Magnetic shielding system and neutron experimental system

Abstract

The application provides a magnetic shielding system and a neutron experiment system, and relates to the technical field of neutron experiments. The magnetic shielding system is arranged in sequence in a first direction, and the first direction is the movement direction of the polarized neutron beam. The first shielding device includes a first shielding shell, and is used for shielding the magnetic field in a second direction and a third direction perpendicular to the first direction. The second guide and the third guide are used for adjusting the direction of the magnetic field. The second shielding device includes a second shielding shell and a third shielding shell, and the third shielding shell is arranged in the second shielding shell. The first shielding shell, the second shielding shell and the third shielding shell are all made of permalloy, so that the first shielding shell, the second shielding shell and the third shielding shell can shield the high-strength magnetic field generated by the magnetic field generating part, and the accuracy of the neutron polarization experiment result is ensured.

Description

Technical Field

[0001] This application relates to the field of neutron experimental technology, specifically to magnetic shielding systems and neutron experimental systems. Background Technology

[0002] Strong magnetic field environments have a wide range of applications in scientific research, industry, medicine and other fields. Their high-intensity magnetic field characteristics provide key support for many cutting-edge technologies and precision experiments.

[0003] In practical applications, strong magnetic field environments invariably generate stray magnetic fields around the target location. These stray magnetic fields are irregularly distributed in magnitude and direction, causing strong interference to nearby equipment and magnetic interactions with existing magnetic components in the space, leading to deviations in the magnetic field at the target location. Therefore, magnetic shielding of the stray fields generated by strong magnetic fields is an indispensable step in practical applications.

[0004] In related technologies, the strong magnetic field shielding scheme in neutron scattering technology has certain shortcomings. For example, the technology uses smaller offline polarized helium-3 equipment, and the magnetic field shielding structure is easier to get close to the core region (high gradient magnetic field region), thus making it easier to achieve the shielding effect. However, for online polarized helium-3 equipment that occupies more space, and for scenarios where the polarization inverter equipment is closer to the center of the strong magnet, there is no suitable magnetic shielding system to support neutron scattering experiments. Summary of the Invention

[0005] The purpose of this application is to provide a magnetic shielding system and a neutron experimental system to improve the current problem of difficulty in conducting high-precision neutron polarization experiments in small space scenarios.

[0006] This application provides a magnetic shielding system for use in a neutron experiment system. The magnetic shielding system includes a first guide, a first shielding device, a second guide, a third guide, and a second shielding device arranged along a first direction. The first direction is the direction of motion of the polarized neutron beam. The first guide, the first shielding device, and the second guide are located upstream of the magnetic field generating device, and the third guide and the second shielding device are located downstream of the magnetic field generating device.

[0007] The first guide is used to adjust the neutron polarization direction and guide the polarized neutron beam to the first shielding device;

[0008] The first shielding device includes a first shielding shell, which is used to shield the magnetic field in a second direction and a third direction perpendicular to the first direction, and the first shielding device is also used to accommodate a radio frequency reversal device, which is used to change the polarization state of neutrons.

[0009] The second guide is used to generate a gradient distribution of the magnetic field within the first shielding shell;

[0010] The third guide is used to adjust the direction of the magnetic field toward the first direction, so that the direction of the magnetic field entering the second shielding device is the first direction;

[0011] The second shielding device includes a second shielding shell and a third shielding shell, wherein the third shielding shell is disposed inside the second shielding shell, and the first shielding shell, the second shielding shell and the third shielding shell are all made of permalloy.

[0012] In one embodiment, the first shielding shell includes a first structural member and a second structural member, the first structural member and the second structural member being symmetrically arranged and fastened together, and a gap being provided between the first structural member and the second structural member to shield external magnetic fields within the first shielding shell.

[0013] In one embodiment, the width of the gap is 1-3 mm;

[0014] And / or, the thickness of the first shielding shell is 1-3 mm.

[0015] In one embodiment, the magnetic shielding system has a first state and a second state;

[0016] When the magnetic shielding system is in the first state, the second direction is the same as the axial direction of the magnetic field generating component, and the first guide is also used to generate a gradient distribution of the magnetic field in the first shielding shell.

[0017] When the neutron experimental system is in the second state, the third direction is the same as the axial direction of the magnetic field generating device.

[0018] In one embodiment, the magnetic shielding system further includes a fourth guide, wherein when the magnetic shielding system is in the second state, the fourth guide is disposed at the upstream end of the first shielding device and located at the downstream end of the first guide, and the fourth guide is also used to generate a gradient distribution of the magnetic field within the first shielding shell.

[0019] In one embodiment, the fourth guide is detachably connected to the first shielding shell, and when the neutron experimental system is in the second state, the fourth guide is connected to the first shielding shell.

[0020] In one embodiment, the second shielding shell is a square structure, and the third shielding shell is a cylindrical structure. In the first direction, the second shielding shell has a first plate and a second plate. The first plate is located upstream of the second plate. A first opening is provided on the first plate, and a second opening is provided on the second plate. The diameter of the second opening is larger than the diameter of the first opening. The first opening, the second opening, and the polarized neutron beam motion direction are coaxially arranged.

[0021] And / or, in the first direction, the third shielding shell has a third plate and a fourth plate, the third plate is located upstream of the fourth plate, the third plate has a third opening, the fourth plate has a fourth opening, the diameter of the fourth opening is larger than the diameter of the third opening, and the third opening, the fourth opening and the polarized neutron beam motion direction are coaxially arranged.

[0022] In one embodiment, the second shielding shell further includes a bottom plate, a top plate, and a side plate, wherein the bottom plate, top plate, side plate, first plate body, and second plate body are detachably connected.

[0023] In one embodiment, the bottom plate and / or the top plate are provided with clearance holes.

[0024] In one embodiment, the thickness of the second shielding shell is 1-3 mm;

[0025] And / or, the thickness of the third shielding shell is 1-3 mm.

[0026] This application also provides a neutron experimental system for neutron polarization experiments, comprising: a magnetic field generating device, a radio frequency reversal device, a helium-3 device, and a magnetic shielding device as described above. The magnetic field generating device is disposed between the second guide and the third guide, the radio frequency reversal device is disposed within the first shielding shell, and the helium-3 device is disposed within the second shielding shell.

[0027] In one embodiment, the distance between the downstream side of the first shielding device and the center of the magnetic field generating element is 40 cm.

[0028] The distance between the center of the magnetic field generating device and the upstream side of the helium-3 device is 27.5 cm;

[0029] The center of the magnetic field generating device is 60 cm away from the center of the helium-3 device.

[0030] According to the neutron experimental system in the above embodiments, a first guide, a first shielding device, a second guide, a third guide, and a second shielding device are sequentially arranged in a first direction, which is the direction of motion of the polarized neutron beam. The first guide is used to control the neutron polarization direction and guide the polarized neutron beam to the first shielding device. The first shielding device includes a first shielding shell, which is used to shield the magnetic field in a second direction perpendicular to the first direction and a third direction perpendicular to the first direction. The second guide is used to create a gradient distribution of the magnetic field within the first shielding shell. The third guide is used to adjust the direction of the magnetic field toward the first direction. The second shielding device includes a second shielding shell and a third shielding shell, with the third shielding shell disposed inside the second shielding shell. The first, second, and third shielding shells are all made of permalloy, which allows them to effectively shield the high-intensity magnetic field generated by the magnetic field generating device, thereby ensuring the accuracy of the neutron polarization experimental results. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of an application scenario for a neutron experimental system in its first state, as provided in an embodiment of this application.

[0032] Figure 2 This is a schematic diagram of the structure of the first shielding device and the second guide in the magnetic shielding system of a neutron experimental system provided in an embodiment of this application.

[0033] Figure 3 This is a schematic diagram of the structure of the second shielding device in the magnetic shielding system of a neutron experimental system provided in an embodiment of this application.

[0034] Figure 4 This is a schematic diagram illustrating an application scenario of a neutron experimental system in its second state, as provided in an embodiment of this application.

[0035] in:

[0036] 1. Neutron experimental system; 10. First guide; 20. First shielding device; 210. First shielding shell; 211. First structural component; 212. Second structural component; 213. Gap; 30. Second guide; 40. Third guide; 50. Second shielding device; 510. Second shielding shell; 511. First plate; 5111. First opening; 512. Second plate; 5121. Second opening; 513. Bottom plate; 514. Top plate; 515. Side plate; 516. Clearance hole; 520. Third shielding shell; 521. Third plate; 5211. Third opening; 522. Fourth plate; 60. Fourth guide; 70. Magnetic field generating component. Detailed Implementation

[0037] The present application will be further described in detail below with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0038] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments, and the operational steps involved in each embodiment can also be rearranged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the specification and drawings are only for clearly describing a particular embodiment and do not imply that they represent the necessary components and / or order.

[0039] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0040] Please also refer to Figure 1 This application provides a neutron experimental system 1, which can be applied to neutron polarization experiments. The system includes a magnetic field generator 70, a magnetic shielding system, a radio frequency reversal device (not shown in the figure), and a helium-3 device (not shown in the figure). This application does not limit the specific form of the magnetic field generator 70; for example, it can be a strong magnetic electromagnet.

[0041] The magnetic shielding system includes, along a first direction, a first guide 10, a first shielding device 20, a second guide 30, a third guide 40, and a second shielding device 50. The first shielding shell 210, the second shielding shell 510, and the third shielding shell 520 are all made of permalloy. The first direction is the direction of motion of the polarized neutron beam, specifically the X direction shown in the figure.

[0042] In this embodiment, the first guide 10, the first shielding device 20, and the second guide 30 are disposed upstream of the magnetic field generating device 70. The first guide 10 is used to regulate the neutron polarization direction and guide the polarized neutron beam to the first shielding device 20. The first shielding device 20 includes a first shielding shell 210, which is used to shield the magnetic field in a second direction perpendicular to the first direction and a third direction perpendicular to the first direction (where the second direction is the Y direction in the figure, and the third direction is the Z direction in the figure). The first shielding device 20 is also used to accommodate a radio frequency reversal device, which is used to change the polarization state of the neutrons. The second guide 30 is used to generate a gradient distribution of the magnetic field within the first shielding shell 210.

[0043] For details, please refer to the following: Figure 1 and Figure 2 In this embodiment, the first shielding shell 210 may include a first structural member 211 and a second structural member 212. As mentioned above, in this embodiment, both the first structural member 211 and the second structural member 212 are made of permalloy. The first structural member 211 and the second structural member 212 are symmetrically arranged and fastened together. A gap 213 is provided between the first structural member 211 and the second structural member 212 to shield external magnetic fields within the first shielding shell 210, such as the magnetic field generated by the magnetic field generator 70. It should be noted that the specific length of the gap 213 described above is not limited in this embodiment; for example, it can be set to 1-3 mm, preferably 2 mm. The thickness of the first shielding shell 210 is also not limited in this embodiment; for example, it can be set to 1-3 mm, preferably 2 mm.

[0044] The third guide 40 and the second shielding device 50 are disposed downstream of the magnetic field generating device 70. The third guide 40 is used to adjust the direction of the magnetic field toward the first direction, so that the direction of the magnetic field entering the second shielding device 50 is the first direction. The second shielding device 50 includes a second shielding shell 510 and a third shielding shell 520, with the third shielding shell 520 disposed inside the second shielding shell 510. The helium-3 device may be disposed inside the second shielding shell 510.

[0045] For details, please refer to the following: Figure 1 and Figure 3 In this embodiment, the second shielding shell 510 can be configured as a square structure, and the third shielding shell 520 can be configured as a cylindrical structure. This embodiment also does not limit the thickness of the second shielding shell 510 and the third shielding shell 520; for example, they can be set to 1-3 mm, preferably 2 mm.

[0046] In a first direction, the first shielding shell 210 may have a first plate 511 and a second plate 512, with the first plate 511 located upstream of the second plate 512. The helium-3 device and the third shielding shell 520 are located between the first plate 511 and the second plate 512. A first opening 5111 is formed on the first plate 511, and a second opening 5121 is formed on the second plate 512. The diameter of the second opening 5121 is larger than the diameter of the first opening 5111, and the first opening 5111, the second opening 5121, and the polarized neutron beam are coaxially arranged.

[0047] It is understood that in some embodiments, in the first direction, the third shielding shell 520 body may have a third plate 521 and a fourth plate 522, the third plate 521 is located upstream of the fourth plate 522, the third plate 521 is provided with a third opening 5211, the fourth plate 522 is provided with a fourth opening (not shown in the figure), the diameter of the fourth opening is larger than the diameter of the third opening 5211, and the third opening 5211, the fourth opening and the polarized neutron beam motion direction are coaxially arranged.

[0048] Furthermore, as mentioned above, in this embodiment, the second shielding shell 510 may further include a bottom plate 513, a top plate 514, and a side plate 515. The bottom plate 513, top plate 514, side plate 515, first plate 511, and second plate 512 together form the second shielding shell 510. As mentioned earlier, in this embodiment, the bottom plate 513, top plate 514, side plate 515, first plate 511, and second plate 512 are all made of permalloy. It is understood that there are two side plates 515; for ease of explanation, only one is shown in the illustration. In this embodiment, the bottom plate 513, top plate 514, side plate 515, first plate 511, and second plate 512 are detachably connected to facilitate assembly or disassembly by the user. In one embodiment, the junctions between the bottom plate 513, top plate 514, side plate 515, first plate 511, and second plate 512 can all be constructed by stacking plates (for ease of explanation, the bottom plate 513, top plate 514, side plate 515, first plate 511, and second plate 512 will be collectively referred to as plates), and the gaps between the plates can be reduced by using non-magnetic copper screws through the pre-drilled holes on the edges of the plates.

[0049] Furthermore, in one embodiment, a clearance hole 516 may be provided on the base plate 513. It is understood that, in addition to the third shielding shell 520 and the helium-3 device, the second shielding shell 510 may also house other electrical components such as a fan. Therefore, the clearance hole 516 can be used for wiring of the aforementioned helium-3 device and electrical components. This facilitates the installation of the helium-3 device and other electrical components, while avoiding or reducing the use of non-standard parts, thereby helping to reduce costs. This application embodiment also does not limit the specific shape of the clearance hole 516 described above. For example, it can be a square hole, a circular hole, or an irregularly shaped hole; the specific shape can be set according to the actual situation.

[0050] Similarly, in some embodiments, the top plate 514 may have a clearance hole 516, as detailed in the aforementioned description of the bottom plate 513, which will not be repeated here. It is understood that in other embodiments, both the bottom plate 513 and the top plate 514 may have clearance holes 516.

[0051] In this embodiment, the first shielding shell 210, the second shielding shell 510, and the third shielding shell 520 are all made of permalloy. As mentioned above, the polarized neutron beam also passes through the first shielding shell 210 along the X-axis. Since there is a radio frequency field coil of the radio frequency flipper at the center of the first shielding shell 210 along the X-axis, a high-frequency radio frequency magnetic field will be generated along this direction in actual applications. At this time, the permalloy metal cavity separated along the Z-axis will not be able to form an eddy current loop inside it due to the 2 mm gap 213. Therefore, it has no significant impact on the radio frequency field inside the radio frequency flipper. The 2 mm gap 213 has little impact on the magnetic circuit formed inside the magnet, thereby achieving the effect of magnetic field shielding inside the first shielding shell 210.

[0052] Please also refer to Figure 1 and Figure 4 In this embodiment, the magnetic shielding system has a first state and a second state, wherein the first state and the second state can be set according to different forms of the magnetic field generating device 70.

[0053] Please see Figure 1 , Figure 1 A schematic diagram of the entire magnetic shielding system is shown when the magnetic shielding system is in its first state. When the magnetic shielding system is in its first state, the second direction is the same as the axial direction of the magnetic field generating element 70, and when the magnetic shielding system is in its first state, the first guide element 10 is also used to generate a gradient distribution of the magnetic field within the first shielding shell 210.

[0054] Please see Figure 4 , Figure 4The diagram shows the structure of the entire magnetic shielding system when it is in the second state. When the magnetic shielding system is in the second state, the third direction is the same as the axial direction of the magnetic field generating element 70.

[0055] Furthermore, in this embodiment, the magnetic shielding system may also include a fourth guide 60. When the magnetic shielding system is in the second state, the fourth guide 60 is disposed at the upstream end of the first shielding device 20 and located at the downstream end of the first guide 10. The fourth guide 60 is also used to generate a gradient distribution of the magnetic field within the first shielding shell 210.

[0056] In one embodiment, the fourth guide 60 can be detachably mounted from the first shielding device 20, which facilitates the user in switching the magnetic shielding system between a first state and a second state. Specifically, when the magnetic shielding system needs to be set to the second state, the user can install the fourth guide 60 onto the first shielding device 20; when the magnetic shielding system needs to be set to the first state, the user can remove the fourth guide 60 from the first shielding device 20.

[0057] Furthermore, this application provides a specific configuration of a neutron experimental system 1, wherein the downstream side of the first shielding device 20 is 40cm away from the center of the magnetic field generating device 70, the center of the magnetic field generating device 70 is 27.5cm away from the upstream side of the helium-3 device, and the center of the magnetic field generating device 70 is 60cm away from the center of the helium-3 device.

[0058] In summary, the neutron experimental system 1 provided in this application embodiment arranges a first guide 10, a first shielding device 20, a second guide 30, a third guide 40 and a second shielding device 50 in a first direction, where the first direction is the direction of motion of the polarized neutron beam. The first guide 10 is used to adjust the neutron polarization direction and guide the polarized neutron beam to the first shielding device 20. The first shielding device 20 includes a first shielding shell 210, which is used to shield the magnetic field in a second direction perpendicular to the first direction and a third direction. The second guide 30 is used to generate a gradient distribution of the magnetic field within the first shielding shell 210. The third guide 40 is used to adjust the direction of the magnetic field toward the first direction. The second shielding device 50 includes a second shielding shell 510 and a third shielding shell 520, with the third shielding shell 520 disposed within the second shielding shell 510. The first shielding shell 210, the second shielding shell 510, and the third shielding shell 520 are all made of permalloy, which allows the first shielding shell 210, the second shielding shell 510, and the third shielding shell 520 to effectively shield the high-intensity magnetic field generated by the magnetic field generating device 70, thereby ensuring the accuracy of the neutron polarization experimental results. The above specific examples are used to illustrate this application only to help understand this application and are not intended to limit this application. For those skilled in the art to which this application pertains, based on the ideas of this application, several simple deductions, modifications, or substitutions can be made.

Claims

1. A magnetic shielding system for use in a neutron experiment system, characterized in that, The magnetic shielding system includes: a first guide, a first shielding device, a second guide, a third guide, and a second shielding device arranged along a first direction, wherein the first direction is the direction of motion of the polarized neutron beam, and the first guide, the first shielding device, and the second guide are disposed at the upstream end of the magnetic field generating device, and the third guide and the second shielding device are disposed at the downstream end of the magnetic field generating device. The first guide is used to adjust the neutron polarization direction and guide the polarized neutron beam to the first shielding device; The first shielding device includes a first shielding shell, which is used to shield the magnetic field in a second direction and a third direction perpendicular to the first direction, and the first shielding device is also used to accommodate a radio frequency reversal device, which is used to change the polarization state of neutrons. The second guide is used to generate a gradient distribution of the magnetic field within the first shielding shell; The third guide is used to adjust the direction of the magnetic field toward the first direction, so that the direction of the magnetic field entering the second shielding device is the first direction; The second shielding device includes a second shielding shell and a third shielding shell, wherein the third shielding shell is disposed inside the second shielding shell, and the first shielding shell, the second shielding shell and the third shielding shell are all made of permalloy.

2. The magnetic shielding system as described in claim 1, characterized in that, The first shielding shell includes a first structural member and a second structural member, the first structural member and the second structural member are symmetrically arranged and the first structural member and the second structural member are fastened together, and there is a gap between the first structural member and the second structural member to shield the external magnetic field inside the first shielding shell.

3. The magnetic shielding system as described in claim 2, characterized in that, The width of the gap is 1-3mm; And / or, the thickness of the first shielding shell is 1-3 mm.

4. The magnetic shielding system as described in claim 1, characterized in that, The magnetic shielding system has a first state and a second state; When the magnetic shielding system is in the first state, the second direction is the same as the axial direction of the magnetic field generating component, and the first guide is also used to generate a gradient distribution of the magnetic field in the first shielding shell. When the neutron experimental system is in the second state, the third direction is the same as the axial direction of the magnetic field generating device.

5. The magnetic shielding system as described in claim 4, characterized in that, The magnetic shielding system further includes a fourth guide, which is disposed at the upstream end of the first shielding device and located at the downstream end of the first guide when the magnetic shielding system is in the second state, and the fourth guide is also used to generate a gradient distribution of the magnetic field in the first shielding shell.

6. The magnetic shielding system as described in claim 5, characterized in that, The fourth guide is detachably connected to the first shielding shell. When the neutron experimental system is in the second state, the fourth guide is connected to the first shielding shell.

7. The magnetic shielding system as described in claim 1, characterized in that, The second shielding shell is a square structure, and the third shielding shell is a cylindrical structure. In the first direction, the second shielding shell has a first plate and a second plate. The first plate is located upstream of the second plate. A first opening is provided on the first plate, and a second opening is provided on the second plate. The diameter of the second opening is larger than the diameter of the first opening. The first opening, the second opening, and the polarized neutron beam motion direction are coaxially arranged. And / or, in the first direction, the third shielding shell has a third plate and a fourth plate, the third plate is located upstream of the fourth plate, the third plate has a third opening, the fourth plate has a fourth opening, the diameter of the fourth opening is larger than the diameter of the third opening, and the third opening, the fourth opening and the polarized neutron beam motion direction are coaxially arranged.

8. The magnetic shielding system as described in claim 1, characterized in that, The second shielding shell also includes a bottom plate, a top plate, and a side plate, wherein the bottom plate, top plate, side plate, first plate body, and second plate body are detachably connected.

9. The magnetic shielding system as described in claim 8, characterized in that, The bottom plate and / or the top plate are provided with clearance holes.

10. The magnetic shielding system as described in claim 8, characterized in that, The thickness of the second shielding shell is 1-3mm; And / or, the thickness of the third shielding shell is 1-3 mm.

11. A neutron experimental system for use in neutron polarization experiments, characterized in that, include: The magnetic field generating device, the radio frequency reversing device, the helium-3 device, and the magnetic shielding device as described in any one of claims 1-10, wherein the magnetic field generating device is disposed between the second guide and the third guide, the radio frequency reversing device is disposed within the first shielding shell, and the helium-3 device is disposed within the second shielding shell.

12. The neutron experimental system as described in claim 11, characterized in that, The distance between the downstream side of the first shielding device and the center of the magnetic field generating element is 40cm. The distance between the center of the magnetic field generating device and the upstream side of the helium-3 device is 27.5 cm; The center of the magnetic field generating device is 60 cm away from the center of the helium-3 device.

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