The technical effects of the present invention are as follows: The superconducting magnetic shielding structure and its testing device based on the stepped splicing synergy effect of the present invention address the technical bottlenecks existing in the existing direct splicing type superconducting magnetic shielding, such as residual magnetic retention, magnetic flux concentration at the seams, and complex processing. Through the composite configuration design of convex splicing and oblique splicing, high-temperature superconducting bulk materials are spliced to form large-size shielding plates. Through the synergistic effect of the two-dimensional special-shaped seams, it can effectively suppress the magnetic flux density gradient of the vertical magnetic field at the seams, reduce the magnetic flux pinning effect. After testing and characterizing the magnetic shielding performance, compared with the linear splicing structure, the two-dimensional special-shaped seam structure of the present invention has doubled the residual magnetic shielding performance under the geomagnetic field.

[0015] The superconducting magnetic shielding structure based on the stepped splicing synergy effect of the present invention can overcome the problem that the shielding area of the existing superconducting magnetic shielding is usually larger than the size of a single block. The present invention can first use a single high-temperature superconducting bulk material to form a superconducting rectangular plate through convex splicing by diamond wire cutting, and then obliquely splice multiple rectangular plates to form a large-size superconducting magnetic shielding plate, thereby suppressing the magnetic flux concentration phenomenon caused by the gap. At the same time, a testing device for the superconducting magnetic shielding structure of the present invention can characterize the magnetic flux concentration phenomenon at the seams and guide the optimization of the splicing method of the superconducting bulk materials.

[0016] Compared with the prior art: In the conventional direct splicing method of a single high-temperature superconducting bulk material, the magnetic flux concentration phenomenon at the gap is obvious. The present invention can effectively suppress the magnetic flux concentration phenomenon at the gap by combining vertical convex splicing and oblique splicing of a single superconducting bulk material. At the same time, a testing device for the superconducting magnetic shielding structure of the present invention can characterize the shielding performance of each part of the superconducting plate, especially at the seams. Brief Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the superconducting magnetic shielding structure based on the stepped splicing synergy effect of the present invention.

[0018] Figure 2 is a schematic structural diagram of a testing device for the superconducting magnetic shielding structure of the present invention.

[0019] The descriptions of the reference numerals are as follows: 1 - superconducting bulk material; 2 - convex splicing gap; 3 - oblique splicing gap; 4 - low-temperature permalloy magnetic shielding barrel; 5 - field homogenizing coil; 6 - liquid inlet; 7 - liquid nitrogen container support block; 8 - liquid nitrogen container; 9 - low-temperature magnetic field sensitive probe; 10 - tetrafluoro elbow joint; 11 - platinum resistance; 12 - support rod; 13 - three-axis displacement stage; 14 - host computer (PC). Detailed Embodiments

[0020] The present invention will be described below with reference to the accompanying drawings ( Figure 1 - Figure 2 ) and embodiments.

[0021] Figure 1 It is a schematic structural diagram of the superconducting magnetic shielding structure based on the stepped splicing synergy effect of the present invention. Figure 2 It is a schematic structural diagram of a test device for a superconducting magnetic shielding structure. Refer to Figures 1 to 2 As shown, the superconducting magnetic shielding structure based on the stepped splicing synergy effect includes a superconducting magnetic shielding cavity enclosed by superconducting block combination surfaces (i.e., superconducting block 1). Each superconducting block in each superconducting block combination surface has a convex splicing structure forming a transverse side and an oblique splicing structure forming a longitudinal side. The adjacent superconducting blocks spliced transversely are bonded with a cryogenic adhesive resistant to liquid nitrogen temperature at the convex splicing gap 2, and the adjacent superconducting blocks spliced longitudinally are bonded with a cryogenic adhesive resistant to liquid nitrogen temperature at the oblique splicing gap 3. Through the synergy effect of the two-dimensional special-shaped stepped splicing joints, the magnetic flux density gradient of the vertical magnetic field at the joints is effectively suppressed, and the flux pinning effect is reduced.

[0022] The superconducting block 1 is a YBCO yttrium barium copper oxide high-temperature superconductor. The oblique splicing gaps 3 are arranged in a staggered manner at an angle of 30° - 60°, and the oblique splicing structure forms a Z-shaped magnetic field attenuation path. The step height of the convex splicing gap 2 is 2 - 4 mm, the step width is 3 - 6 mm, and the step joint fold angle is 90° ± 2°. The convex splicing structure utilizes the characteristic that magnetic flux lines cannot mutate to suppress magnetic flux concentration.

[0023] A test device for a superconducting magnetic shielding structure includes a liquid nitrogen container 8. The superconducting block combination surface used in the above-mentioned superconducting magnetic shielding structure based on the stepped splicing synergy effect is placed inside the liquid nitrogen container 8. An inlet 6 is provided above the liquid nitrogen container 8. The liquid nitrogen container 8 is located inside a uniform magnetic field coil 5, and the uniform magnetic field coil 5 is located inside a cryogenic permalloy magnetic shielding barrel 4. A tetrafluoro elbow joint 10 is provided above the superconducting block combination surface. The lower port of the tetrafluoro elbow joint 10 is connected to a cryogenic magnetic field sensitive probe 9 extending towards the superconducting block combination surface. The left port of the tetrafluoro elbow joint 10 is connected to a three-axis displacement stage 13 through a support rod 12, and the three-axis displacement stage 13 is connected to a host computer 14. A platinum resistor 11 is attached to the cryogenic magnetic field sensitive probe 9.

[0024] The outer bottom surface of the liquid nitrogen container 8 is connected to the liquid nitrogen container support block 7. The shimming coil 5 is used to generate a three-axis uniform magnetic field of 5 nT to 60,000 nT, and the magnetic field uniform area formed by the shimming coil 5 is 150×150×150 mm. The liquid inlet 6 is used to add liquid nitrogen to cool the superconducting block material combination surface. The platinum resistance 11 is used to indicate the position of the liquid nitrogen, indicating that the liquid nitrogen has covered the low-temperature magnetic field sensitive probe 9 at a temperature of 77 K, and the liquid nitrogen is supplemented at any time by observing the temperature change during the test. The three-axis displacement stage 13 scans the magnetic field on the surface of the entire superconducting plate 1 by moving in the X, Y, and Z directions. The host computer 14 is used to record experimental data.

[0025] Due to the limitation of the crystal growth process of existing high-temperature superconducting bulk materials, it is difficult to realize large-size high-temperature superconducting magnetic shielding bulk materials. In the existing spliced superconducting magnetic shielding, due to the magnetic flux concentration at the joints, there is residual remanent magnetism in the magnetic shielding. Based on the stepped splicing synergy effect of the superconducting magnetic shielding structure, this invention innovatively proposes a composite configuration design of convex splicing and oblique splicing. The single high-temperature superconducting bulk materials are spliced to form a large-size magnetic shielding bulk material, solving the magnetic flux concentration phenomenon caused by the splicing of the superconducting magnetic shielding. And a test device for the superconducting magnetic shielding structure is designed and realized, which can test the magnetic shielding performance of various spliced large-size superconducting plates. Through the test of the magnetic device, the shielding coefficient of the stepped spliced large-size superconducting plate of this invention can be increased by about 5 times in the geomagnetic field environment.

[0026] The superconducting magnetic shielding structure based on the stepped splicing synergy effect uses YBCO high-temperature superconducting bulk materials as the basic unit, and forms an integral shielding body through low-temperature glue bonding. Two splicing gaps are innovatively set: a right-angled convex splicing gap with a step height of 2-4 mm and a splicing angle of 90°±2°; an oblique splicing gap: staggered at an angle of 30°-60° to form a Z-shaped magnetic field attenuation channel, realizing a three-stage magnetic field gradient attenuation.

[0027] A test device for a superconducting magnetic shielding structure includes a low-temperature permalloy magnetic shielding barrel 4, a shimming coil 5, a liquid inlet 6, a liquid nitrogen container support block 7, a liquid nitrogen container 8, a low-temperature magnetic field sensitive probe 9, a tetrafluoro elbow joint 10, a platinum resistance 11, a support rod 12, a three-axis displacement stage 13, and a host computer 14.

[0028] The low-temperature permalloy magnetic shielding barrel 4 is made of low-temperature permalloy and is used to shield external magnetic fields.

[0029] The shimming coil 5 is used to generate a three-axis uniform magnetic field.

[0030] The liquid inlet 6 is the working inlet for adding liquid nitrogen.

[0031] The liquid nitrogen container support block 7 is used to support the liquid nitrogen container 8 to the required height.

[0032] The liquid nitrogen container 8 is used for storing superconducting plates 1 and storing liquid nitrogen.

[0033] The low-temperature magnetic field sensitive probe 9 is used to measure the three-axis magnetic field under low-temperature environmental conditions.

[0034] The tetrafluoro elbow joint 10 is used to connect the low-temperature magnetic field sensitive probe 9 and the support rod 12.

[0035] The support rod 12 is used to connect the three-axis displacement stage 13 and the low-temperature magnetic field sensitive probe 9, and at the same time provides a wiring path for the test elements inside.

[0036] The three-axis displacement stage 13 scans the magnetic field on the test object with the probe.

[0037] The host computer 14 is used to record the magnetic field changes during the probe scanning process.

[0038] A spliced superconducting magnetic shielding structure and its shielding performance testing device, comprising: an overall shielding body formed by bonding multiple YBCO high-temperature 1-superconducting blocks with a low-temperature adhesive; the splicing interface includes a convex splicing gap 2 with a right-angled geometric feature; a magnetic field attenuation channel formed by an oblique splicing gap 3; a field uniforming coil 5 integrated inside the shielding body; a liquid inlet 6 for replenishing liquid nitrogen; a liquid nitrogen container support block 7 for supporting the liquid nitrogen container 8 and a liquid nitrogen container 8 for placing the spliced plates and providing liquid nitrogen; a low-temperature magnetic field sensitive probe 9 for measuring the magnetic shielding coefficient of the measuring device; a tetrafluoro elbow joint 10 for connecting the probe and the support rod; a support rod 12 for support; a three-axis displacement stage 13 capable of displacing in the X, Y, and Z directions; a host computer 14 for recording test data; and an outermost low-temperature permalloy magnetic shielding barrel 4.

[0039] The low-temperature permalloy magnetic shielding barrel 4 can maintain a shielding coefficient of 10 6 under low-temperature environmental conditions. The field uniforming coil 5 can generate a three-axis uniform magnetic field of 5 nT - 60000 nT, and the magnetic field uniform region is 150×150×150 mm. The liquid inlet 6 is made of low-temperature-resistant polytetrafluoroethylene. Both the liquid nitrogen container support block 7 and the liquid nitrogen container 8 are made of low-temperature-resistant EVA (EVA resin is ethylene-vinyl acetate copolymer). The low-temperature magnetic field sensitive probe 9 can measure the three-axis magnetic field under low-temperature environmental conditions. The tetrafluoro elbow joint 10 is made of low-temperature-resistant polytetrafluoroethylene. The support rod 12 is a custom-rigidity polytetrafluoroethylene hollow support rod, the rigidity of which can meet the requirement of no deformation during testing, and the internal hollow can meet the wiring of the platinum resistance 11 and the low-temperature magnetic field sensitive probe 9. The three-axis displacement stage 13 can displace 150 mm in each of the X, Y, and Z directions. The host computer 14 can record the magnetic field changes during the probe scanning process.

[0040] The present invention relates to the field of high-temperature superconducting magnetic shielding technology, and specifically discloses a superconducting magnetic shielding structure based on the synergistic effect of stepped splicing and its testing device. Aiming at the technical bottlenecks existing in the existing direct splicing type superconducting magnetic shielding, such as residual magnetic remanence, magnetic flux concentration at the joints, and complex processing, the present invention innovatively proposes a composite configuration design of convex splicing and oblique splicing to splice high-temperature superconducting bulk materials into large-size shielding plates. Among them, the convex splicing structure forms a stepped fitting on the transverse joint surface of the bulk materials, and the oblique splicing forms an inclined butt joint structure of 30-60° on the longitudinal joint surface. Through the synergistic effect of the two-dimensional special-shaped joints, the magnetic flux density gradient of the vertical magnetic field at the joints is effectively suppressed, and the magnetic flux pinning effect is reduced. This structure adopts modular prefabricated unit bodies, and the interlocking splicing surface is formed by diamond wire cutting, significantly simplifying the processing process and reducing the material loss rate. In addition, the invention discloses a magnetic shielding performance testing device for the spliced superconducting magnetic shielding, which can test and characterize the magnetic shielding performance of the spliced superconducting plates. The spliced structure of the present invention improves the residual magnetic shielding performance by more than 5 times under the geomagnetic field, and a testing device for the shielding performance of the spliced superconducting plates can characterize the superconducting shielding performance.

[0041] Reference Figure 1 , as can be seen from the figure, the device of the present invention includes a superconducting bulk material 1, which is a YBCO bulk material of 40×40×40 cm sintered by solid-phase reaction. After being processed into the required shape by diamond wire cutting, it is annealed in oxygen to obtain a superconducting bulk material; first, three bulk materials are subjected to convex splicing to generate a convex splicing gap 2; then, an oblique splicing gap 3 is generated by oblique splicing, and the splicing is bonded with a low-temperature adhesive resistant to liquid nitrogen temperature.

[0042] Reference Figure 2 , in this device, the low-temperature permalloy magnetic shielding barrel 4 shields the external geomagnetic field and various interference fields for the entire testing device, and the central residual magnetic is ≤5 nT. During the test, first place the liquid nitrogen container support block 7 and the liquid nitrogen container 8 in the central area of the shielding barrel to ensure that the superconducting bulk material 1 is in the uniform area, then cover the lid of the low-temperature permalloy magnetic shielding barrel 4, assemble the low-temperature magnetic field sensitive probe 9, the tetrafluoro elbow joint 10, the platinum resistance 11, and the support rod 12 and clamp them on the three-axis displacement stage 13 and extend them into the liquid nitrogen container. Subsequently, perform electrical demagnetization on the low-temperature permalloy magnetic shielding barrel 4. At this time, turn on the upper computer 14 to measure the internal residual magnetic, and then turn it off to prevent the superconducting bulk material from capturing the magnetic field generated by the probe during the cooling process. Then, slowly add liquid nitrogen to cool the superconducting plate through the liquid inlet 6, and use the platinum resistance 11 to indicate the position of the liquid nitrogen. 77K or -196°C indicates that the liquid nitrogen has covered the test probe, and observe the temperature change at any time during the test to supplement the liquid nitrogen. The test can be started about 20 minutes after adding liquid nitrogen for cooling. Move in the X and Y directions through the three-axis displacement stage, slowly scan the magnetic field on the surface of the entire superconducting plate, and record the experimental data through the upper computer 14.

[0043] Compared with the traditional spliced superconducting magnetic shield, the structure of the present invention changes the direct splicing method into a combined splicing method of convex splicing and oblique splicing. The test analysis shows that the magnetic flux concentration phenomenon at the joint is significantly suppressed, and the residual magnetism is reduced by about 5 times.

[0044] Solve the Faraday equation using the H-form finite element method:

[0045]

[0046] where is the vector differential operator, E is the electric field, B is the magnetic field, and t is the time. Use the magnetic field H as the state variable and describe the special electrical properties of the superconductor with the non-linear resistivity:

[0047]

[0048] where ρ is the non-linear resistivity, E0 is the characteristic electric field (generally 10 -4 V / m), J is the current density, J c is the critical current density, and n is the factor representing the steepness of the transition from the superconducting state to the normal state.

[0049] From the magnetic perspective, the superconductor is modeled as a material with a relative magnetic permeability μ r = 1. The Faraday equation expressed in terms of the magnetic field is:

[0050]

[0051] where μ0 is the vacuum magnetic permeability, H is the external magnetic field, and the divergence of the magnetic flux density is ensured to be zero by choosing zero initial conditions. Through the quasi-static approximation of Ampere's law, the current density J is derived from the magnetic field:

[0052]

[0053] Apply a triaxial H x 、H y 、H z external magnetic field of 30000 nT + 200 nT * sin(2πf), where f = 50 Hz. The central residual magnetisms of the convex splicing type and the direct splicing type are shown in Table 1, where B x is the residual magnetism in the x-axis, B y is the residual magnetism in the y-axis, and B z is the residual magnetism in the z-axis.

[0054] Table 1

[0055]

[0056] The content not described in detail in the specification of the present invention belongs to the prior art well-known to those skilled in the art. It is hereby specified that the above description helps those skilled in the art to understand the present invention, but does not limit the protection scope of the present invention. Any implementation that is an equivalent replacement, modification and improvement, and / or simplification of the above description without departing from the substantial content of the present invention falls within the protection scope of the present invention.

Claims

1. A superconducting magnetic shielding structure based on the synergistic effect of stepped splicing, characterized in that It includes a superconducting magnetic shielding cavity enclosed by the combined surfaces of superconducting blocks. Each superconducting block in each combined surface of superconducting blocks has a convex splicing structure forming a lateral side and an oblique splicing structure forming a longitudinal side. The adjacent superconducting blocks spliced horizontally are bonded with a cryogenic adhesive resistant to liquid nitrogen temperature at the convex splicing gap, and the adjacent superconducting blocks spliced longitudinally are bonded with a cryogenic adhesive resistant to liquid nitrogen temperature at the oblique splicing gap. Through the synergistic effect of the two-dimensional special-shaped stepped splicing joints, the magnetic flux density gradient of the vertical magnetic field at the joints is effectively suppressed, and the flux pinning effect is reduced.

2. The superconducting magnetic shielding structure based on the step splicing synergy according to claim 1, wherein The superconducting block is a YBCO yttrium barium copper oxide high-temperature superconductor.

3. The superconducting magnetic shielding structure based on the stepped splicing synergy according to claim 1, characterized in that, The oblique splicing gaps are arranged staggeredly at an angle of 30° to 60°, and the oblique splicing structure forms a Z-shaped magnetic field attenuation path.

4. The superconducting magnetic shielding structure based on the stepped splicing synergy according to claim 1, characterized in that, The stepped height of the convex splicing gap is 2 to 4 mm, the stepped width is 3 to 6 mm, and the stepped joint fold angle is 90° ± 2°. The convex splicing structure utilizes the characteristic that magnetic flux lines cannot mutate to suppress magnetic flux concentration.

5. A test device for a superconducting magnetic shielding structure, characterized in that, It includes a liquid nitrogen container. Inside the liquid nitrogen container is placed the combined surface of superconducting blocks used in the above superconducting magnetic shielding structure based on the stepped splicing synergistic effect. An inlet for liquid nitrogen is provided above the liquid nitrogen container. The liquid nitrogen container is located inside a shimming coil, and the shimming coil is located inside a cryogenic permalloy magnetic shielding barrel. A tetrafluoro elbow joint is provided above the combined surface of superconducting blocks. The lower port of the tetrafluoro elbow joint is connected to a cryogenic magnetic field sensitive probe extending towards the combined surface of superconducting blocks. The left port of the tetrafluoro elbow joint is connected to a three-axis displacement stage through a support rod. The three-axis displacement stage is connected to a host computer, and a platinum resistor is attached to the cryogenic magnetic field sensitive probe.

6. The test device for a superconducting magnetic shielding structure according to claim 5, characterized in that The outer bottom surface of the liquid nitrogen container is connected to a liquid nitrogen container support block.

7. The test device for a superconducting magnetic shielding structure according to claim 5, characterized in that, The shimming coil is used to generate a three-axis uniform magnetic field of 5 nT to 60000 nT, and the magnetic field uniform area formed by the shimming coil is 150×150×150 mm.

8. The test device for a superconducting magnetic shielding structure according to claim 5, characterized in that The inlet for liquid nitrogen is used to add liquid nitrogen to cool the combined surface of superconducting blocks. The platinum resistor is used to indicate the position of liquid nitrogen, indicating that the liquid nitrogen has covered the cryogenic magnetic field sensitive probe at a temperature of 77 K, and liquid nitrogen is supplemented at any time by observing the temperature change during the test. The three-axis displacement stage scans the magnetic field on the surface of the entire superconducting plate by moving in the X, Y, and Z directions. The host computer is used to record experimental data.

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