Multi-channel periodic permanent magnet focusing system and design method thereof

Abstract

The invention provides a multi-channel periodic permanent magnet focusing system and a design method thereof. The multi-channel periodic permanent magnet focusing system comprises a plurality of pole shoes and a plurality of magnetic groups which are periodically and alternately arranged along the axial direction of a magnetic focusing system, a plurality of pole shoe through holes which are arranged along the circumferential direction of the pole shoe and are used for assembling the slow wave structure are formed in the pole shoe; the magnetic group comprises inner magnetic steel and outer magnetic steel surrounding the outer side of the inner magnetic steel; the inner magnetic steel and the outer magnetic steel are coaxially arranged. The multi-channel periodic permanent magnet focusing system can solve the problem that an existing magnetic focusing system is poor in electron beam restraining capacity.

Description

Technical Field

[0001] The present invention relates to the field of microwave vacuum electronic technology, and more specifically, to a multi-channel periodic permanent magnet focusing system and a design method thereof. Background Art

[0002] The traveling wave tube is a vacuum amplifier device. As the final power amplifier of the radar, it has now 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 axial magnetic field strength of the focusing system in the electron beam channel, and negatively correlated with the angular magnetic field strength.

[0003] By integrating multiple RF amplification channels in the same traveling wave tube, sharing a set of focusing systems to form an array integration, the cross-sectional size of a single channel can be effectively reduced to meet the application requirements of array systems represented by active phased arrays. A typical array arrangement is that the amplification channels are arranged in a circular ring shape along the angular direction on a cross section perpendicular to the axis of the traveling wave tube, with the axis of the traveling wave tube as the axis. At this time, for the periodic permanent magnet focusing system, the inner diameter of the magnetic steel needs to be larger than the outer edge of the amplification channel, resulting in an increase in the inner diameter and a decrease in the magnetic field strength, thereby reducing the ability to confine the electron beam. In addition, since the amplification channel deviates from the system axis, an angular field component will be generated in the amplification channel, further reducing the ability to confine the electron beam. Summary of the invention

[0004] In view of the above problems, the present invention provides a multi-channel periodic permanent magnetic focusing system to solve the problem that the existing magnetic focusing system has poor electron beam confinement capability.

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

[0006] The present invention provides a multi-channel periodic permanent magnet focusing system, comprising:

[0007] A plurality of pole shoes and a plurality of magnetic groups are periodically and alternately arranged along the axial direction of the magnetic focusing system;

[0008] The pole shoe is formed with a plurality of pole shoe through holes arranged along the circumference of the pole shoe for assembling the slow-wave structure;

[0009] The magnetic group includes an inner magnetic steel and an outer magnetic steel surrounding the outer side of the inner magnetic steel; the inner magnetic steel and the outer magnetic steel are coaxially arranged.

[0010] A preferred solution is that the pole shoe includes a pole shoe head and a pole shoe annular surface surrounding the outer side of the pole shoe head, and the pole shoe head and the pole shoe annular surface are coaxially arranged; and a pole shoe through hole is formed on the pole shoe head.

[0011] The preferred solution is that the radius of the pole shoe annular surface is r1, the distance between the center of the circle corresponding to the pole shoe through hole and the axis of the magnetic focusing system is r3; the radius of the pole shoe through hole is r4, 0<r4<r1-r3.

[0012] A preferred solution is that the outer magnetic steel is in a circular ring shape, and the inner radius of the outer magnetic steel is R2, and the value range is: R2≥r3+r4.

[0013] A preferred solution is that the inner magnetic steel is in a disc shape, and the radius of the inner magnetic steel is R3, with a value range of 0<R3≤r3-r4.

[0014] A preferred solution is that the multi-channel periodic permanent magnet focusing system further includes a spacer ring, which is disposed around the inner magnetic steel and the outer magnetic steel.

[0015] A preferred solution is that the inner magnetic steel is abutted and fixed between two pole shoes.

[0016] A preferred solution is that the inner magnetic steel and the outer magnetic steel in the same magnetic group have the same magnetization direction, and the magnetic steels in two adjacent magnetic groups have opposite magnetization directions.

[0017] The preferred solution is that the half-period length of the magnetic focusing system is p, the thickness of the pole shoe annulus is d1, the thickness of the pole shoe head is d2, the thickness of the outer magnetic steel is d3, the thickness of the inner magnetic steel is d4, and p≥max(d1+d3, d2+d4).

[0018] The present invention also provides a design method for a multi-channel periodic permanent magnet focusing system, the method comprising:

[0019] A plurality of pole shoes and a plurality of magnetic groups are periodically and alternately arranged along the axial direction of the magnetic focusing system;

[0020] The pole shoe is formed with a plurality of pole shoe through holes arranged along the circumference of the pole shoe;

[0021] The magnetic group includes an inner magnetic steel and an outer magnetic steel surrounding the outer side of the inner magnetic steel, and the inner magnetic steel and the outer magnetic steel are coaxially arranged.

[0022] The beneficial effects of the present invention are:

[0023] The present invention arranges the inner magnetic steel at the center of the outer magnetic steel, and can effectively improve the magnetic field strength on the side close to the center of the magnetic focusing system in the channel without increasing the size of the magnetic focusing system, thereby improving the axial magnetic field strength in the channel, while optimizing the magnetic field distribution form and reducing the angular magnetic field strength, thereby effectively improving the magnetic focusing system's ability to constrain electron beams. The traveling wave tube using the multi-channel periodic permanent magnetic focusing system provided by the present invention can integrate multiple radio frequency amplification channels together, realize the array arrangement of multiple slow-wave structures, and can be widely used in new generation mobile communications, radar and other equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0025] Figure 1 It is a schematic diagram of the structure of the existing four-channel periodic permanent magnet focusing system based on a single magnet.

[0026] Figure 2 It is a radial cross-sectional schematic diagram of the four-channel periodic permanent magnet focusing system of the present invention.

[0027] Figure 3A-3C It is a schematic axial cross-sectional view of the four-channel periodic permanent magnet focusing system of the present invention.

[0028] Figure 4 It is a BH characteristic curve diagram of the pole shoe material during the simulation process of the present invention.

[0029] Figure 5 This is the magnetic field intensity distribution diagram of the central section of the magnet of the existing four-channel periodic permanent magnet focusing system based on a single magnet.

[0030] Figure 6 It is a magnetic field intensity distribution diagram of the central section of the magnetic steel of the four-channel periodic permanent magnet focusing system of the present invention.

[0031] Figure 7 It is a comparison diagram of the axial magnetic field intensity on the channel axis of the existing four-channel periodic permanent magnet focusing system based on a single magnetic steel and the four-channel periodic permanent magnet focusing system of the present invention.

[0032] Figure 8 It is a comparison diagram of the angular magnetic field strength of the existing four-channel periodic permanent magnet focusing system based on a single magnetic steel and the four-channel periodic permanent magnet focusing system of the present invention at a point where the center section of the pole shoe is 0.12 mm away from the channel axis. DETAILED DESCRIPTION

[0033] 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.

[0034] 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.

[0035] 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.

[0036] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0037] 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.

[0038] The magnetic steel structure commonly used in the periodic permanent magnet focusing system is a single-layer magnetic steel, and the inner diameter of the magnetic steel needs to be larger than the outer edge of the amplifying channel. When this single-layer magnetic steel structure is applied to a multi-channel periodic permanent magnet focusing system, the inner diameter of the single-layer magnetic steel is further increased, and the magnetic field strength is reduced. If the multi-channel periodic permanent magnet focusing system based on a layered magnetic steel structure wants to increase the magnetic field strength, it is necessary to increase the outer diameter of the single-layer magnetic steel, which will cause the external dimensions of the permanent magnet focusing system to be too large and unable to meet the use requirements. In addition, since the axes of the amplifying channels of the multi-channel periodic permanent magnet focusing system are not coaxial with the axes of the magnetic focusing system, an angular field component will be generated in the amplifying channel, causing the electron beam to diverge, reducing the focusing system's ability to constrain the electron beam.

[0039] In order to solve the problems existing in the prior art, the present invention provides a multi-channel periodic permanent magnet focusing system based on dual magnetic steel. Figures 1 to 8 As shown, specifically, the multi-channel periodic permanent magnet focusing system includes: a plurality of pole shoes and a plurality of magnetic groups that are periodically and alternately arranged along the axial direction of the magnetic focusing system. The magnetic group includes an inner magnetic steel 22 and an outer magnetic steel 21 surrounding the outer side of the inner magnetic steel 22. The inner magnetic steel 22 and the outer magnetic steel 21 are coaxially arranged. The pole shoe is formed with a plurality of pole shoe through holes 13 arranged along the circumference of the pole shoe for assembling the slow-wave structure. Along the axial direction of the magnetic focusing system, the coaxially arranged pole shoe through holes 13 form a channel for assembling the slow-wave structure. The present invention can effectively improve the axial magnetic field strength in the channel, while greatly reducing the angular magnetic field strength, thereby achieving better electron beam focusing performance and ensuring that the external dimensions of the magnetic focusing system do not increase. The inner magnetic steel and the outer magnetic steel in the same magnetic group have the same magnetization direction, and the magnetization directions of the magnetic steels in the two adjacent magnetic groups are opposite.

[0040] Regarding the structure of the pole shoe, the pole shoe includes a pole shoe head 12 and a pole shoe annular surface 11 surrounding the outer side of the pole shoe head 12, and the pole shoe head 12 is coaxially arranged with the pole shoe annular surface 11; a pole shoe through hole 13 is formed on the pole shoe head 12. A plurality of pole shoe through holes 13 are arranged around the pole shoe head 12, and the number of the pole shoe through holes 13 is n, where n>1.

[0041] Further, combined with Figure 3A As shown, the radius of the pole shoe annular surface 11 is r1, the radius of the pole shoe head 12 is r2, and the distance between the center of the circle corresponding to the pole shoe through hole 13 and the axis L of the magnetic focusing system is r3; 0<r3<r1. The radius of the pole shoe through hole 13 is r4, 0<r4<r1-r3. The outer magnetic steel 21 is in the shape of a circular ring, and the inner radius of the outer magnetic steel 21 is R2, and the value range is: R2≥r3+r4. The inner magnetic steel 221 is in the shape of a disk, and the radius of the inner magnetic steel 221 is R3, and the value range is: 0<R3≤r3-r4. The thickness d4 of the inner magnetic steel 221 needs to be less than or equal to the distance between two adjacent pole shoe heads 12, and the thickness of the inner magnetic steel 221 is specifically determined according to the magnetic field shape in the channel. The half-period length of the magnetic focusing system is p, the thickness of the pole shoe annulus 11 is d1, the thickness of the pole shoe head 12 is d2, the thickness of the outer magnetic steel 21 is d3, the thickness of the inner magnetic steel 22 is d4, and p≥max(d1+d3, d2+d4).

[0042] In order to increase the axial magnetic field strength of the system and improve the magnetic field shape, in the axial direction of the magnetic focusing system, the thickness of the pole shoe head is greater than or equal to the thickness of the pole shoe annular surface.

[0043] Combination Figure 3B As shown, in order to achieve better alignment of the inner and outer magnetic steels, the multi-channel periodic permanent magnet focusing system also includes a spacer ring 23, and the spacer ring 23 is arranged around the inner magnetic steel 222 and the outer magnetic steel 21. Specifically, the spacer ring 23 surrounds the outer side of the inner magnetic steel 222, and the outer magnetic steel 21 surrounds the outer side of the spacer ring 23. The inner magnetic steel 222, the spacer ring 23 and the outer magnetic steel 21 are coaxially arranged. An opening 24 for the slow-wave structure to pass through is formed on the spacer ring 23. Furthermore, the spacer ring 23 is formed with an opening 24 corresponding to the position of the pole shoe through hole 13, so as to avoid the pole shoe through hole 13 for the slow-wave structure to pass through. In a specific embodiment, the pole shoe through hole 13 and the opening 24 are both circular holes. In order to ensure that the slow-wave structure is smoothly assembled into the channel, the radius of the opening 24 should be greater than or equal to the radius of the pole shoe through hole 13. The thickness of the inner magnetic steel 222 needs to be less than or equal to the distance between two adjacent pole shoe heads 12. The material of the spacer ring 23 is usually a paramagnetic material such as nickel-copper alloy, which will not affect the magnetic field strength.

[0044] Combination Figure 3CAs shown, optionally, the inner magnetic steel 223 is abutted and fixed between the two pole shoes. The two opposite side walls of the inner magnetic steel 223 are respectively abutted against the inner side walls of the two pole shoes, so that the inner magnetic steel 223 is fixed between the two pole shoes. More specifically, the inner magnetic steel 223 abuts against the pole shoe head 12, and the outer magnetic steel 21 abuts against the pole shoe annular surface 11. In this embodiment, the thickness of the inner magnetic steel 223 needs to be equal to the spacing between two adjacent pole shoe heads 12.

[0045] Reference Figure 3A The figure shows an axial cross-sectional schematic diagram of a four-channel periodic permanent magnetic focusing system based on dual magnetic steels of the present invention. Wherein r1 is the outer radius of the pole shoe annulus 11, r2 is the radius of the pole shoe head 12, r3 is the distance between the center of the circle corresponding to the pole shoe through hole 13 and the axis L of the magnetic focusing system, r4 is the radius of the pole shoe through hole 13, d1 is the thickness of the pole shoe annulus 11, d2 is the thickness of the pole shoe head 12, R1 is the outer radius of the outer magnetic steel 21, R2 is the inner radius of the outer magnetic steel 21, R3 is the radius of the inner magnetic steel 221, d3 is the thickness of the outer magnetic steel 21, d4 is the thickness of the inner magnetic steel 221, and p is the half-period length of the magnetic focusing system.

[0046] The four-channel periodic permanent magnet focusing system based on double magnetic steel of the present invention and the four-channel periodic permanent magnet focusing system based on single magnetic steel for comparison are simulated using three-dimensional electromagnetic software, and the relevant magnetic field strength and field distribution characteristics are calculated.

[0047] Among them, refer to Figure 4 The BH characteristic curve of the pole shoe material during the simulation is shown, and the remanent magnetism Br of the magnetic steel is set to 10000Gs.

[0048] The specific structural dimensions of a four-channel periodic permanent magnet focusing system based on dual magnetic steel provided by the present invention are as follows (unit: mm): r1=6.9, r2=4.4, r3=2.5, r4=1.1, d1=0.9, d2=1.2, R1=8.0, R2=5.0, R3=1.0, d3=2.0, d4=1.8, p=3.0.

[0049] A four-channel periodic permanent magnet focusing system based on a single magnet used for comparison has the same structural dimensions as the above-mentioned four-channel periodic permanent magnet focusing system based on double magnets, except that it does not include an inner magnet.

[0050] Reference Figure 5 The figure shows the magnetic field intensity distribution of the central section of the four-channel periodic permanent magnet focusing system based on a single magnet. Figure 6 As shown, the magnetic field intensity distribution of the central section of the magnetic steel of the four-channel periodic permanent magnet focusing system based on double magnetic steel of the present invention is shown. By comparison, it can be seen that Figure 6 The color corresponding to the medium magnetic field intensity is darker, indicating that the magnetic field intensity of the present invention is significantly greater than that of the four-channel periodic permanent magnet focusing system based on a single magnetic steel.

[0051] Reference Figure 7 As shown, it is a comparison diagram of the axial magnetic field intensity on the channel axis of a four-channel periodic permanent magnet focusing system based on a single magnet and a four-channel periodic permanent magnet focusing system based on a double magnet of the present invention. It can be seen that the peak value of the axial magnetic field intensity on the channel axis of the four-channel periodic permanent magnet focusing system based on a single magnet is 3314Gs, and the peak value of the axial magnetic field intensity on the channel axis of the four-channel periodic permanent magnet focusing system based on a double magnet is 3519Gs. The axial magnetic field intensity of the present invention is 6.2% higher than that of the four-channel periodic permanent magnet focusing system based on a single magnet.

[0052] Reference Figure 8 As shown, it is a comparison diagram of the angular magnetic field intensity of a four-channel periodic permanent magnet focusing system based on a single magnet and a four-channel periodic permanent magnet focusing system based on double magnets of the present invention at a point 0.12 mm from the channel axis on the center section of the pole shoe. It can be seen that the peak angular magnetic field intensity of the channel of the four-channel periodic permanent magnet focusing system based on a single magnet is 17.25 Gs, and the peak angular magnetic field intensity of the channel of the four-channel periodic permanent magnet focusing system based on double magnets of the present invention is 1.59 Gs. The angular magnetic field intensity of the present invention is reduced by 90.8% compared with the four-channel periodic permanent magnet focusing system based on a single magnet.

[0053] The present invention also provides a design method for a multi-channel periodic permanent magnet focusing system, the method comprising: arranging a plurality of pole shoes and a plurality of magnetic groups in a periodic and alternating manner along the axial direction of the magnetic focusing system, wherein a plurality of pole shoe through holes 13 arranged circumferentially along the pole shoes are formed on the pole shoes, the magnetic group comprising an inner magnetic steel 22 and an outer magnetic steel 21 surrounding the outer side of the inner magnetic steel 22; the inner magnetic steel 22 and the outer magnetic steel 21 are coaxially arranged.

[0054] In summary, the present invention can effectively improve the magnetic field strength on the side close to the center of the magnetic focusing system in the channel without increasing the external dimensions of the magnetic focusing system by arranging the inner magnetic steel at the center of the outer magnetic steel, thereby improving the axial magnetic field strength in the channel, while optimizing the magnetic field distribution pattern and reducing the angular magnetic field strength, thereby effectively improving the magnetic focusing system's ability to constrain electron beams. The traveling wave tube using the multi-channel periodic permanent magnetic focusing system provided by the present invention can integrate multiple radio frequency amplification channels together to achieve an array arrangement of multiple slow-wave structures, and can be widely used in new generation mobile communications, radars and other equipment.

[0055] 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 multi-channel periodic permanent magnet focusing system, characterized in that: include: A plurality of pole shoes and a plurality of magnetic groups are periodically and alternately arranged along the axial direction of the magnetic focusing system; The pole shoe is formed with a plurality of pole shoe through holes arranged along the circumference of the pole shoe for assembling the slow-wave structure; The magnetic group includes an inner magnetic steel and an outer magnetic steel surrounding the outer side of the inner magnetic steel; the inner magnetic steel and the outer magnetic steel are coaxially arranged.

2. The multi-channel periodic permanent magnet focusing system according to claim 1, characterized in that: The pole shoe comprises a pole shoe head and a pole shoe annular surface surrounding the outer side of the pole shoe head, and the pole shoe head and the pole shoe annular surface are coaxially arranged; a pole shoe through hole is formed on the pole shoe head.

3. The multi-channel periodic permanent magnet focusing system according to claim 2, characterized in that: The radius of the pole shoe annular surface is r1, and the distance between the center of the circle corresponding to the pole shoe through hole and the axis of the magnetic focusing system is r3; the radius of the pole shoe through hole is r4, 0<r4<r1-r3.

4. The multi-channel periodic permanent magnet focusing system according to claim 3, characterized in that: The outer magnetic steel is in a circular ring shape, and the inner radius of the outer magnetic steel is R2, and the value range is: R2≥r3+r4.

5. The multi-channel periodic permanent magnet focusing system according to claim 3, characterized in that: The inner magnetic steel is in a disc shape, and the radius of the inner magnetic steel is R3, with a value range of 0<R3≤r3-r4.

6. The multi-channel periodic permanent magnet focusing system according to claim 1, characterized in that: The multi-channel periodic permanent magnet focusing system also includes a spacer ring, which is arranged around the inner magnetic steel and the outer magnetic steel.

7. The multi-channel periodic permanent magnet focusing system according to claim 1, characterized in that: The inner magnetic steel is abutted and fixed between the two pole shoes.

8. The multi-channel periodic permanent magnet focusing system according to claim 1, characterized in that: The magnetization directions of the inner magnetic steel and the outer magnetic steel in the same magnetic group are the same, and the magnetization directions of the magnetic steels in two adjacent magnetic groups are opposite.

9. The multi-channel periodic permanent magnet focusing system according to claim 2, characterized in that: The half-period length of the magnetic focusing system is p, the thickness of the pole shoe annulus is d1, the thickness of the pole shoe head is d2, the thickness of the outer magnetic steel is d3, the thickness of the inner magnetic steel is d4, and p≥max(d1+d3, d2+d4).

10. A design method for a multi-channel periodic permanent magnet focusing system, characterized in that: The method includes: A plurality of pole shoes and a plurality of magnetic groups are periodically and alternately arranged along the axial direction of the magnetic focusing system; The pole shoe is formed with a plurality of pole shoe through holes arranged along the circumference of the pole shoe; The magnetic group includes an inner magnetic steel and an outer magnetic steel surrounding the outer side of the inner magnetic steel, and the inner magnetic steel and the outer magnetic steel are coaxially arranged.

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