A Method and Structure for Suppressing High-Order Mode Oscillation of a Multi-Beam Klystron

Abstract

The present invention discloses a method and structure for suppressing high-order mode oscillations in a multi-beam klystron. The present invention belongs to the technical field of vacuum electronic devices. The method proposed in the present invention adds a mode filter structure to the inner wall of the coaxial resonator of the multi-beam klystron. Its length is equal to half of the wavelength of the operating mode and is close to three-quarters of the wavelength of the high-order mode. Based on the principle of half-wavelength repeatability, this structure has the characteristic of having little influence on the frequency of the operating mode. Based on the principle of quarter-wavelength impedance transformation, this structure has the characteristic of having a greater influence on the high-order mode. By optimizing the design of the dimensions of the mode filter structure, it is possible to suppress spurious modes and eliminate the influence of high-order mode self-excited oscillations without affecting the frequency, field magnitude, and symmetry of the operating mode of the multi-beam klystron, providing technical support for the simulation design and engineering tube manufacturing of the multi-beam klystron.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum electronic devices, and particularly relates to a method and structure for suppressing high-order mode oscillation of a multi-beam klystron. Background Art

[0002] With the rapid development of applications such as communication, electronic countermeasure, and accelerator, higher power and higher efficiency requirements are put forward for radiation sources. As a radiation source of vacuum electronic devices, it has higher power and better stability than solid-state devices. Therefore, in the demand scenarios of high frequency bands and high power, vacuum electronic devices still play an irreplaceable role.

[0003] As a typical device of vacuum electronic devices, the multi-beam klystron has attracted much attention in microwave vacuum electronic devices due to its excellent performance in high power and high efficiency. The coaxial resonator structure, as a commonly used resonator structure for multi-beam klystrons, plays a decisive role in the beam-wave interaction. However, in multi-beam klystrons, due to the existence of high-order modes, self-excited oscillation of non-working modes will be caused under certain conditions, making the multi-beam klystron unable to work normally. Summary of the Invention

[0004] In order to solve the problem of self-excited oscillation of high-order modes in existing multi-beam klystrons, the present invention provides a method and structure for suppressing high-order mode oscillation of a multi-beam klystron. The present invention effectively suppresses the self-excited oscillation of high-order modes of a multi-beam klystron by adding a mode filter structure in the coaxial resonator of the multi-beam klystron and optimizing the design of the size parameters of the mode filter structure.

[0005] The present invention is realized by the following technical solutions:

[0006] A method for suppressing high-order mode oscillation of a multi-beam klystron, the method comprising:

[0007] Obtaining the wavelength of the working mode according to the frequency of the working mode of the multi-beam klystron;

[0008] Adding a section of mode filter structure inside the coaxial resonator of the multi-beam klystron, the length of the mode filter structure being equal to half of the wavelength of the working mode of the multi-beam klystron;

[0009] Judging whether the internal space of the coaxial resonator of the multi-beam klystron can accommodate the added mode filter structure. If it can, proceed to the next step; otherwise, it is necessary to first shorten the length of the added mode filter structure by filling a medium in the mode filter structure added inside the coaxial resonator of the multi-beam klystron so that the internal space of the coaxial resonator of the multi-beam klystron can accommodate the added mode filter structure;

[0010] Determine how much the frequency of the high-order mode needs to be changed to avoid self-excited oscillation, and accordingly determine the width of the mode filter structure added inside the coaxial resonator of the multi-beam klystron.

[0011] Due to the existence of high-order modes in the multi-beam klystron, self-excited oscillation of non-working modes will be caused under certain conditions, resulting in the abnormal operation of the multi-beam klystron. In view of this, the present invention proposes a method for suppressing high-order mode oscillation of a multi-beam klystron. By adding a mode filter structure inside the coaxial resonator of the multi-beam klystron and optimizing the design of the size parameters of the mode filter structure, the influence of high-order mode self-excited oscillation of the multi-beam klystron can be effectively eliminated without affecting the frequency, field magnitude and symmetry of the working mode, providing technical support for the simulation design and engineering tube manufacturing of the multi-beam klystron.

[0012] As a preferred embodiment, the method of the present invention further includes:

[0013] Fine-tune the length of the mode filter structure added inside the coaxial resonator of the multi-beam klystron to correct the frequency of the working mode of the multi-beam klystron.

[0014] As a preferred embodiment, the method of the present invention calculates the wavelength of the working mode through the following formula:

[0015] λ = c / f

[0016] Wherein, f is the frequency of the working mode of the multi-beam klystron, and c is the wave velocity of the working mode of the multi-beam klystron.

[0017] As a preferred embodiment, the method of the present invention further includes:

[0018] When the internal space of the coaxial resonator of the multi-beam klystron cannot accommodate the added mode filter structure, fill the added mode filter structure with a medium to shorten the length of the added mode filter structure to Wherein, ε r is the relative dielectric constant of the filling medium.

[0019] As a preferred embodiment, for an S-band 16-beam 5MW multi-beam klystron, in the present invention, the frequency of the high-order mode needs to be changed by 60 MHz to ensure that it does not undergo self-excited oscillation.

[0020] In a second aspect, the present invention also proposes a mode filter structure for a coaxial resonator of a multi-beam klystron. The mode filter structure is composed of a radial groove and a coaxial groove provided at the center inside the coaxial resonator of the multi-beam klystron;

[0021] Wherein, the sum of the radial length of the radial groove and the axial length of the coaxial groove is equal to half of the wavelength of the working mode of the multi-beam klystron;

[0022] The lengths and widths of the radial slots and coaxial slots are determined by the method described in the present invention.

[0023] As a preferred embodiment, a radial slot is axially opened along the radial direction at the center inside the coaxial resonator of the multi-beam klystron of the present invention;

[0024] On either side of the radial slot, a coaxial slot is axially opened along the axis of the coaxial resonator of the multi-beam klystron.

[0025] As a preferred embodiment, the width of the radial slot of the present invention is 0.5 mm and the radial length is 14.8 mm.

[0026] As a preferred embodiment, the inner diameter of the coaxial slot of the present invention is 3.2 mm, the outer diameter is 12 mm, and the axial length is 45.3 mm.

[0027] In a third aspect, the present invention also provides a multi-beam klystron, which includes a coaxial resonator, and a mode filter structure as described in the present invention is arranged inside the coaxial resonator.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] 1. The method proposed by the present invention adds a mode filter structure to the inner wall of the coaxial resonator of the multi-beam klystron. Its length is equal to half of the working mode wavelength and is close to three-quarters of the high-order mode wavelength. Based on the principle of half-wavelength repeatability, this structure has the characteristic of having little influence on the frequency of the working mode. Based on the principle of quarter-wavelength impedance transformation, this structure has the characteristic of having a greater influence on the high-order mode. By optimizing the design of the dimensions of the mode filter structure, it is possible to suppress spurious modes and eliminate the influence of high-order mode self-excitation oscillation without affecting the working mode frequency, the magnitude and symmetry of the field of the multi-beam klystron;

[0030] 2. The method proposed by the present invention can effectively suppress high-order mode self-excitation oscillation, provides technical support for the simulation design and engineering visualization of the multi-beam klystron, and has important significance; the structure designed by the method of the present invention is convenient for actual processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, form a part of this application, and do not constitute a limitation to the embodiments of the present invention. In the drawings:

[0032] Figure 1 It is a schematic flow chart of the method of the embodiment of the present invention.

[0033] Figure 2 It is a schematic diagram of the coaxial resonator structure of the embodiment of the present invention.

[0034] Figure 3 For Figure 3 Partial enlarged view and cross-sectional view of A in the structure shown. Among them, (a) is the partial enlarged view and (b) is the cross-sectional view.

[0035] Figure 4 It is a comparison diagram of the longitudinal electric field of a multi-beam klystron varying with the radial length before and after the filter mode structure.

[0036] Figure 5 It is a comparison diagram of the longitudinal electric field at the center of the gap of a multi-beam klystron varying with the angular degree before and after the filter mode structure.

[0037] Reference numerals and corresponding component names:

[0038] 1 - coaxial resonator, 2 - radial groove, 3 - coaxial line groove, 4 - filter mode structure. Specific implementation manners

[0039] In the following, the term "comprising" or "may comprise" that can be used in various embodiments of the present invention indicates the presence of the functions, operations or elements of the present invention, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present invention, the terms "comprising", "having" and their cognates are only intended to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be construed as precluding the existence or addition of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items first.

[0040] In various embodiments of the present invention, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0041] Expressions (such as "first", "second", etc.) used in various embodiments of the present invention may modify various components in various embodiments, but do not limit the corresponding components. For example, the above expressions do not limit the order and / or importance of the components. The above expressions are only used for the purpose of distinguishing one element from other elements. For example, without departing from the scope of various embodiments of the present invention, the first element may be called the second element, and similarly, the second element may also be called the first element.

[0042] It should be noted that: If a description "connects" a component to another component, the first component can be directly connected to the second component, and a third component can be "connected" between the first component and the second component. Conversely, when a component is "directly connected" to another component, it can be understood that there is no third component between the first component and the second component.

[0043] The terms used in the various embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the various embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the present invention pertain. The terms (such as those defined in a commonly used dictionary) will be interpreted as having the same meaning as their contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in the various embodiments of the present invention.

[0044] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to embodiments and the accompanying drawings. The illustrative embodiments and descriptions thereof of the present invention are only for explaining the present invention and do not serve as a limitation to the present invention.

[0045] Embodiment 1

[0046] Due to the existence of high-order modes in a multi-beam klystron, under certain conditions, this will cause self-excited oscillations of non-working modes, resulting in the multi-beam klystron being unable to work properly. Therefore, in order to suppress the self-excited oscillation problem of high-order modes in a multi-beam klystron, this embodiment proposes a method for suppressing high-order mode oscillations in a multi-beam klystron. The method proposed in this embodiment adds a mode filter structure inside the coaxial resonator of the multi-beam klystron. The length of this structure is equal to half of the wavelength of the working mode and is close to three-quarters of the wavelength of the high-order mode. Based on the principle of half-wavelength repeatability, this structure has little influence on the frequency of the working mode. Based on the principle of quarter-wavelength impedance transformation, this structure has a greater influence on high-order modes. By optimizing the design of the size parameters of the mode filter structure, the self-excited oscillations of high-order modes in the multi-beam klystron can be effectively suppressed.

[0047] As Figure 1 shown, the method proposed in this embodiment specifically includes the following steps:

[0048] Step 1: Obtain the wavelength of the operating mode based on the frequency of the multi-beam klystron operating mode. Specifically, the wavelength of the operating mode is calculated by the following formula: λ = c / f, where f is the frequency of the multi-beam klystron operating mode, and c is the wave velocity of the multi-beam klystron operating mode.

[0049] Step 2: Add a mode filter structure inside the coaxial resonator of the multi-beam klystron. The length of this mode filter structure is equal to half of the wavelength (λ / 2) of the multi-beam klystron operating mode, and this structure has the characteristics of having less influence on the operating mode frequency and greater influence on the higher-order mode frequency.

[0050] Step 3: Determine whether the internal space of the coaxial resonator of the multi-beam klystron can accommodate the added mode filter structure. If it can, proceed to the next step; otherwise, it is necessary to shorten the length of the added mode filter structure by filling a medium in the added mode filter structure inside the coaxial resonator of the multi-beam klystron so that the internal space of the coaxial resonator of the multi-beam klystron is sufficient to accommodate the added mode filter structure. Specifically, shorten the length of the added mode filter structure to where ε r is the relative permittivity of the filling medium.

[0051] Step 4: Determine how much the frequency of the higher-order mode needs to be changed so that self-excited oscillation does not occur, thereby determining the width of the mode filter structure added inside the coaxial resonator of the multi-beam klystron.

[0052] The method proposed in this embodiment can effectively suppress the self-excited oscillation of the higher-order mode without affecting the operating mode frequency, the magnitude and symmetry of the field of the multi-beam klystron by adding a mode filter structure inside the coaxial resonator of the multi-beam klystron and optimizing the design of the size of the mode filter structure, providing technical support for the simulation design and engineering tube manufacturing of the multi-beam klystron; the structure designed by the method proposed in this embodiment is convenient for actual processing.

[0053] Furthermore, since the mode filter structure added inside the coaxial resonator of the multi-beam klystron will have a small perturbation on the operating mode frequency, the method proposed in this embodiment may further include:

[0054] Step 5: Fine-tune the length of the mode filter structure added inside the coaxial resonator of the multi-beam klystron to correct the operating mode frequency back.

[0055] This embodiment also proposes a mode filter structure 4 for the coaxial resonator of a multi-beam klystron, as shown in Figure 2 and Figure 3 This structure specifically includes: a radial groove 2 and a coaxial groove 3 provided at the center inside the coaxial resonator 1 of the multi-beam klystron, where the radial length of the radial groove 2 plus the axial length of the coaxial groove 3 is half of the wavelength of the operating mode.

[0056] Furthermore, the size of the filter mode structure proposed in this embodiment is designed by the above method proposed in this embodiment. Specifically, taking a 16-beam 5MW multi-beam klystron in the S-band as an example, the width of the radial groove 2 opened along the radial direction at the center of the inner wall of the coaxial resonator 1 is 0.5 mm, and the radial length is 14.8 mm; a coaxial groove 3 is opened along the axial direction of the coaxial resonator on either side of the radial groove 2, and the inner diameter of the coaxial groove 3 is 3.2 mm, the outer diameter is 12 mm, and the axial length is 45.3 mm.

[0057] This embodiment also proposes a multi-beam klystron, which includes a coaxial resonator 1, and the above filter mode structure 4 is externally added inside the coaxial resonator. This structure has little influence on the working mode of the multi-beam klystron and has a greater influence on the high-order modes. It can achieve the purpose of suppressing the self-excited oscillation of the high-order modes without affecting the working mode frequency, the magnitude and symmetry of the field of the multi-beam klystron.

[0058] Embodiment 2

[0059] Taking the 16-beam 5MW multi-beam klystron in the S-band as an example, this embodiment conducts a simulation test on the method proposed in the above embodiment, and the specific process is as follows:

[0060] (1) Obtain the wavelength of the working mode according to the frequency of the above multi-beam klystron;

[0061] (2) Judge whether the internal space of the coaxial resonator of the multi-beam klystron can accommodate a structure of half a wavelength. In this example, the internal space of the multi-beam klystron is sufficient, and there is no need to shorten the structure length by filling a medium in the structure added inside the coaxial resonator.

[0062] (3) Judge that the high-order mode frequency needs to be changed by 60 MHz to ensure that it does not have self-excited oscillation, and determine the width of the structure added inside the coaxial resonator by optimization in the simulation software.

[0063] (4) The added structure will have a very small perturbation on the working mode frequency, and the frequency of the working mode can be corrected back by slightly adjusting the length of the added structure. At this time, the frequency of the high-order mode has changed greatly. Specifically, the high-order mode frequency has changed from 3219 MHz to 3287 MHz.

[0064] Based on the above process, it is finally obtained that: the width of the radial groove opened inside the coaxial resonator is 0.5 mm, and the radial length is 14.8 mm; a coaxial groove is opened on either side of the radial groove, the inner diameter of the coaxial groove is 3.2 mm, the outer diameter is 12 mm, and the axial length is 45.3 mm.

[0065] At the same time, a simulation test is carried out on the multi-beam klystron before and after adding the filter mode structure, and the results are as followsFigure 4 and Figure 5 the comparison diagram of the test results shown

[0066] Among them, Figure 4 shows the comparison diagram of the longitudinal electric field of the multi-beam klystron varying with the radial length before and after adding the filter mode structure, Figure 5 shows the comparison diagram of the longitudinal electric field at the center of the gap of the multi-beam klystron varying with the angular degree before and after adding the filter mode structure. From Figure 4 and Figure 5 it can be seen that adding the filter mode structure outside the coaxial resonant cavity of the multi-beam klystron basically has no influence on the magnitude and symmetry of the field of the working mode of the multi-beam klystron. From this, it can be known that the method proposed in this embodiment can effectively suppress the self-excited oscillation of the high-order mode of the multi-beam klystron without affecting the frequency, magnitude and symmetry of the working mode.

[0067] The specific embodiments described above further elaborate on the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for suppressing high-order mode oscillations in a multi-beam klystron, characterized in that, The method includes: Obtaining the wavelength of the operating mode according to the frequency of the multi-beam klystron operating mode; Adding a mode filter structure inside the coaxial resonator of the multi-beam klystron, where the length of the mode filter structure is equal to half of the wavelength of the multi-beam klystron operating mode; Judging whether the internal space of the coaxial resonator of the multi-beam klystron can accommodate the added mode filter structure. If it can, proceed to the next step; otherwise, it is necessary to first shorten the length of the added mode filter structure by filling a medium in the mode filter structure added inside the coaxial resonator of the multi-beam klystron so that the internal space of the coaxial resonator of the multi-beam klystron can accommodate the added mode filter structure; Judging how much the frequency of the higher-order mode needs to be changed so as not to generate self-excited oscillation, and determining the width of the mode filter structure added inside the coaxial resonator of the multi-beam klystron accordingly.

2. A method for suppressing high-order mode oscillation of a multi-beam klystron according to claim 1, characterized in that, The method further includes: Fine-tuning the length of the mode filter structure added inside the coaxial resonator of the multi-beam klystron to correct the frequency of the multi-beam klystron operating mode back.

3. A method for suppressing high-order mode oscillation of a multi-beam klystron according to claim 1 or 2, characterized in that, The method calculates the wavelength of the operating mode through the following formula: λ = c / f where f is the frequency of the multi-beam klystron operating mode and c is the wave velocity of the multi-beam klystron operating mode.

4. A method for suppressing high-order mode oscillation of a multi-beam klystron according to claim 1 or 2, characterized in that, The method further includes: When the internal space of the multi-beam klystron coaxial resonator cannot accommodate the added mode filter structure, the length of the added mode filter structure is shortened to the original by filling the added mode filter structure in the multi-beam klystron coaxial resonator with a medium. where ε r is the relative permittivity of the filling medium.

5. A method for suppressing high-order mode oscillation of a multi-beam klystron according to claim 1 or 2, characterized in that For an S-band 16-beam 5MW multi-beam klystron, the frequency of the higher-order mode needs to be changed by 60 MHz to ensure that it does not generate self-excited oscillation.

6. A multi-beam klystron coaxial resonator mode filter structure, characterized in that, The mode filter structure is composed of a radial groove and a coaxial groove provided at the center inside the coaxial resonator of the multi-beam klystron; where the sum of the radial length of the radial groove and the axial length of the coaxial groove is equal to half of the wavelength of the multi-beam klystron operating mode; The lengths and widths of the radial groove and the coaxial groove are determined by the method according to any one of claims 1-5.

7. A multi-beam klystron coaxial resonant cavity mode filter structure according to claim 6, characterized in that, A radial groove is opened radially along the center inside the coaxial resonator of the multi-beam klystron; A coaxial groove is opened axially along either side of the radial groove inside the coaxial resonator of the multi-beam klystron.

8. A multi-beam klystron coaxial resonator mode filter structure according to claim 7, characterized in that, The width of the radial groove is 0.5 mm and the radial length is 14.8 mm.

9. The multi-beam klystron coaxial resonant cavity mode filter structure according to claim 8, wherein The inner diameter of the coaxial groove is 3.2 mm, the outer diameter is 12 mm, and the axial length is 45.3 mm.

10. A multi-beam klystron, characterized in that, The multi-beam klystron includes a coaxial resonator, and a mode filter structure according to any one of claims 6-9 is provided inside the coaxial resonator.

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