A pole piece and periodic permanent magnet focusing system

Abstract

The application provides a pole shoe and a periodic permanent magnet focusing system. The pole shoe comprises a through hole penetrating through the surfaces of both sides of the pole shoe along the pole shoe axis, a pole shoe head surrounding the edge of the through hole, and a pole shoe ring surface surrounding the outside of the pole shoe head. The through hole, the pole shoe head and the pole shoe ring surface are coaxially arranged. The through hole comprises a centrally arranged assembly slot in a rectangular structure for assembling a slow wave structure. The assembly slot comprises two opposite first edge portions in a first direction and two opposite second edge portions in a second direction. The through hole further comprises two first notches respectively extending outward from the two opposite first edge portions of the assembly slot and two second notches respectively extending outward from the two opposite second edge portions of the assembly slot. The pole shoe can improve the shape of the inner hole of the pole shoe in the focusing system, improve the utilization rate of the inner hole cross section, and further improve the strength of the focusing magnetic field.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microwave vacuum electron technology. More particularly, it relates to a pole shoe and a periodic permanent magnet focusing system. BACKGROUND

[0002] Traveling wave tube is a kind of vacuum amplifier, which is used as the final stage power amplifier of radar and has been applied in many weapon equipments. The focusing system is one of the core components of the traveling wave tube, which can constrain the radial divergence of the electron beam and make the electron beam transmit stably along the axial direction. The periodic permanent magnet focusing system is one of the commonly used focusing systems in the traveling wave tube, which can constrain the electron beam by the Lorentz force received by the electron beam in the periodically transformed magnetic field. The constraining ability of the periodic permanent magnet focusing system to the electron beam is positively related to the magnetic field strength in the electron beam channel.

[0003] The inner hole of the pole shoe of the periodic permanent magnet focusing system is usually circular. This structure is used for the traditional spiral line slow wave structure with a circular cross section, and the circular inner hole can well adapt to the shape of the slow wave structure. However, for the folded waveguide and staggered double grid type slow wave structure with a rectangular cross section, the circular inner hole will cause the opening area ratio to be larger than the actual cross section size, and part of the area is wasted, thereby reducing the strength of the focusing magnetic field. SUMMARY

[0004] In view of the above problems, the present application provides a pole shoe which can improve the shape of the inner hole of the pole shoe in the focusing system, improve the utilization rate of the inner hole cross section, and further improve the strength of the focusing magnetic field.

[0005] To achieve the above object, the present application adopts the following technical scheme:

[0006] The present application provides a pole shoe, which comprises a through hole penetrating through the two side surfaces of the pole shoe along the pole shoe axis, a pole shoe head surrounding the edge of the through hole, and a pole shoe ring surface surrounding the outside of the pole shoe head, wherein the through hole, the pole shoe head and the pole shoe ring surface are coaxially arranged.

[0007] The through hole comprises a central assembly groove in a rectangular structure for assembling the slow wave structure; the assembly groove comprises two opposite first edge portions in a first direction and two opposite second edge portions in a second direction.

[0008] The through hole further comprises two first notches respectively extending outward from the two opposite first edge portions of the assembly groove, and two second notches respectively extending outward from the two opposite second edge portions of the assembly groove.

[0009] Preferably, the two first notches are symmetrically arranged about the assembly groove, and the two second notches are symmetrically arranged about the assembly groove.

[0010] Preferably, the first slot and the second slot have the same structural size.

[0011] Preferably, the slot width of the first slot is equal to the length of the first edge of the assembly slot.

[0012] Preferably, the slot width of the second slot is equal to the length of the second edge of the assembly slot.

[0013] Preferably, the cross section of the assembly slot is square.

[0014] Preferably, the assembly slot and the first slot form a receiving cavity for assembling the slow wave structure or the assembly slot and the second slot form a receiving cavity for assembling the slow wave structure.

[0015] The present application also provides a periodic permanent magnet focusing system comprising the pole piece and the magnetic steel as described above; the pole pieces and the magnetic steels are periodically and alternately arranged along the pole piece axis.

[0016] Preferably, the magnetic field directions of the two adjacent magnetic steels are opposite.

[0017] Preferably, the magnetic steel has a ring structure; and the pole piece ring surface and the magnetic steel have a spacing distance.

[0018] The present application has the following advantages:

[0019] Compared with the existing periodic permanent magnet focusing system based on the circular inner hole pole piece structure, the cross-shaped through hole of the present application can better adapt to the folded waveguide and the staggered double grid slow wave structure with a rectangular cross section, effectively reduce the opening area of the pole piece, improve the utilization rate of the through hole cross section, and further improve the focusing magnetic field strength. The periodic permanent magnet focusing system of the present application has a stronger focusing magnetic field strength and a stronger electron beam confinement ability. The traveling wave tube with the periodic permanent magnet focusing system of the present application can be widely applied to new generation mobile communication, radar and other equipment. BRIEF DESCRIPTION OF DRAWINGS

[0020] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0021] Figure 1 is a schematic diagram of the existing rectangular outer boundary folded waveguide slow wave structure cross section.

[0022] Figures 2A-2C is a schematic diagram of the existing circular inner hole pole piece structure.

[0023] Figure 3 is a schematic diagram of the existing periodic permanent magnet focusing system based on the circular inner hole pole piece structure.

[0024] Figures 4A-4Cis a structural schematic diagram of a pole shoe of the present application.

[0025] Figures 4D-4E is a structural schematic diagram of a through hole of the present application.

[0026] Figure 5 is a structural schematic diagram of a periodic permanent magnet focusing system of the present application.

[0027] Figure 6 is a comparison diagram of axial magnetic field strength of a periodic permanent magnet focusing system based on a circular hole pole shoe structure and the periodic permanent magnet focusing system of the present application.

[0028] Figure 7 is a distribution isochine diagram of magnetic field in a through hole of the periodic permanent magnet focusing system of the present application in an axial section.

[0029] Figure 8 is a distribution diagram of angular magnetic field strength at d / 2 from the axis of the periodic permanent magnet focusing system of the present application at different angular positions.

[0030] Figure 9 is an isochine distribution diagram of magnetic field in a rectangular hole of a periodic permanent magnet focusing system based on a rectangular hole pole shoe structure in an axial section. DETAILED DESCRIPTION

[0031] Various exemplary embodiments of the present application will now be described in detail with reference to the figures. It should be noted that the relative arrangements, numerical expressions, and values of the components and steps set forth in these embodiments are not limiting to the scope of the present application unless otherwise specifically stated.

[0032] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the scope of the application its application or uses.

[0033] Techniques and equipment known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered part of the specification where appropriate.

[0034] In all of the examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0035] It should be noted that like numbers and letters refer to like items throughout the drawings, and once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0036] In the millimeter wave terahertz band, the electron beam channel of the traveling wave tube is usually small, and the Coulomb force between electrons is greater, which puts higher requirements on the strength of the focusing magnetic field. By reducing the cross-sectional size of the circular inner hole of the existing focusing system, the strength of the focusing magnetic field can be effectively improved. However, due to the physical size limitation of the slow wave structure, the cross-sectional size of the circular inner hole of the existing focusing system cannot be infinitely reduced, resulting in limited improvement in the strength of the focusing magnetic field.

[0037] In order to solve the problem that the existing periodic permanent magnet focusing system cannot be well adapted to the rectangular cross-section of the folded waveguide and the staggered double-grid type slow wave structure, resulting in a decrease in the strength of the focusing magnetic field, the present application provides a pole shoe, which is combined with Figures 1-9 As shown in the figure, specifically, the pole shoe 1 includes a through hole 11 penetrating through the two side surfaces of the pole shoe along the pole shoe axis, a pole shoe head 12 surrounding the edge of the through hole 11, and a pole shoe ring surface 13 surrounding the outside of the pole shoe head 12, and the through hole 11, the pole shoe head 12 and the pole shoe ring surface 13 are coaxially arranged. The through hole 11 includes a centrally arranged assembly groove 111, which is in a rectangular structure for assembling the slow wave structure. The assembly groove 111 includes two opposite first edge portions in a first direction, and two opposite second edge portions in a second direction. The through hole 11 further includes two first notches 112 formed by extending outward from the two opposite first edge portions of the assembly groove 111, and two second notches 113 formed by extending outward from the two opposite second edge portions of the assembly groove 111. The two first notches 112 are arranged along the first direction, and the two second notches 113 are arranged along the second direction, and the first direction is orthogonal to the second direction. Referring to Figure 4B and Figure 4C As shown in the figure, the first direction is the X direction, the second direction is the Y direction, and the third direction is the Z direction, which is perpendicular to the X direction and the Y direction. The axial direction of the pole shoe 1 and the through hole 11 is the Z direction. The cross-section of the through hole 11 of the present application is in the shape of a cross, which can better fit the shape of the slow wave structure with a rectangular cross-section, and has better adaptability. Assembling the same slow wave structure with a rectangular cross-section, compared with the circular inner hole, the cross-sectional area of the through hole 11 of the present application is smaller, and has a stronger magnetic field strength.

[0038] In the above embodiment, the first notch 112 and the second notch 113 are in communication with the assembly groove 111, and the first notch 112, the second notch 113 and the assembly groove 111 form the through hole 11 with a cross-sectional shape of a cross, and the slow wave structure is assembled into the through hole 11. By changing the circular inner hole of the conventional concentric circular pole shoe structure to a cross-shaped through hole, the present application can better adapt to the folded waveguide and the staggered double-grid type slow wave structure with a rectangular cross-section, effectively reduce the opening area of the through hole 11 on the pole shoe 1, and improve the cross-sectional utilization rate of the through hole 11.

[0039] Further, in order to ensure that the opening area of the through hole 11 on the pole shoe 1 is as small as possible, based on the slow wave structure with different size and rectangular cross section, the assembly groove 111 and the first slot 112 form a receiving cavity for assembling the slow wave structure, or the assembly groove 111 and the second slot 113 form a receiving cavity for assembling the slow wave structure. That is, the slow wave structure can be assembled into the receiving cavity formed by the assembly groove 111 and the two first slots 112, without occupying the space of the second slot 113, or the slow wave structure can be assembled into the receiving cavity formed by the assembly groove 111 and the two second slots 113, without occupying the space of the first slot 112. In addition, the slow wave structure with rectangular cross section can also be assembled only through the assembly groove 111, so as not to occupy the space of the first slot 112 and the second slot 113, and the first slot 112 and the second slot 113 can be used as magnetic field adjusting gaps to adjust the magnetic field form. The cross section of the through hole 11 of the present application is more suitable for the shape of the slow wave structure with rectangular cross section, so as to have better adaptability, and the cross section area of the through hole 11 is smaller.

[0040] More specifically, the first slot 112 extends along a first direction, and the second slot 113 extends along a second direction. In order to ensure the uniformity of the magnetic field, the two first slots 112 are symmetrically arranged about the assembly groove 111, and the two second slots 113 are symmetrically arranged about the assembly groove 111. The assembly groove 111 is a rectangular cross section channel, and the rectangular area in the dashed box in Figure 4D is the assembly groove 111.

[0041] Further, in order to further improve the uniformity of the magnetic field and facilitate processing, the first slot 112 and the second slot 113 have the same structure size. At this time, the cross section of the assembly groove 111 is square.

[0042] In a specific embodiment, referring to Figure 4D , the slot width of the first slot 112 is equal to the length of the first edge of the assembly groove 111, the slot width of the first slot 112 extends along the Y direction, and the first edge of the assembly groove 111 extends along the Y direction. The slot width of the second slot 113 is equal to the length of the second edge of the assembly groove 111, the slot width of the second slot 113 extends along the X direction, and the second edge of the assembly groove 111 extends along the X direction. Through the above arrangement, the processing process can be more simple and convenient, and the processing difficulty can be reduced. The through hole 11 can also have the structure form in Figure 4E , that is, the slot width of the first slot 122 is smaller than the length of the first edge of the assembly groove 121. The slot width of the second slot 123 is smaller than the length of the second edge of the assembly groove 121. It also can achieve the effect of improving the utilization rate of the cross section of the through hole, and further improving the focusing magnetic field strength.

[0043] In one embodiment, the assembly groove 111 is square in cross-section. Figure 4D As shown in the figure, the cross-section of the assembly groove 111 is square. When a slow wave structure with square cross-section is assembled in the through hole 11, the slow wave structure is assembled in the assembly groove 111, and the four corners of the slow wave structure are fixed at the intersection of the first slot 112 and the second slot 113. When a slow wave structure with rectangular cross-section is assembled, the slow wave structure is assembled in the assembly groove 111 and the first slot 112 or the second slot 113, and the four corners of the slow wave structure are respectively fixed with the corners of the first slot 112 or the second slot 113.

[0044] Specifically, for a slow wave structure with square cross-section, for example, the cross-section of the slow wave structure is 10mm in length. The cross-section of the assembly groove 111 for assembling the slow wave structure is square, and the length of the four sides is also 10mm, and the cross-sectional area is 100mm 2 . Then the minimum radius of the circular inner hole corresponding to the above-mentioned slow wave structure with square cross-section is The cross-sectional area of the circular inner hole is about 157mm 2 . The present application can adjust the size of the first slot 112 and the second slot 113 so that the overall cross-sectional area of the through hole 11 is less than 157mm 2 . The size of the circular through hole cannot be adjusted after it is determined. Similarly, when the cross-section of the slow wave structure is rectangular, the present application can adjust the size of the first slot 112 or the second slot 113 so that the overall cross-sectional area of the through hole 11 is less than the cross-sectional area of the corresponding circular inner hole.

[0045] In the axial direction of the pole shoe, the thickness of the pole shoe head 12 is greater than or equal to the thickness of the pole shoe ring surface 13. Through the above arrangement, it is beneficial to improve the axial magnetic field strength of the magnetic focusing system, and it is beneficial to improve the magnetic field form.

[0046] The present application also provides a periodic permanent magnet focusing system, comprising the pole shoe 1 and the magnetic steel 2 as described above; a plurality of pole shoes 1 and a plurality of magnetic steels 2 are periodically arranged alternately along the axial direction of the pole shoe, and the magnetic field directions of the two adjacent magnetic steels 2 are opposite. The periodic permanent magnet focusing system can realize the improvement of the focusing magnetic field strength. The magnetic steel 2 is in a ring structure. The pole shoe ring surface 13 and the magnetic steel 2 include a spacing distance s, and the value range is: 0≤s≤p-L1-L. The spacing distance s has the following two effects: 1) by adjusting the size of the spacing distance s, the magnetic field strength of the periodic permanent magnet focusing system can be adjusted; 2) with the spacing distance s, the magnetic steel and the pole shoe are not completely attached, which is beneficial to the subsequent process of the traveling wave tube flow rate adjustment.

[0047] Referring to Figure 1As shown in the figure, a0 is the wide side of the outer boundary of the waveguide, b0 is the narrow side of the outer boundary of the waveguide, and d0 is the diameter of the electron beam channel. The specific structure size is as follows (unit: mm): a0=1.980, b0=1.270, d0=0.240.

[0048] Referring to Figures 2A-2C As shown in the figure, it is a circular inner hole pole shoe structure, wherein 101 is a circular inner hole, 102 is a pole shoe head, 103 is a pole shoe ring surface, d1 is the outer boundary diameter of the pole shoe ring surface, d2 is the outer boundary diameter of the pole shoe head, d3 is the diameter of the circular inner hole, L1 is the thickness of the pole shoe ring surface, and L2 is the thickness of the pole shoe head. The specific structure size of a circular inner hole pole shoe structure for comparison is as follows (unit: mm): d1=10.000, d2=2.100, d3=1.176, L1=1.200, and L2=1.800.

[0049] Referring to Figure 3 As shown in the figure, it is a periodic permanent magnet focusing system based on a circular inner hole pole shoe structure, wherein 10 is a circular inner hole pole shoe structure, 20 is a magnetic steel, D1 is the outer diameter of the magnetic steel, D2 is the inner diameter of the magnetic steel, L is the thickness of the magnetic steel, p is the length of the magnetic field period, and s is the distance between the magnetic steel and the pole shoe ring surface. The specific structure size of a periodic permanent magnet focusing system based on a circular inner hole pole shoe structure for comparison is as follows (unit: mm): D1=11.000, D2=2.400, L=2.400, and p=3.600. Without considering subsequent processes, the maximum magnetic field strength can be obtained when the interval distance s=0 in the above scheme.

[0050] Referring to Figures 4A-4D As shown in the figure, it is a pole shoe structure of the application, d1 is the outer boundary diameter of the pole shoe ring surface 13, d2 is the outer boundary diameter of the pole shoe head 12, a1 is the opening width of the wide side of the through hole 11 along the X direction, a2 is the slot width of the second slot 113 along the X direction, b1 is the opening width of the wide side of the through hole 11 along the Y direction, b2 is the slot width of the first slot 112 along the Y direction, L1 is the thickness of the pole shoe ring surface 13, and L2 is the thickness of the pole shoe head 12. d2>a1>a2>0; d2>b1>b2>0. The application can adjust a1, a2, b1, and b2 to reduce the cross-sectional size of the through hole 11, thereby achieving the purpose of improving the focusing magnetic field strength. The specific structure size of the pole shoe structure of the application is as follows (unit: mm): d1=10.000, d2=2.100, a1=1.980, a2=1.270, b1=1.980, b2=1.270, L1=1.200, and L2=1.800.

[0051] Referring to Figure 5As shown in the figure, the periodic permanent magnet focusing system of the application, D1 is the outer diameter of the magnetic steel 2, D2 is the inner diameter of the magnetic steel 2, L is the thickness of the magnetic steel 2, p is the length of the magnetic field period, and s is the distance between the magnetic steel 2 and the ring surface 13 of the pole shoe. 0 < D2 < D1; p >= L1 + L; 0 <= s <= p = L1 - L. The specific structure size of the periodic permanent magnet focusing system of the application is as follows (unit: mm): D1 = 11.000, D2 = 2.400, L = 2.400, and p = 3.600. Without considering subsequent processes, the maximum magnetic field strength can be obtained when the interval distance s = 0 in the above scheme.

[0052] The periodic permanent magnet focusing system with the above size parameters of the application and the periodic permanent magnet focusing system based on the circular inner hole pole shoe structure with the above size parameters are simulated by using three-dimensional electromagnetic software, and the related magnetic field strength and field distribution characteristics are calculated.

[0053] Specifically, referring to Figure 6 As shown in the figure, the periodic permanent magnet focusing system based on the circular inner hole pole shoe structure and the periodic permanent magnet focusing system of the application axial magnetic field strength comparison diagram on the axis, the peak value of the periodic permanent magnet focusing system based on the circular inner hole pole shoe structure axial magnetic field strength on the axis is 0.8146T. The peak value of the periodic permanent magnet focusing system of the application axial magnetic field strength on the axis is 0.8730T, which is 7.17% higher than that of the periodic permanent magnet focusing system based on the circular inner hole pole shoe structure. The application has stronger focusing magnetic field strength.

[0054] Referring to Figure 7 As shown in the figure, the periodic permanent magnet focusing system of the application is a periodic permanent magnet focusing system based on the circular inner hole pole shoe structure, and the periodic permanent magnet focusing system of the application axial magnetic field strength comparison diagram on the axis, the peak value of the periodic permanent magnet focusing system based on the circular inner hole pole shoe structure axial magnetic field strength on the axis is 0.8146T. The peak value of the periodic permanent magnet focusing system of the application axial magnetic field strength on the axis is 0.8730T, which is 7.17% higher than that of the periodic permanent magnet focusing system based on the circular inner hole pole shoe structure. The application has stronger focusing magnetic field strength.

[0055] Referring to Figure 8 As shown in the figure, the periodic permanent magnet focusing system of the application is a periodic permanent magnet focusing system based on the circular inner hole pole shoe structure, and the periodic permanent magnet focusing system of the application axial magnetic field strength comparison diagram on the axis, the peak value of the periodic permanent magnet focusing system based on the circular inner hole pole shoe structure axial magnetic field strength on the axis is 0.8146T. The peak value of the periodic permanent magnet focusing system of the application axial magnetic field strength on the axis is 0.8730T, which is 7.17% higher than that of the periodic permanent magnet focusing system based on the circular inner hole pole shoe structure. The application has stronger focusing magnetic field strength. -5 T, which is 0.00029% of the peak value of the axial magnetic field strength on the axis, can be ignored.

[0056] Referring to Figure 9 As shown in the figure, the periodic permanent magnet focusing system based on the rectangular inner hole pole shoe structure is an inner hole magnetic field axial cross-section equipotential line distribution diagram. The focusing system based on the rectangular inner hole pole shoe structure has the same structure parameters as the periodic permanent magnet focusing system of the application except that there is no distance between the magnetic steel and the ring surface of the pole shoe and the inner hole cross section is rectangular. It can be seen that the rectangular inner hole magnetic field axial cross-section equipotential line of the focusing system is not concentric circular, indicating that the angular distribution of its magnetic field is not uniform, which is not conducive to the focusing of the circular electron beam.

[0057] Compared with the existing periodic permanent magnet focusing system based on the circular inner hole pole shoe structure, the through hole with the cross section of the application can better adapt to the folded waveguide with the rectangular cross section and the staggered double grid type slow wave structure, and can effectively reduce the pole shoe opening area, improve the through hole cross section utilization rate, and further improve the focusing magnetic field strength. The periodic permanent magnet focusing system has stronger focusing magnetic field strength and stronger electron beam confinement ability. The traveling wave tube with the periodic permanent magnet focusing system can be widely applied to new generation mobile communication, radar and other equipment.

[0058] Obviously, the above embodiments of the application are only examples for clearly illustrating the application, and are not intended to limit the embodiments of the application. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description, and all the embodiments cannot be exhausted here. Any obvious changes or variations derived from the technical solutions of the application still fall within the protection scope of the application.

Claims

1. An extreme boot, characterized in that, The pole shoe includes a through hole located on the pole shoe axis that penetrates both sides of the pole shoe surface, a pole shoe head surrounding the edge of the through hole, and a pole shoe annular surface surrounding the outside of the pole shoe head. The through hole, the pole shoe head, and the pole shoe annular surface are coaxially arranged. The through hole includes a centrally located mounting groove with a rectangular cross-section; the mounting groove includes two opposite first sides in a first direction and two opposite second sides in a second direction. The through hole also includes two first slots formed by extending outward from the two opposite first sides of the assembly groove, and two second slots formed by extending outward from the two opposite second sides of the assembly groove; the cross-section of the through hole is cross-shaped. The slow-wave structure is assembled only through the assembly slot, or the assembly slot and the first slot form a receiving cavity for assembling the slow-wave structure, or the assembly slot and the second slot form a receiving cavity for assembling the slow-wave structure.

2. The pole shoe according to claim 1, characterized in that, The two first slots are symmetrically arranged with respect to the assembly slot, and the two second slots are symmetrically arranged with respect to the assembly slot.

3. The pole shoe according to claim 1, characterized in that, The first slot and the second slot have the same structural dimensions.

4. The pole shoe according to claim 1, characterized in that, The width of the first slot is equal to the length of the first side of the assembly slot.

5. The pole shoe according to claim 1, characterized in that, The width of the second slot is equal to the length of the second side of the assembly slot.

6. The pole shoe according to claim 1, characterized in that, The assembly slot has a square cross-section.

7. A periodic permanent magnet focusing system, characterized in that, It includes the pole shoes and magnets as described in any one of claims 1-6; a plurality of pole shoes and a plurality of magnets are arranged alternately and periodically along the axial direction of the pole shoes.

8. The periodic permanent magnet focusing system according to claim 7, characterized in that, The magnetic fields of two adjacent magnets are in opposite directions.

9. The periodic permanent magnet focusing system according to claim 7, characterized in that, The magnet has a ring-shaped structure; there is a gap between the pole shoe ring surface and the magnet.

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