Pole shoe and periodic permanent magnet focusing system

Abstract

The invention provides a pole shoe and a periodic permanent magnet focusing system, the pole shoe comprises a through hole located on the axis of the pole shoe and penetrating through the surfaces of the two sides of the pole shoe, a pole shoe head surrounding the edge of the through hole and a pole shoe ring surface surrounding the outer side of the pole shoe head, and the through hole, the pole shoe head and the pole shoe ring surface are coaxially arranged; the through hole comprises a centrally-arranged assembling groove, and the assembling groove is of a rectangular structure and is used for assembling the slow-wave structure; the assembling groove comprises two opposite first edge parts in a first direction and two opposite second edge parts in a second direction; the through hole further comprises two first notches formed by extending two opposite first edge portions of the assembling groove outwards respectively and two second notches formed by extending two opposite second edge portions of the assembling groove outwards respectively. The pole shoe can improve the shape of the pole shoe inner hole in a focusing system and improve the section utilization rate of the inner hole, thereby further improving the intensity of a focusing magnetic field.

Description

Technical Field

[0001] The present invention relates to the field of microwave vacuum electronic technology, and more specifically, to a pole shoe and a periodic permanent magnet focusing system. Background Art

[0002] The traveling wave tube is a vacuum amplifier device. As the final power amplifier of the radar, it has been put forward clear application requirements in many weapons and equipment. The focusing system is one of the core components of the traveling wave tube. Its function is to constrain the radial divergence of the electron beam so that the electron beam can be transmitted stably along the axial direction. The periodic permanent magnet focusing system is one of the commonly used focusing systems in the traveling wave tube. The principle is to constrain the electron beam through the Lorentz force received by the electron beam in the periodically changing magnetic field. Its ability to constrain the electron beam is positively correlated with the magnetic field strength of the focusing system in the electron beam channel.

[0003] The inner hole shape of the pole shoe commonly used in the periodic permanent magnet focusing system is circular. This structure is used for the traditional helical slow-wave structure with a circular cross section. The circular inner hole can be well adapted to the shape of the slow-wave structure. However, for the folded waveguide and staggered double-grid slow-wave structures with a rectangular cross section, the circular inner hole will cause the opening area to be larger than the actual cross-sectional size, and part of the area will be wasted, thereby reducing the focusing magnetic field strength. Summary of the invention

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

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a pole shoe, the pole shoe comprising a through hole located on the pole shoe axis and penetrating through the two side surfaces of the pole shoe, a pole shoe head surrounding the edge of the through hole and a pole shoe annular surface surrounding the outer side of the pole shoe head, the through hole, the pole shoe head and the pole shoe annular surface are coaxially arranged;

[0007] The through hole comprises a centrally arranged assembly groove, which is a rectangular structure for assembling the slow-wave structure; the assembly groove comprises two opposite first sides in a first direction, and two opposite second sides in a second direction;

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

[0009] A preferred solution is that the two first notches are symmetrically arranged with respect to the assembly slot, and the two second notches are symmetrically arranged with respect to the assembly slot.

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

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

[0012] Preferably, the width of the second notch is equal to the length of the second side of the assembly groove.

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

[0014] A preferred solution is that the assembly groove and the first notch form an accommodating cavity for assembling the slow-wave structure, or the assembly groove and the second notch form an accommodating cavity for assembling the slow-wave structure.

[0015] The present invention also provides a periodic permanent magnet focusing system, comprising the pole shoes and magnetic steel as described above; a plurality of pole shoes and a plurality of magnetic steels are periodically and alternately arranged along the axial direction of the pole shoes.

[0016] The preferred solution is that the magnetic fields of two adjacent magnetic steels are in opposite directions.

[0017] A preferred solution is that the magnetic steel is in an annular structure; and there is a spacing distance between the pole shoe annular surface and the magnetic steel.

[0018] The beneficial effects of the present invention are:

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

[0020] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0021] Figure 1 It is a schematic cross-sectional view of an existing rectangular outer boundary folded waveguide slow-wave structure.

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

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

[0024] Figure 4A-4CIt is a schematic structural diagram of the pole shoe of the present invention.

[0025] Figure 4D-4E It is a schematic structural diagram of the through hole of the present invention.

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

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

[0028] Figure 7 It is a distribution equipotential line diagram of the magnetic field in the through hole of the periodic permanent magnet focusing system of the present invention on the axial section.

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

[0030] Fig. 9 It is the equipotential line distribution diagram of the magnetic field in the rectangular hole on the axial section of the periodic permanent magnet focusing system based on the rectangular hole pole shoe structure. DETAILED DESCRIPTION

[0031] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

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

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

[0034] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0035] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0036] In the millimeter wave terahertz band, the electron injection channel of the traveling wave tube is usually small, and the Coulomb force between electrons is larger, which puts higher requirements on the strength of the focusing magnetic field. Although the strength of the focusing magnetic field can be effectively improved by reducing the cross-sectional size of the circular inner hole of the pole shoe in the existing focusing system, 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 folded waveguide with a rectangular cross-section and the staggered double-grid slow-wave structure, resulting in a reduction in the intensity of the focusing magnetic field. Figures 1 to 9 As shown, specifically, the pole shoe 1 includes a through hole 11 located on the pole shoe axis and penetrating through the two side surfaces of the pole shoe, a pole shoe head 12 surrounding the edge of the through hole 11, and a pole shoe annular 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 annular surface 13 are coaxially arranged. The through hole 11 includes a centrally arranged assembly groove 111, and the assembly groove 111 is a rectangular structure for assembling a slow-wave structure. The assembly groove 111 includes two opposite first sides in a first direction, and two opposite second sides in a second direction. The through hole 11 also includes two first notches 112 formed by respectively extending outwards from the two opposite first sides of the assembly groove 111, and two second notches 113 formed by respectively extending outwards from the two opposite second sides 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. Refer to Figure 4B and Figure 4C As shown, the first direction is the X direction, the second direction is the Y direction, and the third direction is the Z direction, and the Z direction is perpendicular to both 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 through hole 11 with a cross-shaped cross section of the present invention can better fit the shape of the slow-wave structure with a rectangular cross section and has better adaptability. When assembling the slow-wave structure with the same rectangular cross section, compared with the circular inner hole, the through hole 11 of the present invention has a smaller cross-sectional area and a stronger magnetic field strength.

[0038] In the above embodiment, the first notch 112 and the second notch 113 are both connected to the assembly groove 111, and the first notch 112, the second notch 113 and the assembly groove 111 form a through hole 11 with a cross-shaped cross section, and the slow-wave structure is assembled into the through hole 11. The present invention can better adapt to the folded waveguide and staggered double-grid slow-wave structures with rectangular cross sections by changing the circular inner hole of the conventional concentric circle pole shoe structure into a cross-shaped through hole, effectively reducing the opening area of ​​the through hole 11 on the pole shoe 1, and improving the cross-sectional utilization of the through hole 11.

[0039] Furthermore, 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 a rectangular cross-sectional shape of different sizes, optionally, the assembly slot 111 and the first slot 112 form a receiving cavity for assembling the slow-wave structure, or the assembly slot 111 and the second slot 113 form a receiving cavity for assembling the slow-wave structure. In other words, the slow-wave structure can be assembled into the receiving cavity formed by the assembly slot 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 slot 111 and the two second slots 113 without occupying the space of the first slot 112. In addition, the slow-wave structure with a rectangular cross-sectional shape can also be assembled only through the assembly slot 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 adjustment gaps to adjust the magnetic field shape. The through hole 11 with a cross-shaped cross section of the present invention can better fit the appearance of the slow-wave structure with a rectangular cross section, thereby having better adaptability, and the cross-sectional area of ​​the through hole 11 is smaller.

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

[0041] Furthermore, 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 structural dimensions. At this time, the cross section of the assembly slot 111 is square.

[0042] In a specific embodiment, referring to Figure 4D As shown, the slot width of the first slot 112 is equal to the length of the first side of the assembly slot 111, the slot width of the first slot 112 extends along the Y direction, and the first side of the assembly slot 111 extends along the Y direction. The slot width of the second slot 113 is equal to the length of the second side of the assembly slot 111, the slot width of the second slot 113 extends along the X direction, and the second side of the assembly slot 111 extends along the X direction. Through the above arrangement, it is possible to ensure that the processing process is simpler and more convenient, and reduce the difficulty of processing. The through hole 11 can also be Figure 4E In the structural form, the slot width of the first slot 122 is smaller than the length of the first side of the assembly slot 121. The slot width of the second slot 123 is smaller than the length of the second side of the assembly slot 121. It can also achieve the effect of improving the utilization rate of the through hole cross section, thereby improving the intensity of the focused magnetic field.

[0043] In a specific embodiment, in combination Figure 4D As shown, the cross section of the assembly groove 111 is square. When a slow-wave structure with a 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 notch 112 and the second notch 113. When a slow-wave structure with a rectangular cross section is assembled, the slow-wave structure is assembled in the assembly groove 111 and the first notch 112 or the second notch 113, and the four corners of the slow-wave structure are respectively fitted and fixed with the corners of the first notch 112 or the second notch 113.

[0044] Specifically, for a slow-wave structure with a square cross section, for example, the cross-sectional side length of the slow-wave structure is 10 mm. The assembly groove 111 for assembling the slow-wave structure has a square cross section, the length of the four sides is also 10 mm, and the cross-sectional area is 100 mm. 2 Then the minimum radius of the circular inner hole corresponding to the above-mentioned square cross-section slow-wave structure is The cross-sectional area of ​​the circular inner hole is approximately 157 mm 2 The present invention can adjust the size of the first notch 112 and the second notch 113 so that the overall cross-sectional area of ​​the through hole 11 is less than 157 mm 2 Similarly, when the cross section of the slow wave structure is rectangular, the present invention can adjust the size of the first notch 112 or the second notch 113 so that the overall cross-sectional area of ​​the through hole 11 is smaller 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 annular surface 13. The above arrangement is helpful to improve the axial magnetic field strength of the magnetic focusing system and improve the magnetic field shape.

[0046] The present invention also provides a periodic permanent magnet focusing system, comprising the pole shoe 1 and the magnet 2 as described above; a plurality of pole shoes 1 and a plurality of magnets 2 are periodically arranged alternately along the axial direction of the pole shoe, and the magnetic fields of two adjacent magnets 2 are in opposite directions. The periodic permanent magnet focusing system can improve the intensity of the focusing magnetic field. The magnet 2 is an annular structure. There is a spacing distance s between the pole shoe annular surface 13 and the magnet 2, and the value range is: 0≤s≤p-L1-L. The spacing distance s has the following two functions: 1) The magnetic field intensity of the periodic permanent magnet focusing system can be adjusted by adjusting the size of the spacing distance s; 2) The spacing distance s can make the magnet and the pole shoe not completely fit, which is beneficial to the subsequent process of debugging the flow rate of the traveling wave tube.

[0047] Reference Figure 1As shown, a0 is the wide side of the waveguide outer boundary, b0 is the narrow side of the waveguide outer boundary, and d0 is the diameter of the electron injection channel. The specific structural dimensions are as follows (unit: mm): a0 = 1.980, b0 = 1.270, d0 = 0.240.

[0048] Reference Figure 2A-2C As shown, 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 annulus, d1 is the outer boundary diameter of the pole shoe annulus, 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 annulus, and L2 is the thickness of the pole shoe head. The specific structural dimensions of a circular inner hole pole shoe structure used for comparison are as follows (unit: mm): d1 = 10.000, d2 = 2.100, d3 = 1.176, L1 = 1.200, L2 = 1.800.

[0049] Reference Figure 3 As shown, it is a schematic diagram of 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 magnetic field period length, and s is the distance between the magnetic steel and the pole shoe annular surface. The specific structural dimensions of a periodic permanent magnet focusing system based on a circular inner hole pole shoe structure for comparison are as follows (unit: mm): D1 = 11.000, D2 = 2.400, L = 2.400, p = 3.600. Without considering the subsequent process, the maximum magnetic field strength can be obtained when the spacing distance s = 0 in the above scheme.

[0050] Reference Figure 4A-4D As shown, it is a schematic diagram of the pole shoe structure of the present invention, d1 is the outer boundary diameter of the pole shoe annular surface 13, d2 is the outer boundary diameter of the pole shoe head 12, a1 is the wide side opening width of the through hole 11 along the X direction, a2 is the slot width of the second notch 113 along the X direction, b1 is the wide side opening width of the through hole 11 along the Y direction, b2 is the slot width of the first notch 112 along the Y direction, L1 is the thickness of the pole shoe annular surface 13, and L2 is the thickness of the pole shoe head 12. d2>a1>a2>0; d2>b1>b2>0. The present invention can reduce the cross-sectional size of the through hole 11 by adjusting a1, a2, b1, and b2, thereby achieving the purpose of improving the intensity of the focusing magnetic field. The specific structural dimensions of the pole shoe structure of the present invention are 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, L2=1.800.

[0051] Reference Figure 5As shown, it is the periodic permanent magnet focusing system of the present invention, 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 magnetic field period length, and s is the distance between the magnetic steel 2 and the pole shoe annular surface 13. 0<D2<D1; p≥L1+L; 0≤s≤p=L1-L. The specific structural dimensions of the periodic permanent magnet focusing system of the present invention are as follows (unit: mm): D1=11.000, D2=2.400, L=2.400, p=3.600. Without considering the subsequent process, the maximum magnetic field strength can be obtained when the spacing distance s=0 in the above scheme.

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

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

[0054] Reference Figure 7 As shown, it is the equipotential line distribution diagram of the magnetic field in the through hole of the periodic permanent magnet focusing system of the present invention in the axial section. Its morphological distribution is concentric circle, indicating that the magnetic field is relatively uniform in the angular distribution.

[0055] Reference Figure 8 As shown in FIG. 1 , the angular magnetic field intensity distribution diagram of the periodic permanent magnet focusing system of the present invention at different angular positions at a distance of d / 2 from the axis. The peak intensity is 2.54×10 -5 T is 0.00029% of the peak value of the axial magnetic field intensity on the axis, and its effect on the focusing performance can be ignored.

[0056] Reference Fig. 9 As shown in FIG. 1 , it is a distribution diagram of equipotential lines of the magnetic field in the inner hole of a periodic permanent magnet focusing system based on a rectangular inner hole pole shoe structure on an axial section. Except that there is no spacing between the magnetic steel and the pole shoe annular surface and the inner hole cross section is rectangular, the other structural parameters of this focusing system based on a rectangular inner hole pole shoe structure are the same as those of the periodic permanent magnet focusing system of the present invention. It can be seen that the equipotential lines of the magnetic field in the rectangular inner hole of the focusing system on the axial section are non-concentric circles, indicating that its magnetic field is unevenly distributed in the angular direction, which is not conducive to the focusing of the circular electron beam.

[0057] In summary, compared with the existing periodic permanent magnet focusing system based on the circular inner hole pole shoe structure, the cross-shaped through hole of the present invention can better adapt to the folded waveguide and staggered double-grid slow-wave structure with a rectangular cross-section, and can effectively reduce the pole shoe opening area, improve the utilization rate of the through hole cross-section, and thus improve the focusing magnetic field strength. The periodic permanent magnet focusing system of the present invention has a stronger focusing magnetic field strength and a stronger ability to constrain the electron beam. The traveling wave tube with the periodic permanent magnet focusing system of the present invention can be widely used in new generation mobile communications, radar and other equipment.

[0058] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A pole shoe, characterized in that: The pole shoe comprises a through hole located on the pole shoe axis and penetrating through the two side surfaces of the pole shoe, a pole shoe head surrounding the edge of the through hole, and a pole shoe annular surface surrounding the outer side of the pole shoe head, wherein the through hole, the pole shoe head and the pole shoe annular surface are coaxially arranged; The through hole comprises a centrally arranged assembly groove, which is a rectangular structure for assembling the slow-wave structure; the assembly groove comprises two opposite first sides in a first direction, and two opposite second sides in a second direction; The through hole further comprises two first notches formed by respectively extending outwards from two opposite first side portions of the assembly groove, and two second notches formed by respectively extending outwards from two opposite second side portions of the assembly groove.

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

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

4. The pole shoe according to claim 1, characterized in that The slot 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 slot 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 cross section of the assembly groove is square.

7. The pole shoe according to claim 1, characterized in that The assembly groove and the first notch form an accommodating cavity for assembling the slow-wave structure, or the assembly groove and the second notch form an accommodating cavity for assembling the slow-wave structure.

8. A periodic permanent magnet focusing system, characterized in that: It comprises the pole shoes and magnetic steel as described in any one of claims 1 to 7; a plurality of pole shoes and a plurality of magnetic steels are periodically and alternately arranged along the axial direction of the pole shoes.

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

10. The periodic permanent magnet focusing system according to claim 8, characterized in that: The magnetic steel is in an annular structure; there is a spacing distance between the pole shoe annular surface and the magnetic steel.

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