An annular permanent magnet quadrupole trap device

Abstract

The application provides a kind of annular permanent magnet four-pole magnetic trap device, and relates to atomic sensing technical field.The device includes: first fixed assembly, first support assembly, first permanent magnet ring array, second support assembly, second permanent magnet ring array, second fixed assembly;First support assembly includes first support part and second support part, first support part is set to the top of first permanent magnet ring array, second support part is set to the bottom of first permanent magnet ring array, and first fixed assembly is set to the top of first support part;Second support assembly includes third support part and fourth support part, third support part is set to the top of second permanent magnet ring array, and fourth support part is set to the bottom of second permanent magnet ring array;Second fixed assembly is set to the bottom of fourth support part.The annular permanent magnet four-pole magnetic trap device provided in the application does not need to be powered by coil, and has low heat load and small space occupation, which meets the integration needs of compact or portable cold atom system.

Description

Technical Field

[0001] This application relates to the field of atomic sensing technology, and more specifically, to a ring-shaped permanent magnet quadrupole magnetic trap device. Background Technology

[0002] Magnetic traps, as a magnetic field source, are widely used in cold atom magnetic trapping, magneto-optical trap loading, and portable quantum sensing systems.

[0003] Currently, traditional cold atom magnetic traps are typically generated by anti-Helmholtz coils, with the magnetic field gradient adjusted by current. However, this method requires continuous power to the coils, occupies a large space, and suffers from problems such as high power consumption, high thermal load, current noise interference, and large system size, making it difficult to meet the integration requirements of compact or portable cold atom systems. Summary of the Invention

[0004] The purpose of this application is to provide a ring permanent magnet quadrupole magnetic trap device to address the shortcomings of the prior art, thereby solving the problems of traditional cold atom magnetic traps requiring continuous power supply from coils, occupying a large overall space, and having high power consumption, high thermal load, current noise interference, and large system size, as well as the difficulty in meeting the integration requirements of compact or portable cold atom systems.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: In a first aspect, embodiments of this application provide a ring-shaped permanent magnet quadrupole magnetic trap device, comprising: a first fixing component, a first support component, a first permanent magnet ring array, a second support component, a second permanent magnet ring array, and a second fixing component; The first support component includes a first support portion and a second support portion. The first support portion is disposed at the top of the first permanent magnet ring array, and the second support portion is disposed at the bottom of the first permanent magnet ring array. The first support component is used to support the first permanent magnet ring array. The first fixing component is disposed on the top of the first support portion, and the first fixing component is used to fix the first support component to the external platform; The second support component includes a third support portion and a fourth support portion. The third support portion is disposed at the top of the second permanent magnet ring array, and the fourth support portion is disposed at the bottom of the second permanent magnet ring array. The second support component is used to support the second permanent magnet ring array. The second fixing component is disposed at the bottom of the fourth support portion, and the second fixing component is used to fix the second support component to the external platform; The second support portion is disposed opposite to the third support portion, and there is a space of a preset height between the second support portion and the third support portion.

[0006] As one possible implementation, the first permanent magnet ring array and the second permanent magnet ring array each include a plurality of equivalent magnet units, and the plurality of equivalent magnet units are arranged at equal intervals along the circumferential direction.

[0007] As one possible implementation, the equivalent magnet unit includes: a first cylindrical permanent magnet, or multiple second cylindrical permanent magnets.

[0008] As one possible implementation, the multiple second cylindrical permanent magnets have the same diameter and the multiple second cylindrical permanent magnets have the same or different heights.

[0009] As one possible implementation, multiple second cylindrical permanent magnets are stacked coaxially along an axial direction, which is the common central axis of the first permanent magnet ring array and the second permanent magnet ring array.

[0010] As one possible implementation, the magnetization directions of the multiple second cylindrical permanent magnets are consistent.

[0011] As one possible implementation, the sum of the heights of the plurality of second cylindrical permanent magnets is equal to the height of the first cylindrical permanent magnet.

[0012] As one possible implementation, the first support part and the second support part are interlocked, and the first support part and the second support part are respectively provided with a first magnet groove, and the first magnet groove is provided with a plurality of first through holes; The number of the first through holes is the same as the number of equivalent magnet units in the first permanent magnet ring array, and the setting position of each of the first through holes corresponds one-to-one with the setting position of each equivalent magnet unit in the first permanent magnet ring array.

[0013] As one possible implementation, the third support part and the fourth support part are interlocked, and the third support part and the fourth support part are respectively provided with a second magnet groove, and the second magnet groove is provided with a plurality of second through holes; The number of the second through holes is the same as the number of equivalent magnet units in the second permanent magnet ring array, and the setting position of each second through hole corresponds one-to-one with the setting position of each equivalent magnet unit in the second permanent magnet ring array.

[0014] As one possible implementation, the first fixing component includes: a first fixing fastener and a first adjusting shim, wherein the first adjusting shim is disposed between the first fixing fastener and the first support portion; The second fixing component includes: a second fixing buckle and a second adjusting shim, wherein the second adjusting shim is disposed between the second fixing buckle and the fourth support portion; The first adjusting shim and the second adjusting shim are used to adjust the end face distance between the first permanent magnet ring array and the second permanent magnet ring array.

[0015] This application provides a toroidal permanent magnet quadrupole magnetic trap device. By employing a first permanent magnet ring array and a second permanent magnet ring array instead of a traditional anti-Helmholtz coil as the magnetic field source, it utilizes the inherent magnetism of discrete axially magnetized cylindrical permanent magnets to generate a quadrupole magnetic field. This eliminates the dependence on continuous coil power supply, thus solving the problems of high power consumption, high thermal load, and current noise interference caused by continuous coil power supply. Simultaneously, a compact stacked structure composed of a first support component, a second support component, a first fixing component, and a second fixing component precisely fixes the first and second permanent magnet ring arrays. This not only significantly reduces the overall volume of the toroidal permanent magnet quadrupole magnetic trap device but also ensures the assembly reliability and error compensation capability of the device. Therefore, the toroidal permanent magnet quadrupole magnetic trap device provided in this application requires no coil power supply, has low thermal load, and occupies little space, meeting the integration requirements of compact or portable cold atom systems. It is highly suitable for quadrupole static magnetic field sources in cold atom devices or other compact experimental platforms. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This paper shows a schematic diagram of the structure of a ring-shaped permanent magnet quadrupole magnetic trap device provided in an embodiment of this application; Figure 2 A top view of a permanent magnet ring array provided in an embodiment of this application is shown; Figure 3 This illustration shows a schematic diagram of a first support portion provided in an embodiment of this application; Figure 4 A schematic diagram of a second support portion provided in an embodiment of this application is shown; Figure 5 A schematic diagram of a third support portion provided in an embodiment of this application is shown; Figure 6 A schematic diagram of a fixing component provided in an embodiment of this application is shown; Figure 7 A schematic diagram of an end face distance provided in an embodiment of this application is shown; Figure 8 A schematic diagram of the diameter of the center circle of a magnet provided in an embodiment of this application is shown.

[0018] Icons: 10-First fixing component; 11-First support component; 12-First permanent magnet ring array; 13-Second support component; 14-Second permanent magnet ring array; 15-Second fixing component; 110-First support part; 111-Second support part; 130-Third support part; 131-Fourth support part; 16-Equivalent magnet unit; a1-First magnet slot; a2-First through hole; a3-First screw hole; b1-Second magnet slot; b2-Second through hole; b3-Second screw hole; 101-First fixing fastener; 102-First adjusting shim; 151-Second fixing fastener; 152-Second adjusting shim. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0020] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] It should be noted that the term "comprising" will be used in the embodiments of this application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0022] As a quadrupole magnetic field source in compact cold atom systems, portable magnetic trapping systems, and low-power experimental platforms, the toroidal permanent magnet quadrupole magnetic trap device is mainly used in cold atom magnetic trapping, magnetic trap loading after magneto-optical traps, low-field region confinement for weak field particle tracking, and static magnetic field experimental devices that require low thermal load, low power supply noise, and miniaturized integration.

[0023] Traditional cold atom quadrupole magnetic traps are typically generated by anti-Helmholtz coils, and the magnetic field gradient can be adjusted by current. However, this requires continuous power supply to the coils, resulting in problems such as power consumption, thermal load, current noise, complex drive systems, and difficulties in miniaturization. For compact or portable cold atom systems, continuous heat dissipation and power supply stability are important limitations. Existing permanent magnet solutions can reduce power supply requirements, such as two-dimensional magneto-optical trap devices, toroidal permanent magnet Zeeman reducers, magnetic field-tunable permanent magnet quadrupoles, permanent magnet quadrupole assembly methods, and quadrupole magnetic field measurement methods. However, these existing solutions usually focus on solving the problems of permanent magnet magnetic field generation, permanent magnet assembly, or magnetic field measurement, without simultaneously achieving minimal space occupation, low power consumption, low thermal load, central axial gradient, central radial gradient, uniform gradient of the working area, and a discrete cylindrical permanent magnet structure that can be fabricated and assembled. In addition, the permanent magnet magnetic trap is not as easy to continuously adjust as the coil current after assembly. The residual magnetism deviation, bracket processing error, magnet pressing state and upper and lower ring spacing deviation will affect the center gradient and uniform area. If there is a lack of observable, pressable, detachable and fine-tunable structure, the magnet may have looseness or extra displacement space in the vertical direction, thereby reducing the magnetic field repeatability.

[0024] To address the aforementioned problems in the prior art, this application provides a ring-shaped permanent magnet quadrupole magnetic trap device. It employs discrete axially magnetized cylindrical permanent magnets to form a symmetrical double-ring array, with the equivalent axial magnetization polarities of the two symmetrical permanent magnet ring arrays being opposite, thereby forming a quadrupole magnetic trap in the central region. This ring-shaped permanent magnet quadrupole magnetic trap device requires no coil power supply or heat dissipation space, occupies a small overall space, and is easy to integrate compactly around a vacuum cavity, optical path, or other experimental interfaces. Furthermore, by incorporating support components, fasteners, adjusting shims, magnet slots, through holes, and reliable limiting structures visible on the magnet parts, it achieves assembly reliability, maintenance convenience, and fine-tuning of the central gradient.

[0025] The following describes in detail, with reference to the accompanying drawings, an embodiment of the present application of a ring-shaped permanent magnet quadrupole magnetic trap device.

[0026] Figure 1 A schematic diagram of a ring-shaped permanent magnet quadrupole magnetic trap device provided in an embodiment of this application is shown. (Refer to...) Figure 1As shown, the annular permanent magnet quadrupole magnetic trap device includes: a first fixing component 10, a first support component 11, a first permanent magnet ring array 12, a second support component 13, a second permanent magnet ring array 14, and a second fixing component 15.

[0027] Optionally, refer to Figure 1 As shown, the first support assembly 11 includes a first support portion 110 and a second support portion 111. The first support portion 110 is disposed at the top of the first permanent magnet ring array 12, and the second support portion 111 is disposed at the bottom of the first permanent magnet ring array 12. The first support assembly 11 is used to support the first permanent magnet ring array 12. The second support assembly 13 includes a third support portion 130 and a fourth support portion 131. The third support portion 130 is disposed at the top of the second permanent magnet ring array 14, and the fourth support portion 131 is disposed at the bottom of the second permanent magnet ring array 14. The second support assembly 13 is used to support the second permanent magnet ring array 14.

[0028] It should be noted that the second support part 111 and the third support part 130 are arranged opposite to each other, and there is a space with a preset height between the second support part 111 and the third support part 130.

[0029] Optionally, refer to Figure 1 As shown, the first fixing component 10 is disposed on the top of the first support portion 110, and the first fixing component 10 is used to fix the first support component 11 to an external platform, such as a vacuum chamber or experimental platform. The second fixing component 15 is disposed on the bottom of the fourth support portion 131, and the second fixing component 15 is used to fix the second support component 13 to the external platform.

[0030] Furthermore, referring to Figure 1 As shown, the first permanent magnet ring array 12 and the second permanent magnet ring array 14 are symmetrically arranged about a symmetrical plane, which is also the central plane between the first permanent magnet ring array 12 and the second permanent magnet ring array 14.

[0031] As one possible implementation, the first permanent magnet ring array 12 and the second permanent magnet ring array 14 each include a plurality of equivalent magnet units. For example, referring to... Figure 2 The top view of the permanent magnet ring array shown shows multiple equivalent magnet units 16 arranged at equal intervals along the circumferential direction. That is, both the first permanent magnet ring array 12 and the second permanent magnet ring array 14 are formed by multiple equivalent magnet units 16 discretely distributed in a ring shape, and the axial direction of each equivalent magnet unit 16 is set along the axial direction of the entire annular permanent magnet quadrupole magnetic trap device, and is axially magnetized.

[0032] Specifically, if the central plane between the first permanent magnet ring array 12 and the second permanent magnet ring array 14 is defined as the xy plane, then the axial direction can be defined as the z-axis. That is, the axial direction of each equivalent magnet unit 16 and the entire annular permanent magnet quadrupole magnetic trap device are both set along the z-axis. Furthermore, the equivalent axial magnetization polarities of the first permanent magnet ring array 12 and the second permanent magnet ring array 14 are opposite, combined with... Figure 1 As shown, structurally, for example, the upper end face of the first permanent magnet ring array 12 is N-pole and the lower end face is S-pole (i.e., the magnetization direction is from top to bottom). Then, the upper end face of the second permanent magnet ring array 14 is S-pole and the lower end face is N-pole (i.e., the magnetization direction is from bottom to top). That is, the polarities of the two adjacent end faces (the lower end of the first permanent magnet ring array 12 and the upper end of the second permanent magnet ring array 14) are the same. This ensures that the magnetization vector directions of the first permanent magnet ring array 12 and the second permanent magnet ring array 14 are opposite, that is, the equivalent axial magnetization polarities of the first permanent magnet ring array 12 and the second permanent magnet ring array 14 are opposite. This allows the two arrays, the first permanent magnet ring array 12 and the second permanent magnet ring array 14, to form a quadrupole magnetic field in the central region when they are superimposed in space.

[0033] Optionally, the equivalent magnet unit 16 includes a first cylindrical permanent magnet, or the equivalent magnet unit 16 includes multiple second cylindrical permanent magnets. That is, the embodiments of this application provide two structures for the equivalent magnet unit 16. The equivalent magnet unit 16 can be composed of a single first cylindrical permanent magnet, or it can be composed of multiple coaxially stacked second cylindrical permanent magnets with the same magnetization direction, so as to reduce the processing cost and cycle of custom magnets.

[0034] It should be noted that when the equivalent magnet unit 16 includes multiple second cylindrical permanent magnets, the diameters of the multiple second cylindrical permanent magnets are the same, and the heights of the multiple second cylindrical permanent magnets are the same or different. However, the heights of the first cylindrical permanent magnet and the multiple second cylindrical permanent magnets need to meet the following height restriction condition: the sum of the heights of the multiple second cylindrical permanent magnets is equal to the height of the first cylindrical permanent magnet.

[0035] For example, the equivalent magnet unit 16 can be composed of a first cylindrical permanent magnet with a height of 14 mm, or two second cylindrical permanent magnets with a height of 7 mm, or a second cylindrical permanent magnet with a height of 6 mm and a second cylindrical permanent magnet with a height of 8 mm. It should be noted that this is only an example, and the height of the first or second cylindrical permanent magnet is not limited to these values. It can be specifically set according to experimental requirements, as long as the two structural forms of the equivalent magnet unit 16 satisfy the above-mentioned height restriction condition for the cylindrical permanent magnet.

[0036] It is worth noting that in the case of multiple second cylindrical permanent magnets with the same diameter and different heights stacked coaxially, the stacking will actually affect the magnetism of the magnets. This will result in differences in the magnetism of the final magnets even though the total height is the same. Therefore, some additional calibration methods need to be introduced for different stacking combinations.

[0037] Optionally, the magnetization directions of the multiple second cylindrical permanent magnets are consistent. For example, one end of the second cylindrical permanent magnet is the N pole and the other end is the S pole. When multiple second cylindrical permanent magnets are stacked coaxially along the axial direction, the magnetization directions of any two adjacent second cylindrical permanent magnets are consistent. That is, the S pole of the first second cylindrical permanent magnet and the N pole of the second second cylindrical permanent magnet are stacked together, ensuring that any two adjacent second cylindrical permanent magnets attract each other rather than repel each other.

[0038] Furthermore, multiple second cylindrical permanent magnets are coaxially stacked along an axial direction, which is the common central axis of the first permanent magnet ring array 12 and the second permanent magnet ring array 14. Based on defining the central plane between the first permanent magnet ring array 12 and the second permanent magnet ring array 14 as the xy plane, this axial direction can be defined as the z-axis.

[0039] As one possible implementation, the first support portion 110 and the second support portion 111 are interlocked. (Refer to...) Figure 3 The schematic diagram of the first support portion shown illustrates that the first support portion 110 is provided with a first magnet groove a1, and the first magnet groove a1 is provided with a plurality of first through holes a2. The first through holes a2 are used for venting, observation, and disassembly.

[0040] Optionally, refer to Figure 4 The schematic diagram of the second support part shown shows that the second support part 111 is also provided with a first magnet groove a1, and the first magnet groove a1 is provided with a plurality of first through holes a2.

[0041] Additionally, refer to Figure 3 As shown, the first support portion 110 is also provided with a plurality of first screw holes a3, referring to... Figure 4 As shown, the second support part 111 is also provided with a plurality of first screw holes a3. The first screw holes a3 are reserved holes for fixing as a fastener.

[0042] It should be noted that the number of first through holes a2 is the same as the number of equivalent magnet units 16 in the first permanent magnet ring array 12, and the position of each first through hole a2 corresponds one-to-one with the position of each equivalent magnet unit 16 in the first permanent magnet ring array 12. In addition, each first through hole a2 is a cylindrical through hole, and each equivalent magnet unit 16 in the first permanent magnet ring array 12 is a cylindrical permanent magnet. From a top view, both the first through holes a2 and each equivalent magnet unit 16 in the first permanent magnet ring array 12 appear as circular holes. However, since the first through hole a2 is used as an auxiliary small hole for venting, observation, and disassembly, the circular hole corresponding to the first through hole a2 is smaller than the circular hole presented by each equivalent magnet unit 16 in the first permanent magnet ring array 12.

[0043] As one possible implementation, the third support portion 130 and the fourth support portion 131 are interlocked. (See reference...) Figure 5 The schematic diagram of the third support portion shown illustrates that the third support portion 130 is provided with a second magnet groove b1, and the second magnet groove b1 is provided with a plurality of second through holes b2. The second through holes b2 are used for venting, observation, and disassembly.

[0044] Optionally, the geometry of the fourth support portion 131 is the same as that of the first support portion 110. The fourth support portion 131 is also provided with a second magnet groove b1, and the second magnet groove b1 is provided with a plurality of second through holes b2.

[0045] Additionally, refer to Figure 5 As shown, the third support portion 130 is also provided with a plurality of second screw holes b3. Similarly, the fourth support portion 131 is also provided with a plurality of second screw holes b3, which are holes reserved for fixing as fasteners.

[0046] It should be noted that the number of second through holes b2 is the same as the number of equivalent magnet units 16 in the second permanent magnet ring array 14, and the position of each second through hole b2 corresponds one-to-one with the position of each equivalent magnet unit 16 in the second permanent magnet ring array 14. Furthermore, each second through hole b2 is a cylindrical through hole, and each equivalent magnet unit 16 in the second permanent magnet ring array 14 is a cylindrical permanent magnet. From a top view, both the second through holes b2 and each equivalent magnet unit 16 in the second permanent magnet ring array 14 appear as circular holes. However, since the second through holes b2 serve as auxiliary small holes for venting, observation, and disassembly, the circular holes corresponding to the second through holes b2 are smaller than the circular holes presented by each equivalent magnet unit 16 in the second permanent magnet ring array 14.

[0047] Optionally, refer to Figures 3-5As shown, the first support portion 110, the second support portion 111, the third support portion 130, and the fourth support portion 131 are respectively provided with magnet slots corresponding to the equivalent magnet unit 16 (such as a cylindrical permanent magnet), that is... Figures 3-5 The first magnet slot a1 and the second magnet slot b1 shown in the diagram have an equivalent magnet unit 16 clamped inside the magnet slot and a partially visible area retained to confirm the magnet's positioning and limiting status.

[0048] Furthermore, continue to refer to Figures 3-5 As shown, the first magnet groove a1 is provided with a plurality of first through holes a2, and the second magnet groove b1 is provided with a plurality of second through holes b2. The first through holes a2 and the second through holes b2 are used to expel air when the equivalent magnet unit 16 (such as a cylindrical permanent magnet) is pressed in, to observe whether the magnet is in place after assembly, and to push the magnet out from the back side when disassembling.

[0049] Figure 6 A schematic diagram of a fixing component provided in an embodiment of this application is shown. (Refer to...) Figure 6 As shown, the first fixing component 10 includes a first fixing buckle 101 and a first adjusting shim 102, with the first adjusting shim 102 disposed between the first fixing buckle 101 and the first support portion 110. The second fixing component 15 includes a second fixing buckle 151 and a second adjusting shim 152, with the second adjusting shim 152 disposed between the second fixing buckle 151 and the fourth support portion 131.

[0050] Optionally, the first adjusting shim 102 and the second adjusting shim 152 are used to adjust the end face distance between the first permanent magnet ring array 12 and the second permanent magnet ring array 14. For example, refer to... Figure 7 As shown, the end face distance is... Figure 7 The gap is marked in the middle. In this embodiment of the application, the first adjusting shim 102 and the second adjusting shim 152 are used to set or fine-tune the end face distance gap. By replacing the first adjusting shim 102 and the second adjusting shim 152 with different thicknesses, the center gradient of the annular permanent magnet quadrupole magnetic trap device can be compensated within a limited range after the annular permanent magnet quadrupole magnetic trap device is assembled.

[0051] It should be noted that the first adjusting shim 102 and the second adjusting shim 152 can be set according to the actual situation. For example, if it is not necessary to adjust the end face distance between the first permanent magnet ring array 12 and the second permanent magnet ring array 14, the first adjusting shim 102 and the second adjusting shim 152 may not be set in the annular permanent magnet quadrupole magnetic trap device provided in this application embodiment. In this case, the first fixing component 10 only includes the first fixing fastener 101, and the second fixing component 15 only includes the second fixing fastener 151.

[0052] In summary, the annular permanent magnet quadrupole magnetic trap device provided in this application does not require continuous power supply from coils. It uses discrete axially magnetized cylindrical permanent magnets to form a quadrupole magnetic field source with small footprint, low power consumption, and low thermal load. Through structural parameters, clamping brackets, through holes for venting, observation, and disassembly, and replaceable adjustment shims, the annular permanent magnet quadrupole magnetic trap device simultaneously meets the requirements of magnetic field target, compact integration, assembly reliability, and subsequent error compensation. It meets the integration requirements of compact or portable cold atom systems. The entire device has low thermal load and small footprint, making it suitable for quadrupole static magnetic field sources in cold atom devices or other compact experimental platforms.

[0053] As one possible implementation, for the above-mentioned annular permanent magnet quadrupole magnetic trap device provided in the embodiments of this application, the structural parameters such as the number N of equivalent magnet units 16 (i.e., the number of single-ring magnets N), the diameter D of the cylindrical permanent magnet (the diameter D of the first or second cylindrical permanent magnet), the height H of the cylindrical permanent magnet (the total axial height of an equivalent magnet unit 16), the diameter phi of the magnet center circle, and the end face distance gap between the first permanent magnet ring array 12 and the second permanent magnet ring array 14 are pre-simulated based on the target design parameters designed according to experimental requirements. The target design parameters include, for example, the axial gradient of the magnetic trap center, the radial gradient of the center, the uniformity of the gradient in the working area, and the available space requirements of the device, so that the magnetic trap forms a quadrupole magnetic field in the central region that meets the experimental requirements.

[0054] The magnetic trap center axial gradient refers to the rate at which the axial component of the magnetic field changes with displacement when the magnetic trap center moves a small distance along the common central axis of the upper and lower permanent magnet ring arrays 12 and 14. The center radial gradient refers to the rate at which the radial component of the magnetic field changes with radial distance when the magnetic trap center makes a small displacement in any radial direction within the central plane between the two permanent magnet ring arrays 12 and 14. The working region gradient uniformity refers to the extent to which the local gradient remains close to the central gradient within a specified finite space after leaving the magnetic trap center. The working region is, for example, a spherical region with a radius of 10 mm centered at the magnetic trap center. For example, a 5% gradient uniformity means that the deviation of the local gradient at each location within this region from the central reference gradient should, in principle, not exceed 5%. This region is where cold atoms will be bound in the future.

[0055] For example, the end face distance gap between the first permanent magnet ring array 12 and the second permanent magnet ring array 14 is as follows: Figure 7 As indicated in the label, the diameter phi of the magnet's central circle is as follows: Figure 8 As shown in the annotation.

[0056] For example, the following describes the simulation process for determining the parameters of each structure in a ring-shaped permanent magnet quadrupole magnetic trap device provided in this application, with reference to a specific embodiment. This simulation process mainly includes the following steps: defining the design objectives, parameterizing the magnet array, searching for candidate parameters using MATLAB, performing fine scanning using COMSOL, and determining the final implementation parameters. In defining the design objectives, the axial gradient at the center of the magnetic trap is first specified to be approximately 20 G / cm, and the radial gradient is approximately 10 G / cm. It is required that within a working area with a radius of 10 mm centered on the magnetic trap center, the deviation of the local gradient from the central gradient should not exceed 5%. Simultaneously, the spatial constraints provided by the vacuum chamber are incorporated, requiring all magnets to be completely located within the specified upper and lower ring regions, and adjacent magnets should not overlap. In parameterizing the magnet array, several parameters are used to fully describe the magnet array, including the number of single-ring magnets N, the diameter D of the cylindrical permanent magnet, the height H of the cylindrical permanent magnet, the diameter phi of the magnet's central circle (phi = 2*R, where R represents the radius of the magnet's central circle), and the nearest end-face distance gap between the upper and lower permanent magnet ring arrays. The equivalent remanence Br of the magnets was uniformly set to 1.21T, serving as a known material parameter and not participating in the final geometry optimization. In the step of searching for candidate parameters using MATLAB, MATLAB automatically generated the magnet array within the allowed parameter range, calculated the central gradient and the gradient distribution within the working region, and simultaneously checked the axial gradient, gradients in multiple radial directions, and the uniformity of the working region to avoid obtaining superficially good results only on a single radial line. The search process employed a genetic algorithm for global search, with integer filtering based on the number of single-ring magnets N, the diameter D of the cylindrical permanent magnet, and the height H of the cylindrical permanent magnet. After filtering with fixed integer parameters N, D, and H, a detailed scan was performed on the magnet's central circle radius R and the nearest end-face distance gap between the upper and lower permanent magnet ring arrays. During this process, only the gradient target, parameter range, and spatial constraints were pre-defined. The high-quality candidates obtained by MATLAB are located near the following parameters: cylindrical permanent magnet diameter D=3mm, cylindrical permanent magnet height H=14mm, number of single-ring magnets N≈68~69, magnet center circle radius R≈52.5~52.7mm, and end face distance gap≈55.5~55.6mm. Since MATLAB is used to quickly narrow down the search range, a more accurate three-dimensional model can then be built in COMSOL.

[0057] Furthermore, in the COMSOL fine scanning step, a more accurate three-dimensional magnetic field calculation was performed near the candidate parameters. Specifically, firstly, other parameters were fixed, and the number of magnets N in a single ring was scanned from 62 to 72. The center gradient, gradient plateau width, and edge changes corresponding to different numbers of magnets N in a single ring were compared. The results showed that when N=68, the axial gradient was 20 G / cm and the radial gradient was about 10 G / cm, which were both close to the center of the magnetic trap. Therefore, it was determined that 68 magnets were used in a single ring. Then, the diameter D of the cylindrical permanent magnet was fixed at 3 mm, the height H of the cylindrical permanent magnet was 14 mm, the number of magnets N=68, and the equivalent remanence of the magnet Br=1.21 T. The radius R of the magnet's center circle and the distance gap between the ends were parametrically scanned. By comparing the axial gradient, radial gradient, and uniformity of the working area for each set of parameters, the following were finally selected: the radius R of the magnet's center circle was 52.5 mm, the distance gap between the ends was 55.5 mm, and the diameter phi of the magnet's center circle was obtained as 105 mm.

[0058] Based on this, simulation can determine the parameters of each structure of the annular permanent magnet quadrupole magnetic trap device provided in this application embodiment under the given target design parameters designed based on experimental requirements. For example, the number of equivalent magnet units 16 N=68, and the total number of magnets in the first permanent magnet ring array 12 and the second permanent magnet ring array 14 is 136. Taking the equivalent magnet unit 16 as a complete first cylindrical permanent magnet as an example, the diameter of the first cylindrical permanent magnet D=3mm, the height of the first cylindrical permanent magnet H=14mm, the diameter of the magnet center circle phi=105mm, the radius of the magnet center circle R=52.5mm, and the end face distance gap between the first permanent magnet ring array 12 and the second permanent magnet ring array 14 is 55.5mm.

[0059] Furthermore, based on the structural parameters determined above, the various structures in the annular permanent magnet quadrupole magnetic trap device can be fabricated using 3D printing additive manufacturing or other non-magnetic or low-magnetic processing methods. In the 3D printed prototype, the support components can be made of PETG or ASA materials, and the fasteners in the fixing components can be made of PA6-CF material with better rigidity. Alternatively, they can be replaced with other non-magnetic materials, low-magnetic composite materials, or non-magnetic metal materials according to the requirements of formal implementation. During processing, the dimensions of the magnet slots, positioning surfaces, gasket holes, and screw holes are controlled. After calibration of the printing equipment, optimization of material parameters, and compensation of key holes and slots, the tolerances of the key positioning dimensions and magnet slot dimensions can be controlled within ±0.05mm.

[0060] In addition, before assembly, check the size, quantity, and magnetization direction of the cylindrical permanent magnets, and clean the magnet slots and through holes. The specific assembly process includes: taking the first permanent magnet ring array 12 on one side as an example, firstly, place each equivalent magnet unit 16 into the first magnet slot a1 provided on the second support part 111 of the first support assembly 11 on that side in circumferential order, so that the axial magnetization direction of each equivalent magnet unit 16 is consistent with the design direction of the ring array on that side. Then, align and fasten the first magnet slot a1 provided on the first support part 110 of the first support assembly 11 with each equivalent magnet unit 16, so that each equivalent magnet unit 16 is reliably clamped by the upper and lower limiting surfaces. During the fastening process, the air in the slot is discharged through the multiple first through holes a2 provided on the first magnet slot a1, and the equivalent magnet unit 16 is observed to be pressed into place through the multiple first through holes a2 and the exposed visible area of ​​the magnet. If it is necessary to disassemble or replace the magnet, the equivalent magnet unit 16 can also be pushed out from the back side of the first through hole a2 to avoid the equivalent magnet unit 16 getting stuck.

[0061] It should be noted that during the assembly process, if the equivalent magnet unit 16 is composed of multiple second cylindrical permanent magnets stacked together, the multiple second cylindrical permanent magnets must first be combined into the target height in a coaxial and unidirectional magnetization manner, and then placed into the magnet slot as a whole.

[0062] Furthermore, based on the end face distance gap determined by simulation and subsequent adjustment requirements, select a first adjusting shim 102 and a second adjusting shim 152 of appropriate thickness. Align the first fixing fastener 101, which is fixed to the vacuum chamber or experimental platform, with the reserved screw holes on the first support part 110 and the first adjusting shim 102, and align the second fixing fastener 151, which is fixed to the vacuum chamber or experimental platform, with the reserved screw holes on the fourth support part 131 and the second adjusting shim 152. Secure the first fixing fastener 101, the first adjusting shim 102, and the first support part 110, and secure the second fixing fastener 151, the second adjusting shim 152, and the fourth support part 131 with non-magnetic or low-magnetic screws.

[0063] For example, the fixing and adjusting shims and the support can be made of M3×6mm flat-head non-magnetic screws, and the fixing fasteners and adjusting shims can be made of M3×6.5mm beveled-head non-magnetic screws. The screws used for fixing the fasteners to the vacuum chamber or experimental platform can be selected according to the actual interface.

[0064] Correspondingly, the second permanent magnet ring array 14 on the other side is assembled in the same manner, ensuring that the first permanent magnet ring arrays 12 and 14 on both the upper and lower sides are symmetrical about the central plane. After assembly, the fasteners are fixed to the vacuum chamber interface or experimental platform, and the relative positions of the first permanent magnet ring arrays 12 and 14 on both the upper and lower sides, the screw tightness, the visible area of ​​the magnets, and the thickness of the gaskets are checked to ensure they meet the design requirements. Furthermore, a triaxial spatial magnetic field measurement system is used to detect the vector magnetic field near the center. This system may include a triaxial displacement stage and a triaxial magnetic sensor. According to the measured results of the triaxial spatial magnetic field measurement system, the axial gradient of the magnetic trap center corresponding to the annular permanent magnet quadrupole magnetic trap device is approximately 19.5 G / cm, and the radial gradient is approximately 9.8 G / cm, which is close to the given design target of approximately 20 G / cm for the axial gradient of the magnetic trap center and approximately 10 G / cm for the radial gradient. In this case, by replacing the adjusting shims of different thicknesses within the range of 0-2mm, the nearest end face distance gap between the upper and lower permanent magnet ring arrays can be adjusted within the range of approximately 54-58mm, and the central radial gradient can have an adjustment range of approximately 9.4-10.4G / cm.

[0065] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A ring-shaped permanent magnet quadrupole magnetic trap device, characterized in that, include: The system comprises a first fixing component, a first support component, a first permanent magnet ring array, a second support component, a second permanent magnet ring array, and a second fixing component. The first support component includes a first support portion and a second support portion. The first support portion is disposed at the top of the first permanent magnet ring array, and the second support portion is disposed at the bottom of the first permanent magnet ring array. The first support component is used to support the first permanent magnet ring array. The first fixing component is disposed on the top of the first support portion, and the first fixing component is used to fix the first support component to the external platform; The second support component includes a third support portion and a fourth support portion. The third support portion is disposed at the top of the second permanent magnet ring array, and the fourth support portion is disposed at the bottom of the second permanent magnet ring array. The second support component is used to support the second permanent magnet ring array. The second fixing component is disposed at the bottom of the fourth support portion, and the second fixing component is used to fix the second support component to the external platform; The second support portion is disposed opposite to the third support portion, and there is a space of a preset height between the second support portion and the third support portion.

2. The annular permanent magnet quadrupole magnetic trap device according to claim 1, characterized in that, The first permanent magnet ring array and the second permanent magnet ring array each include a plurality of equivalent magnet units, and the plurality of equivalent magnet units are arranged at equal intervals along the circumferential direction.

3. The annular permanent magnet quadrupole magnetic trap device according to claim 2, characterized in that, The equivalent magnet unit includes: a first cylindrical permanent magnet, or multiple second cylindrical permanent magnets.

4. The annular permanent magnet quadrupole magnetic trap device according to claim 3, characterized in that, The diameters of the multiple second cylindrical permanent magnets are the same, and the heights of the multiple second cylindrical permanent magnets may be the same or different.

5. The annular permanent magnet quadrupole magnetic trap device according to claim 3, characterized in that, Multiple second cylindrical permanent magnets are stacked coaxially along an axial direction, which is the common central axis of the first permanent magnet ring array and the second permanent magnet ring array.

6. The annular permanent magnet quadrupole magnetic trap device according to claim 3, characterized in that, The magnetization directions of the multiple second cylindrical permanent magnets are consistent.

7. The annular permanent magnet quadrupole magnetic trap device according to claim 3, characterized in that, The sum of the heights of the plurality of second cylindrical permanent magnets is equal to the height of the first cylindrical permanent magnet.

8. The annular permanent magnet quadrupole magnetic trap device according to claim 2, characterized in that, The first support part and the second support part are interlocked, and the first support part and the second support part are respectively provided with a first magnet groove, and the first magnet groove is provided with a plurality of first through holes; The number of the first through holes is the same as the number of equivalent magnet units in the first permanent magnet ring array, and the setting position of each of the first through holes corresponds one-to-one with the setting position of each equivalent magnet unit in the first permanent magnet ring array.

9. A ring-shaped permanent magnet quadrupole magnetic trap device according to claim 2, characterized in that, The third support and the fourth support are interlocked, and the third support and the fourth support are respectively provided with a second magnet groove, and the second magnet groove is provided with a plurality of second through holes. The number of the second through holes is the same as the number of equivalent magnet units in the second permanent magnet ring array, and the setting position of each second through hole corresponds one-to-one with the setting position of each equivalent magnet unit in the second permanent magnet ring array.

10. A ring-shaped permanent magnet quadrupole magnetic trap device according to claim 1, characterized in that, The first fixing component includes: a first fixing buckle and a first adjusting shim, wherein the first adjusting shim is disposed between the first fixing buckle and the first support portion; The second fixing component includes: a second fixing buckle and a second adjusting shim, wherein the second adjusting shim is disposed between the second fixing buckle and the fourth support portion; The first adjusting shim and the second adjusting shim are used to adjust the end face distance between the first permanent magnet ring array and the second permanent magnet ring array.

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