Coaxial integrated permanent magnet focusing system

Abstract

The invention provides a coaxial integrated permanent magnet focusing system, which comprises a cathode base, a shell, a first permanent magnet group and a second permanent magnet group, and is characterized in that the shell is connected with the cathode base through an insulating connecting piece; the first permanent magnet group is arranged in the cathode base, the second permanent magnet group is arranged in the shell, and the first permanent magnet group is fixedly connected with the second permanent magnet group through the insulating connecting piece to form a permanent magnet focusing system together, so that the built-in integrated layout is realized, and the problems that a traditional focusing system is huge in weight and size and poor in focusing effect are solved. The technical problem that a large number of space positions and power consumption are needed for providing a focusing magnetic field is solved, high compactness and miniaturization of the system structure are achieved, the size and weight of the focusing system are greatly reduced, the optimized magnet arrangement can generate the focusing magnetic field with high peak value and high uniformity in an electron beam transmission area, and the focusing effect is good. The rigidity and the flow rate of the beam are effectively improved, and the impedance of the device is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of high-power microwave device technology, and more specifically to a coaxial integrated permanent magnet focusing system. Background Technology

[0002] High-power microwave devices, such as coaxial multi-beam klystron amplifiers (CMB-RKA), have broad application prospects in scientific research, medical treatment, and defense due to their high power and high efficiency. In such devices, to prevent the electron beam from diverging during its long-distance transmission from the cathode to the high-frequency structure, a focusing system must be used to apply a confinement magnetic field that matches the electron's trajectory.

[0003] Existing focusing methods mainly include electromagnetic focusing and permanent magnet focusing. Electromagnetic focusing systems typically use solenoid coils to generate an axial magnetic field. The advantage of this method is that the magnetic field strength and distribution can be precisely controlled by adjusting the current. However, the system is bulky, requiring a high-power power supply and cooling system, resulting in high energy consumption and complex structure. Furthermore, the huge power consumption generates a large amount of Joule heat; poor heat dissipation will affect magnetic field stability and device lifespan, making it difficult to meet the requirements of portable and modular applications with stringent size, weight, and power consumption constraints. To address the energy consumption issue of electromagnetic focusing, conventional permanent magnet focusing systems often use permanent magnets (such as neodymium iron boron and samarium cobalt) to provide the focusing magnetic field. Conventional permanent magnet focusing systems typically employ an external structure that encapsulates the permanent magnet outside the beam transmission channel. While this method does not require a power supply, when applied to high-power microwave devices with coaxial structures, generating a sufficiently strong and uniform magnetic field in the beam transmission region usually requires a large volume and mass of permanent magnet material for encapsulation, making the entire focusing system very bulky and severely limiting the device's power-to-weight ratio and mobility. Therefore, there is an urgent need in this field for a new permanent magnet focusing scheme that can fundamentally solve the problems of large weight, large size and low beam flow efficiency of existing focusing systems while ensuring high uniformity and high peak magnetic field, so as to promote the development of high-power microwave devices towards miniaturization, lightweighting and equipmentization.

[0004] Therefore, existing technologies still need further development. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a coaxial integrated permanent magnet focusing system to solve the technical problems of the huge weight and volume of existing beam focusing systems, so as to achieve miniaturization and lightweighting of the focusing system.

[0006] To achieve the above-mentioned technical objectives, according to a first aspect of the present invention, the present invention provides a coaxial integrated permanent magnet focusing system, comprising: Cathode base; The outer casing is connected to the cathode base via an insulating connector; The first permanent magnet assembly is disposed inside the cathode base; The second permanent magnet assembly is disposed inside the outer casing; The first permanent magnet group is fixedly connected to the second permanent magnet group through an insulating connector, together forming a permanent magnet focusing system.

[0007] Specifically, the system also includes a cathode structure disposed on the cathode base and a high-frequency structure fixedly disposed outside the housing. The cathode base, the high-frequency structure, and the housing together constitute a diode structure.

[0008] Specifically, the permanent magnet focusing system is used to provide a focusing magnetic field for the electron beam transmission region between the cathode structure and the high-frequency structure.

[0009] Specifically, the high-frequency structure is used to receive the electron beam constrained and transmitted by the focusing magnetic field, and to generate high-power microwaves through beam-wave interaction.

[0010] Specifically, the outer shell and the outer surface of the high-frequency structure together constitute the anode barrel.

[0011] Specifically, the first permanent magnet assembly includes a negative radially magnetized cylindrical magnet and an axially longitudinally magnetized cylindrical magnet, which are coaxially adjacent to each other inside the cathode base.

[0012] Specifically, the second permanent magnet assembly includes radially magnetized cylindrical magnets and negatively axially magnetized cylindrical magnets, which are coaxially adjacent and arranged inside the housing.

[0013] Specifically, the first permanent magnet group and / or the second permanent magnet group include permanent magnets that are magnetized at an angle.

[0014] Specifically, the projection shapes of the first permanent magnet group and the second permanent magnet group on the plane are angularly symmetrical.

[0015] Specifically, the first permanent magnet group and / or the second permanent magnet group are combined in an angular direction by multiple fan-shaped magnets to form a cylindrical structure.

[0016] Beneficial effects: This invention provides a coaxial integrated permanent magnet focusing system, including a cathode base and a housing, with the housing connected to the cathode base via an insulating connector. A first permanent magnet group is disposed inside the cathode base, and a second permanent magnet group is disposed inside the housing. The first permanent magnet group and the second permanent magnet group are fixedly connected via the insulating connector, together forming a permanent magnet focusing system. This integrated, built-in layout solves the technical problems of traditional focusing systems being heavy and bulky, requiring significant space and power consumption to provide a focusing magnetic field. It achieves a highly compact and miniaturized system structure, significantly reducing the size and weight of the focusing system. Furthermore, the optimized magnet arrangement generates a high-peak, high-uniformity focusing magnetic field in the electron beam transmission region, effectively improving beam rigidity and flux, enhancing the system's mechanical stability and assembly convenience. Simultaneously, it avoids the magnetic field surrounding the diode portion, thereby significantly improving device impedance and laying a solid foundation for the equipmentization of high-power microwave devices. Attached Figure Description

[0017] Figure 1 This is a two-dimensional cross-sectional schematic diagram of the coaxial integrated permanent magnet focusing system provided in a specific embodiment of the present invention; Figure 2 This is a two-dimensional cross-sectional schematic diagram of the coaxial integrated permanent magnet focusing system provided in a specific embodiment of the present invention; Figure 3 This is a two-dimensional cross-sectional schematic diagram of the permanent magnet focusing system provided in a specific embodiment of the present invention; Figure 4 This is a schematic diagram of the magnetic field strength of the permanent magnet focusing system provided in a specific embodiment of the present invention; The reference numerals in the above figures are as follows: 1. Insulating connector; 2. Negative axial longitudinal magnetized cylindrical magnet; 3. Radial magnetized cylindrical magnet; 4. Negative radial magnetized cylindrical magnet; 5. Axial longitudinal magnetized cylindrical magnet; 6. Cathode structure; 7. Cathode base; 8. Outer shell; 9. High frequency structure. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings; therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0019] The core innovation of the coaxial integrated permanent magnet focusing system provided by this invention lies in decomposing and optimizing the traditional large permanent magnet structure, which is wrapped around the beam channel, into two compact permanent magnet groups, which are respectively built into the cathode base 7 and the outer shell 8 of the system. They are fixed into a rigid whole by insulating connectors 1, thereby achieving miniaturization, lightweighting and high performance of the system. Compared with traditional permanent magnet focusing systems, this invention has the characteristics of high peak magnetic field, low radial magnetic field, low weight, low weight increase due to the increase in uniform region length, high beam current, strong beam rigidity, high diode impedance and adjustable diode impedance. It can not only replace the electromagnetic focusing system and conventional uniform permanent magnet focusing system in high-power microwave sources, but also provide a uniform magnetic field focusing system for various coaxial multi-beam klystrons, coaxial high-power vacuum electronic devices and high-power vacuum electronic devices with different structures.

[0020] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0021] Please see Figure 1 This embodiment provides a coaxial integrated permanent magnet focusing system, including a cathode base 7, a housing 8, a first permanent magnet group, and a second permanent magnet group. The housing 8 is connected to the cathode base 7 via an insulating connector 1. This connection method not only ensures electrical isolation but also guarantees the stability and reliability of the entire structure. The first permanent magnet group is disposed inside the cathode base 7, and the second permanent magnet group is disposed inside the housing 8. The first permanent magnet group and the second permanent magnet group are fixedly connected via the insulating connector 1, together forming the permanent magnet focusing system. This solves the technical problem of traditional focusing systems, which use an external structure to enclose the magnets outside the beam channel, resulting in a large weight and volume of the beam focusing system, requiring significant space and power consumption to provide the focusing magnetic field.

[0022] It should be noted that the cathode base 7 in this embodiment is typically made of non-magnetic, high-strength titanium alloy to support the first permanent magnet assembly inside and the cathode structure 6 on top. The outer shell 8 in this embodiment is also preferably made of titanium alloy, and it houses the second permanent magnet assembly inside. Meanwhile, the insulating connector 1 is the key to realizing the "integrated" structure of this invention. It is made of high-strength insulating material (such as special ceramics), which not only achieves vacuum sealing and high-voltage insulation between the cathode base 7 and the outer shell 8, but also firmly fixes the two together through its rigid structure, preventing the cathode base 7 and the outer shell 8 from shifting under the strong magnetic force, thus ensuring the structural stability of the entire system.

[0023] Preferably, in this embodiment, the titanium alloy cathode base 7 and the titanium alloy shell 8 that enclose the two permanent magnet groups are not fixed in structure. Usually, in order to reduce weight, it is only necessary to enclose the magnets. Their surfaces are provided with fixed structures to connect the insulating connectors 1. Their size and structure are based on a comprehensive consideration of diode impedance, system weight, system rigidity and the interaction force between magnets, and need to be set according to actual needs.

[0024] See Figure 1 and Figure 2 In this embodiment, the coaxial integrated permanent magnet focusing system further includes a cathode structure 6 disposed on the cathode base 7 and a high-frequency structure 9 fixedly disposed outside the housing 8. The cathode base 7, the high-frequency structure 9, and the housing 8 together constitute a diode structure. The permanent magnet focusing system is used to provide a focusing magnetic field for the electron beam transmission region between the cathode structure 6 and the high-frequency structure 9. The high-frequency structure 9 is used to receive the electron beam constrained and transmitted by the focusing magnetic field and generate high-power microwaves through beam-wave interaction. The outer surfaces of the housing 8 and the high-frequency structure 9 together constitute an anode barrel, ensuring the integrity and functionality of the permanent magnet focusing system.

[0025] Preferably, the cathode structure 6 in this embodiment is an explosive emission cathode structure, disposed on the cathode base, for generating an electron beam under a high-voltage pulse. This cathode structure 6 is a replaceable design and can be replaced with different structures such as a ring cathode or a pencil cathode according to actual needs, enhancing the system's versatility. The high-frequency structure 9 is fixedly disposed at the outer end of the housing 8. It can be understood that the high-frequency structure 9 can be the core high-frequency circuit of an electrovacuum device such as a klystron, traveling wave tube, or backward wave tube. The outer surfaces of the housing 8 and the high-frequency structure 9 together constitute the anode barrel of the system. Thus, the cathode base 7 (serving as a cathode support), the anode barrel (composed of the outer surfaces of the housing 8 and the high-frequency structure 9), and the explosive emission cathode structure together form a diode structure for emitting an electron beam.

[0026] During operation, a high-voltage pulse is applied between the diode structures, causing the explosive emission cathode structure 6 to generate a high-current electron beam. The first and second permanent magnet groups work together to generate a high-intensity, highly uniform axial focusing magnetic field throughout the entire electron beam propagation region from the cathode emitting surface to the interior of the high-frequency structure 9. This magnetic field constrains the electron beam, enabling it to stably traverse a relatively long drift distance and ultimately inject into the high-frequency structure 9. Within the high-frequency structure 9, the electron beam transfers its kinetic energy to electromagnetic waves through beam-wave interaction, thereby generating high-power microwaves.

[0027] It should be noted that by optimizing the size, relative position, and magnetization direction of the two permanent magnet assemblies, this system can generate a magnetic field with excellent uniformity. In a preferred embodiment (see...), Figure 4The system can generate an average magnetic field of about 0.45T in a uniform region of 220mm, with a magnetic field uniformity of more than 95% (i.e., non-uniformity within 3%). This excellent magnetic field quality ensures that the electron beam does not diverge during transmission and has extremely high beam flux.

[0028] See Figure 1 In this embodiment, the first permanent magnet assembly includes a negative radially magnetized cylindrical magnet 4 and an axially longitudinally magnetized cylindrical magnet 5. The negative radially magnetized cylindrical magnet 4 and the axially longitudinally magnetized cylindrical magnet 5 are coaxially adjacent and arranged inside the cathode base 7, meaning they are arranged side-by-side axially, sharing the same central axis and embedded together within the internal space of the cathode base 7. The outer wall of the negative radially magnetized cylindrical magnet 4 is tightly fitted to the inner wall of the cathode base 7, ensuring the stability and consistency of the magnetic field distribution. The axially longitudinally magnetized cylindrical magnet 5 is located at one end of the negative radially magnetized cylindrical magnet 4, and the two are connected through a precision-machined contact surface, forming a complete magnetic circuit system, ensuring effective transmission and distribution of the magnetic field. This design of placing the magnets inside the cathode base 7 further reduces the weight of the permanent magnet focusing system.

[0029] See Figure 1 In this embodiment, the second permanent magnet assembly includes a radially magnetized cylindrical magnet 3 and a negative-axis longitudinally magnetized cylindrical magnet 2, which are coaxially adjacent and arranged inside the housing 8. The outer wall of the radially magnetized cylindrical magnet is tightly fitted to the inner wall of the housing, ensuring the stability of the magnetic field. The negative-axis longitudinally magnetized cylindrical magnet 2 is located at one end of the radially magnetized cylindrical magnet 3, forming a precise magnetic field distribution between them, ensuring the efficient operation of the permanent magnet focusing system.

[0030] According to the above technical solution, the first permanent magnet built into the cathode base 7 and the second permanent magnet built into the outer shell 8 are fixedly connected together through the connection of the insulating connector 1, and the magnetic circuits are coupled to each other to form an integrated permanent magnet focusing system.

[0031] In a preferred embodiment, the first permanent magnet group and / or the second permanent magnet group include angled magnetized permanent magnets. Angled magnetized permanent magnets can generate a more complex magnetic field distribution in a specific area, which helps optimize the transmission trajectory of the electron beam and improve the focusing effect. The angled magnetized permanent magnets employ a special magnetization process so that the direction of their internal magnetic moments is at a certain angle to the axial or radial direction, thereby forming more precise magnetic field control in space and further improving the system performance.

[0032] It is understood that the magnetization direction of each magnet in the first permanent magnet group and the second permanent magnet group in this embodiment can be locally adjusted. For example, a magnetic block magnetized at an angle of 45° can be inserted into the cylindrical magnet 2 that is longitudinally magnetized along the negative axis, which can further optimize the magnetic potential energy and thus greatly reduce the weight of the system.

[0033] Furthermore, the projection shapes of the first and second permanent magnet groups on the plane are angularly symmetrical. This symmetrical design ensures the uniformity of the magnetic field distribution, avoids the influence of non-uniform forces on the electron beam during transmission, improves the focusing quality and stability of the electron beam, and the angularly symmetrical design also helps to counteract any parasitic magnetic fields that may exist in the system, further optimizing the focusing effect and ensuring the efficient operation of the system.

[0034] It should be noted that in this embodiment, the radial thickness and longitudinal length of the magnets in the first and second permanent magnet groups are variable, and the projection of their two-dimensional plane (rz) is not limited to rectangles. They are generally irregular shapes, and their structures are usually only symmetrical in the angular direction. Adjusting the size usually means a change in the magnitude of the magnetic field. Their size, structure, and magnetization direction are a comprehensive consideration of the length of the required uniform magnetic field region, the magnetic field strength, and the magnetic field uniformity. The length of the magnet in the longitudinal direction can be increased, while the radial width also needs to be scaled proportionally.

[0035] In a preferred embodiment, the first permanent magnet group and / or the second permanent magnet group are assembled into a cylindrical structure by combining multiple sector magnets angularly. Each sector magnet is precision-machined to ensure that the combined structure forms a cylindrical shape. This modular design facilitates the manufacturing and installation of the magnets, while ensuring the accuracy of the magnetic field distribution and the efficient operation of the system.

[0036] It should be noted that the angular symmetry design of the coaxial integrated permanent magnet focusing system in this embodiment, and the characteristic that the magnet's projection on the RZ plane can be an irregular shape, provide great flexibility in design. Different magnetic field distribution requirements can be precisely adapted by changing the magnet's contour. Furthermore, the magnetization direction of the magnet can be flexibly adjusted (e.g., an angled magnet 2' can be used to optimize the magnetic potential energy), and the cylindrical magnet can also be composed of multiple fan-shaped magnets combined angularly, further enhancing the design optimization space and process feasibility.

[0037] It is understood that when the coaxial integrated permanent magnet focusing system of this embodiment is working, the cathode structure 6 generates an electron beam. Under the action of the electric field formed between the cathode base 7 and the high-frequency structure 9, the electron beam gains acceleration energy. The focusing magnetic field generated by the permanent magnet focusing system constrains and focuses the electron beam, causing the electron beam to be transmitted to the high-frequency structure 9 along a predetermined trajectory. The high-frequency structure 9 receives the focused electron beam and converts the energy of the electron beam into high-power microwave output through the beam-wave interaction mechanism, ensuring the efficient operation of the system.

[0038] It should be noted that this coaxial integrated permanent magnet focusing system features a compact structure and high integration, reducing the connection and adjustment issues between multiple independent components in traditional systems. This improves the system's reliability and stability. The rational configuration of the permanent magnets generates a precise magnetic field distribution, effectively improving the focusing quality of the electron beam, thereby enhancing the power and efficiency of the microwave output and ensuring efficient system operation. Through this design, the system achieves not only high structural integration but also functional optimization, resulting in greater stability and reliability throughout its operation.

[0039] Please see Figure 3 and Figure 4 The following section uses a 26-beam coaxial multi-beam klystron amplifier as the focusing object of a coaxial integrated permanent magnet focusing system. At 300kV and 4000A, a 99% diode beam current introduction rate is achieved, and the beam current throughput after passing through a 200mm drift tube reaches 99%, essentially assuming no beam transmission loss. The specific parameters of the system are as follows: The first permanent magnet group (located inside the cathode base 7) has an outer radius of 141 mm, a minimum inner radius of 10 mm, and a thickness of 60 mm. The outer radius of the axial magnet is 75 mm. The second permanent magnet assembly (located inside the outer casing 8) has a maximum outer radius of 140mm, a minimum inner radius of 66mm, and a thickness of 290mm. The axially magnetized magnet is 240mm thick and includes a magnet magnetized at a 45° angle. Figure 3 As shown, the maximum outer radius of the 45° inclined magnet is 144mm, the thickness is 80mm, and the inner radius of the small axial magnet is 75mm. Operating point: Diode voltage 300kV, beam current 4000A; Performance results: such as Figure 4As shown, the horizontal axis represents the position along the Z-axis, in millimeters (mm), ranging from 0 to 200 mm; the vertical axis represents the magnetic flux density (B), in tesla (T), ranging from 0.0 to 0.6 T. Curve Bz represents the magnetic flux density component in the Z-direction, i.e., the projection of the magnetic field onto the Z-axis. In this embodiment, with the magnetized material br being 1.4 T, the simulation achieved a uniform magnetic field region length of 220 mm and an average magnetic field strength of 0.45 T. The uniformity of the uniform magnetic field generated by this structure is within 3%. The generated uniform region extends from the cathode emitting surface to the desired high-frequency structure 9, with radial and angular uniformity both exceeding 95%. This demonstrates that... This embodiment improves the external magnet structure used for the uniform magnetic field required for beam focusing in traditional high-power microwave systems to a diode-embedded magnet structure. While stabilizing beam transmission, the magnetic field encasing the diode is placed inside the cathode base 7, reducing the weight by more than 40% compared to traditional permanent magnet focusing systems. At the same time, the increase in the total weight of the magnet caused by increasing the length of the uniform region is reduced by 30% compared to traditional uniform focusing systems, greatly reducing the weight and volume of the focusing system. Since there is no magnetic field encasing the diode, the device impedance is significantly increased. While improving beam rigidity and beam quality, the weight of the magnet is greatly reduced, and the beam flux is significantly improved compared to traditional permanent magnet focusing systems.

[0040] Furthermore, the coaxial integrated permanent magnet focusing system in this embodiment is used to focus the electron beam emitted by explosion, but it can also be used to focus other electron guns, such as thermionic cathode electron beams. At the same time, the permanent magnet focusing system in this embodiment can be used as a permanent magnet focusing system for various vacuum electronic devices, including but not limited to coaxial multi-beam klystrons, triaxial klystrons, traveling wave tubes, and backward wave tubes, further expanding the application scenarios of the present invention.

[0041] It should be noted that this embodiment provides a coaxial integrated permanent magnet focusing system, including a cathode base and a housing. The housing is connected to the cathode base via an insulating connector. A first permanent magnet group is disposed inside the cathode base, and a second permanent magnet group is disposed inside the housing. The first permanent magnet group and the second permanent magnet group are fixedly connected via the insulating connector, together forming a permanent magnet focusing system. This achieves a built-in integrated layout, solving the technical problems of traditional focusing systems being heavy and bulky, requiring a large amount of space and power consumption to provide a focusing magnetic field. This achieves a highly compact and miniaturized system structure, significantly reducing the size and weight of the focusing system. Furthermore, the optimized magnet arrangement can generate a high-peak, high-uniformity focusing magnetic field in the electron beam transmission region, effectively improving the rigidity and flux of the beam, enhancing the mechanical stability and assembly convenience of the system, and avoiding the magnetic field surrounding the diode part, thereby significantly improving the device impedance. This lays a solid foundation for the equipmentization of high-power microwave devices.

[0042] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0043] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0044] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A coaxial integrated permanent magnet focusing system, characterized in that, The system comprises: a cathode base (7); an outer shell (8) connected to the cathode base (7) through an insulating connector (1); a first permanent magnet group arranged inside the cathode base (7); a second permanent magnet group arranged inside the outer shell (8); wherein the first permanent magnet group is fixedly connected to the second permanent magnet group through the insulating connector (1), and together they form a permanent magnet focusing system.

2. The coaxial integrated permanent magnetic focusing system of claim 1, wherein, The system further comprises a cathode structure (6) arranged on the cathode base (7), and a high-frequency structure (9) fixedly arranged outside the outer shell (8), and the cathode base (7), the high-frequency structure (9) and the outer shell (8) together form a diode structure.

3. The coaxial integrated permanent magnetic focusing system of claim 2, wherein, The permanent magnet focusing system is used to provide a focusing magnetic field for an electron beam transmission region between the cathode structure (6) and the high-frequency structure (9).

4. The coaxial integrated permanent magnetic focusing system of claim 3, wherein, The high-frequency structure (9) is used to receive an electron beam constrained and transmitted by the focusing magnetic field, and generate high-power microwaves through beam-wave interaction.

5. The coaxial integrated permanent magnetic focusing system of claim 4, wherein, The outer shell (8) and the outer surface of the high-frequency structure (9) together form an anode bucket.

6. The coaxial integrated permanent magnetic focusing system of claim 1, wherein, The first permanent magnet group comprises a negative radial magnetization cylindrical magnet (4) and an axial longitudinal magnetization cylindrical magnet (5), and the negative radial magnetization cylindrical magnet (4) and the axial longitudinal magnetization cylindrical magnet (5) are coaxially and adjacently arranged inside the cathode base (7).

7. The coaxial integrated permanent magnetic focusing system of claim 1, wherein, The second permanent magnet group comprises a radial magnetization cylindrical magnet (3) and a negative axial longitudinal magnetization cylindrical magnet (2), and the radial magnetization cylindrical magnet (3) and the negative axial longitudinal magnetization cylindrical magnet (2) are coaxially and adjacently arranged inside the outer shell (8).

8. The coaxial integrated permanent magnetic focusing system of claim 1, wherein, The first permanent magnet group and / or the second permanent magnet group comprises a magnet with an inclined angle magnetization.

9. The coaxial integrated permanent magnetic focusing system of claim 1, wherein, The projection shape of the first permanent magnet group and the second permanent magnet group on a plane is angularly symmetrical.

10. The coaxial integrated permanent magnetic focusing system of claim 1, wherein, The first permanent magnet group and / or the second permanent magnet group is composed of a plurality of sector magnets in the angular direction to form a cylindrical structure.

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