Multistage depressed collector for ultra wide band traveling wave tube

Abstract

The invention provides a multistage depressed collector for an ultra wide band traveling wave tube. The multistage depressed collector comprises an insulating porcelain cylinder with an inner cavity, an inner collector accommodated and fixed in the inner cavity of the insulating porcelain cylinder, and an outer collector fixedly arranged on the outer wall of the insulating porcelain cylinder, the inner collector comprises a preceding-stage collector and a final-stage collector which are arranged along the axial direction of the insulating porcelain cylinder; the preceding-stage collector comprises a top wall part, a through hole for an electron beam to pass through is formed in the top wall part, and the surface of one side, facing the last-stage collector, of the top wall part comprises a protruding structure protruding towards the last-stage collector. The collector can effectively restrain reflection of secondary electrons, reduce the electron backflow rate, achieve high recovery efficiency and improve the efficiency of the ultra-wideband traveling wave tube.

Description

Technical Field

[0001] The present invention relates to the field of vacuum electronic technology, and more specifically, to a multi-stage step-down collector for an ultra-wideband traveling wave tube. Background Art

[0002] Traveling wave tubes are widely used in radar, communication, electronic countermeasures, etc. due to their wide bandwidth, high efficiency, and high power. With the upgrading of electronic warfare and information warfare weapon equipment systems, higher requirements are placed on technical indicators such as traveling wave tube efficiency and power. As a key component for traveling wave tubes to recover electron injection energy and improve overall efficiency, optimizing the design of collectors is of great significance to improving the efficiency of traveling wave tubes. At present, traveling wave tubes generally use three-stage step-down collectors to improve overall efficiency. However, in ultra-wideband traveling wave tubes, the electron energy distribution after the interaction between high and low frequency points is very different, and the electron velocity at the entrance of the collector is quite different. It is difficult for the three-stage step-down collector to sort several electron velocity groups by setting the voltage at each level of the collector, which is not conducive to improving the efficiency of the high-frequency band. At the same time, when electrons hit the collector surface, secondary electron emission may occur, resulting in reflux. Summary of the invention

[0003] In view of the above problems, the present invention provides a multi-stage step-down collector for an ultra-wideband traveling wave tube to improve the efficiency of the traveling wave tube.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

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

[0006] It comprises an insulating porcelain cylinder with an inner cavity, an inner collector fixed in the inner cavity of the insulating porcelain cylinder, and an outer collector fixed on the outer wall of the insulating porcelain cylinder; the inner collector comprises a front collector and a final collector arranged along the axial direction of the insulating porcelain cylinder;

[0007] The front-stage collector comprises a top wall portion, on which a through hole for electron injection is formed, and a surface of the top wall portion on one side facing the final-stage collector comprises a protruding structure protruding toward the final-stage collector.

[0008] A preferred solution is that the protrusion structure includes multiple layers of annular protrusions surrounding the through hole; and the protrusion heights of the annular protrusions on the top wall of the same front-stage collector are equal.

[0009] Preferably, the multiple layers of annular protrusions are all arranged coaxially with the through holes.

[0010] Preferably, the axial cross-section of the annular protrusion is triangular.

[0011] A preferred solution is that the angle α formed by the two side edges of the axial cross section of each annular protrusion on the top wall of the same front-stage collector is the same.

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

[0013] Preferably, the angle α is 75°.

[0014] Preferably, a surface of one side of the top wall portion facing the final collecting electrode comprises a sputtered molybdenum layer.

[0015] Preferably, the multi-stage step-down collector includes a plurality of front-stage collectors arranged axially along the insulating porcelain tube, each front-stage collector includes a cylindrical side wall portion fixed to the top wall portion; the side walls of two adjacent front-stage collectors are fixed.

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

[0017] The beneficial effects of the present invention are:

[0018] The multi-stage step-down collector for an ultra-wideband traveling wave tube provided by the present invention increases the electron recovery area by arranging a serrated protrusion structure on the top wall to address the problems that the collector required for the ultra-wideband traveling wave tube has a large working dynamic range and the collector recovery efficiency of the low-end frequency point and the high-end frequency point after interaction is low. When primary and secondary electrons hit the top wall, the protrusion structure can reflect the electrons at a certain angle and form multiple reflections on the protrusion structure. During the reflection process, the electron energy is reduced, the kinetic energy decreases, and it is finally captured and recovered by the inner collector, which effectively suppresses the electron backflow in the saturation state. The multi-stage step-down collector for an ultra-wideband traveling wave tube of the present invention improves the overall efficiency of the ultra-wideband traveling wave tube by designing the protrusion structure on the top wall and using surface modification technology for the ultra-wideband traveling wave tube, so that the saturation efficiency of the traveling wave tube is increased by 7%, reaching more than 40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

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

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

[0022] Figure 3 yes Figure 2 A partial enlarged view of .

[0023] Attached markings: 1. Insulating porcelain tube, 21. Front-stage collector, 22. Final-stage collector, 211. Top wall, 212. Through hole, 213. Annular protrusion, 214. Side wall, 215. Parallel edge, 216. Bevel edge, 217. Annular groove, 3. External collector. DETAILED DESCRIPTION

[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 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] In order to improve the collector efficiency and solve the problem of electron backflow in the collector, the present invention designs a multi-stage step-down collector with a sawtooth convex structure for an ultra-wideband traveling wave tube. The ultra-wideband traveling wave tube is an electronic device that can effectively amplify signals in an extremely wide frequency range. Its design allows operation in a frequency range from several GHz to tens of GHz. The collector can realize the sorting and recovery of various electron speed groups. At the same time, the sawtooth convex structure of the inner wall of the inner collector head can improve the recovery capacity of secondary electrons, suppress the backflow phenomenon, and improve the efficiency of the traveling wave tube. Figures 1 to 3As shown, specifically, the multi-stage step-down collector for an ultra-wideband traveling wave tube comprises: an insulating porcelain tube 1 with an inner cavity, an inner collector accommodated and fixed in the inner cavity of the insulating porcelain tube 1, and an outer collector 3 fixed on the outer wall of the insulating porcelain tube 1; the inner collector comprises a plurality of front-stage collectors 21 and a final-stage collector 22 arranged along the axial direction of the insulating porcelain tube 1; the front-stage collector comprises a top wall portion 211, a through hole 212 for electron injection is formed on the top wall portion 211, and a protruding structure protruding toward the final-stage collector 22 is formed on the surface of the top wall portion 211 on one side facing the final-stage collector 22. The structural design of the present invention is reasonable. Compared with the conventional step-down collector structure, the collector can effectively suppress the reflection of secondary electrons and reduce the electron reflux rate. At the same time, it can achieve a higher recovery efficiency, so that the efficiency of the ultra-wideband traveling wave tube is improved. It can be understood that Figure 1 The arrow in the figure indicates the trajectory of the electrons entering the collector. The electrons become increasingly divergent from left to right along the collector axis, and the deflection becomes increasingly larger, so the size of the through hole needs to become increasingly 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 front-stage collector 21 have the same protrusion height in the axial direction of the collector. It can be understood that the protrusion height refers to the height of the annular protrusion 213 protruding toward the final collector 22. The protrusion structure can absorb reflected electrons multiple times, reduce the emission capacity of secondary electrons, complete the collection of secondary electrons, and further improve the backflow suppression effect and collector efficiency. The multiple layers of annular protrusions 213 are all arranged coaxially with the through hole 212, which makes it easy to collect secondary electrons with large residual energy, has a better "interception" effect on reflected electrons, and is less difficult to process. The size and number of the annular protrusions 213 on the top wall portion 211 are specifically determined according to the size of the top wall portion 211.

[0031] In a specific embodiment, the axial cross section of the annular protrusion 213 is triangular. In the axial cross section of the collector, the annular protrusion 213 is continuously arranged in the direction from the axis of the top wall portion 211 to the edge of the top wall portion 211, presenting a sawtooth shape. Its advantage is that it can help the electrons to hit the collector surface and then be reflected and recovered by the inner collector again at a certain angle. More specifically, the axial cross section of the annular protrusion 213 is designed to be triangular, based on the backflow trajectory of the secondary electrons, so that after hitting the hypotenuse of the triangle, it can hit the parallel side of another triangle again after reflection.

[0032] Furthermore, the angle α formed by the two sides of the axial section of each annular protrusion 213 on the top wall 211 of the same front-stage collector 21 is the same, and the triangular area corresponding to the axial section of each annular protrusion 213 on the top wall 211 of the same front-stage collector 21 is the same, and the connecting line of the tips of each triangular section of the top wall 211 of the same front-stage collector 21 is a straight line. This setting, on the one hand, is based on the simulation results of the electron trajectory, and the reflected electrons can be recovered to a large extent. On the other hand, because of different angles, the benefits of staggered arrangement are not great, and there is no consistency, and the processing cost will be high.

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

[0034] More specifically, the angle α is 75°. When setting the angle, it is necessary to consider the uncertainty of the incident angles of the primary electrons and the secondary electrons. Therefore, in order to ensure as much as possible that the electrons are reflected to the edge of the adjacent triangle after hitting one edge of the annular raised triangle, the electrons lose energy in multiple reflections until they are captured and recovered. Based on the above description, the angle α is selected to be 75°.

[0035] In a specific embodiment, the surface of the top wall portion 211 facing the final collector 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 side wall of the top wall portion 211 adopts a surface modification method of sputtering molybdenum on the surface to reduce its secondary electron emission ability. Since oxygen-free copper has excellent thermal conductivity, electrical conductivity, machinability and welding performance among metal materials, it is often used as an ideal collector material. The disadvantage is that its secondary electron emission coefficient is relatively high. One method to reduce or inhibit its secondary electron emission is to start with the modification of the morphology of oxygen-free copper. Experiments have shown that a rough surface with holes can reduce the secondary electron emission ability. When the surface is rough, a part of the secondary electrons are absorbed by the hole wall. After the surface modification, the surface of the material after sputtering molybdenum is scanned by an electron microscope, showing that the texture surface after ion surface modification has high density, "burrs" with a certain spacing and height, which can effectively inhibit secondary electron emission. After many tests, the thickness of sputtered molybdenum was 0.5um 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 a specific embodiment, the multi-stage step-down collector includes a plurality of front-stage collectors 21 arranged axially along the insulating porcelain tube 1, and each front-stage collector 21 includes a cylindrical side wall portion 214 fixed to the top wall portion 211; the side wall portions 214 of two adjacent front-stage collectors 21 are fixed, and the top wall portion 211 of the front-stage collector 21 close to the final collector 22 is located inside the side wall portion 214 of the front-stage collector 21 away from the final collector 22. Figure 1 As shown, the side wall portion 214 of the previous stage collector 21 is sleeved outside the top wall portion 211 of the next stage collector 21 from left to right along the collector axis L. The front stage collector 21 is a split structure. This form of splitting the front stage collector 21 reduces the difficulty of mechanical processing of the protruding structure, and can also meet the needs 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. According to the size of the solder sheet, the depth of the annular groove 217 is 0.25mm and the width is 0.3mm.

[0037] Specifically, after the top wall 211 and the side wall 214 are preassembled, a gold, silver, and copper solder sheet is placed in the annular groove 217 at the connection, and the top wall 211 and the side wall 214 are welded and connected in a hydrogen furnace. Furthermore, in order to better sort the complex electron velocity group and thus improve the collector efficiency, the number of the front collector 21 is at least four.

[0038] The assembly method of the multi-stage step-down collector of the present invention is as follows: the top wall portion 211 is machined to form a serrated convex 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 sputtering molybdenum on the inner surface, the thickness of the sputtered molybdenum is set to 0.5um, 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 a gold, silver and copper solder sheet is placed in the annular groove 217 at the matching position 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 between the top wall portion 211 and the side wall portion 214. The welded inner collector and the outer collector 3, the insulating porcelain tube 1 and other parts are placed in the mold for fixation and brazing, and finally the assembly work of the entire collector is completed.

[0039] In summary, the multi-stage step-down collector for an ultra-wideband traveling wave tube provided by the present invention increases the electron recovery area by providing a serrated protrusion structure on the top wall portion, in order to solve the problem that the collector required for the ultra-wideband traveling wave tube has a large working dynamic range and the collector recovery efficiency of the low-end frequency point and the high-end frequency point after the interaction is low. When the primary and secondary electrons hit the top wall portion, the protrusion structure can reflect the electrons at a certain angle and form multiple reflections on the protrusion structure. During the reflection process, the electron energy is reduced, the kinetic energy decreases, and it is finally captured and recovered by the inner collector, which effectively suppresses the electron backflow in the saturation state. The multi-stage step-down collector for an ultra-wideband traveling wave tube of the present invention improves the overall efficiency of the ultra-wideband traveling wave tube by designing the protrusion structure on the top wall portion and using surface modification technology for the ultra-wideband traveling wave tube, so that the saturation efficiency of the traveling wave tube is increased by 7%, reaching more than 40%.

[0040] 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-stage step-down collector for an ultra-wideband traveling wave tube, characterized in that: It comprises an insulating porcelain cylinder with an inner cavity, an inner collector fixed in the inner cavity of the insulating porcelain cylinder, and an outer collector fixed on the outer wall of the insulating porcelain cylinder; the inner collector comprises a front collector and a final collector arranged along the axial direction of the insulating porcelain cylinder; The front-stage collector includes a top wall portion, on which a through hole for electrons to pass is formed, and a surface of the top wall portion on one side facing the final-stage collector includes a protruding structure protruding toward the final-stage collector.

2. The multi-stage step-down collector for an ultra-wideband traveling wave tube according to claim 1 is characterized in that: The protrusion structure includes multiple layers of annular protrusions surrounding the through hole; the protrusion heights of the annular protrusions on the top wall of the same front-stage collector are equal.

3. The multi-stage step-down collector for an ultra-wideband traveling wave tube according to claim 2, characterized in that: The annular protrusion is coaxially arranged with the through hole.

4. The multi-stage step-down collector for an ultra-wideband traveling wave tube according to claim 2, characterized in that: The axial cross section of the annular protrusion is triangular.

5. The multi-stage step-down collector for an ultra-wideband traveling wave tube according to claim 4 is characterized in that: The angle α formed by the two side edges of the axial cross section of each annular protrusion on the top wall of the same front-stage collector is the same.

6. The multi-stage step-down collector for an ultra-wideband traveling wave tube according to claim 4, characterized in that: The inner side of the axial cross section of the annular protrusion is a parallel side parallel to the collector axis, and the outer side of the annular protrusion is a hypotenuse forming an angle with the collector axis.

7. The multi-stage step-down collector for an ultra-wideband traveling wave tube according to claim 4, characterized in that: The angle α is 75°.

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

9. 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 collector includes a plurality of front-stage collectors arranged axially along the insulating porcelain tube, each of which includes a cylindrical side wall portion fixed to the top wall portion; the side walls of two adjacent front-stage collectors are fixed.

10. 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 collecting electrodes is at least four.

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