Elliptical three-stage depressed collector

Abstract

The invention discloses an elliptic three-stage depressed collector, and relates to the technical field of vacuum electronics. The collector comprises an elliptical metal outer cylinder with radiating fins, an elliptical ceramic inner cylinder, and a first-stage collector assembly, a second-stage collector assembly and a third-stage collector assembly which are sequentially arranged in the ceramic inner cylinder along the axial direction, each collector assembly comprises an elliptical collection cavity, and is provided with an input channel and an output opening. According to the collector, the maximum value of power dissipation density can be reduced to a certain extent, the reflux rate of secondary electrons is reduced, and meanwhile better heat dissipation is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum electronics, and particularly relates to an elliptical three-stage depressed collector structure. Background Art

[0002] A sheet-beam traveling-wave tube is a vacuum amplification device that works based on the mechanism of electron cyclotron maser instability. Compared with other vacuum electronic devices, it has the characteristics of high frequency, wide bandwidth, high power, high gain, etc., and has important application prospects in technical fields such as electronic countermeasures, radar imaging, missile guidance, and satellite communication. Due to the development of military equipment and various civilian fields, the demand for high power and high frequency in vacuum electronic devices is increasing day by day, and sheet-beam traveling-wave tubes have received more and more attention and research.

[0003] A traveling-wave tube is composed of five parts: an electron gun, an input / output energy coupling structure, a slow-wave structure, a focusing system, and a collector. After the electron beam emitted by the electron gun enters the coupling structure, it undergoes beam-wave interaction with electromagnetic waves to form bunching blocks, and finally enters the collector and is collected. When traditional pencil-shaped electron beams develop towards high frequencies, due to the size commensurability effect, the electron beam becomes smaller and smaller, and its own space charge force will become larger, making it more difficult to focus. As a result, it becomes extremely difficult to increase the output power by increasing the current in the high-frequency band. However, due to the larger aspect ratio of the sheet electron beam, when the current increases, the transverse size can be increased to reduce the current density, thereby reducing the influence of the space charge force and reducing the focusing difficulty of the current. At the same time, the flat sheet electron beam is more suitable for planar slow-wave structures, facilitating the integration and miniaturization of devices. Therefore, sheet-beam vacuum electronic devices have received more and more attention.

[0004] According to the working principle of a sheet-beam traveling-wave tube, the ways to improve the efficiency of the traveling-wave tube device usually include improving the interaction part to increase the interaction efficiency and recovering the electron energy. However, limited by the principle of beam-wave interaction, it is very difficult to further improve the interaction efficiency of the traveling-wave tube in the future. Therefore, it is a very common method to apply a multi-stage depressed collector to recover the electron beam after interaction to improve the efficiency of the traveling-wave tube.

[0005] The existing design of multi-stage depressed collectors faces the following difficulties:

[0006] 1) Since it is impossible for the depressed collector to achieve 100% recovery of the remaining electron energy, the remaining kinetic energy of the electrons will be converted into heat energy inside the collector. In high-power sheet-beam traveling-wave tubes, the internal electrodes of the collector heat up significantly, and when the heat dissipation capacity is insufficient, it may cause the device to melt.

[0007] 2) After the interaction between the strip electron beam and the wave occurs, the distribution of the electron beam is more disordered than that of the traditional pencil-shaped electron beam. At the same time, affected by the complex electric field inside the depressed collector, the electron trajectories inside the collector are more disordered. Compared with the pencil-shaped electron beam, the axisymmetry is lacking, making it more difficult to design a multi-stage depressed collector that can absorb the electron energy more uniformly.

[0008] 3) The breakdown of the electric field needs to be considered inside the multi-stage depressed collector. At the same time, for insulation, ceramics are usually used as the outer cylinder; this makes it necessary to keep the temperature from being too high, otherwise it will cause the ceramics to leak air and affect the performance of the whole tube. Summary of the Invention

[0009] Aiming at the problem of uneven distribution of electron collision power in the prior art, the present invention proposes an elliptical three-stage depressed collector. The collector of the present invention can, to a certain extent, reduce the maximum value of the power dissipation density, reduce the reflux rate of secondary electrons, and achieve better heat dissipation at the same time.

[0010] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] An elliptical three-stage depressed collector, characterized in that it includes: an elliptical metal outer cylinder with heat dissipation fins;

[0012] An elliptical ceramic inner cylinder arranged inside the metal outer cylinder;

[0013] A first-stage collector assembly, a second-stage collector assembly, and a third-stage collector assembly that are located inside the ceramic inner cylinder and distributed axially in sequence;

[0014] The first-stage collector assembly includes: a first elliptical cylinder, a first input end face that protrudes inwardly and is arranged at the input end of the first elliptical cylinder, and a first output end face that protrudes outwardly and is arranged at the output end of the first elliptical cylinder. The three jointly enclose a first collection cavity; wherein, a first input channel is arranged in the middle of the first input end face for injecting a strip electron beam; a smooth curved surface groove is arranged outside the first input channel; a first output port is arranged in the middle of the first output end face;

[0015] The second-stage collector assembly includes: a second elliptical cylinder, a second input end face that protrudes inwardly and is arranged at the input end of the second elliptical cylinder, and a second output end face that protrudes outwardly and is arranged at the output end of the second elliptical cylinder. The three jointly enclose a second collection cavity; wherein, a second input channel is arranged in the middle of the second input end face, and the input end of the second input channel extends into the first output port; a second output port is arranged in the middle of the second output end face;

[0016] The third-stage collector assembly includes: a third elliptical cylinder, a third input end face that bulges outwardly at the input end of the third elliptical cylinder, and a third output end face provided at the output end of the third elliptical cylinder. The three together enclose a second collection cavity. Among them, a third input channel is provided in the middle of the third input end face, and the input end of the third input channel extends into the second output port. Along the electron beam input direction, the second collection cavity smoothly changes from the output end of the third input channel to an elliptical inner wall first, then gradually changes to a circular inner wall through a transition section, and finally connects to a hemispherical inner wall. A conical structure that bulges in the electron input direction is provided in the middle of the hemispherical inner wall.

[0017] Further, the ceramic inner cylinder is divided into a first ceramic inner cylinder section and a second ceramic inner cylinder section, and there is a gap between the two sections. The first-stage collector assembly and the second-stage collector assembly are located within the first ceramic inner cylinder section, and the third-stage collector assembly is located within the second ceramic inner cylinder section.

[0018] Further, one end of the second ceramic inner cylinder section close to the first ceramic inner cylinder section bulges a circular ring structure towards the central axis; it is used to isolate the electric field between the second collector assembly and the third collector assembly.

[0019] Further, the first input channel is in the shape of a cuboid, and the channel diameter matches the strip electron beam. The second input channel and the third input channel are in the shape of a frustum of a pyramid, and any cross-section perpendicular to the axis is a rectangle with the same aspect ratio of length to width. Moreover, the output end face diameter of the second input channel is smaller than the input end face diameter of the third input channel. The opening shapes of the first output port and the second output port are rectangles.

[0020] Further, the heat dissipation fins are evenly distributed along the circumference, and the length is the same as the length of the metal outer cylinder; at the same time, cooling water is used to dissipate heat from the heat dissipation fins.

[0021] Further, the top angle of the conical structure is provided with a rounded corner to prevent tip arcing.

[0022] The principle and beneficial effects of the present invention:

[0023] 1) The position and velocity distribution of the strip electron beam after interaction are not uniform in the angular direction. By adopting an elliptical collector structure, it can be realized that after the electrons are collected by the collector, the remaining energy distribution is more uniform, reducing the power dissipation density, and thus reducing the temperature while controlling the overall volume.

[0024] 2) The present invention digs grooves around the electron input channel of the first-stage collector assembly to capture the electrons that flow back from the second-stage collector assembly and the third-stage collector assembly to the vicinity of the input channel of the first-stage collector assembly, increasing the electron collision area, and thus reducing the power dissipation density and the proportion of electrons flowing out of the collector.

[0025] 3) The present invention changes the front-end transition structure between the first-stage collector assembly and the second-stage collector assembly to a negative slope inclination (i.e., convex in the electron transmission direction), so as to form a groove between the input channel and the elliptical collector cavity, in order to intercept the generated secondary electrons, thereby reducing the electron reflux rate.

[0026] 4) The present invention isolates the collector voltage by using insulating ceramics, adds a metal outer cylinder and heat dissipation fins outside the insulating ceramic layer, and uses water cooling with a faster flow rate instead of oil cooling for heat dissipation, thereby reducing the temperature of the collector during operation.

[0027] 5) The present invention adopts a hemispherical cavity at the tail end of the third-stage collector assembly, which increases the contact area between electrons and the collector and reduces the power dissipation density; at the same time, a conical structure is arranged at the bottom end of the hemispherical cavity, further increasing the contact area between electrons and the collector and reducing the generation of secondary electrons. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] To more fully understand the present disclosure and its advantages, reference will now be made to the following description in conjunction with the accompanying drawings, in which:

[0029] Figure 1 Schematically shows a three-dimensional structure diagram of a multi-stage step-down collector according to an embodiment of the present disclosure;

[0030] Figure 2 Schematically shows a three-dimensional structure diagram of an outer cylinder according to an embodiment of the present disclosure;

[0031] Figure 3 Schematically shows a three-dimensional structure diagram of an inner cylinder according to an embodiment of the present disclosure;

[0032] Figure 4 Schematically shows a three-dimensional structure diagram of the first-stage collector assembly of a multi-stage step-down collector according to an embodiment of the present disclosure;

[0033] Figure 5 Schematically shows a three-dimensional structure diagram of the second-stage collector assembly of a multi-stage step-down collector according to an embodiment of the present disclosure;

[0034] Figure 6 Schematically shows a three-dimensional structure diagram of the third-stage collector assembly of a multi-stage step-down collector according to an embodiment of the present disclosure;

[0035] Figure 7 Is a schematic diagram of a typical strip electron beam.

[0036] Description of the attached reference numerals: 1. Metal outer cylinder; 2-1. First ceramic inner cylinder section; 2-2. Second ceramic inner cylinder section; 3. Heat dissipation fins; 4. First-stage collector assembly; 4-1. First input channel; 4-2. First input end face; 4-3. First output end face; 4-4. Smooth curved surface groove; 4-5. First output port; 5. Second-stage collector assembly; 5-1. Second input channel; 5-2. Second input end face; 5-3. Second output end face; 5-4. Second output end face; 6. Third-stage collector assembly; 6-1. Third input channel; 6-2. Third input end face; 6-3. Gradually changing to a circular inner wall transition section; 6-4. Hemispherical inner wall; 6-5. Conical structure. Detailed implementation mode

[0037] Taking the Ka-band elliptical multi-stage depressed collector as an example, the present invention will be further elaborated in detail with reference to the accompanying drawings:

[0038] This embodiment is an elliptical three-stage depressed collector applied to the Ka band. As Figure 1 shown, the structure includes: an elliptical metal outer cylinder with heat dissipation fins; the thickness of the metal outer cylinder is 0.2 mm, the length is 64.5 mm, the major axis length a of the inner wall of the metal outer cylinder is 28 mm, and the minor axis length b is 23.6 mm; the heat dissipation fins are evenly distributed along the circumference, the height of the heat dissipation fins is 3 mm, the width is 2.28 mm, and the length is the same as the length of the metal outer cylinder; at the same time, cooling water is used to dissipate heat from the heat dissipation fins.

[0039] An elliptical ceramic inner cylinder arranged inside the metal outer cylinder; as Figure 2 shown, the ceramic inner cylinder is divided into a first ceramic inner cylinder section and a second ceramic inner cylinder section, and there is a 1-mm gap between the two sections; one end of the second ceramic inner cylinder section close to the first ceramic inner cylinder section protrudes a circular ring structure for isolating the electric field between the second collector assembly and the third collector assembly towards the central axis, the axial thickness of the circular ring structure is 2 mm, the inner major axis radius is 22 mm, and the minor axis radius is 17.6 mm.

[0040] The first-stage collector assembly is arranged inside the first ceramic inner cylinder section, the second-stage collector assembly is located inside, and the third-stage collector assembly is arranged inside the second ceramic inner cylinder section; the central axes of the three collector assemblies coincide with the axis of the ceramic inner cylinder, and there is a certain interval (not in contact) between the three collector assemblies, and different voltages are connected during operation.

[0041] As Figure 3As shown in the figure, the first-stage collector assembly includes: a first elliptical cylinder with a major axis of 22 mm, a minor axis of 17.6 mm, and a length of 2 mm on the inner wall; a first input end face disposed at the input end of the first elliptical cylinder and protruding inward (the protruding height is 2 mm); a first output end face disposed at the output end of the first elliptical cylinder and protruding outward (the protruding height is 7.2 mm). The three together enclose a first collection cavity. Among them, a first input channel with a length of 5.2 mm and a width of 2 mm is provided in the middle of the first input end face for injecting a ribbon electron beam, such as Figure 7 As shown in the figure, the electron distribution at the entrance of the multi-stage depressed collector for the ribbon beam is a distorted rectangle with a length of 4 mm and a width of 0.5 mm. A smooth curved surface groove is provided outside the first input channel, and the maximum depth of the groove is 4 mm. A first output port with a length of 14 mm and a width of 13 mm is provided in the middle of the first output end face. The first input end face is set as a smooth convex structure inward, which cooperates with the smooth curved surface groove around the electron beam channel to capture the secondary electrons generated by the collision of the electrons flowing back to this area, so as to reduce the backflow. The first output end face is set as a smooth convex structure outward, which works together with the end output port to reduce the influence of the electric field of the second collector assembly, avoid the concentrated distribution of electrons at the front end of the collection cavity, make the electrons more evenly distributed in the first collection cavity. At the same time, make the electrons not move along the radial direction as much as possible, so that the electron energy can be recovered as much as possible. The principle of the second collector assembly is the same as that of the first collector assembly.

[0042] As Figure 4 As shown in the figure, the second-stage collector assembly includes: a second elliptical cylinder with a major axis of 22 mm, a minor axis of 17.6 mm, and a length of 8.68 mm on the inner wall; a second input end face disposed at the input end of the second elliptical cylinder and smoothly protruding inward (the protruding height is 2 mm); a second output end face disposed at the output end of the second elliptical cylinder and smoothly protruding outward (the protruding height is 6 mm). The three together enclose a second collection cavity. Among them, a second input channel with a length of 3 mm is provided in the middle of the second input end face. The second input channel is in the shape of a cuboid with dimensions of 10 mm * 9 mm, and the input end of the second input channel extends into the first output port. A second output port with a length of 21 mm and a width of 21 mm is provided in the middle of the second output end face.

[0043] As Figure 5As shown, the third-stage collector assembly includes: a third elliptical cylinder, a third input end face that protrudes outward and is disposed at the input end of the third elliptical cylinder, and a third output end face that is disposed at the output end of the third elliptical cylinder. The three together enclose a second collection cavity. Among them, a third input channel with a length of 3 mm is provided in the middle of the third input end face. The third input channel is in the shape of a cuboid with dimensions of 14 mm * 14 mm, and the input end of the third input channel extends into the second output port. Along the electron beam input direction, the second collection cavity smoothly changes from the output end of the third input channel to an elliptical inner wall (the length of this gradual change section is 4 mm, the major axis of the elliptical inner wall is 22 mm, and the minor axis is 17.6 mm), then gradually changes through a transition section with a length of 8.4 mm to a circular inner wall with a radius of 17.6 mm, and finally connects to a hemispherical inner wall with a radius of 17.6 mm. A conical structure that protrudes in the electron input direction is provided in the middle of the hemispherical inner wall. The height of the conical structure is 35 mm, the bottom radius is 8.5 mm, and the top angle of the conical structure is provided with a rounded corner to prevent tip arcing. The hemispherical inner wall can increase the electron collection area, reduce the power dissipation density, and thus reduce the temperature. The conical structure can further increase the electron collection area, reduce the generation of secondary electrons, and at the same time form a radial electric field with the second-stage collector assembly, increasing the radial force received by the electron beam, so that the electron beam diffuses faster radially and the power dissipation density is uniform.

Claims

1. An elliptical three-stage step-down collector, characterized in that: include: An oval metal outer cylinder with heat dissipation fins; An elliptical ceramic inner cylinder disposed in the metal outer cylinder; A first-stage collector assembly, a second-stage collector assembly, and a third-stage collector assembly are located inside the ceramic inner cylinder and are sequentially distributed along the axial direction; The first-stage collector assembly includes: a first elliptical cylinder, a first input end surface disposed at the input end of the first elliptical cylinder and convex inwardly, and a first output end surface disposed at the output end of the first elliptical cylinder and convex outwardly, the three together enclose a first collecting cavity; wherein a first input channel is disposed in the middle of the first input end surface for injecting a band-shaped electron beam; a smooth curved groove is disposed on the outer side of the first input channel; and a first output port is disposed in the middle of the first output end surface; The second-stage collector assembly includes: a second elliptical cylinder, a second input end surface disposed at the input end of the second elliptical cylinder and convex inwardly, and a second output end surface disposed at the output end of the second elliptical cylinder and convex outwardly, the three together enclosing a second collecting chamber; wherein a second input channel is disposed in the middle of the second input end surface, and the input end of the second input channel extends into the first output port; and a second output port is disposed in the middle of the second output end surface; The third-stage collector assembly includes: a third elliptical cylinder, a third input end face which is arranged at the input end of the third elliptical cylinder and protrudes outward, and a third output end face which is arranged at the output end of the third elliptical cylinder, and the three together form a second collecting chamber; wherein a third input channel is arranged in the middle of the third input end face, and the input end of the third input channel extends into the second output port; along the electron injection input direction, the second collecting chamber first smoothly changes into an elliptical inner wall from the output end of the third input channel, and then changes into a circular inner wall through a transition section, and finally connects to a hemispherical inner wall; a conical structure which protrudes toward the electron input direction is arranged in the middle of the hemispherical inner wall.

2. An elliptical three-stage step-down collector as claimed in claim 1, characterized in that: The ceramic inner cylinder is divided into a first ceramic inner cylinder section and a second ceramic inner cylinder section, and a gap is provided between the two sections; the first-stage collector assembly and the second-stage collector assembly are located in the first ceramic inner cylinder section, and the third-stage collector assembly is located in the second ceramic inner cylinder section.

3. An elliptical three-stage step-down collector as claimed in claim 2, characterized in that: One end of the second ceramic inner tube segment close to the first ceramic inner tube segment protrudes toward the central axis with a ring structure, which is used to isolate the electric field between the second collector assembly and the third collector assembly.

4. An elliptical three-stage step-down collector as claimed in claim 3, characterized in that: The first input channel is in the shape of a cuboid, and the channel aperture matches the strip electron beam; the second input channel and the third input channel are in the shape of a cuboid, and the output end face aperture of the second input channel is smaller than the input end face aperture of the third input channel; the opening shapes of the first output port and the second output port are rectangular.

5. An elliptical three-stage step-down collector as claimed in claim 4, characterized in that: The heat dissipation fins are evenly distributed along the circumference, and the length is the same as the length of the metal outer tube; at the same time, cooling water is used to dissipate heat from the heat dissipation fins.

6. An elliptical three-stage step-down collector as described in claim 4 or 5, wherein the top corners of the conical structure are rounded to prevent sparks at the tip.

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