A multi-stage depressed collector for an ultra-wideband traveling wave tube

Abstract

This invention provides a multi-stage step-down collector for an ultra-wideband traveling wave tube (UWB), comprising an insulating ceramic cylinder with an inner cavity, an inner collector fixed within the inner cavity of the insulating ceramic cylinder, and an outer collector fixed to the outer wall of the insulating ceramic cylinder. The inner collector includes a pre-stage collector and a final-stage collector arranged axially along the insulating ceramic cylinder. The pre-stage collector includes a top wall portion with a through-hole for electron beam passage, and the surface of the top wall portion facing the final-stage collector includes a protruding structure that bulges towards the final-stage collector. This collector can effectively suppress secondary electron reflection, reduce electron backflow rate, and achieve higher recovery efficiency, thereby improving the efficiency of the UWB.

Description

Technical Field

[0001] This invention relates to the field of vacuum electronics technology. More specifically, it relates to a multi-stage step-down collector for an ultra-wideband traveling wave tube. Background Technology

[0002] Traveling wave tubes (TWTs), with their wide bandwidth, high efficiency, and high power, are widely used in radar, communications, and electronic warfare. With the upgrading of electronic warfare and information warfare weapon systems, higher requirements are being placed on the efficiency and power of TWTs. As a key component for recovering electron energy and improving overall efficiency, optimizing the collector design is crucial for enhancing TWT efficiency. Currently, TWTs generally employ a three-stage step-down collector to improve overall efficiency. However, in ultra-wideband TWTs, the electron energy distribution after the interaction between high and low frequencies differs significantly, resulting in substantial differences in electron velocity at the collector inlet. A three-stage step-down collector makes it difficult to separate several electron velocity groups by setting the voltage at each stage, which is detrimental to improving efficiency in the high-frequency band. Furthermore, when electrons strike the collector surface, secondary electron emission may occur, leading to backflow. Summary of the Invention

[0003] To address the above problems, this invention provides a multi-stage step-down collector for an ultra-wideband traveling wave tube (TWT) to improve TWT efficiency.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention provides a multi-stage step-down collector for an ultra-wideband traveling wave tube, comprising:

[0006] It includes an insulating ceramic cylinder with an inner cavity, an inner collecting electrode fixed in the inner cavity of the insulating ceramic cylinder, and an outer collecting electrode fixed on the outer wall of the insulating ceramic cylinder; the inner collecting electrode includes a front collecting electrode and a final collecting electrode arranged along the axial direction of the insulating ceramic cylinder.

[0007] The front-stage collector includes a top wall portion with a through hole for electron beam to pass through. The side surface of the top wall portion facing the final-stage collector includes a protruding structure that protrudes towards the final-stage collector.

[0008] A preferred embodiment is that the protrusion structure includes multiple layers of annular protrusions surrounding the through hole; the annular protrusions on the top wall of the same pre-collector electrode have equal protrusion heights.

[0009] In a preferred embodiment, all the multiple annular protrusions are arranged coaxially with the through hole.

[0010] A preferred embodiment is that the axial cross-section of the annular protrusion is triangular.

[0011] In a preferred embodiment, the included angle α formed by the two sides of the axial section of each annular protrusion on the top wall of the same pre-collector electrode is the same.

[0012] A preferred embodiment is that the inner side of the axial section of the annular protrusion is a parallel side parallel to the collecting pole axis, and the outer side of the annular protrusion is a hypotenuse forming an angle with the collecting pole axis.

[0013] A preferred embodiment is that the included angle α is 75°.

[0014] A preferred embodiment is that the surface of the top wall portion facing the final collecting electrode includes a sputtered molybdenum layer.

[0015] A preferred embodiment is that the multi-stage voltage-reducing collector includes multiple pre-stage collectors arranged axially along the insulating ceramic cylinder, each pre-stage collector including a cylindrical sidewall portion fixed to the top wall portion; the sidewall portions of two adjacent pre-stage collectors are fixed.

[0016] Preferably, the number of the front-stage collecting electrodes is at least four.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention provides a multi-stage step-down collector for ultra-wideband traveling wave tubes (TWTs). Addressing the issues of large operating dynamic range and low electron recovery efficiency at low and high frequencies after interaction in TWTs, this invention increases the electron recovery area by incorporating a serrated protrusion structure on the top wall. When primary and secondary electrons collide with the top wall, the protrusion reflects the electrons at a certain angle, resulting in multiple reflections. During reflection, the electron energy and kinetic energy decrease, ultimately leading to their capture and recovery by the inner collector, effectively suppressing electron backflow in the saturated state. This multi-stage step-down collector for ultra-wideband TWTs, through the design of the protrusion structure on the top wall and surface modification technology, improves the overall efficiency of the TWT, increasing its saturation efficiency by 7% to over 40%. Attached Figure Description

[0019] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0021] Figure 2 This is a schematic diagram of the top wall portion of the present invention.

[0022] Figure 3 yes Figure 2 A magnified view of a portion of the image.

[0023] Attached markings: 1. Insulating porcelain tube, 21. Pre-stage collecting electrode, 22. Final stage collecting electrode, 211. Top wall, 212. Through hole, 213. Annular protrusion, 214. Side wall, 215. Parallel edge, 216. Beveled edge, 217. Annular groove, 3. External collecting electrode. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0025] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0026] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0027] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0029] To improve collector efficiency and address the electron backflow problem, this invention designs a multi-stage step-down collector for an ultra-wideband traveling wave tube (TWT) with a sawtooth-shaped protrusion structure. An ultra-wideband TWT is an electronic device capable of effectively amplifying signals over an extremely wide frequency range, designed to operate from several GHz to tens of GHz. This collector can sort and recover multiple electron velocity groups, while the sawtooth-shaped protrusion structure on the inner wall of the collector head improves the recovery of secondary electrons, suppresses backflow, and increases TWT efficiency. Figures 1 to 3As shown, a multi-stage step-down collector for an ultra-wideband traveling wave tube specifically includes: an insulating ceramic cylinder 1 with an inner cavity, an inner collector fixed within the inner cavity of the insulating ceramic cylinder 1, and an outer collector 3 fixed to the outer wall of the insulating ceramic cylinder 1; the inner collector includes a plurality of pre-stage collectors 21 and a final-stage collector 22 arranged along the axial direction of the insulating ceramic cylinder 1; the pre-stage collector includes a top wall portion 211, on which a through hole 212 for electron beam passage is formed, and the surface of the top wall portion 211 facing the final-stage collector 22 includes a protruding structure protruding towards the final-stage collector 22. The present invention has a reasonable structural design. Compared with conventional step-down collector structures, this collector can effectively suppress the reflection of secondary electrons, reduce the electron backflow rate, and achieve higher recovery efficiency, thereby improving the efficiency of the ultra-wideband traveling wave tube. It is understood that... Figure 1 The arrows in the diagram indicate the electron trajectories entering the collector. Along the collector axis from left to right, the electrons become increasingly divergent and deflected, thus requiring the via size to become larger and larger.

[0030] In the above embodiment, the protrusion structure includes multiple layers of annular protrusions 213 surrounding the through hole 212. The annular protrusions 213 on the top wall portion 211 of the same pre-stage collector 21 have equal protrusion heights along the collector axis. It can be understood that the protrusion height refers to the height of the annular protrusion 213 protruding towards the final collector 22. This protrusion structure can absorb reflected electrons multiple times, reducing the emission capability of secondary electrons, completing the collection of secondary electrons, and further improving the backflow suppression effect and collector efficiency. The multiple layers of annular protrusions 213 are all coaxially arranged with the through hole 212, which facilitates the collection of secondary electrons with higher remaining energy, provides a better "interception" effect for reflected electrons, and reduces processing difficulty. The size and number of annular protrusions 213 on the top wall portion 211 are specifically determined based on the size of the top wall portion 211.

[0031] In one specific embodiment, the axial cross-section of the annular protrusion 213 is triangular. The annular protrusion 213 is continuously arranged in a sawtooth shape along the direction from the axis of the top wall 211 to its edge in the axial cross-section of the collecting electrode. Its advantage is that it facilitates the reflection of electrons after they strike the collecting electrode surface, allowing them to be recovered by the inner collecting electrode at a certain angle. More specifically, designing the axial cross-section of the annular protrusion 213 as a triangle is based on the return trajectory of secondary electrons, ensuring that after impacting the hypotenuse of the triangle, they can be reflected and then impact the parallel side of another triangle.

[0032] Furthermore, the included angle α formed by the two sides of the axial cross-section of each annular protrusion 213 on the top wall 211 of the same pre-collector 21 is the same, and the area of ​​the triangle corresponding to the axial cross-section of each annular protrusion 213 on the top wall 211 of the same pre-collector 21 is the same, and the line connecting the tips of each triangle cross-section of the top wall 211 of the same pre-collector 21 is a straight line. This arrangement is based on the simulation results of electron trajectories, which can recover reflected electrons to a large extent. On the other hand, different angles and staggered arrangement have little benefit and lack consistency, resulting in high processing costs.

[0033] In one specific embodiment, the inner side of the axial cross-section of the annular protrusion 213 is a parallel side 215 parallel to the collecting pole axis L, and the outer side of the annular protrusion 213 is a hypotenuse 216 forming an angle with the collecting pole axis L. It should be noted that the inner side here refers to the side of the same triangular cross-section that is close to the through hole 212, and the outer side refers to the side of the same triangular cross-section that is away from the through hole 212. The collecting pole axis L coincides with the axis of the through hole 212 and the axis of the insulating ceramic cylinder 1.

[0034] More specifically, the included angle α is 75°. This angle is set to account for the uncertain incident angles of primary and secondary electrons. Therefore, to ensure that electrons, after colliding with one side of the annular convex triangle, are reflected to the side of an adjacent triangle, the electrons lose energy through multiple reflections until they are captured and recovered. Based on the above description, the angle α is chosen to be 75°.

[0035] In one specific embodiment, the surface of the top wall portion 211 facing the final collector electrode 22 includes a sputtered molybdenum layer, which covers the top wall portion 21. The above-mentioned surface modification technology can further improve the electron collection efficiency. Specifically, the inner wall of the top wall portion 211 is modified by surface sputtering molybdenum to reduce its secondary electron emission capability. Oxygen-free copper, due to its excellent thermal conductivity, electrical conductivity, and machinability and weldability among metallic materials, is often used as an ideal collector electrode material. Its drawback is its high secondary electron emission coefficient. One method to reduce or suppress its secondary electron emission is to modify the morphology of oxygen-free copper. Experiments have shown that a rough, porous surface can reduce secondary electron emission capability; when the surface is rough, some secondary electrons are absorbed by the hole walls. After surface modification, scanning the surface of the material after molybdenum sputtering using an electron microscope shows that the textured surface after ion surface modification has a high density of "burrs" with a certain spacing and height, which can effectively suppress secondary electron emission. After multiple tests, the sputtered molybdenum thickness was set at 0.5 μm and the time was 30 minutes. The plated parts were inspected to ensure that the film layer was uniform and smooth, without peeling or bulging.

[0036] In one specific embodiment, the multi-stage voltage-reducing collector includes a plurality of pre-stage collectors 21 arranged axially along the insulating ceramic cylinder 1. Each pre-stage collector 21 includes a cylindrical sidewall portion 214 fixed to a top wall portion 211. The sidewall portions 214 of adjacent pre-stage collectors 21 are fixed, and the top wall portion 211 of the pre-stage collector 21 near the final stage collector 22 is located within the sidewall portion 214 of the pre-stage collector 21 away from the final stage collector 22. Figure 1 As shown, along the collecting electrode axis L from left to right, the side wall portion 214 of the previous stage pre-collecting electrode 21 is fitted onto the top wall portion 211 of the subsequent stage pre-collecting electrode 21. The pre-collecting electrode 21 has a split structure. This splitting of the pre-collecting electrode 21 reduces the machining difficulty of the protruding structure and also meets the requirement of surface modification on the inner wall surface of the top wall portion. The top wall portion 211 and the side wall portion 214 are assembled by embedding, and an annular groove 217 with a certain depth and width is formed on the outer circumferential surface of the connection. In accordance with the solder sheet size, the depth of the annular groove 217 is 0.25 mm and the width is 0.3 mm.

[0037] Specifically, after the top wall portion 211 and the side wall portion 214 are pre-assembled, gold, silver, and copper solder sheets are placed in the annular groove 217 at the connection point, and then placed into a hydrogen furnace to achieve the welding connection between the top wall portion 211 and the side wall portion 214. Furthermore, in order to better achieve the sorting of complex electron velocity groups and thus improve the efficiency of the collecting electrode, the number of the front-stage collecting electrodes 21 is at least four.

[0038] The assembly method of the multi-stage step-down collector electrode of the present invention is as follows: The top wall portion 211 is machined to form a serrated protrusion structure on its inner wall surface; the top wall portion 211 is positioned in a special fixture and placed in a sputtering device for surface modification treatment of molybdenum sputtering on the inner surface, the thickness of the sputtered molybdenum is set to 0.5 μm, and the time is 30 minutes. The top wall portion 211 and the side wall portion 214 are placed in a special mold for installation, and gold, silver and copper solder sheets are placed in the annular groove 217 at the mating point of the top wall portion 211 and the side wall portion 214. The welding mold is placed in a hydrogen furnace for brazing to achieve the connection of the top wall portion 211 and the side wall portion 214. The welded inner collector electrode, the outer collector electrode 3, the insulating ceramic cylinder 1 and other parts are placed in the mold for fixing and brazing, and finally the assembly of the entire collector electrode is completed.

[0039] In summary, the multi-stage step-down collector for ultra-wideband traveling wave tubes (TWTs) provided by this invention addresses the problems of large operating dynamic range and low electron recovery efficiency at low and high frequencies after interaction in ultra-wideband TWTs. By incorporating a serrated protrusion structure on the top wall, the electron recovery area is increased. When primary and secondary electrons collide with the top wall, the protrusion structure reflects the electrons at a certain angle, resulting in multiple reflections. During reflection, the electron energy and kinetic energy decrease, ultimately leading to their capture and recovery by the inner collector, effectively suppressing electron backflow in the saturated state. This multi-stage step-down collector for ultra-wideband TWTs, through the design of the protrusion structure on the top wall and surface modification technology, improves the overall efficiency of ultra-wideband TWTs, increasing the saturation efficiency by 7% to over 40%.

[0040] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A multi-stage step-down collector for an ultra-wideband traveling wave tube, characterized in that, It includes an insulating ceramic cylinder with an inner cavity, an inner collecting electrode fixed in the inner cavity of the insulating ceramic cylinder, and an outer collecting electrode fixed on the outer wall of the insulating ceramic cylinder; the inner collecting electrode includes a front collecting electrode and a final collecting electrode arranged along the axial direction of the insulating ceramic cylinder. The front-stage collector includes a top wall portion, on which a through hole is formed for electron beam to pass through, and the side surface of the top wall portion facing the final-stage collector includes a protruding structure that protrudes towards the final-stage collector. The protrusion structure includes multiple layers of annular protrusions surrounding the through hole; the annular protrusions on the top wall of the same front-stage collector have the same protrusion height; The annular protrusion is coaxially aligned with the through hole; The axial cross-section of the annular protrusion is triangular; The included angle α formed by the two sides of the axial section of each annular protrusion on the top wall of the same pre-collector electrode is the same. The inner side of the axial section of the annular protrusion is a parallel side that is parallel to the axis of the collecting pole, and the outer side of the annular protrusion is a hypotenuse that forms an angle α with the axis of the collecting pole. The included angle α is 75°.

2. The multi-stage step-down collector for an ultra-wideband traveling wave tube according to claim 1, characterized in that, The top wall portion includes a sputtered molybdenum layer on the side facing the final collector electrode.

3. The multi-stage step-down collector for an ultra-wideband traveling wave tube according to claim 1, characterized in that, The multi-stage step-down collecting electrode includes multiple pre-stage collecting electrodes arranged along the axial direction of the insulating ceramic cylinder. Each pre-stage collecting electrode includes a cylindrical sidewall portion fixed to the top wall portion; the sidewall portions of two adjacent pre-stage collecting electrodes are fixed.

4. The multi-stage step-down collector for an ultra-wideband traveling wave tube according to claim 1, characterized in that, The number of the front-stage collector electrodes is at least four.

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