Traveling wave tube output coupling system and traveling wave tube

Abstract

The present invention provides a traveling wave tube output coupling system and a traveling wave tube. The traveling wave tube output coupling system includes an output waveguide and an adapter connected to the output waveguide. The adapter defines a channel extending axially therethrough. The inner wall of the channel includes a first transition slope. The inner wall of the output waveguide includes a second transition slope. The first and second transition slopes connect to provide a smooth and gradual transition between the inner wall of the output waveguide and the inner wall of the channel. The inner wall of the output waveguide includes a stepped waveguide transmission structure arranged along the waveguide transmission direction. The stepped waveguide transmission structure extends into the adapter channel. The output coupling system also includes an energy transmission inner conductor arranged along the waveguide transmission direction. The energy transmission inner conductor passes through the channel and is fixedly coupled to the end of the stepped waveguide transmission structure. This output coupling system can achieve impedance matching, improve the transmission performance of the output coupling system, and reduce the standing wave ratio.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave vacuum electronic devices, and more particularly to a traveling wave tube output coupling system and a traveling wave tube. Background Art

[0002] In the traveling wave tube, the signal propagates along the spiral line in the high-frequency system, interacts with the electron beam to complete power amplification, and the amplified signal is output to the outside of the traveling wave tube through the output coupling system. When the output coupling system is fully matched with the high-frequency system, all energy is effectively transmitted and there is no reflected signal. At this time, the standing wave ratio, a parameter that measures the reflection and transmission performance in the line, is 1. The larger the value of the standing wave ratio, the more severe the reflection and the worse the transmission performance, resulting in a smaller output power of the traveling wave tube. The design of the output coupling system is to ensure that the standing wave ratio is as small as possible within a sufficiently wide frequency band, and that it can withstand a large power, has a solid structure, and good welding consistency. The conventional output coupling system of the traveling wave tube is assembled from four parts: waveguide flange 1, waveguide 2, energy transmission inner conductor 3, and waveguide converter 4. The high-frequency system is mainly composed of parts such as tee 5, pole shoe 6, heat conducting plate 7, spiral line 8, etc. Figure 1-Figure 3 As shown in the figure, in the output coupling system, the chassis of the waveguide converter 4 is welded to the waveguide 2, and the other end is connected to the tee 5. One end of the energy transmission inner conductor 8 is connected to the waveguide 2, and the other end is connected to the helix, achieving power coupling output. However, its disadvantages are that its structure uses a coaxial conversion method using a tee, and the waveguide converter 4 converts from coaxial to waveguide. The system's standing wave ratio is between 1.62 and 1.77, and the reflected power accounts for 5.6% to 7.7% of the total power entering the output coupling system. The greater the TWT output power, the greater the reflected power. Furthermore, the reflected power causes the helix near the output end to heat up, increasing helix losses and reducing the TWT output power. Summary of the Invention

[0003] In view of the above problems, the present invention provides a traveling wave tube output coupling system that can achieve impedance matching, improve the transmission performance of the output coupling system, and reduce the standing wave ratio.

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

[0005] The present invention provides a traveling wave tube output coupling system, comprising:

[0006] An output waveguide and an adapter connected to the output waveguide;

[0007] The adapter is provided with a channel extending through the adapter along its own axis; the inner wall of the channel includes a first transition slope; the inner wall of the output waveguide includes a second transition slope; the first transition slope and the second transition slope are connected to form a smooth and gradual transition between the inner wall of the output waveguide and the inner wall of the channel;

[0008] The inner wall of the output waveguide includes a stepped waveguide transmission structure arranged along the waveguide transmission direction; the stepped waveguide transmission structure extends into the adapter channel;

[0009] The output coupling system further comprises an energy transmission inner conductor arranged along the waveguide transmission direction;

[0010] The energy transmission inner conductor is arranged in the hole and is fixedly connected to the end of the stepped waveguide transmission structure.

[0011] A preferred embodiment is that the adapter includes a round-to-square structure; the round-to-square structure includes a circular opening for the energy transmission inner conductor to pass through and a rectangular opening for connecting to the output waveguide; the first transition slope is formed between the circular opening and the rectangular opening; the first transition slope is an annular slope and gradually increases toward the inner diameter of the output waveguide.

[0012] A preferred solution is that the adapter also includes an annular matching structure connected to the round-to-square structure; the annular matching structure includes a channel connected to the hole, the axis of the channel is perpendicular to the axis of the hole, and the end of the energy transmission inner conductor extends into the channel.

[0013] Preferably, the second transition slope is an annular slope whose inner diameter gradually decreases toward the adapter.

[0014] A preferred solution is that the first transition slope is formed by smoothly connecting a straight slope and a curved surface; the second transition slope includes a straight slope; and the first transition slope and the second transition slope have the same slope.

[0015] A preferred solution is that the operating frequency band of the traveling wave tube output coupling system is the Ka band.

[0016] A preferred solution is that the end portion of the adapter having the rectangular opening is inserted into the output waveguide and fixed to the output waveguide by welding.

[0017] The present invention also provides a traveling wave tube, which includes the traveling wave tube output coupling system described above.

[0018] A preferred solution is that the traveling wave tube further includes a mating pole shoe for mating with the traveling wave tube output coupling system; the traveling wave tube output coupling system is arranged between the two mating pole shoes; and both mating pole shoes include a welding plane for welding with the output waveguide and a welding groove for welding with the adapter.

[0019] A preferred solution is that the traveling wave tube output coupling system also includes a connector, which includes an annular fixing plate fixed to the output waveguide and a connecting structure arranged on the annular fixing plate; the connecting structure is contoured to the mating pole shoe and fixed to the outer circle of the mating pole shoe.

[0020] The beneficial effects of the present invention are:

[0021] The inner wall of the output waveguide of the present invention forms a smooth and gradual transition with the inner wall of the channel, and a combination of linear impedance transformation on a transition slope and multi-stage stepped impedance transformation is used to achieve impedance matching, improve the transmission performance of the output coupling system, and reduce the standing wave ratio. The present invention eliminates the waveguide converter used in the prior art, and the stepped waveguide transmission structure extends into the adapter, shortening the length of the adapter and the energy transmission inner conductor, reducing the length of the entire output coupling system in the width direction of the traveling wave tube, and further compressing the outer dimensions of the traveling wave tube in the width direction. Because the waveguide converter is made of nickel-copper material with poor thermal conductivity, when the continuous wave output power of the Ka-band helical traveling wave tube reaches above 400W, the maximum surface temperature of the high-frequency system exceeds 100°C, which is very detrimental to the stable operation of the traveling wave tube. The present invention adopts a method of direct contact welding of the output waveguide to the adapter and the matching pole shoes on both sides of the adapter, which opens up a heat dissipation path, increases the welding contact area, and improves thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the coordination between the conventional output coupling system and the high-frequency system.

[0024] Figure 2 yes Figure 1 Schematic diagram of the structure of the middle three-way.

[0025] Figure 3 yes Figure 1 Vertical cross-section of .

[0026] Figure 4 It is a schematic diagram of the coordination between the output coupling system and the high-frequency system of the present invention.

[0027] Figure 5 yes Figure 4 Vertical cross-section of .

[0028] Figure 6 yes Figure 4 Schematic diagram of the structure of the intermediate connection component.

[0029] Figure 7 yes Figure 4 Schematic diagram of the structure of the matching pole shoe.

[0030] Figure 8 yes Figure 4 Schematic diagram of the structure of the connecting parts.

[0031] Figure 9 This is a diagram showing the standing wave ratio test after the output coupling system of the present invention and the high-frequency system are assembled.

[0032] Figure 10 This is a comparison diagram of the output powers of a traveling wave tube (TWT #8) using a conventional output coupling system and a traveling wave tube (TWT #9) using the output coupling system of the present invention. DETAILED DESCRIPTION

[0033] 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 of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0038] The conventional material of the waveguide conversion head 4 is nickel-copper alloy, and the thermal conductivity at room temperature is 91.7W / (m*k). As the temperature rises, the thermal conductivity gradually decreases. When the traveling wave tube outputs high power, the power is maximum near the tee 5 in the output section. The energy of high-frequency defocusing and high-frequency loss is almost concentrated in this area, which is also the part with the highest temperature in the entire high-frequency structure. When the temperature is too high, the heat in this area is difficult to be discharged, which will produce a vicious cycle and cause the helix 8 to burn out at the output end. If the waveguide conversion head 4 is directly changed to oxygen-free copper material with a thermal conductivity 3-4 times higher than that of nickel-copper alloy, since the waveguide 2 is made of oxygen-free copper, during laser welding, due to the high thermal conductivity of copper material, copper-copper laser welding can hardly reach the welding temperature and is almost impossible to weld. When assembling the conventional output coupling system, the waveguide 2 is first laser welded to the square end of the waveguide conversion head 4, and then the cylindrical end of the waveguide conversion head 4 is laser welded to the tee 5. Regarding welding, due to the large size of the waveguide, the tee 5 needs to be designed as a long cylindrical structure, and a certain gap must be maintained between the waveguide 2, the waveguide converter 4 and the pole shoe 6 to avoid affecting the installation of the magnetic steel between the pole shoes. This creates a "bottleneck" between the high-frequency system and the output coupling system, that is, the size of the connection between the two is smaller than that of the high-frequency system and the output coupling system. In addition, the outer diameter of the tee 5 is usually small, generally a few millimeters. During laser welding, the output coupling system and the traveling wave tube high-frequency system need to be held by hand, which is inconvenient to operate and can easily affect the docking effect due to external force. After the entire output coupling system and the traveling wave tube high-frequency system are fixed by laser welding, they need to be placed in a hydrogen furnace for final welding. When the output coupling system is long and heavy, it is very easy to cause welding deformation at the high temperature of 800℃-900℃ after entering the furnace, affecting the transmission performance between the traveling wave tube high-frequency system and the output coupling system, resulting in poor standing wave ratio and welding consistency.

[0039] In order to solve the above problems, the present invention provides a traveling wave tube output coupling system, combined with Figures 1 to 10 As shown, the traveling wave tube output coupling system specifically includes: an output waveguide 20 and an adapter 30 connected to the output waveguide 20; the adapter 30 is provided with a channel 321 extending through the adapter 30 along its own axial direction; the inner wall of the channel 321 includes a first transition slope 31; the inner wall of the output waveguide 20 includes a second transition slope 21; the first transition slope 31 and the second transition slope 21 are connected to each other to achieve a smooth and gradual transition between the inner wall of the output waveguide 20 and the inner wall of the channel 321; the inner wall of the output waveguide 20 includes a stepped waveguide transmission structure 22 arranged along the waveguide transmission direction; the lower end of the stepped waveguide transmission structure 22 extends into the channel 321 of the adapter 30; the output coupling system also includes an energy transmission inner conductor 40 arranged along the waveguide transmission direction; the waveguide transmission direction is the same as the axial direction of the adapter 30 itself; the energy transmission inner conductor 40 is arranged in the channel 321 and is fixed to the lower end of the stepped waveguide transmission structure 22.

[0040] The present invention achieves a smooth transition between the interior of the adapter 30 and the interior of the output waveguide 20 by designing a transition slope, and adopts a combination of linear impedance transformation and multi-stage stepped impedance transformation to achieve impedance matching, improve the transmission performance of the output coupling system, and reduce the standing wave ratio. The present invention removes the conventional waveguide conversion head and changes the stepped waveguide transmission structure 22 connecting the output waveguide and the energy transmission inner conductor from an embedded type to extend outside the output waveguide 20 and into the interior of the adapter 30, thereby shortening the length of the adapter 30 and the energy transmission inner conductor 40. The size of the entire output coupling system in the width direction of the traveling wave tube is reduced, and the width dimension of the traveling wave tube is further compressed. Because the waveguide conversion head is made of nickel-copper material with poor thermal conductivity, when the continuous wave output power of the Ka-band helical traveling wave tube reaches above 400W, the maximum surface temperature of the high-frequency system exceeds 100°C, which is very detrimental to the stable operation of the traveling wave tube. The output coupling system provided by the present invention opens up a heat dissipation path, increases the welding contact area, and improves thermal conductivity.

[0041] In the above embodiment, the adapter 30 is coaxially arranged with the output waveguide 20 and the energy transmission inner conductor 40; the adapter 30 includes a round-to-square structure 32 and an annular matching structure 33 fixedly connected to the round-to-square structure 32; the round-to-square structure 32 includes a circular opening for the energy transmission inner conductor 40 to pass through and a rectangular opening for connecting to the output waveguide; the circular opening is coaxial with the rectangular opening, and the cross-sectional area of ​​the rectangular opening is larger than the cross-sectional area of ​​the circular opening; in this embodiment, the axial direction of the round-to-square structure 32 is defined as the axial direction of the adapter 30, the axis of the round-to-square structure 32 and the axis of the annular matching structure 33 are perpendicular to each other, and the two are integrally formed. It can be understood that the annular matching structure 33 is a conventional structure commonly used for connecting and matching high-frequency systems, and the annular matching structure 33 is The channel 331 is connected to the circular opening of the round-to-square structure 32, and the axis of the channel 331 is perpendicular to the axis of the channel 321. The lower end of the energy transmission inner conductor 40 extends into the channel 331; the first transition slope 31 is formed between the circular opening and the rectangular opening; the first transition slope 31 is an annular slope and its inner diameter gradually increases toward the output waveguide 20. The circular opening allows the energy transmission inner conductor 40 to pass through and enter the channel 331 to connect with the helical slow-wave structure 72 of the high-frequency system. The annular matching structure 33 formed below the circular opening serves as a partial tube shell to match the high-frequency system and realize the connection with the high-frequency system; the second transition slope 21 is an annular slope whose inner diameter gradually decreases toward the adapter 30 to cooperate with the first transition slope 31 to achieve a smooth and gradual transition between the inner cavities of the two. The first transition bevel 31 has the same slope as the second transition bevel 21. The first transition bevel 31 is formed by four straight bevels and four curved surfaces smoothly connected, and the straight bevels and curved surfaces enclose a channel 321. The second transition bevel 21 includes four straight bevels. The four straight bevels of the first transition bevel 31 are connected to the four straight bevels of the second transition bevel 21 in a one-to-one correspondence. The straight bevels of the first transition bevel 31 and the straight bevels of the connected second transition bevel 21 have the same slope, thereby achieving a better matching effect. The adapter 30 and the output waveguide 20 are both made of oxygen-free copper. The operating frequency band of the traveling wave tube output coupling system is the Ka band. The traveling wave tube with the output coupling system of the present application can avoid the situation where the helix burns at the output end when operating in the Ka band.

[0042] The present invention further provides a traveling wave tube (TWT), comprising the TWT output coupling system described above. The TWT further comprises a mating pole piece 71 for mating with the TWT output coupling system; the TWT output coupling system is disposed between two mating pole pieces 71; each mating pole piece 71 comprises a welding plane 51 for welding to the output waveguide and a welding groove 52 for welding to the adapter 30; the TWT output coupling system further comprises a connector 60, comprising an annular fixing plate 61 fixed to the output waveguide 20 and a connecting structure 62 disposed on the annular fixing plate 61; the connecting structure 62 is configured to conform to the mating pole piece 71 and is fixed to the outer circumference of the mating pole piece 71. Specifically, the annular fixing plate 61 and the connecting structure 62 are a laser welding adapter plate and a laser welding fixing frame respectively. The connecting structure 62 includes four connecting claws 621, and a matching pole shoe 71 is fixed to the two connecting claws 621 on the same side. The present invention designs corresponding matching laser welding adapter plates and laser welding fixing frames. After the flange 10 and the output waveguide 20 are assembled, the laser welding adapter plate is fixed to the output waveguide 20, and then the laser welding fixing frame is installed to connect the laser welding adapter plate, and the laser welding fixing frame is connected to the matching pole shoes 71 on both sides of the adapter 30, thereby avoiding the "bottleneck" connection state between the output coupling system and the high-frequency system and improving the structural strength.

[0043] In a specific embodiment, in order to achieve high-power stable output of the traveling wave tube, an integrated round-to-square structure adapter 30 is designed, so that its interior is transitioned from a cylindrical cavity with a diameter of 1.8 mm to a rectangular opening with a length of 4 mm and a width of 3 mm. The rectangular opening is docked with the output waveguide 20, and the end of the adapter 30 with the rectangular opening is inserted into the output waveguide 20 and welded to the output waveguide 30, and the transition slope is used to achieve a smooth and gradual transition of the internal cavities of the two. Finally, the inner cavity of the output waveguide 20 transitions to the standard waveguide size; the stepped waveguide transmission structure 22 connecting the output waveguide 20 and the energy transmission inner conductor 40 extends out of the output waveguide 20 and is directly embedded in the adapter 30; the upper part of the output waveguide 20 is a flange 10 that is convenient for welding. The output coupling system reduces the effects of poor transmission performance and high standing wave ratio (SWR) caused by impedance mismatch, thereby improving transmission performance. A step 34 is designed on the outer side of the adapter 30, allowing the adapter 30 to fit into the weld groove 52 on the inner wall surface of the two mating pole shoes 71 on either side. The top of the mating pole shoes 71 is flattened to connect to the output waveguide 20, ensuring full contact between the output waveguide 20, the integrated circular adapter 30, and the two mating pole shoes 71. A laser-welded adapter plate is placed on the outer ring of the lower end of the output waveguide 20, and a laser-welded fixture is installed below the laser-welded adapter plate. The four connecting legs of the laser-welded fixture are connected to the two mating pole shoes 71 and secured by laser welding, significantly improving the contact area and structural strength of the entire structure. This output coupling system has a low SWR, high power capacity, and enhanced structural strength and welding consistency.

[0044] Further, combined Figure 9 As shown, under the same design parameters and structural dimensions, and the same labor, assembly, and welding conditions, multiple traveling wave tubes (1#-7#) provided by the present invention were tested using a test instrument. The final standing wave ratio was basically controlled between 1.43 and 1.47. Compared with traveling wave tubes with conventional output coupling systems (standing wave ratio of 1.62-1.77), the assembly consistency of the present invention is greatly improved, the transmission performance is also improved, and the reflected power is reduced by nearly 50%. The output coupling system provided by the present invention can reduce the length of the adapter 30 from 12mm in a conventional tee to 8.5mm, the length of the energy transmission inner conductor 40 from 12.4mm to 9.6mm, and the length of the entire output coupling system in the width direction of the traveling wave tube from 30.5mm to 23.6mm, which is conducive to miniaturization. The adapter 30 and the output waveguide 20 are directly connected by embedding, and are in full contact with the inner side and the upper top plane of the matching pole shoe 71. The four connecting legs of the laser welding fixture are connected to the two matching pole shoes 71 respectively, so that the contact area between the entire output coupling system and the high-frequency system is reduced from 87.3mm 2 Increased to 126mm 2, effectively improving the heat dissipation capacity and power capacity of the high-frequency output section of the traveling wave tube and the output coupling system; the laser welding adapter plate and laser welding fixing frame, as well as the output waveguide 20, the adapter 30 and the matching pole shoe 71 are all welded by laser welding, which reduces the difficulty of welding operation, avoids the "bottleneck" connection state between the output coupling system and the high-frequency system, and improves the structural strength.

[0045] Further, refer to Figure 10 As shown, under the same design parameters, environment, and test conditions, a comparative test was conducted on two sample traveling wave tubes (TWT #8) using a conventional output coupling system and a TWT #9 using the output coupling system of the present invention. When power was first applied, the output power of TWT #9 was 11W higher than that of TWT #8. After one hour of operation, the entire system under test reached thermal equilibrium. The maximum surface temperature of the high-frequency system was measured at 117°C for TWT #8 and 92°C for TWT #9 at the same location. As the operating time increased, the output power of TWT #8 gradually decreased, becoming increasingly noticeable, while the output power of TWT #9 remained stable with minimal fluctuations. The present invention increases the output power of the TWT, effectively reduces the maximum operating temperature of the TWT, avoids various adverse effects caused by excessive temperature, improves the reliability of the TWT, and facilitates long-life operation.

[0046] The specific assembly steps of the present invention are as follows: first, insert the upper end of the output waveguide 20 into the flange 10 and ensure alignment; install the laser welding adapter plate, and fix the contact surface of the output waveguide 20 and the laser welding adapter plate by laser welding; install the laser welding fixing frame, and fix it to the laser welding adapter plate by laser welding; install the energy transmission inner conductor 40; after the entire output coupling system completes the process assembly, it is then docked with the welded high-frequency system, and the energy transmission inner conductor 40 is laser welded to the spiral slow-wave structure 72 in the high-frequency system; and the four connecting legs of the laser welding fixing frame are respectively docked with the matching pole shoes 71 on both sides of the adapter 30, and fixed by laser welding; finally, solder wire is placed on the contact surface of each part and put into the hydrogen furnace for brazing.

[0047] In summary, the inner wall of the output waveguide of the present invention forms a smooth and gradual transition with the inner wall of the channel, and a combination of linear impedance transformation on a transition slope and multi-stage stepped impedance transformation is used to achieve impedance matching, improve the transmission performance of the output coupling system, and reduce the standing wave ratio. The present invention eliminates the waveguide converter used in the prior art, and the stepped waveguide transmission structure extends into the adapter, shortening the length of the adapter and the energy transmission inner conductor, thereby reducing the length of the entire output coupling system in the width direction of the traveling wave tube and further compressing the outer dimensions of the traveling wave tube in the width direction. Since the waveguide converter is made of nickel-copper material with poor thermal conductivity, when the continuous wave output power of the Ka-band helical traveling wave tube reaches above 400W, the maximum surface temperature of the high-frequency system exceeds 100°C, which is very detrimental to the stable operation of the traveling wave tube. The present invention adopts the form of direct contact welding of the output waveguide with the adapter and the matching pole shoes on both sides of the adapter, which opens up a heat dissipation path, increases the welding contact area, and improves thermal conductivity.

[0048] 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 scope of protection of the present invention.

Claims

1. A traveling wave tube output coupling system, characterized in that: include: An output waveguide and an adapter connected to the output waveguide; The adapter is provided with a channel extending through the adapter along its own axis; the inner wall of the channel includes a first transition slope; the inner wall of the output waveguide includes a second transition slope; the first transition slope and the second transition slope are connected to form a smooth and gradual transition between the inner wall of the output waveguide and the inner wall of the channel; The inner wall of the output waveguide includes a stepped waveguide transmission structure arranged along the waveguide transmission direction; the stepped waveguide transmission structure extends into the adapter channel; The output coupling system further comprises an energy transmission inner conductor arranged along the waveguide transmission direction; The energy transmission inner conductor is arranged in the hole and is fixedly connected to the end of the stepped waveguide transmission structure.

2. The traveling wave tube output coupling system according to claim 1, characterized in that: The adapter includes a round-to-square structure; the round-to-square structure includes a circular opening for the energy transmission inner conductor to pass through and a rectangular opening for connecting to the output waveguide; the first transition slope is formed between the circular opening and the rectangular opening; the first transition slope is an annular slope and gradually increases toward the inner diameter of the output waveguide.

3. The traveling wave tube output coupling system according to claim 2, characterized in that: The adapter also includes an annular matching structure connected to the round-to-square structure; the annular matching structure includes a channel connected to the hole, the axis of the channel is perpendicular to the axis of the hole, and the end of the energy transmission inner conductor extends into the channel.

4. The traveling wave tube output coupling system according to claim 1, characterized in that: The second transition slope is an annular slope that gradually decreases toward the inner diameter of the adapter.

5. The traveling wave tube output coupling system according to claim 1, characterized in that: The first transition slope is formed by smoothly connecting a straight slope and a curved surface; the second transition slope includes a straight slope; and the first transition slope has the same slope as the second transition slope.

6. The traveling wave tube output coupling system according to claim 1, characterized in that: The operating frequency band of the traveling wave tube output coupling system is the Ka band.

7. The traveling wave tube output coupling system according to claim 2, characterized in that: The end portion of the adapter with the rectangular opening is inserted into the output waveguide and fixed to the output waveguide by welding.

8. A traveling wave tube, characterized in that: The traveling wave tube output coupling system comprises the traveling wave tube output coupling system according to any one of claims 1 to 7.

9. The traveling wave tube according to claim 8, characterized in that The traveling wave tube also includes a matching pole shoe for matching with the traveling wave tube output coupling system; the traveling wave tube output coupling system is arranged between the two matching pole shoes; the two matching pole shoes both include a welding plane for welding with the output waveguide and a welding groove for welding with the adapter.

10. The traveling wave tube according to claim 9, characterized in that: The traveling wave tube output coupling system also includes a connector, which includes an annular fixing plate fixed to the output waveguide and a connecting structure arranged on the annular fixing plate; the connecting structure is configured to imitate the matching pole shoe and is fixed to the outer circle of the matching pole shoe.

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