CN217183728U

CN217183728U - Magnetic shielding device

Info

Publication number: CN217183728U
Application number: CN202220308573.0U
Authority: CN
Inventors: 曹进; 蔡勇; 李锡瑞
Original assignee: Shanghai Astronomical Observatory of CAS
Current assignee: Shanghai Astronomical Observatory of CAS
Priority date: 2022-02-16
Filing date: 2022-02-16
Publication date: 2022-08-12
Anticipated expiration: 2032-02-16

Abstract

The utility model relates to a magnetic shielding device, include: the magnetic shielding main body comprises a plurality of layers of nested shielding cylinders, and the side surfaces, the top surfaces and the bottom surfaces of the shielding cylinders are in smooth transition; the sleeve is sleeved on the outer side of the magnetic shielding main body and formed by splicing two half sleeves with the same size and shape. The magnetic shielding device of the utility model has the advantages that the magnetic shielding main body comprises a plurality of layers of nested shielding cylinders, the sides, the top surface and the bottom surface of the shielding cylinders are in smooth transition, and the shielding effect is good; the upper supporting piece and the lower supporting piece are arranged between the shielding cylinders of all layers, so that the space between the shielding cylinders of all layers can be kept, and the heat inside the shielding cylinders can be conducted to the outside.

Description

Magnetic shielding device

Technical Field

The utility model relates to a hydrogen atom selects attitude technical field, more specifically relates to a magnetic screen device.

Background

As shown in fig. 1, the secondary state selection system of the hydrogen pulse includes a primary state selection magnet, a quantum state inversion device and a secondary state selection magnet, and the quantum state inversion device is respectively communicated with the primary state selection magnet and the secondary state selection magnet to realize circulation of the hydrogen atom beam. In a quantum state inversion device, a gradient magnetic field with the transverse direction of 0-4Gs and a longitudinal linear polarization magnetic field with the longitudinal direction of 0.2Gs need to be generated through a plurality of groups of coils, and any other external magnetic field higher than 0.01Gs can influence the operation of a secondary state selection system, even the secondary state selection system is disabled. However, the field strength of the pole tips of the first stage state selection magnet and the second stage state selection magnet connected with the quantum state inversion device is as high as 10000Gs, and the geomagnetic field generated by the earth is not lower than 0.5Gs, so that a magnetic shielding device is required to be arranged outside the quantum state inversion device to shield the strong external magnetic field, so that the strong external magnetic field is lower than 0.01 Gs.

As shown in FIG. 2, the magnetic shield structure generally takes the form of a multi-layered cylindrical tube nest, wherein R is _i And L _i The average radius and average length of the ith layer (i ═ 1,2 … n), respectively, and Δ R and Δ L are the radial and axial spacing between layers, respectively. As shown in fig. 3, a conventional magnetic shield device comprises four layers of shield cans 100, each layer being made of a high permeability 1J85 permalloy having a thickness of 0.8mm, with a layer-to-layer spacing of 7 mm; the diameter of each top cover except the top cover at the outermost layer is 20mm, a hole 101 is formed in the center of the circle and used for placing a wrench for mechanical tuning, the shielding cylinder 100 and the shielding bottom 200 are fastened in an inserting mode, the magnetic field intensity of the shielding device from the outside to the central axis of an internal environment is reduced to 2E-8T from 0.5E-4T, and the shielding coefficient is 2500.

However, the permalloy 1J85 is adopted in the existing magnetic shielding device, although the permeability of 1J85 is very high, and the magnetic shielding device has excellent performance when shielding a weaker external magnetic field such as a geomagnetic field, the saturation magnetic induction intensity is only 7000Gs, the magnetic field generated by a state selection magnet outside the quantum state reversing device can be more than 10000Gs at most, and if 1J85 is directly used as the material of an external shielding cylinder, the external shielding is magnetized by a strong external magnetic field, so that the shielding effect is lost; the edges of the cylinder and the bottom of the existing magnetic shielding device are right-angle edges, which are not beneficial to the passing of magnetic lines of force in the wall of the shielding cylinder and have poor shielding effect; in addition, because the coil in the quantum state reversal device can generate heat while generating a magnetic field, and the secondary state selection system operates in a vacuum environment, the heat emitted by the coil can only be dissipated in a heat conduction and heat radiation mode, and no heat transmission design exists between layers of the conventional magnetic shielding device, the heat generated by the coil cannot be transmitted and is increased continuously, so that the temperature of the quantum state reversal device is continuously increased and even reaches the melting point of the coil, and the failure of the secondary state selection system is caused.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a magnetic shielding device can effectively shield external magnetic field and conduct heat, makes quantum state reversal device can normal operating.

The utility model provides a magnetic shielding device, include:

the magnetic shielding main body comprises a plurality of layers of nested shielding cylinders, and the side surfaces, the top surfaces and the bottom surfaces of the shielding cylinders are in smooth transition;

the sleeve is sleeved on the outer side of the magnetic shielding main body and formed by splicing two half sleeves with the same size and shape.

Furthermore, an upper supporting piece and a lower supporting piece are arranged between the two adjacent layers of shielding cylinders, the upper supporting piece is tightly attached to the upper portions of the two adjacent layers of shielding cylinders, and the lower supporting piece is tightly attached to the lower portions of the two adjacent layers of shielding cylinders.

Further, the upper support and the lower support are both made of boron nitride material.

Furthermore, the shielding cylinder comprises a shielding cylinder body and a shielding bottom, and the shielding cylinder body is connected with the shielding bottom in an inserting manner.

Further, the distance between two adjacent shielding cylinders is 2-5 mm.

Further, the distance between two adjacent shielding cylinders is 4 mm.

Furthermore, the shielding cylinder has four layers, the outer two layers of shielding cylinders are made of 1J50 permalloy, and the inner two layers of shielding cylinders are made of 1J85 permalloy.

Furthermore, the top surface and the bottom surface of each layer of shielding cylinder are provided with atomic beam through holes.

Furthermore, one end of each half sleeve is provided with a flange plate, and the two half sleeves are connected with each other through the flange plates.

Further, fixing claws are arranged in the two half sleeves, and the magnetic shielding main body is located between the fixing claws of the two half sleeves.

The magnetic shielding device of the utility model has the advantages that the magnetic shielding main body comprises a plurality of layers of nested shielding cylinders, the sides, the top surface and the bottom surface of the shielding cylinders are in smooth transition, and the shielding effect is good; the upper supporting piece and the lower supporting piece are arranged between the shielding cylinders of all layers, so that the space between the shielding cylinders of all layers can be kept, and the heat inside the shielding cylinders can be conducted to the outside.

Drawings

FIG. 1 is a block diagram of a secondary state selection system for a conventional hydrogen pulse system;

FIG. 2 is a schematic diagram of a prior art multi-layer cylindrical nested magnetic shield structure;

fig. 3 is a schematic structural view of a conventional magnetic shield apparatus;

fig. 4 is a schematic structural view of a half of a magnetic shield apparatus according to an embodiment of the present invention, taken along an axis;

fig. 5 is an overall structural schematic view of a magnetic shield device according to an embodiment of the present invention;

fig. 6 is a schematic structural view of a half of a magnetic shield main body according to an embodiment of the present invention, which is cut along an axis;

fig. 7 is an overall structural schematic view of a magnetic shield main body according to an embodiment of the present invention;

fig. 8 is a schematic structural view of an upper support according to an embodiment of the present invention;

fig. 9 is a schematic structural view of a lower support member according to an embodiment of the present invention;

fig. 10 is a schematic view of a relation of a magnetic shield main body according to an embodiment of the present invention with an upper support member and a lower support member.

Detailed Description

The following description of the preferred embodiments of the present invention will be made with reference to the accompanying drawings.

As shown in fig. 4, an embodiment of the present invention provides a magnetic shielding device, which includes a sleeve 1 and a magnetic shielding main body 2, wherein the sleeve 1 is sleeved outside the magnetic shielding main body 2, and is formed by splicing two half sleeves 11 having the same size and shape (both are hollow cylindrical structures), and the two half sleeves are made of aluminum alloy and used for fixing the magnetic shielding main body 2; the sleeve 1 is connected with the first stage state selection magnet and the second stage state selection magnet at the same time, so that heat on the surface of the magnetic shielding main body 2 can be conducted to the state selection magnet, heat in the magnetic shielding main body 2 is dissipated, and the phenomenon that the coil of the quantum state reversing device is melted due to overhigh temperature is avoided.

One end of each half sleeve 11 is provided with a flange 111, and a plurality of threaded holes are formed in the flange 111 along the circumferential direction, so that the two half sleeves 11 are in threaded connection through the flange 111. Precise positioning between the half shells 11 is achieved by the flange 111.

Fixing claws 112 are provided in both the half sleeves 11 and are connected to the first stage state selection magnet and the second stage state selection magnet, respectively, to fix the magnetic shield device to the state selection magnet. As shown in fig. 5, the magnetic shield body 2 can be placed between the fixing claws 112 of the two half sleeves 11, and when the two half sleeves 11 are connected to each other, the magnetic shield body 2 can be pressed by the fixing claws 112.

As shown in fig. 6, the magnetic shield body 2 includes a plurality of nested shield cylinders 21, and the quantum state reversal device is located in and screwed to the shield cylinder 21 of the innermost layer. In this embodiment, the shielding canister 21 has four layers, wherein the outer two layers are made of 1J50 permalloy, and the inner two layers are made of 1J85 permalloy. 1J50 has a lower magnetic permeability than 1J85, but its saturation magnetic induction is higher, and it is not easy to be magnetized by external magnetic field and lose shielding effect, so it is used as the material of the outer two layers. The external magnetic field intensity can be reduced to be lower than the saturation magnetic induction intensity of 1J85 permalloy through the shielding of the outer two layers, so in order to improve the shielding effect of the magnetic shielding, the inner two layers adopt 1J85 permalloy with higher magnetic permeability.

The shielding cylinder 21 comprises a shielding cylinder body 211 and a shielding bottom 212, as shown in fig. 7, the shielding cylinder body 211 and the shielding bottom 212 may be connected in an inserting manner, that is, the shielding cylinder body 211 is inserted into the shielding bottom 212, so as to form a closed shielding cylinder 21, which may facilitate the installation of the shielding cylinders 21 and the quantum state inversion devices of each layer.

In order to further improve the shielding effect, the side surfaces and the top surface or the bottom surface of the shielding cylinder body 211 and the shielding bottom 212 are in smooth transition, which is more beneficial to the passing of magnetic lines of force compared with the right-angle transition, thereby ensuring better magnetic shielding effect.

Atomic beam through holes 22 are formed in the shielding cylinder main body 211 and the shielding bottom 212 of each layer of shielding cylinder 21 and used for incidence and emergence of hydrogen atomic beams.

The distance between each layer of shielding cylinder 21 can be obtained through finite element simulation calculation, the larger the layer distance is, the higher the shielding coefficient is, and the better the magnetic shielding effect is, but the volume and the mass of the magnetic shielding device can be increased along with the distance, so that the miniaturization of a hydrogen pulse secondary state selection system is not facilitated, and therefore the size and the mass of the magnetic shielding effect and the magnetic shielding device need to be comprehensively considered in the selection of the distance. In the embodiment, the distance between two adjacent shielding cylinders 21 is 2-5mm, preferably 4mm, so that a good magnetic shielding effect can be realized, and the miniaturization requirement of the secondary state selection system can be met.

An upper supporting piece 23 and a lower supporting piece 24 are clamped between two adjacent layers of shielding cylinders 21 so as to conduct heat generated by the quantum state inversion device to the sleeve 1 through the shielding cylinders 21 and the supporting pieces of each layer and finally to the outside; while the upper support 23 and the lower support 24 can maintain the gap between the respective layers at a preset value.

As shown in fig. 8-10, the upper supporting member 23 is circular and is configured to be a profile shape of the top of the shielding cylinder body 211, so that it is closely attached to the adjacent two layers of the shielding cylinder body 211. The lower supporting member 24 is disc-shaped and has a top surface contoured to the bottom surface of the shielding bottom 212 and a side surface contoured to the inner surface of the shielding bottom 212 of the adjacent layer, so that it is closely attached to the shielding bottoms 212 of the adjacent layers. The upper support 23 and the lower support 24 are both hollow in the middle, so that on one hand, the atom beam can pass through smoothly, and on the other hand, the overall mass can be reduced as much as possible under the condition of ensuring heat transfer. After the upper support 23 and the lower support 24 are placed at the corresponding positions, they are pressed by the sleeve 1 and prevented from falling.

The upper supporting piece 23 and the lower supporting piece 24 are both formed by sintering and pressing cubic boron nitride powder, the heat conductivity coefficient can reach 79.54W/m.K, and the shapes of the upper supporting piece and the lower supporting piece between the layers are the same except for the size and the shape.

The secondary state selection system operates in a vacuum environment, and heat transfer finite element simulation is carried out on the magnetic shielding device for comparing the influence of the boron nitride supporting piece on the magnetic shielding device. In simulation, the surface of the quantum state inversion device is a coil heat source, and the heating power is 10W/m ² The initial environment temperature is 303.15K, under the condition of no support, the heat generated by the coil is accumulated continuously, the temperature is increased continuously and can be higher than 2500K finally, and at the moment, the quantum state reversal device cannot normally operate due to the fact that the coil is melted; after the upper supporting piece and the lower supporting piece are added, heat generated by the coil can be conducted to the outside through the supporting pieces and the shielding cylinder in time, the temperature of the quantum state reversing device is only increased by 0.17K compared with the ambient temperature, and the quantum state reversing device can normally operate. Can know through the simulation result, the utility model discloses a heat conduction that magnetic shielding device can be fine.

The embodiment of the utility model provides a magnetic shielding device, its magnetic shielding main part 2 includes the nested shielding section of thick bamboo 21 of multilayer, and smooth transition between the side of shielding section of thick bamboo 21 and top surface and bottom surface shields effectually; the upper support 23 and the lower support 24 between the shielding cylinders 21 of each layer can not only maintain the spacing between the shielding cylinders 21 of each layer, but also conduct the heat inside the shielding cylinders 21 to the outside.

What has been described above is only the preferred embodiment of the present invention, not for limiting the scope of the present invention, but various changes can be made to the above-mentioned embodiment of the present invention. All the simple and equivalent changes and modifications made according to the claims and the content of the specification of the present invention fall within the scope of the claims of the present invention. The present invention is not described in detail in the conventional technical content.

Claims

1. A magnetic shield device, characterized by comprising:

2. The magnetic shield device according to claim 1, wherein an upper support member and a lower support member are disposed between two adjacent shielding cylinders, the upper support member is closely attached to the upper portion of each of the two adjacent shielding cylinders, and the lower support member is closely attached to the lower portion of each of the two adjacent shielding cylinders.

3. Magnetic shielding device according to claim 2, characterized in that the upper and lower supports are both made of boron nitride material.

4. The magnetic shield device according to claim 1, wherein the shield cylinder comprises a shield cylinder body and a shield bottom, and the shield cylinder body is connected with the shield bottom in a plugging manner.

5. Magnetic shielding device according to claim 1, characterized in that the spacing between two adjacent shielding cylinders is 2-5 mm.

6. Magnetic shielding device according to claim 5, characterized in that the spacing between two adjacent shielding cylinders is 4 mm.

7. The magnetic shield device of claim 1, wherein said shield cans are four-layered, and wherein the outer two-layered shield can is 1J50 permalloy and the inner two-layered shield can is 1J85 permalloy.

8. The magnetic shield device according to claim 1, characterized in that the top surface and the bottom surface of each layer of shield cylinder are provided with atom beam through holes.

9. Magnetic shielding device as claimed in claim 1, characterized in that one end of each sleeve half is provided with a flange, by means of which the two sleeve halves are connected to each other.

10. Magnetic shield arrangement according to claim 1, characterized in that fixing claws are arranged in both sleeve halves, the magnetic shield body being located between the fixing claws of the sleeve halves.