Active and passive magnetic shielding system for shipborne paleomagnetic superconducting magnetometer

Abstract

The invention discloses an active and passive magnetic shielding system for a shipborne paleomagnetic superconducting magnetometer. The active and passive magnetic shielding system comprises a passive magnetic shielding chamber, a degaussing coil winding, a torque-free coil winding, a magnetic sensor, a program-controlled degaussing current source and a control feedback unit, the passive magnetic shielding chamber is of a closed hexahedron structure formed by laying a plurality of layers of high-permeability shielding material permalloy. The degaussing coil winding is installed in a magnetic shielding layer of the passive magnetic shielding chamber to provide a degaussing magnetic field, the program control degaussing current source provides current excitation for the degaussing coil winding, and the torque-free coil winding can generate a needed magnetic field and reproduce a feedback magnetic field in a set area. The magnetic sensor collects a magnetic field in the passive magnetic shielding chamber in real time and feeds back the magnetic field to the control feedback unit, and the control feedback unit feeds back and provides corresponding current to the torque-free coil winding in real time according to the collected magnetic field, so that the torque-free coil winding generates a required magnetic field; the problem that a ship-borne static interference magnetic field is extremely large is solved in an active and passive composite shielding mode, and the high magnetic field shielding effectiveness is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic field protection and magnetic field shielding, and particularly relates to a main and passive magnetic shielding system for an on-board paleomagnetic superconducting magnetometer. Background Art

[0002] A paleomagnetic laboratory needs to shield the earth's magnetic field and external environmental interference magnetic field to provide a clean working magnetic field environment for equipment such as long-core superconducting magnetometers, rotating magnetometers, thermal demagnetizers, and alternating demagnetizers. A paleomagnetic laboratory built on land generally realizes the function of shielding the magnetic field through a magnetic shielding room, using high-permeability silicon steel or pure iron materials, and the residual magnetic field in the shielding room is controlled within 500 nT.

[0003] An on-board paleomagnetic laboratory built on a large experimental research ship needs to overcome adverse factors such as hull vibration, marine salt spray environment, surrounding complex ferromagnetic substances, the inherent magnetic field of the hull itself, and the induced magnetic field in different hull postures to ensure reliable operation. The most critical influencing factor is the extremely large static interference magnetic field formed by the superposition of the hull's inherent magnetic field and the induced magnetic field in different hull postures.

[0004] The above problems cannot be solved by using the shielding scheme on land. The restrictive factors include the shielding ability of shielding materials such as silicon steel and pure iron. If more excellent permalloy materials are used, due to the extremely large static interference magnetic field, in order to achieve the expected shielding efficiency, simply increasing the permalloy material is unrealistic and very uneconomical (the price of permalloy is expensive). Summary of the Invention

[0005] In view of this, the present invention provides a main and passive magnetic shielding system for an on-board paleomagnetic superconducting magnetometer, which uses a main and passive composite shielding method to solve the problem of extremely large on-board static interference magnetic field and achieve high magnetic field shielding efficiency.

[0006] The technical solution of the present invention is realized as follows:

[0007] A main and passive magnetic shielding system for an on-board paleomagnetic superconducting magnetometer includes a passive magnetic shielding room, a degaussing coil winding, a toroidal coil winding, a magnetic sensor, a programmable degaussing current source, and a control feedback unit;

[0008] The passive magnetic shielding chamber is a closed hexahedron structure laid by multiple layers of high-permeability magnetic shielding material Permalloy; the degaussing coil winding is installed in the magnetic shielding layer of the passive magnetic shielding chamber to provide a degaussing magnetic field, the programmable degaussing current source provides current excitation for the degaussing coil winding, the torque-free coil winding can generate the required magnetic field and reproduce the feedback magnetic field in the set area, the magnetic sensor real-time collects the magnetic field in the passive magnetic shielding chamber and feeds it back to the control feedback unit, and the control feedback unit can perform closed-loop control, calculate in real time according to the collected magnetic field and provide the corresponding current to the torque-free coil winding to generate the required magnetic field.

[0009] Further, the degaussing coil winding includes three groups of degaussing coils orthogonal to each other in pairs, including a horizontal degaussing coil, a north-south degaussing coil, and an east-west degaussing coil; the horizontal degaussing coil generates a degaussing magnetic field flowing horizontally; the north-south degaussing coil generates a degaussing magnetic field flowing north-south; the east-west degaussing coil generates a degaussing magnetic field flowing east-west.

[0010] Further, each group of degaussing coils is respectively wrapped with a corresponding magnetic shielding layer inside and outside. When the degaussing coil is connected to the set alternating oscillation current, a closed-loop oscillating alternating magnetic field will be generated in the magnetic shielding layer.

[0011] Further, the torque-free coil winding is placed outside the superconducting magnetometer, so that the magnetic field uniform area of the torque-free coil winding covers the working area of the superconducting magnetometer, the magnetic sensor is installed on one side of the working area of the superconducting magnetometer, and the control feedback unit is placed outside the magnetic shielding chamber; among them, the magnetic sensor real-time collects the magnetic field after the primary shielding of the passive magnetic shielding chamber and transmits it to the control feedback unit, and the control feedback unit calculates the reverse compensation current and provides it to the torque-free coil winding to make the remaining magnetic field in the working area of the superconducting magnetometer smaller and more uniform.

[0012] Further, the torque-free coil winding is a coil structure that generates a magnetic field inside the coil winding and the magnetic field outside the coil decreases rapidly.

[0013] Further, the magnetic sensor is a three-axis fluxgate sensor, with a magnetic field range of ±100 μT, a frequency range of DC~3 kHz, and a resolution of 0.1 nT.

[0014] Beneficial effects:

[0015] 1. The present invention provides a main and passive magnetic shielding system for a shipborne paleomagnetic superconducting magnetometer. In order to solve the problem that the static interference magnetic field of the shipborne paleomagnetic shielding chamber is different under different ship attitudes, a main and passive combined shielding system suitable for shipborne working conditions is designed and invented, which can achieve the expected magnetic shielding effect.

[0016] 2. The present invention provides a shipborne paleomagnetic permalloy magnetic shielding chamber equipped with a degaussing system. By winding corresponding degaussing coils around the magnetic shielding layer under different navigation postures, unidirectional and integral programmable degaussing can be performed, improving the degaussing quality and efficiency.

[0017] 3. The present invention provides a shipborne active magnetic shielding field coil. In the form of a toroidal coil, it effectively avoids the adverse effect of reducing the magnetic field uniformity due to the coupling effect with the shielding chamber, improves the shielding efficiency, and is more economical and practical when combined with passive magnetic shielding. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the active and passive shielding system provided by the present invention.

[0019] Figure 2 It is a schematic diagram of the three-axis integral degaussing coil winding and magnetic field flow direction that are pairwise orthogonal provided by the present invention; (a) is a schematic diagram of the coil, and (b) is a schematic diagram of the magnetic field flow direction.

[0020] Figure 3 It is a schematic diagram of the horizontal direction degaussing coil winding and magnetic field flow direction provided by the present invention; (a) is a schematic diagram of the coil, and (b) is a schematic diagram of the magnetic field flow direction.

[0021] Figure 4 It is a schematic diagram of the north-south direction degaussing coil winding and magnetic field flow direction provided by the present invention; (a) is a schematic diagram of the coil, and (b) is a schematic diagram of the magnetic field flow direction.

[0022] Figure 5 It is a schematic diagram of the east-west direction degaussing coil winding and magnetic field flow direction provided by the present invention; (a) is a schematic diagram of the coil, and (b) is a schematic diagram of the magnetic field flow direction.

[0023] Figure 6 It is a flow chart of the design steps of the active and passive magnetic shielding system provided by the present invention.

[0024] Figure 7 It is the simulation result of the internal residual magnetic field distribution map when the passive magnetic shielding chamber works alone.

[0025] Figure 8 It is the simulation result of the internal residual magnetic field distribution map when the active and passive composite magnetic shielding works simultaneously. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will be described in detail below with reference to the drawings and by way of examples.

[0027] As Figure 1 shown, a shipborne paleomagnetic superconducting magnetometer active and passive magnetic shielding system includes a passive magnetic shielding chamber, a degaussing coil winding, a toroidal coil winding, a magnetic sensor, a programmable degaussing current source, and a control feedback unit;

[0028] The passive magnetic shielding chamber is formed by laying multiple layers of high-permeability shielding material permalloy into a closed hexahedron structure. The degaussing coil winding is installed in the shielding layer to provide a degaussing magnetic field. The programmable degaussing current source provides current excitation for the degaussing coil winding. The torque-free coil winding can generate the required magnetic field and reproduce the feedback magnetic field in a certain area. The magnetic sensor can collect the magnetic field in real time and feed it back to the torque-free coil control unit. The torque-free coil control unit can perform closed-loop control and provide corresponding current to the torque-free coil winding in real-time negative feedback according to the collected magnetic field, so that it generates the required magnetic field.

[0029] As Figure 2 Shown in (a) and (b) of [], it is a simulation of a three-axis integral degaussing coil winding and magnetic field flow direction that are orthogonal to each other in pairs. The degaussing coil winding is composed of three groups of degaussing coils that are orthogonal to each other in pairs, which are respectively defined as the horizontal degaussing coil, the north-south degaussing coil, and the east-west degaussing coil. Each group of degaussing coils is wrapped with corresponding magnetic shielding layers inside and outside. When the degaussing coils are connected to a set specific alternating oscillation current, a closed-loop oscillating alternating magnetic field will be generated in the magnetic shielding layer.

[0030] As Figure 3 Shown in (a) and (b) of [], it is a simulation of the horizontal degaussing coil and magnetic field flow direction. The horizontal degaussing coil can generate a degaussing magnetic field flowing horizontally.

[0031] As Figure 4 Shown in (a) and (b) of [], it is a simulation of the north-south degaussing coil and magnetic field flow direction. The north-south degaussing coil can generate a degaussing magnetic field flowing north-south.

[0032] As Figure 5 Shown in (a) and (b) of [], it is a simulation of the east-west degaussing coil and magnetic field flow direction. The east-west degaussing coil can generate a degaussing magnetic field flowing east-west.

[0033] Among them, the earth's magnetic field can be decomposed into horizontal and vertical components. The horizontal component can be further decomposed into north-south and east-west components. Generally, the north-south component is larger than the east-west component. For the magnetic shielding chamber built on a scientific research ship, the attitude of the hull is changing in real time, and it is impossible to replicate the orientation that is beneficial to the shielding effect of the magnetic shielding chamber built on land. Therefore, the short side direction of the magnetic shielding chamber is parallel to the north-south component, and the long side direction is perpendicular to the north-south component.

[0034] That is to say, on the premise that the magnetic shielding layer in the vertical direction meets the design requirements, the magnetic shielding layers in the north-south and east-west directions need to be evenly laid with the same number of layers to meet the same shielding efficiency in different orientations, and the degaussing windings wrapped in the north-south direction also need degaussing windings with the same degaussing power to be wrapped in the east-west direction.

[0035] The magnetic shielding room is built inside the cabin of the scientific research ship. The scientific research ship itself is a huge ferromagnetic substance, and the earth's magnetic fields induced when it docks in different orientations are different in magnitude.

[0036] When the scientific research ship is sailing normally, its sailing attitude changes at any time. The earth's magnetic fields induced by the scientific research ship in different attitudes are different in magnitude, and are more obvious than when it is docked.

[0037] The scientific research ship itself has an inherent magnetic field.

[0038] The magnetic shielding room is built inside the cabin of the scientific research ship and is installed simultaneously with other ship equipment during construction. Among them, other large ferromagnetic equipment on the ship and the main hull structure itself directly affect the magnitude and direction of the inherent magnetic field of the hull. After the hull and large ferromagnetic equipment are completed, it is very difficult to change the magnitude and direction of the inherent magnetic field of the hull, and it is very difficult to eliminate it.

[0039] The magnetic shielding room is built inside the cabin of the scientific research ship. When the ship is docked in different orientations and sailing in different attitudes, the inherent magnetic field and the induced magnetic field of the hull are superimposed to form a huge static interference magnetic field, and the magnitude of this huge static interference magnetic field cannot be predicted in advance during the design stage of the magnetic shielding room.

[0040] When the inherent magnetic field and the induced magnetic field of the hull are superimposed to form a huge static interference magnetic field in a certain heading or several headings of the hull, it is very difficult to achieve the expected shielding effect simply by using a Permalloy magnetic shielding room, and an active shielding scheme needs to be added.

[0041] The active magnetic shielding system of the present invention includes a toroidal coil winding, a magnetic sensor, and a control feedback unit. Among them, the toroidal coil winding is placed outside the superconducting magnetometer, so that the magnetic field uniform area of the toroidal coil covers the working area of the superconducting magnetometer. The magnetic sensor is installed near the working area of the superconducting magnetometer on one side, and the control feedback unit is placed outside the magnetic shielding room. Among them, the magnetic sensor collects the magnetic field after the primary shielding of the shielding room in real time and transmits it to the control feedback unit. The control feedback unit calculates the reverse compensation current and supplies it to the toroidal coil winding, so that the remaining magnetic field in the working area of the superconducting magnetometer is smaller and more uniform.

[0042] The toroidal coil winding generates a magnetic field inside the coil winding, and the magnetic field outside the coil decreases sharply. Since the Permalloy shielding layer is a soft magnetic material, there is still a relatively large magnetic field outside the ordinary magnetic field coil at a distance from the shielding layer, which will magnetize the Permalloy shielding layer and cause the shielding effect to decline. Similarly, the Permalloy soft magnetic shielding layer will also affect the uniformity inside the magnetic field coil and affect the active shielding effect. The toroidal coil can effectively avoid the adverse effects caused by the coupling with the magnetic shielding room.

[0043] The magnetic sensor is a three-axis fluxgate sensor, with a magnetic field range of ±100 μT, a frequency range of DC~3 kHz, and a resolution of 0.1 nT.

[0044] It can be seen that, as Figure 6 shown, the main and passive shielding system of the shipborne paleomagnetic superconducting magnetometer provided by the present invention mainly includes the following design steps: S1, construction of the passive magnetic shielding chamber. Specifically, before construction, the environmental magnetic field of the construction site is measured, the measured values are preliminarily judged to estimate the magnitude of the static interference magnetic field, and the passive magnetic shielding layer is designed according to the required shielding coefficient; S2, installation of the degaussing coil windings. Specifically, the horizontal degaussing coil, the north-south degaussing coil and the east-west degaussing coil are installed respectively; S3, installation of the active magnetic shielding coil system. Specifically, the three-axis torque-free magnetic field coil, the magnetic sensor and the control feedback unit are installed respectively.

[0045] The present invention uses the Ansys Electronics Desktop finite element analysis software to model and simulate the passive magnetic shielding chamber and the main and passive composite shielding. The simulation results when the passive magnetic shielding chamber works alone are as Figure 7 shown. The simulation results when the main and passive composite shielding works simultaneously are as Figure 8 shown.

[0046] In summary, the above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A main and passive magnetic shielding system for an on-board paleomagnetic superconducting magnetometer, characterized in that, It includes a passive magnetic shielding chamber, a degaussing coil winding, a toroidal coil winding, a magnetic sensor, a programmable degaussing current source, and a control feedback unit; The passive magnetic shielding chamber is a closed hexahedron structure laid by multiple layers of high-permeability shielding material permalloy; the degaussing coil winding is installed in the magnetic shielding layer of the passive magnetic shielding chamber to provide a degaussing magnetic field, the programmable degaussing current source provides current excitation for the degaussing coil winding, the toroidal coil winding can generate the required magnetic field and reproduce the feedback magnetic field in the set area, the magnetic sensor real-time collects the magnetic field in the passive magnetic shielding chamber and feeds it back to the control feedback unit, and the control feedback unit can perform closed-loop control, calculate in real time according to the collected magnetic field and provide the corresponding current to the toroidal coil winding to make it generate the required magnetic field.

2. The main and passive magnetic shielding system of the shipborne paleomagnetic superconducting magnetometer according to claim 1, characterized in that, The degaussing coil winding includes three groups of pairwise orthogonal degaussing coils, including a horizontal degaussing coil, a north-south degaussing coil, and an east-west degaussing coil; the horizontal degaussing coil generates a degaussing magnetic field flowing horizontally; the north-south degaussing coil generates a degaussing magnetic field flowing north-south; the east-west degaussing coil generates a degaussing magnetic field flowing east-west.

3. The main and passive magnetic shielding system of the shipborne paleomagnetic superconducting magnetometer according to claim 2, characterized in that, Each group of degaussing coils is respectively wrapped with a corresponding magnetic shielding layer inside and outside. When the degaussing coil is connected to the set AC oscillating current, a closed-loop oscillating AC magnetic field will be generated in the magnetic shielding layer.

4. The main and passive magnetic shielding system of the shipborne paleomagnetic superconducting magnetometer according to claim 1, wherein The toroidal coil winding is placed outside the superconducting magnetometer, so that the magnetic field uniform area of the toroidal coil winding covers the working area of the superconducting magnetometer. The magnetic sensor is installed on one side of the working area of the superconducting magnetometer, and the control feedback unit is placed outside the magnetic shielding chamber; among them, the magnetic sensor real-time collects the magnetic field after the primary shielding of the passive magnetic shielding chamber and transmits it to the control feedback unit. The control feedback unit calculates the reverse compensation current and provides it to the toroidal coil winding to make the remaining magnetic field in the working area of the superconducting magnetometer smaller and more uniform.

5. The main and passive magnetic shielding system of the shipborne paleomagnetic superconducting magnetometer according to claim 1 or 4, characterized in that The toroidal coil winding is a coil structure that generates a magnetic field inside the coil winding and the magnetic field outside the coil decreases rapidly.

6. The main and passive magnetic shielding system of the shipborne paleomagnetic superconducting magnetometer according to claim 1, wherein, The magnetic sensor is a three-axis fluxgate sensor with a magnetic field range of ±100 μT, a frequency range of DC~3 kHz, and a resolution of 0.1 nT.

Images