A one-dimensional array multi-channel periodic permanent magnet focusing system and its design method

Abstract

This invention provides a one-dimensional array multi-channel periodic permanent magnet focusing system and its design method. The system includes pole shoes and magnetic groups spaced apart along a first direction. The pole shoes and magnetic groups are periodically alternated along the first direction to form multiple periodic permanent magnet structures. Each magnetic group includes two first magnets spaced apart along a second direction. Both the first magnets and the pole shoes extend along a third direction. The pole shoes have several through holes spaced apart along the third direction for mounting slow-wave structures. These through holes constitute a through-hole unit. The two first magnets are located on opposite sides of the through-hole unit along the second direction. The magnetic group also includes two second magnets disposed between the two first magnets. The two second magnets are located on opposite sides of the through-hole unit along the third direction. This system integrates multiple amplification channels within a single magnetic focusing system without affecting the focusing performance of the electron beam.

Description

Technical Field

[0001] This invention relates to the field of microwave vacuum electronics technology. More specifically, it relates to a one-dimensional array multi-channel periodic permanent magnet focusing system and its design method. Background Technology

[0002] A traveling wave tube (TWT) is a vacuum electronic device typically used as the final stage power amplifier in transmitters, with specific application requirements in many fields such as communications and radar. The focusing system is one of the core components of a TWT; its function is to constrain the radial divergence of the electron beam, allowing it to propagate stably along the axial direction.

[0003] Periodic permanent magnet focusing systems are one of the commonly used focusing systems in traveling wave tubes (TWTs). They work by using the Lorentz force received by the electron beam in a periodically changing magnetic field to constrain the beam. Typically, a single periodic permanent magnet focusing system can only focus the electron beam within one amplification channel, and cannot focus the electron beam in multiple channels. In other words, traditional single-channel periodic permanent magnet focusing systems cannot be applied to integrated TWTs. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a one-dimensional array multi-channel periodic permanent magnet focusing system to integrate multiple amplification channels into a single magnetic focusing system, thereby reducing the distance between amplification channels, increasing unit density, and without affecting the focusing performance of the magnetic focusing system on the electron beam.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a one-dimensional array multi-channel periodic permanent magnet focusing system, comprising:

[0007] The pole shoes and magnetic groups are spaced apart along a first direction; the pole shoes and magnetic groups are periodically alternated along the first direction to form multiple periodic permanent magnet structures;

[0008] The magnetic assembly includes two first magnets spaced apart along a second direction; both the first magnets and the pole shoes extend along a third direction; the pole shoes have a plurality of through holes spaced apart along a third direction, the through holes being used to assemble the slow wave structure; the plurality of through holes constitute a through hole unit; the two first magnets are respectively located on both sides of the through hole unit along the second direction.

[0009] The magnetic assembly also includes two second magnets disposed between the two first magnets; the two second magnets are respectively located on both sides of the through hole unit along a third direction.

[0010] The preferred arrangement is that the two first magnets are symmetrically arranged about the through-hole unit; the two second magnets are symmetrically arranged about the through-hole unit.

[0011] The preferred embodiment is that the diameter of the through hole is D1, the width of the pole shoe in the third direction is W1, and the number of through holes is n;

[0012] The preferred solution is that the spacing between two adjacent through holes in the third direction is D2;

[0013] The preferred embodiment is that the width of the first magnet in the third direction is W2; W2≥D2×(n-1)+D1.

[0014] The preferred embodiment is that the distance between the two first magnets in the second direction is S1, and the height of the pole shoe in the second direction is H1; D1≤S1

[0015] The preferred solution is that the distance between the two second magnets in the third direction is S2; D2×(n-1)+D1≤S2≤W1.

[0016] The preferred embodiment is that the height of the second magnet in the second direction is H3; 0 < H3 ≤ S1.

[0017] The preferred arrangement is that the magnetic field direction of the first magnet in the same magnetic group is the same, the magnetic field direction of the first magnet in two adjacent magnetic groups is opposite, and the magnetic field direction of the first magnet and the second magnet in the same magnetic group is the same.

[0018] This invention also provides a design method for a one-dimensional array multi-channel periodic permanent magnet focusing system, comprising the following steps:

[0019] Several pole shoes and several magnetic groups are periodically and alternately arranged along the first direction;

[0020] The magnetic assembly includes two first magnets spaced apart along a second direction; both the first magnets and the pole shoes extend along a third direction; the pole shoes have a plurality of through holes spaced apart along a third direction, the through holes being used to assemble the slow wave structure; the plurality of through holes constitute a through hole unit; the two first magnets are respectively located on both sides of the through hole unit along the second direction.

[0021] The magnetic assembly also includes two second magnets disposed between the two first magnets; the two second magnets are respectively located on both sides of the through hole unit along a third direction.

[0022] The beneficial effects of this invention are as follows:

[0023] ​This invention integrates multiple through-holes with slow-wave structures into a single focusing system, enabling the array integration of traveling wave tube (TWT) amplification channels in a one-dimensional linear direction. This is suitable for one-dimensional linear array integration of TWTs and effectively reduces the cross-sectional size of individual through-holes, increasing the through-hole unit density and adapting to the application requirements of arrayed systems, such as active phased arrays. This invention ensures that the ratio of the angular magnetic field peak value to the axial magnetic field peak value within the channel of the periodic permanent magnet focusing system does not exceed 0.086%, thus not affecting the focusing performance of the electron beam. Furthermore, the magnetic field distribution in each channel is concentrically circular, meeting the magnetic field shape requirements for focusing cylindrical electron beams. The magnetic axis within each channel coincides with the channel axis, preventing the electron beam's gyration radius from increasing due to magnetic axis deviation during focusing, which would otherwise reduce focusing capability. Attached Figure Description

[0024] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0025] Figure 1 This is one of the structural schematic diagrams of the one-dimensional array multi-channel periodic permanent magnet focusing system of the present invention.

[0026] Figure 2 This is the second schematic diagram of the structure of the one-dimensional array multi-channel periodic permanent magnet focusing system of the present invention.

[0027] Figure 3 This is the third schematic diagram of the one-dimensional array multi-channel periodic permanent magnet focusing system of the present invention.

[0028] Figure 4 This is a schematic diagram of a one-dimensional array multi-channel periodic permanent magnet focusing system without a second magnet, used for comparison.

[0029] Figure 5 This is a BH characteristic curve of the pole shoe material during the simulation process of this invention.

[0030] Figure 6 This is a diagram showing the magnetic field intensity distribution at the center of the pole shoe of the one-dimensional array multi-channel periodic permanent magnet focusing system of the present invention.

[0031] Figure 7 This is a schematic diagram of the main aperture numbers of the one-dimensional array multi-channel periodic permanent magnet focusing system of the present invention.

[0032] Figure 8 This is a diagram showing the axial magnetic field intensity distribution along the axial direction of each hole in the one-dimensional array multi-channel periodic permanent magnet focusing system of the present invention.

[0033] Figure 9 This is a diagram showing the angular magnetic position distribution of each channel at a distance r from the axis on the cross-section of the pole shoe center of the one-dimensional array multi-channel periodic permanent magnet focusing system of the present invention.

[0034] Figure 10 This is a diagram showing the distribution of magnetic field intensity along the width direction on the symmetrical axis of the tangential surface at the center of the pole shoe of the one-dimensional array multi-channel periodic permanent magnet focusing system of the present invention.

[0035] Figure 11 This is a schematic diagram of the main aperture numbers of a one-dimensional array multi-channel periodic permanent magnet focusing system without a second magnet, used for comparison.

[0036] Figure 12 This is a diagram showing the magnetic field intensity distribution at the center section of the pole shoe of a one-dimensional array multi-channel periodic permanent magnet focusing system without a second magnet, used for comparison.

[0037] Figure 13 This is a diagram showing the axial magnetic field strength distribution along the axial direction of each channel in a one-dimensional array multi-channel periodic permanent magnet focusing system without a second magnet, used for comparison.

[0038] Figure 14 This is a diagram showing the angular magnetic position distribution of each channel at a distance r from the axis on the cross-section of the pole shoe center of a one-dimensional array multi-channel periodic permanent magnet focusing system without a second magnet, used for comparison.

[0039] Figure 15 This is a diagram showing the distribution of magnetic field strength along the width direction on the symmetrical axis of the tangential surface at the center of the pole shoe of a one-dimensional array multi-channel periodic permanent magnet focusing system without a second magnet, used for comparison.

[0040] Reference numerals: 1. Pole shoe, 21. First magnet, 22. Second magnet, 3. Through hole. Detailed Implementation

[0041] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0042] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0043] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0044] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0045] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0046] To integrate multiple amplification channels into a single magnetic focusing system, reduce the distance between amplification channels, increase unit density, and without affecting the focusing performance of the magnetic focusing system for electron beams, this invention provides a one-dimensional array multi-channel periodic permanent magnet focusing system, combined with... Figures 1 to 15 As shown, the one-dimensional array multi-channel periodic permanent magnet focusing system specifically includes: pole shoes 1 and magnetic groups spaced apart along a first direction z; the pole shoes 1 and magnetic groups are periodically alternated along the first direction z to form multiple periodic permanent magnet structures. The magnetic group includes two first magnets 21 spaced apart along a second direction y; both the first magnets 21 and the pole shoes 1 extend along a third direction x. A plurality of through holes 3 spaced apart along the third direction x are formed on the pole shoes, and the through holes 3 are used to assemble slow-wave structures. The plurality of through holes 3 constitute a through-hole unit; the two first magnets 21 are respectively located on both sides of the through-hole unit along the second direction y. The magnetic group also includes two second magnets 22 disposed between the two first magnets 21; the two second magnets 22 are respectively located on both sides of the through-hole unit along the third direction x. For example, when there are seven through holes 3, the seven through holes 3 form a through hole unit. Two first magnets 21 are located on both sides of the through hole unit along the second direction (y-direction), and two second magnets 22 are located on both sides of the through hole unit along the third direction (x-direction). That is, the two first magnets 21 and the two second magnets 22 enclose the through hole unit. Furthermore, the aforementioned through holes 3 are used to form channels for assembling the slow-wave structure. The axis of the channel is set along the first direction, that is, the through holes 3 coaxially arranged on each pole piece 1 along the first direction are connected in the first direction (z-direction) to form a channel. The slow-wave structure is assembled within this channel. All of the above channels serve as amplification channels to achieve focusing of multiple electron beams. (Refer to...) Figures 1 to 3 As shown, the z-direction is the first direction, the y-direction is the second direction, and the x-direction is the third direction. The x-direction is perpendicular to the y-direction, and the z-direction is perpendicular to both the x- and y-directions. This invention can integrate multiple channels into the same focusing system, achieving array integration of channels in a one-dimensional linear direction, thus applicable to one-dimensional linear array integrated traveling wave tubes. It can also reduce the cross-sectional size of individual channels, reduce the distance between channels, and increase the channel unit density. The traveling wave tube based on the one-dimensional array multi-channel periodic permanent magnet focusing system of this invention can be widely used in arrayed systems represented by active phased arrays.

[0047] In one embodiment, two first magnets 21 are symmetrically arranged with respect to the through-hole unit; two second magnets 22 are symmetrically arranged with respect to the through-hole unit.

[0048] More specifically, an pole piece 1 contains n through holes 3, where n is a natural number greater than 1. The diameter of each through hole 3 is D1, and the width of the pole piece 1 in the third direction is W1, where W1 > 0. The height of the pole piece 1 in the second direction is H1, where H1 > 0. The thickness of the pole piece 1 in the first direction is L1, where L1 > 0. The number of through holes 3 is n. The distance between two adjacent through holes 3 in the third direction is D2; Furthermore, regarding the first magnet 21, the first magnet 21 has a strip-shaped structure. The height of the first magnet 21 in the second direction is H2, where H2 > 0. The width of the first magnet 21 in the third direction is W2; W2 ≥ D2 × (n-1) + D1. The interval between two first magnets 21 in the second direction is S1, and the height of the pole piece 1 in the second direction is H1; D1 ≤ S1 < H1. Regarding the second magnet 22, the second magnet 22 is a rectangular block, symmetrically arranged on both sides of the through-hole unit and located within the area enclosed by the first magnet 21 and the pole piece 1. The width of the second magnet 22 in the third direction is W3; W3 > 0. The interval between two second magnets 22 in the third direction is S2; D2 × (n-1) + D1 ≤ S2 ≤ W1. The height of the second magnet 22 in the second direction is H3; 0 < H3 ≤ S1. The first magnet 21 and the second magnet 22 have the same thickness L2 in the first direction, where L2 > 0.

[0049] In one specific embodiment, the magnetic field direction of the first magnet 21 in the same magnetic group is the same, and the magnetic field direction of the first magnet 21 in two adjacent magnetic groups is opposite. The magnetic field direction of the first magnet 21 and the second magnet 22 in the same magnetic group is the same. The half-cycle length of the periodic permanent magnet focusing system is L, and its value range is: L = L1 + L2; the magnetic field direction of the first magnet 21 is the same within the same half-cycle, the magnetic field direction of the first magnet 21 is opposite within adjacent half-cycles, and the magnetic field direction of the first magnet 21 and the second magnet 22 is the same within the same half-cycle.

[0050] Reference Figures 1-3The diagram shows a structural schematic of a one-dimensional array seven-channel periodic permanent magnet focusing system provided by the present invention. Wherein, W1 is the pole shoe width, H1 is the pole shoe height, D1 is the diameter of the through-hole, and D2 is the distance between two adjacent through-holes in the third direction. W2 is the width of the first magnet, H2 is the height of the first magnet, S1 is the distance between two first magnets in the second direction, W3 is the width of the second magnet, S2 is the distance between two second magnets in the third direction, and H3 is the height of the second magnet. L1 is the pole shoe thickness, L2 is the thickness of the first magnet and the thickness of the second magnet, and L is the half-cycle length of the magnetic focusing system. Specifically, the structural dimensions of the one-dimensional array seven-channel periodic permanent magnet focusing system of the present invention are as follows (unit: mm): W1 = 40, H1 = 8, L1 = 1, D1 = 1.5, D2 = 5, W2 = 40, H2 = 5, S1 = 4, W3 = 1.25, H3 = 4, S2 = 37.5, L2 = 2, L = 3.

[0051] Reference Figure 4 The diagram shows a schematic of a one-dimensional array seven-channel periodic permanent magnet focusing system without a second magnet for comparison. It is understood that the aforementioned one-dimensional array seven-channel periodic permanent magnet focusing system without a second magnet, except for the absence of a second magnet, has the same structural dimensions as the one-dimensional array seven-channel periodic permanent magnet focusing system provided by this invention.

[0052] The one-dimensional array seven-channel periodic permanent magnet focusing system provided by the present invention and the one-dimensional array seven-channel periodic permanent magnet focusing system without a second magnet used for comparison were simulated using three-dimensional electromagnetic software, and the relevant magnetic field strength and field distribution characteristics were calculated.

[0053] Among them, reference Figure 5 The simulation results show the BH characteristic curves of the pole shoe material, with the remanence Br of the magnet set to 10000 Gs.

[0054] Reference Figure 6 As shown, the magnetic field intensity distribution of the pole shoe center section of the one-dimensional array seven-channel periodic permanent magnet focusing system of the present invention is shown. The magnetic field distribution shape in the channel is concentric circle, which can meet the requirements of cylindrical electron beam focusing for magnetic field shape.

[0055] Reference Figure 7 The diagram shows the main aperture numbering of the one-dimensional array seven-channel periodic permanent magnet focusing system of this invention. The seven apertures are numbered 1, 2, 3, 4, 5, 6, and 7 from left to right. Because the magnetic field distribution is symmetrical, the magnetic field in aperture 1 is symmetrical to that in aperture 7, the magnetic field in aperture 2 is symmetrical to that in aperture 6, and the magnetic field in aperture 3 is symmetrical to that in aperture 5. Therefore, it is only necessary to compare the magnetic fields in apertures 1, 2, 3, and 4.

[0056] Reference Figure 8 The diagram shows the axial magnetic field strength distribution along the axial direction of the channels 1, 2, 3, and 4 of the one-dimensional array seven-channel periodic permanent magnet focusing system of this invention. The maximum axial magnetic field strength along the channel 1 is 3340.5 Gs; along the channel 2 it is 3341.6 Gs; along the channel 3 it is 3344 Gs; and along the channel 4 it is 3344.7 Gs. The maximum difference in the maximum axial magnetic field strength among the four channels is 4.2 Gs, indicating good magnetic field consistency.

[0057] Reference Figure 9 The diagram shows the angular magnetic field distribution along the angular direction at a distance r from the axis in each channel on the cross-section of the pole shoe center of the one-dimensional array seven-channel periodic permanent magnet focusing system of the present invention. Here, r is the preset electron beam channel radius, taken as r = 0.12 mm, and the electron beam will be confined within a channel of radius r. The maximum angular magnetic field at a distance r from the axis in channel 1 is 2.85 Gs, accounting for 0.085% of the peak value of the axial magnetic field on the axis; the maximum angular magnetic field at a distance r from the axis in channel 2 is 2.87 Gs, accounting for 0.086% of the peak value of the axial magnetic field on the axis; the maximum angular magnetic field at a distance r from the axis in channel 3 is 1.98 Gs, accounting for 0.059% of the peak value of the axial magnetic field on the axis; and the maximum angular magnetic field at a distance r from the axis in channel 4 is 1.5 Gs, accounting for 0.045% of the peak value of the axial magnetic field on the axis. Therefore, the maximum value of the angular magnetic field at a distance r from the axis in the above four aperture channels accounts for no more than 0.086% of the peak value of the axial magnetic field on the axis, and will not affect the electron beam focusing performance.

[0058] Reference Figure 10 The diagram shows the distribution of magnetic field strength along the width direction on the symmetrical axis of the pole shoe center tangential plane of the one-dimensional array seven-channel periodic permanent magnet focusing system of the present invention. Taking the position of the axis of the No. 4 aperture channel as the origin, the minimum magnetic field strength in aperture channels 1 to 7 are located at the lateral positions of -15mm, -10mm, -5mm, 0mm, 5mm, 10mm, and 15mm, respectively, meaning that the magnetic axis in each channel coincides with the axis of the circular channel. Therefore, when focusing the electron beam, the deviation of the magnetic axis from the electron beam axis will not cause an increase in the electron beam gyration radius, and will not affect the electron beam focusing performance.

[0059] Reference Figure 11The diagram shows the main aperture numbers of a one-dimensional array seven-channel periodic permanent magnet focusing system without a second magnet, used for comparison. The seven apertures are numbered 1, 2, 3, 4, 5, 6, and 7 from left to right. Because the magnetic field distribution is symmetrical, the magnetic field in aperture 1 is symmetrical to that in aperture 7, the magnetic field in aperture 2 is symmetrical to that in aperture 6, and the magnetic field in aperture 3 is symmetrical to that in aperture 5. Therefore, it is only necessary to compare the magnetic fields in apertures 1, 2, 3, and 4.

[0060] Reference Figure 12 The figure shows the magnetic field intensity distribution of a one-dimensional array seven-channel periodic permanent magnet focusing system without a second magnet, used for comparison. The magnetic field distribution in hole 1 is obviously non-concentric, indicating the presence of an angular field that affects the focusing of the electron beam.

[0061] Reference Figure 13 The figure shows the axial magnetic field strength distribution along the axis of apertures 1, 2, 3, and 4 of a one-dimensional array seven-channel periodic permanent magnet focusing system without a second magnet, used for comparison. The maximum axial magnetic field strength along the axis of aperture 1 is 3076.4 Gs; that of aperture 2 is 3276.2 Gs; that of aperture 3 is 3298.9 Gs; and that of aperture 4 is 3301.4 Gs. The maximum difference between the maximum axial magnetic field strengths along the axes of these four apertures is 4.2 Gs.

[0062] Reference Figure 14 The figure shows the angular magnetic field distribution along the angular direction at a distance r from the axis in each channel on the cross-section of the pole shoe center of a one-dimensional array seven-channel periodic permanent magnet focusing system without a second magnet, used for comparison. Here, r is the preset electron beam channel radius, taken as r = 0.12 mm, confining the electron beam within a channel of radius r. The maximum angular magnetic field at a distance r from the axis in channel 1 is 224.25 Gs, accounting for 7.289% of the peak value of the axial magnetic field on the axis; the maximum angular magnetic field at a distance r from the axis in channel 2 is 23.89 Gs, accounting for 0.729% of the peak value of the axial magnetic field on the axis; the maximum angular magnetic field at a distance r from the axis in channel 3 is 3.54 Gs, accounting for 0.107% of the peak value of the axial magnetic field on the axis; and the maximum angular magnetic field at a distance r from the axis in channel 4 is 1.24 Gs, accounting for 0.038% of the peak value of the axial magnetic field on the axis. Therefore, the maximum angular magnetic field value at a distance r from the axis within the four aperture channels accounts for 7.289% of the peak value of the axial magnetic field on the axis. This will affect the electron beam focusing performance.

[0063] Reference Figure 15The diagram shows the magnetic field strength distribution along the width direction on the symmetrical axis of the pole shoe center tangential surface of a one-dimensional array seven-channel periodic permanent magnet focusing system without a second magnet, used for comparison. Taking the location of the axis of channel 4 as the origin, the minimum magnetic field strength in channels 1 to 7 is located at the lateral positions of -15.15mm, -10.01mm, -5mm, 0mm, 5mm, 10.01mm, and 15.15mm, respectively. This means that the magnetic axis in channels 1, 2, 6, and 7 deviates from the axis of the circular channel, with the outermost channels 1 and 7 showing the largest deviation (0.15mm), while channels 2 and 6 show slightly smaller deviations (0.01mm). Therefore, when focusing the electron beam in channels 1, 2, 6, and 7, the deviation of the magnetic axis from the electron beam axis causes the electron beam's gyration radius to increase, resulting in a thicker electron beam and a decrease in focusing ability.

[0064] The present invention also provides a design method for a one-dimensional array multi-channel periodic permanent magnet focusing system, the method comprising the following steps: periodically alternatingly assembling a plurality of pole shoes 1 and a plurality of magnetic groups along a first direction; the magnetic group includes two first magnets 21 spaced apart along a second direction; both the first magnets 21 and the pole shoes 1 extend along a third direction; a plurality of through holes 3 spaced apart along the third direction are formed on the pole shoes 1, the through holes 3 being used to assemble a slow-wave structure; the plurality of through holes 3 constitute a through-hole unit; the two first magnets 21 are respectively located on both sides of the through-hole unit along the second direction; the magnetic group further includes two second magnets 22 disposed between the two first magnets 21; the two second magnets 22 are respectively located on both sides of the through-hole unit along the third direction.

[0065] In summary, this invention integrates multiple through-holes with slow-wave structures into a single focusing system, enabling the array integration of traveling wave tube (TWT) amplification channels in a one-dimensional linear direction. This makes it suitable for one-dimensional linear array integration of TWTs and effectively reduces the cross-sectional size of individual through-holes, increasing the through-hole unit density and meeting the application requirements of arrayed systems, such as active phased arrays. This invention ensures that the ratio of the angular magnetic field peak value to the axial magnetic field peak value within the channel of the periodic permanent magnet focusing system does not exceed 0.086%, thus not affecting the focusing performance of the electron beam. Furthermore, the magnetic field distribution in each channel is concentrically circular, meeting the magnetic field shape requirements for focusing cylindrical electron beams. The magnetic axis in each channel coincides with the channel axis, preventing the electron beam's gyration radius from increasing due to the magnetic axis deviating from the electron beam axis during focusing, which would otherwise reduce focusing capability.

[0066] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A one-dimensional array multi-channel periodic permanent magnet focusing system, characterized in that, include: The pole shoes and magnetic groups are spaced apart along a first direction; the pole shoes and magnetic groups are periodically alternated along the first direction to form multiple periodic permanent magnet structures; The magnetic assembly includes two first magnets spaced apart along a second direction; both the first magnets and the pole shoes extend along a third direction; the pole shoes have a plurality of through holes spaced apart along a third direction, the through holes being used to assemble the slow wave structure; the plurality of through holes constitute a through hole unit; the two first magnets are respectively located on both sides of the through hole unit along the second direction. The magnetic assembly also includes two second magnets disposed between the two first magnets; the two second magnets are respectively located on both sides of the through hole unit along a third direction.

2. The one-dimensional array multi-channel periodic permanent magnet focusing system according to claim 1, characterized in that, The two first magnets are symmetrically arranged about the through-hole unit; the two second magnets are symmetrically arranged about the through-hole unit.

3. The one-dimensional array multi-channel periodic permanent magnet focusing system according to claim 1, characterized in that, The diameter of the through hole is D1, the width of the pole shoe in the third direction is W1, and the number of through holes is n; 4. The one-dimensional array multi-channel periodic permanent magnet focusing system according to claim 3, characterized in that, The distance between two adjacent through holes in the third direction is D2; 5. The one-dimensional array multi-channel periodic permanent magnet focusing system according to claim 4, characterized in that, The width of the first magnet in the third direction is W2; W2≥D2×(n-1)+D1.

6. The one-dimensional array multi-channel periodic permanent magnet focusing system according to claim 3, characterized in that, The distance between the two first magnets in the second direction is S1, and the height of the pole shoe in the second direction is H1; D1≤S1<H1.

7. The one-dimensional array multi-channel periodic permanent magnet focusing system according to claim 4, characterized in that, The distance between the two second magnets in the third direction is S2; D2×(n-1)+D1≤S2≤W1.

8. The one-dimensional array multi-channel periodic permanent magnet focusing system according to claim 6, characterized in that, The height of the second magnet in the second direction is H3; 0 < H3 ≤ S1.

9. The one-dimensional array multi-channel periodic permanent magnet focusing system according to claim 1, characterized in that, The magnetic field direction of the first magnet in the same magnetic group is the same, the magnetic field direction of the first magnet in two adjacent magnetic groups is opposite, and the magnetic field direction of the first magnet and the second magnet in the same magnetic group is the same.

10. A design method for a one-dimensional array multi-channel periodic permanent magnet focusing system, characterized in that, Includes the following steps: Several pole shoes and several magnetic groups are periodically and alternately arranged along the first direction; The magnetic assembly includes two first magnets spaced apart along a second direction; both the first magnets and the pole shoes extend along a third direction; the pole shoes have a plurality of through holes spaced apart along a third direction, the through holes being used to assemble the slow wave structure; the plurality of through holes constitute a through hole unit; the two first magnets are respectively located on both sides of the through hole unit along the second direction. The magnetic assembly also includes two second magnets disposed between the two first magnets; the two second magnets are respectively located on both sides of the through hole unit along a third direction.

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