A spliced high-temperature superconducting magnetic shielding device and a combined device

Abstract

A spliced high-temperature superconducting magnetic shielding device and a combined device, which at least solve the problem of self-generated magnetic noise that cannot be solved by a magnetic shielding device made of soft magnetic materials. After combining with the spliced superconducting magnetic shielding, the residual magnetism or magnetic noise can be reduced by at least 1-3 orders of magnitude. It is characterized in that it includes a spliced magnetic shielding barrel formed by splicing and enclosing several blocks. The blocks are superconducting blocks sintered from high-temperature superconducting powder. Superconducting powder is filled in the splicing seams between adjacent blocks, and the splicing seams between adjacent blocks are sealed with superconducting tape. High-temperature superconductivity means that the liquid nitrogen temperature at which the superconducting phenomenon occurs is ≥77K.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic shielding technology that must be used in the measurement of extremely weak magnetic fields in quantum precision measurement, and particularly relates to a spliced high-temperature superconducting magnetic shielding device and a combined device. Background Art

[0002] In recent years, the rapid development of quantum precision measurement technology has made the methods for measuring extremely weak magnetic fields more diversified. Among them, the realization of high-sensitivity magnetic field measurement based on the atomic spin effect has become the latest research direction. In a new type of ultra-high-sensitivity magnetic field measurement device, the atomic magnetometer operating in the spin-exchange relaxation-free state is the most prominent. Theoretically, it can reach a sensitivity of the order of aT (10 -18 T). However, one of the conditions required to achieve the spin-exchange relaxation-free state is a weak magnetic environment close to zero. Generally, materials with high magnetic permeability are selected to make a magnetic shielding barrel with high shielding performance to effectively isolate the environmental magnetic field. However, the sensitivity of the magnetic field measurement device is limited by magnetic noise, and one of the sources of its magnetic noise is the noise of the magnetic shielding barrel itself.

[0003] Generally, due to the magnetic hysteresis loss and eddy current loss of soft magnetic materials, the magnetic shielding barrel will generate thermomagnetic noise and Johnson current noise. For soft magnetic materials with both high magnetic permeability and high resistivity, its noise mainly comes from thermomagnetic noise. The noise δB of an infinitely long magnetic shielding barrel magn is:

[0004] ,

[0005] where μ'(T) and μ''(T) are the real and imaginary parts of the complex magnetic permeability respectively, μ0 is the magnetic permeability in vacuum, k is the Boltzmann constant, r L is the inner diameter of the shielding barrel, t is the thickness of the shielding barrel, T is the temperature, ω = 2πf, and f is the frequency. For soft magnetic materials with high magnetic permeability and low resistivity, its magnetic noise mainly comes from Johnson current noise generated by the random thermal motion of electrons. For an infinitely long cylindrical magnetic shielding barrel, its magnetic noise δB eddy is:

[0006] ,

[0007] where r L is the inner diameter of the shielding barrel, k is the Boltzmann constant, T is the temperature, t is the thickness of the shielding barrel, σ is the conductivity of permalloy, μ'(T) is the real part of the complex magnetic permeability, and C(μ'(T)) is a constant. Summary of the Invention

[0008] The present invention provides a spliced high-temperature superconducting magnetic shielding device and a combined device, so as to solve at least the problem of self-generated magnetic noise that cannot be solved by a magnetic shielding device made of soft magnetic materials. After combining with the spliced superconducting magnetic shielding, the residual magnetism or magnetic noise can be reduced by at least 1-3 orders of magnitude.

[0009] The technical solution of the present invention is as follows:

[0010] A spliced high-temperature superconducting magnetic shielding device, characterized in that it includes a spliced magnetic shielding barrel formed by splicing and enclosing a number of blocks. The blocks are superconducting blocks sintered from high-temperature superconducting powder. Superconducting powder is filled in the splicing seams between adjacent blocks, and the splicing seams between adjacent blocks are sealed with superconducting tape. High-temperature superconductivity means that the liquid nitrogen temperature at which the superconducting phenomenon occurs is ≥77K.

[0011] The high-temperature superconducting powder is yttrium barium copper oxide YBCO or bismuth strontium calcium copper oxide BSCCO.

[0012] An oxygen-free copper cold conduction belt is attached to the outer surface of the barrel body of the spliced magnetic shielding barrel. Oxygen-free copper cold conduction discs are provided on both the top end face and the bottom end face of the spliced magnetic shielding barrel. The oxygen-free copper cold conduction belt and the oxygen-free copper cold conduction discs are both connected to a low-temperature cycle refrigeration system, and the low-temperature cycle refrigeration system is configured with a buffer vibration isolation structure.

[0013] A working cavity located on a support device is provided on the inner bottom surface of the spliced magnetic shielding barrel. The working cavity is composed of a heat insulation material and a non-magnetic radiation screen. Both the working cavity and the spliced magnetic shielding barrel have a through-hole in the transverse direction and a through-hole in the longitudinal direction.

[0014] The spliced magnetic shielding barrel is of a square structure, and each side is formed by splicing a number of blocks.

[0015] The superconducting block satisfies the following expression:

[0016] ,

[0017] where χ is the magnetic susceptibility of the superconductor, M is the magnetization intensity, H is the external magnetic field, μ is the magnetic permeability of the superconductor, and μ0 is the magnetic permeability in vacuum.

[0018] A combined magnetic shielding device, characterized in that it includes a soft magnetic material magnetic shielding device with the above-mentioned spliced high-temperature superconducting magnetic shielding device built therein.

[0019] The soft magnetic material magnetic shielding device includes a multi-layer permalloy housing. A window mirror is provided on the light through-hole at the middle waist of the outermost layer of permalloy. There is an outward extending structure below the middle waist of the outermost layer of permalloy. The side of the extending structure is connected to a vacuum pump through a vacuum valve, and the side of the extending structure is connected to a compound vacuum gauge. A support frame is provided on the inner bottom surface of the multi-layer permalloy housing, and the support frame supports the bottom of the spliced high-temperature superconducting magnetic shielding device.

[0020] The technical effects of the present invention are as follows: The present invention provides a spliced high-temperature superconducting magnetic shielding device and a combined device, which solve the problems that the shielding performance of the soft magnetic material magnetic shielding is limited by its own magnetic noise and cannot be further improved, and the existing superconducting magnetic shielding is limited by the large-size process and low-temperature working conditions and cannot transmit light. A magnetic shielding device combining spliced superconducting magnetic shielding and soft magnetic material magnetic shielding is proposed, which further reduces the magnetic noise of the magnetic shielding system and realizes higher magnetic shielding performance, and is of great significance in creating a zero magnetic environment and improving the sensitivity of ultra-high sensitive extremely weak magnetic field measurement devices. The present invention can be applied to quantum sensors sensitive to magnetic fields such as atomic inertial measurement, atomic clocks, and quantum computers. The extremely weak magnetic field and extremely low magnetic noise environment provided by the present invention are suitable for scientific experiments and industrial applications such as quantum precision measurement and atomic magnetometers. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of a spliced high-temperature superconducting magnetic shielding combined device of the present invention.

[0022] Figure 2 is Figure 1 a schematic structural diagram of the square spliced superconducting magnetic shielding device in

[0023] The description of the reference numerals is as follows: 1 - soft magnetic material magnetic shielding device; 2 - square spliced superconducting magnetic shielding device; 3 - light through-hole; 4 - window mirror; 5 - support frame; 6 - oxygen-free copper cold conduction belt; 7 - low-temperature circulation refrigeration system; 8 - buffer vibration isolation structure; 9 - compound vacuum gauge; 10 - vacuum pump; 11 - superconducting tape; 12 - working cavity; 13 - oxygen-free copper cold conduction disk; 14 - vacuum valve. Detailed Embodiments

[0024] The following describes the present invention in conjunction with the drawings ( Figure 1 - Figure 2 ) and embodiments.

[0025] Figure 1 It is a schematic structural diagram of a spliced high-temperature superconducting magnetic shielding combined device of the present invention. Figure 2 is Figure 1 a schematic structural diagram of the square spliced superconducting magnetic shielding device in. Referring to Figure 1 to Figure 2 as shown, a spliced high-temperature superconducting magnetic shielding device includes a spliced magnetic shielding barrel formed by splicing a plurality of blocks (for exampleFigure 2 The square splicing superconducting magnetic shielding device in 2), the bulk material is a superconducting bulk material sintered from high-temperature superconducting powder, superconducting powder is filled in the splicing seam between adjacent bulk materials, the splicing seam between adjacent bulk materials is sealed with a superconducting strip 11, and high-temperature superconductivity means that the liquid nitrogen temperature at which the superconducting phenomenon occurs is ≥ 77K.

[0026] The high-temperature superconducting powder is yttrium barium copper oxide YBCO or bismuth strontium calcium copper oxide BSCCO. An oxygen-free copper cold-conducting strip 6 is attached to the outer surface of the barrel body of the splicing magnetic shielding barrel, oxygen-free copper cold-conducting discs 13 are arranged on both the top end face and the bottom end face of the splicing magnetic shielding barrel, the oxygen-free copper cold-conducting strip 6 and the oxygen-free copper cold-conducting discs 13 are both connected to a low-temperature cycle refrigeration system 7, and the low-temperature cycle refrigeration system 7 is configured with a buffer vibration isolation structure 8. A working cavity 12 located on a support device is arranged on the inner bottom surface of the splicing magnetic shielding barrel, the working cavity 12 is composed of a heat-insulating material and a non-magnetic radiation screen, and both the working cavity 12 and the splicing magnetic shielding barrel have a horizontally penetrating light-transmitting hole and a vertically penetrating light-transmitting hole. The splicing magnetic shielding barrel is of a square structure, and each side is formed by splicing a plurality of bulk materials.

[0027] The superconducting bulk material satisfies the following expression:

[0028] ,

[0029] where χ is the magnetic susceptibility of the superconductor, M is the magnetization intensity, H is the external magnetic field, μ is the magnetic permeability of the superconductor, and μ0 is the magnetic permeability of vacuum.

[0030] A combined magnetic shielding device includes a soft magnetic material magnetic shielding device 1 with the above-mentioned splicing high-temperature superconducting magnetic shielding device built therein. The soft magnetic material magnetic shielding device 1 includes a multi-layer permalloy shell, a window mirror 4 is arranged on the light-transmitting hole 3 in the middle waist of the outermost layer of permalloy, an outward extending structure is provided below the middle waist of the outermost layer of permalloy, the side surface of the extending structure is connected to a vacuum pump 10 through a vacuum valve 14, the side surface of the extending structure is connected to a compound vacuum gauge 9, a support frame 5 is arranged on the inner bottom surface of the multi-layer permalloy shell, and the support frame 5 supports the bottom of the splicing high-temperature superconducting magnetic shielding device.

[0031] The present invention provides a superconducting magnetic shielding and a superconducting tape splicing combined magnetic shielding device, which overcomes the difficulties of limited size and low shielding efficiency of superconducting magnetic shielding, and aims to solve the problem that the magnetic shielding performance of traditional soft magnetic materials cannot be further improved due to their own magnetic noise. The combined magnetic shielding device includes components such as a soft magnetic material magnetic shielding, a square splicing superconducting magnetic shielding body, superconducting tapes, and a cryogenic cycle refrigeration system. The soft magnetic material magnetic shielding shields the external environmental magnetic field, and the superconducting magnetic shielding and superconducting tapes reduce the residual magnetism and its magnetic noise inside the soft magnetic material magnetic shielding, achieving ultra-high magnetic shielding performance. The present invention solves the magnetic noise problem of soft magnetic materials, proposes a combination scheme of soft magnetic material magnetic shielding and superconducting magnetic shielding, constructs an environment with ultra-low residual magnetism and magnetic noise, and is applicable to fields such as quantum precision measurement and its applications, improving the sensitivity and performance of quantum precision measurement.

[0032] A splicing superconducting magnetic shielding and combined magnetic shielding device, wherein the splicing superconducting magnetic shielding is composed of superconducting bulk materials sintered from high-temperature superconducting powders and superconducting tapes, and the superconducting powders are spliced together;

[0033] The high-temperature superconducting powder refers to a material that can exhibit superconducting phenomena above the liquid nitrogen temperature (77K), and is also called a copper oxide superconductor, including yttrium barium copper oxide YBCO (YBa2Cu3O7), bismuth strontium calcium copper oxide BSCCO (Bi2Sr2Ca2Cu3O10), etc.;

[0034] The combined magnetic shielding device includes: a soft magnetic material magnetic shielding, a square splicing superconducting magnetic shielding body, a cryogenic cycle refrigeration system, a vacuum pump, a compound vacuum gauge, a vacuum valve, a light passing hole, a support frame, a working chamber, and a buffer vibration isolation structure.

[0035] The soft magnetic material magnetic shielding is made of a high magnetic permeability material (magnetic permeability greater than 10,000, such as permalloy, Fe-based amorphous alloy, etc.), and serves as the vacuum outer shell of the combined magnetic shielding device to shield the external magnetic field. After shielding, the residual magnetism in the barrel is about 1 nT, and at the same time, it is used to create a vacuum environment with a vacuum degree of 10 -4 Pa.

[0036] The square splicing superconducting magnetic shielding body is used to shield the magnetic field and magnetic noise inside the soft magnetic material magnetic shielding, ensuring an extremely weak magnetic environment inside; the shielding body is formed by splicing multiple square superconducting bulk materials into a six-sided closed magnetic shielding body, and the joints are filled with splicing of superconducting tapes, superconducting powders, superconducting bulk materials, etc., to ensure the continuity of the overall structure and the shielding performance.

[0037] The low-temperature cycle refrigeration system is used to provide a low-temperature environment (below the superconducting critical temperature) to ensure that the superconducting magnetic shield operates in the superconducting state. It is magnetically shielded and connected to the outer soft magnetic material through a buffer vibration isolation structure, and the cold is transferred to the superconducting magnetic shield through a cold conduction plate and a cold conduction belt to ensure that it remains in the superconducting state. The cold conduction plate and the cold conduction belt are made of non-magnetic and high-thermal conductivity materials such as oxygen-free copper.

[0038] The vacuum pump and the compound vacuum gauge are connected to the outer magnetic shield through a vacuum valve to pump out the gas in the entire device and the working chamber, which is used to achieve a vacuum environment to prevent cold loss, and at the same time measure and control the vacuum environment to ensure the stability and reliability of the vacuum environment.

[0039] The vacuum valve is arranged on the device shell and is used to connect the vacuum pump and the compound vacuum gauge for easy operation and maintenance.

[0040] The light passing holes are respectively located on the side walls, upper and lower bottoms of the soft magnetic material magnetic shield shell, the centers of the six faces of the spliced superconducting magnetic shield, and the upper and lower bottoms and side walls of the working chamber. To ensure the passage of the light beam, there are also corresponding openings on the upper and lower cold conduction plates.

[0041] The support frame is used to support the spliced superconducting magnetic shield to the required height.

[0042] The working chamber is composed of heat insulation materials and a non-magnetic radiation shield to ensure that the internal temperature is not affected by the external low-temperature environment. The inside of it is a working area for conducting experiments in an extremely weak magnetic field and an extremely low magnetic noise environment.

[0043] The buffer vibration isolation structure is used to mitigate the influence of the vibration of the refrigerator.

[0044] The cold head of the low-temperature refrigerator of the entire device is connected to the cold conduction plates at the upper and lower bottoms and the cold conduction belts on the side walls of the superconducting magnetic shield through cold conduction belts; the soft magnetic material magnetic shield shell, the spliced superconducting magnetic shield, and the working chamber are assembled concentrically through the light passing holes. The spliced superconducting magnetic shield is placed on the support frame, the bottom of the cold conduction plate is connected to the support frame, and the soft magnetic material magnetic shield shell is connected to the compound vacuum gauge and the vacuum pump through a vacuum valve.

[0045] A method of using the spliced superconducting magnetic shield and the combined magnetic shield device described above to provide an extremely weak magnetic field and an extremely low magnetic noise environment, which is suitable for scientific experiments and industrial applications such as quantum precision measurement and atomic magnetometer.

[0046] A square spliced superconducting magnetic shield, such as Figure 2As shown, yttrium barium copper oxide (YBa2Cu3O7, abbreviated as YBCO) is selected and made into superconducting bulk materials with dimensions of 10 cm × 10 cm × 5 mm through a sintering process. These superconducting bulk materials will be used to piece together a square pieced superconducting magnetic shield 2 with a volume of 30 cm × 30 cm × 30 cm. YBCO superconducting tapes 11 are pasted at the joints, and at the same time, YBCO superconducting powder is filled to reduce the influence of magnetic leakage at the joints on the shielding performance.

[0047] A combined magnetic shielding device, as Figure 1 shown, multiple layers of soft magnetic material permalloy are selected as the soft magnetic material magnetic shield 1. The outermost layer of permalloy magnetic shield serves as the device housing. The upper half is designed as a cylindrical barrel with an inner diameter of 450 mm and a height of 400 mm, and the lower half is a racetrack-shaped cavity as shown. The two are pieced together to form the entire device housing, combined with multiple internal layers of permalloy to shield the external magnetic field and create a vacuum environment. Through holes 3 with a diameter of 30 mm are reserved on the upper and lower bottom surfaces of the housing, and through holes 3 with a diameter of 18 mm are reserved on the side walls, which are sealed with flanges and window mirrors 4 to allow optical detection and pumping optical paths to pass through. The housing is provided with multiple vacuum valves 14 for connecting to a vacuum pump 10 and a compound vacuum gauge 9. A buffer vibration isolation structure 8 is installed thereon and connected to an external cryogenic circulation refrigeration system 7.

[0048] In this embodiment, the pieced superconducting magnetic shield uses yttrium barium copper oxide (YBa2Cu3O7, abbreviated as YBCO), and superconducting bulk materials with dimensions of 10 cm × 10 cm × 5 mm are pieced together to form a square closed superconducting magnetic shield body 2 with a volume of 30 cm × 30 cm × 30 cm. Openings are reserved at the centers of the six faces, with an opening diameter of 30 mm on the upper and lower bottom surfaces and an opening diameter of 18 mm on the side walls. YBCO superconducting tapes 11 are pasted at the joints, and at the same time, YBCO superconducting powder is filled to reduce the influence of magnetic leakage at the joints on the shielding performance.

[0049] In this embodiment, the cryogenic circulation refrigeration system 7 includes an oxygen-free copper cold conduction disk 13, cold conduction tapes 6, and a buffer vibration isolation structure 8. The cold conduction disk 13 is attached to the upper and lower surfaces of the square pieced superconducting magnetic shield body 2, and cold conduction tapes 6 are pasted on the sides and connected to the cold head of the cryogenic circulation refrigeration system 7 to ensure that the superconducting magnetic shield body remains in the superconducting state. The cryogenic circulation refrigeration system 7 needs to ensure that the working temperature is lower than the critical temperature of YBCO (about 92 K or -181°C).

[0050] In this embodiment, the internal support frame 5 is made of epoxy resin material and is placed inside the device to support the square pieced superconducting magnetic shield body 2, the working cavity 12, and the multiple layers of permalloy magnetic shield barrels. The bottom of the support frame for supporting the superconducting magnetic shield is connected to the bottom of the inner layer of the soft magnetic material magnetic shield, and the top is connected to the cold conduction disk at the bottom of the superconducting magnetic shield body to ensure the stability of the superconducting shield body.

[0051] In this embodiment, the working chamber 12 is composed of heat-insulating materials and a non-magnetic radiation screen, with a diameter of 180 mm, a height of 250 mm, a 18-mm light-passing hole left on the side wall, and 30-mm light-passing holes left on the upper and lower bottom surfaces. It is located inside the device, and its interior is the working area, providing an experimental environment with an extremely weak magnetic field and extremely low magnetic noise.

[0052] In this embodiment, the working chamber 12 is placed inside the square spliced superconducting magnetic shield 2, and the openings are aligned by supporting with the support frame 5. The square spliced superconducting magnetic shield 2 is connected to the cold head of the cryogenic circulation refrigeration system 7 through the heat conduction belt 6 and the heat conduction disk 13. The heat conduction disk is fixed on the support frame inside the soft magnetic material magnetic shield. Confirm that the positions of the light-passing holes are aligned to ensure that the light beam can pass through smoothly. Connect the vacuum pump 10, the compound vacuum gauge 9, and the vacuum valve 14 to ensure that all interfaces are well sealed, and start the vacuum pumping operation to check whether the vacuum degree meets the requirements. Start the cryogenic circulation refrigeration system 7 and gradually lower the temperature to make the square spliced superconducting magnetic shield 2 enter the superconducting state. Monitor the temperature change to ensure that the temperature of each part is uniform, especially to ensure that the temperature is lower than the critical temperature of YBCO (about 92 K or -181 °C). Use the compound vacuum gauge 9 to monitor the vacuum environment in real time, adjust the working parameters of the vacuum pump 10, and maintain a stable vacuum degree. Test the shielding effect of the device, measure the internal and external magnetic field intensities, and confirm the effectiveness of the square spliced superconducting magnetic shield. Adjust the power of the cryogenic circulation refrigeration system 7 according to actual needs to optimize the cooling efficiency and stability. Record the magnetic field data under different temperature conditions, especially the change of the magnetic field during the process of the superconducting magnetic shield changing from room temperature to the superconducting state, evaluate the performance of the spliced superconducting magnetic shield and the combined magnetic shield device in reducing magnetic noise, and compare the performance improvement compared with the single soft magnetic material magnetic shield. Theoretically, the residual magnetic field that can be achieved only by using a multi-layer permalloy magnetic shielding barrel is about 1 nT, and the magnetic noise is 10 fT / Hz 1 / 2 , after combining with the spliced superconducting magnetic shield, the residual magnetic field and magnetic noise can be reduced by at least 1-3 orders of magnitude, and its effect is affected by the gaps and processing defects of the spliced superconducting magnetic shield.

[0053] In order to further improve the measurement sensitivity of the extremely weak magnetic field, the design of a high-performance magnetic shielding system is crucial. Since the magnetic noise of the soft magnetic material comes from itself and cannot be completely eliminated, and the superconductor has the zero-resistance effect and the Meissner effect. For high-temperature superconductors, they belong to the second type of superconductors, that is, when the demagnetization factor is zero, the magnetic field intensity is in the Meissner state when it is below the lower critical magnetic field intensity H c1 below, in the mixed state when it is between H c1 and the upper critical magnetic field intensity H c2 , and in the normal state when it is above H c2 of the superconductor.

[0054] Among them, the lower critical magnetic field is:

[0055] ,

[0056] where Φ0 is the magnetic flux quantum, λ is the surface penetration depth, and ξ is the coherence length.

[0057] When the applied magnetic field H < H c1 , the type-II superconductor is in the Meissner state. At this time, the magnetic field inside the superconductor is completely expelled, showing perfect diamagnetism. The reverse magnetic field generated by the superconducting current on its surface cancels out the external magnetic field, achieving complete magnetic field shielding.

[0058] In the Meissner state, the magnetic susceptibility χ of the superconductor satisfies:

[0059] ,

[0060] The corresponding magnetic permeability μ = μ0(1 + χ) = 0, indicating the complete repulsion of the superconductor to the external magnetic field H. In addition, the superconducting-normal phase interface energy of the type-II superconductor is negative. When H < H c1 , forming a magnetic flux line requires overcoming an energy barrier, so the formation of magnetic flux lines can be effectively suppressed, maintaining the stability of the Meissner state. And there are no magnetic flux lines inside the superconductor, so there is no loss caused by magnetic flux flow. In theory, zero loss can be achieved. Therefore, superconducting magnetic shielding can be used as a new magnetic shielding means to design a new type of superconducting magnetic shielding and combined magnetic shielding device to provide support for improving the measurement sensitivity of extremely weak magnetic fields in an extremely weak magnetic field environment. In addition, the present invention will also be applied to quantum sensors sensitive to magnetic fields such as atomic inertial measurement, atomic clocks, and quantum computers.

[0061] 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 pointed out 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 makes equivalent replacements, modifications, improvements, and / or simplifies the above description without departing from the essential content of the present invention falls within the protection scope of the present invention.

Claims

1. A spliced high-temperature superconducting magnetic shielding device, characterized in that, It includes a spliced magnetic shielding barrel formed by splicing several blocks. The blocks are superconducting blocks sintered from high-temperature superconducting powder. Superconducting powder is filled in the splicing seams between adjacent blocks, and the splicing seams between adjacent blocks are sealed with superconducting tapes. High-temperature superconductivity means that the liquid nitrogen temperature at which the superconducting phenomenon occurs is ≥ 77K; The superconducting block satisfies the following expression: ， where χ is the magnetic susceptibility of the superconductor, M is the magnetization intensity, H is the external magnetic field, μ is the magnetic permeability of the superconductor, and μ0 is the magnetic permeability in vacuum.

2. The spliced high-temperature superconducting magnetic shielding device according to claim 1, wherein, The high-temperature superconducting powder is yttrium barium copper oxide YBCO or bismuth strontium calcium copper oxide BSCCO.

3. The spliced high-temperature superconducting magnetic shielding device according to claim 1, characterized in that An oxygen-free copper cold conduction belt is attached to the outer surface of the barrel body of the spliced magnetic shielding barrel. Oxygen-free copper cold conduction discs are provided on both the top end face and the bottom end face of the spliced magnetic shielding barrel. The oxygen-free copper cold conduction belt and the oxygen-free copper cold conduction discs are both connected to a low-temperature cycle refrigeration system, and the low-temperature cycle refrigeration system is configured with a buffer vibration isolation structure.

4. The spliced high-temperature superconducting magnetic shielding device according to claim 1, characterized in that A working cavity located on a support device is provided on the inner bottom surface of the spliced magnetic shielding barrel. The working cavity is composed of a heat insulation material and a non-magnetic radiation screen. Both the working cavity and the spliced magnetic shielding barrel have a horizontally penetrating light passing hole and a vertically penetrating light passing hole.

5. The spliced high-temperature superconducting magnetic shielding device according to claim 1, wherein The spliced magnetic shielding barrel is of a square structure, and each side is formed by splicing multiple blocks.

6. A combined magnetic shielding device, characterized in that, It includes a soft magnetic material magnetic shielding device with the spliced high-temperature superconducting magnetic shielding device according to one of claims 1-5 built therein.

7. The combined magnetic shielding device according to claim 6, wherein, The soft magnetic material magnetic shielding device includes a multi-layer permalloy shell. A window mirror is provided on the light passing hole in the middle waist of the outermost layer of permalloy. There is an outward extending structure below the middle waist of the outermost layer of permalloy. The side of the extending structure is connected to a vacuum pump through a vacuum valve, and the side of the extending structure is connected to a compound vacuum gauge. A support frame is provided on the inner bottom surface of the multi-layer permalloy shell, and the support frame supports the bottom of the spliced high-temperature superconducting magnetic shielding device.

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