Electron gun for terahertz traveling wave tube and traveling wave tube

Abstract

The invention provides an electron gun for a terahertz traveling wave tube and the traveling wave tube. The electron gun comprises an anode piece; the focusing electrode piece is positioned in the anode piece; the outer insulating ceramic ring is positioned between the anode piece and the focusing pole piece; the cathode piece is positioned in the focusing electrode piece; the inner insulating ceramic ring is positioned between the cathode piece and the focusing pole piece; the anode piece, the focusing pole piece and the cathode piece are all made of non-magnetic metal materials. Stress release structures are formed at the sealing part of the focusing electrode piece and the outer insulating ceramic ring and the sealing part of the cathode piece and the inner insulating ceramic ring; the stress release structure is configured to release tensile stress formed in the sealing process due to the difference of thermal expansion coefficients of different materials by changing the geometrical shape of the corresponding sealing position.

Description

Technical Field

[0001] This invention relates to the field of microwave vacuum electronics technology. More specifically, it relates to an electron gun and a traveling wave tube for use in a terahertz traveling wave tube. Background Technology

[0002] Traveling wave tubes (TWTs) possess advantages such as high frequency, high power, high efficiency, wide bandwidth, and high gain, and are widely used in radar, satellites, and electronic warfare. However, for potential applications such as secure communication and high-speed communication, even higher frequency TWTs are required as technical support. The electron gun is a key component of these devices, used to generate an electron beam that meets the application requirements.

[0003] Due to the thermal initial velocity effect, terahertz traveling wave tubes (TWBs) operating at frequencies above 0.1 THz require an immersion flow electron optical system, meaning the entire electron gun must be placed within a uniform permanent magnet focusing magnetic field. Without this focusing method, the radius of the converged electron beam would increase, especially at higher TWB operating frequencies, affecting throughput and ultimately reducing output power. However, the magnetic sealing metal materials commonly used in current electron guns interfere with the uniform magnetic field after the electron gun is placed within it, further reducing the TWB's output power. Summary of the Invention

[0004] The purpose of this invention is to provide an electron gun and a traveling wave tube for a terahertz traveling wave tube, so as to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides an electron gun for a terahertz traveling wave tube, comprising: Anode components; A focusing electrode located inside the anode component; The outer insulating ceramic ring is located between the anode and the focusing electrode; The cathode element located inside the focusing electrode; And the inner insulating ceramic ring located between the cathode and the focusing electrode; The anode, focusing electrode, and cathode are all made of non-magnetic metal materials. The sealing joints between the focusing electrode and the outer insulating ceramic ring, and between the cathode and the inner insulating ceramic ring, are all equipped with stress-relieving structures. The stress relief structure is configured to release tensile stress formed during the sealing process due to the difference in thermal expansion coefficients of different materials by changing the geometry of the corresponding sealing joint.

[0006] A preferred embodiment is that the stress relief structure includes a first stress relief structure formed at the sealing junction of the focusing electrode and the outer insulating ceramic ring, and a second stress relief structure formed at the sealing junction of the cathode and the inner insulating ceramic ring.

[0007] A preferred embodiment is that a first chamfer, which is annular and coaxially arranged with the outer insulating ceramic ring, is formed on the inner peripheral edge of the outer insulating ceramic ring; the first chamfer is symmetrically formed at both ends of the outer insulating ceramic ring along the electron beam transmission direction; a first annular boss is formed on the outer peripheral surface of the focusing electrode, which corresponds to and mates with the inner peripheral surface of the outer insulating ceramic ring; the inner peripheral surface of the outer insulating ceramic ring and the first annular boss mate to form a first stress relief structure; The inner circumferential surface of the inner insulating ceramic ring has a second chamfer that is annular and coaxially arranged with the inner insulating ceramic ring. The second chamfer is symmetrically formed at both ends of the inner insulating ceramic ring along the electron beam transmission direction. The outer circumferential surface of the cathode has a second annular boss that corresponds to and mates with the inner circumferential surface of the inner insulating ceramic ring. The inner circumferential surface of the inner insulating ceramic ring and the second annular boss mate to form a second stress relief structure.

[0008] In a preferred embodiment, the inner circumferential surface of the outer insulating ceramic ring is fitted and sealed to the outer circumferential surface of the first annular protrusion, and the length of the inner circumferential surface of the outer insulating ceramic ring in the electron beam transmission direction is less than that of the outer circumferential surface; the inner circumferential surface of the inner insulating ceramic ring is fitted and sealed to the outer circumferential surface of the second annular protrusion, and the length of the inner circumferential surface of the inner insulating ceramic ring in the electron beam transmission direction is less than that of the outer circumferential surface.

[0009] In a preferred embodiment, the first chamfer and the second chamfer are both inclined surfaces forming a 45-degree angle with the surface of the corresponding insulating ceramic ring, and the cross-sections of the first annular boss and the second annular boss are both rectangular.

[0010] In a preferred embodiment, the length of the inner circumferential surface of the outer insulating ceramic ring in the electron beam transmission direction is equal to the length of the first annular protrusion in the electron beam transmission direction; and the length of the inner circumferential surface of the inner insulating ceramic ring in the electron beam transmission direction is equal to the length of the second annular protrusion in the electron beam transmission direction.

[0011] In a preferred embodiment, the thickness of the first annular boss and the second annular boss are both in the range of 0.25~0.42mm in the direction perpendicular to the electron beam transmission direction, and the length of the hypotenuse corresponding to the first chamfer and the second chamfer are both in the range of 1.06~1.77mm.

[0012] The preferred solution is that, for the same stress-relief structure, the length of the bevel corresponding to the chamfer is 4.24 times the thickness of the annular boss.

[0013] The present invention also provides a traveling wave tube comprising an electron gun as described above.

[0014] The preferred embodiment is that the operating frequency range of the traveling wave tube is above 0.1THz; the traveling wave tube further includes a slow wave circuit, a collecting electrode, a uniform permanent magnet focusing system and a titanium pump, wherein the electron gun, the slow wave circuit, the collecting electrode and the titanium pump are arranged sequentially along the axial direction of the uniform permanent magnet focusing system, and the uniform permanent magnet focusing system is arranged around the electron gun, the slow wave circuit and the collecting electrode.

[0015] The beneficial effects of this invention are as follows: This invention provides an electron gun for a terahertz traveling wave tube, comprising an anode; a focusing electrode located inside the anode; an outer insulating ceramic ring located between the anode and the focusing electrode; a cathode located inside the focusing electrode; and an inner insulating ceramic ring located between the cathode and the focusing electrode to fix them relatively in place. The anode, focusing electrode, and cathode are all made of non-magnetic metal. Stress relief structures are formed at the sealing points of the focusing electrode and the outer insulating ceramic ring, and at the sealing points of the cathode and the inner insulating ceramic ring. These stress relief structures are configured to release tensile stress generated during the sealing process due to differences in the thermal expansion coefficients of the different materials by changing the geometry of the corresponding sealing points. The core advantage of this invention lies in the coordinated structural design of the sealing interfaces between the inner and outer insulating ceramic rings and the non-magnetic metal focusing and cathode components to form stress relief structures. This allows for the release of tensile stress generated during the sealing process due to differences in the thermal expansion coefficients of the different materials by changing the geometry of the corresponding sealing interfaces, without altering the performance of the electron gun. This invention successfully resolved the core contradiction between the stringent requirements of immersion flow electron optics systems for a non-magnetic environment and the mismatch in the thermal expansion coefficients of materials. This made the manufacture of high-performance, high-reliability non-magnetic electron guns a reality, ensuring that the magnetic flux density and electron beam focusing ability of the traveling wave tube (TWT) magnetic focusing system remained unaffected, thereby increasing the TWT's output power. The electron gun of this invention has strong versatility, applicable not only to various TWTs employing immersion flow systems but also to all high-power microwave devices sensitive to magnetization and requiring electron guns, greatly expanding its applicability. Attached Figure Description

[0016] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0017] Figure 1 This is a schematic diagram of an existing electron gun.

[0018] Figure 2 This is a schematic diagram showing a crack in the insulating ceramic ring of an existing electron gun.

[0019] Figure 3 This is a schematic diagram of the electron gun of the present invention.

[0020] Figure 4This is a partially enlarged view of the electron gun of the present invention.

[0021] Figure 5 This is a schematic diagram of the traveling wave tube structure of the present invention. Detailed Implementation

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] In existing electron gun packaging processes, such as Figure 1As shown, the existing electron gun includes an anode 101, a focusing electrode 102, a cathode 103, a first insulating support 104, and a second insulating support 105. The first insulating support 104 and the second insulating support 105 need to be hermetically sealed with these metal components (anode 101, focusing electrode 102, and cathode 103) through high-temperature brazing. While the ceramic sealing metal commonly used in vacuum devices has a thermal expansion coefficient that matches alumina ceramic well at high temperatures, it is itself magnetic. This type of magnetic material not only interferes with the positioning and fixation of the traveling wave tube during testing but also interferes with the magnetic focusing system, weakening the effective magnetic field strength, thereby affecting the electron beam's focusing ability and reducing device performance. More specifically, under existing ceramic-metal sealing technology, the electron gun components inside the magnet, due to the metal's magnetism, not only affect the fixation of the traveling wave tube during testing but also weaken the magnetic induction intensity of the magnetic focusing system, thus weakening the electron beam's focusing ability. For example, when the traveling wave tube operates at 1 THz, the radius of the focused electron beam increases from 0.012 mm to over 0.02 mm, an increase of more than 67%. The electron beam channel diameter of slow-wave structures above 1THz is only 0.046mm. If assembly errors are included, the enlargement of the electron beam will affect its throughput, which in turn affects the beam-wave interaction and ultimately the output power.

[0028] Therefore, to meet the application requirement of a completely non-magnetic interior for the traveling wave tube magnet, the original magnetic metal in the electron gun must be replaced with a non-magnetic metal. However, the coefficient of thermal expansion of the non-magnetic metal at high temperatures is typically 1.5 to 2 times that of alumina ceramic. During cooling, because the shrinkage of the non-magnetic metal is much greater than that of the ceramic, significant tensile stress will be generated at the interface with the ceramic ring, leading to cracking of the ceramic ring. In other words, the mismatch in the coefficients of thermal expansion between the ceramic and the non-magnetic metal during cooling can cause excessively high encapsulation tensile stress and cracking of the ceramic ring. Figure 2 The area circled in red in the diagram indicates the location of the ceramic crack. Based on the above description, this invention provides an electron gun for a terahertz traveling wave tube, combined with... Figures 1 to 5As shown, the electron gun for a terahertz traveling wave tube specifically includes: an anode 1; a focusing electrode 2 located inside the anode 1; an outer insulating ceramic ring 4 located between the anode 1 and the focusing electrode 2; a cathode 3 located inside the focusing electrode 2; and an inner insulating ceramic ring 6 located between the cathode 3 and the focusing electrode 2. The anode 1, focusing electrode 2, and cathode 3 are all made of non-magnetic metal. Stress relief structures are formed at the sealing points of the focusing electrode 2 and the outer insulating ceramic ring 4, and at the sealing points of the cathode 3 and the inner insulating ceramic ring 6. These stress relief structures are configured to disperse and reduce the tensile stress formed during the sealing process due to the difference in thermal expansion coefficients of different materials by changing the geometry of the corresponding sealing points. This stress relief structure introduces a tensile stress buffer zone at the sealing interface. During the cooling process, a portion of the contraction strain of the non-magnetic metal is released by the geometric deformation of the sealing point, thereby blocking the direct transmission of high tensile stress to the ceramic ring. Ultimately, while ensuring the sealing strength, the integrity of the insulating ceramic ring is ensured, providing a reliable guarantee for the overall tube performance. Specifically, the electron gun of this invention provides a highly stable vacuum environment inside, ensuring the normal formation and emission of the electron beam. This makes the use of non-magnetic materials possible, fundamentally eliminating interference from internal components on the working magnetic field. It does not affect the magnetic induction intensity curve of the magnetic focusing system, ensuring the focusing capability of the magnetic focusing system for the electron beam, improving the electron beam throughput, and thus increasing the output power of the traveling wave tube. Compared to conventional electron guns using magnetic metal components, the electron gun of this invention provides better electron beam focusing, makes traveling wave tube testing and fixation more convenient, and reduces the damage rate.

[0029] It should be noted that a stress relief structure is not required at the sealing interface between the anode component 1 and the outer insulating ceramic ring 4, because according to existing experimental data, the conventional material of the outer insulating ceramic ring 4 is 95% alumina ceramic. The maximum compressive stress that 95% alumina ceramic can withstand is 2100 MPa, and the maximum tensile stress is 190 MPa. During the cooling process, the anode component 1 mainly generates compressive stress of 60 MPa, and tensile stress of 100 MPa at the edges. Since the stress that 95% alumina ceramic can withstand is greater than the actual stress generated by the anode component 1, the compressive stress on the outside of the outer insulating ceramic ring 4 by the anode component 1 will not cause the outer insulating ceramic ring 4 to crack. Similarly, the compressive and tensile stresses on the outside of the inner insulating ceramic ring 6 by the cathode component 3 will not cause the inner insulating ceramic ring 6 to crack.

[0030] Furthermore, the stress relief structure includes a first stress relief structure formed at the sealing point between the focusing electrode 2 and the outer insulating ceramic ring 4, and a second stress relief structure formed at the sealing point between the cathode 3 and the inner insulating ceramic ring 6. More specifically, a first chamfer 41, which is annular and coaxially arranged with the outer insulating ceramic ring 4, is formed on the inner peripheral edge of the outer insulating ceramic ring 4; two first chamfers 41 are symmetrically formed at both ends of the outer insulating ceramic ring 4 along the electron beam transmission direction (vertical direction); a first annular boss 5 is formed on the outer peripheral surface of the focusing electrode 2, which corresponds to and mates with the inner peripheral surface of the outer insulating ceramic ring 6; the inner peripheral surface of the outer insulating ceramic ring 4 and the first annular boss 5 mate to form the first stress relief structure. The inner circumferential surface of the inner insulating ceramic ring 6 has a second chamfer 61 formed in an annular shape and coaxially with the inner insulating ceramic ring 6; two second chamfers 61 are symmetrically formed at both ends of the inner insulating ceramic ring 6 along the electron beam transmission direction (vertical direction); a second annular boss 7 is formed on the outer circumferential surface of the cathode 3, corresponding to and engaging with the inner circumferential surface of the inner insulating ceramic ring 6; the inner circumferential surface of the inner insulating ceramic ring 6 and the second annular boss 7 engage to form a second stress relief structure. It is understood that the two first chamfers 41 are respectively formed at the corners connecting the inner circumferential surface of the outer insulating ceramic ring 4 and the upper and lower annular surfaces, and the two second chamfers 61 are respectively formed at the corners connecting the inner circumferential surface of the inner insulating ceramic ring 6 and the upper and lower annular surfaces. It is understood that a chamfer refers to a bevel or bevel formed by removing material at the edge or corner of a workpiece through cutting, grinding, or other processing methods. In this application, the first chamfer 41 and the second chamfer 61 are actually both annular bevels.

[0031] In one specific embodiment, the inner circumferential surface of the outer insulating ceramic ring 4 is fitted and sealed to the outer circumferential surface of the first annular protrusion 5, and the length of the inner circumferential surface of the outer insulating ceramic ring 4 in the electron beam transmission direction (vertical direction) is less than that of the outer circumferential surface. The inner circumferential surface of the inner insulating ceramic ring 6 is fitted and sealed to the outer circumferential surface of the second annular protrusion 7, and the length of the inner circumferential surface of the inner insulating ceramic ring 6 in the electron beam transmission direction is less than that of the outer circumferential surface. The first chamfer 41 and the second chamfer 61 are both inclined surfaces forming a 45-degree angle with the surface of the insulating ceramic ring, i.e., in the vertical cross-sectional view. Figure 5 In the middle section, the portion 42 cut off from the right-angled corner of the outer insulating ceramic ring 4 has an isosceles right-angled triangle cross-section, and the same applies to the inner insulating ceramic ring 6. The first chamfer 41 and the second chamfer 61 both appear as hypotenuses in the vertical cross-sectional view, and the length of these hypotenuses is equal to... The length of the right-angled side of the isosceles right-angled triangle cross-section of the removed portion 42 times. The cross-sections of both the first annular boss 5 and the second annular boss 7 are rectangular. It can be understood that the inner circumferential surface here refers to the surface facing the cathode element 3, and the outer circumferential surface refers to the surface facing away from the cathode element 3.

[0032] Furthermore, the length of the inner circumferential surface of the outer insulating ceramic ring 4 in the electron beam transmission direction is equal to the length of the first annular protrusion 5 in the electron beam transmission direction; the length of the inner circumferential surface of the inner insulating ceramic ring 6 in the electron beam transmission direction is equal to the length of the second annular protrusion 7 in the electron beam transmission direction.

[0033] Thermal stress calculations were performed on a standard, unmodified electron gun structure in ANSYS. If the inner sealing metal is a conventional, magnetic ceramic seal, the stress is 150 MPa. If the inner sealing metal is non-magnetic, the maximum stress point is located at the connection between the insulating ceramic ring and the inner sealing metal, at 300 MPa. The 95% alumina ceramic used as the insulating ceramic ring has a tensile strength of 190 MPa and moderate toughness.

[0034] The thermal stress of the electron gun structure of this application was calculated in ANSYS, and the results are shown in Tables 1 and 2 below.

[0035] Table 1. Influence of the chamfer length on the stress magnitude at the sealing interface

[0036] Table 2. Influence of different thicknesses of the annular boss on the stress magnitude at the sealing interface.

[0037] Based on the above data, in the direction perpendicular to the electron beam transmission direction (horizontal direction), the thickness of the first annular boss 5 and the second annular boss 7 both range from 0.25 to 0.42 mm. The thicknesses of the first annular boss 5 and the second annular boss 7 can be the same or different. Furthermore, in the direction perpendicular to the electron beam transmission direction (horizontal direction), the length of the hypotenuse corresponding to the first chamfer 41 and the second chamfer 61 both range from 1.06 to 1.77 mm. The lengths of the hypotenuse corresponding to the first chamfer 41 and the second chamfer 61 can be the same or different. When the length of the hypotenuse corresponding to the first chamfer 41 and the second chamfer 61 is both 1.4 mm and the thickness of the first annular boss 5 and the second annular boss 7 is both 0.33 mm, that is, when the length of the hypotenuse corresponding to the chamfer of the same set of stress relief structures is three times (4.24 times) the thickness of the annular boss, the optimal stress value of 150 MPa can be obtained. It should be noted that the data in Table 1 shows the relationship between the chamfer length and the stress at the sealing interface when the chamfer is designed alone. When the chamfer length is consistently 1.4 mm, the stress reaches an optimal value of 210 MPa. However, 210 MPa is still higher than the tensile strength of 95% alumina ceramic (190 MPa). Therefore, a corresponding annular boss is added to the chamfer design, resulting in the data in Table 2. At this point, when the thickness of the annular boss is consistently 0.33 mm, the stress drops to an optimal value of 150 MPa, which is lower than the tensile strength of 95% alumina ceramic (190 MPa), and the difference is the largest. Thus, the optimal stress values ​​and their corresponding dimensional parameters are obtained.

[0038] The present invention also provides a traveling wave tube (TWT), which includes an electron gun 10 as described above. Further, the operating frequency range of the TWT is above 0.1 THz; the TWT also includes a slow-wave circuit 20, a collector electrode 30, a uniform permanent magnet focusing system, and a titanium pump 50. The electron gun 10, slow-wave circuit 20, collector electrode 30, and titanium pump 50 are arranged sequentially along the axial direction of the uniform permanent magnet focusing system, which is arranged around the electron gun 10, slow-wave circuit 20, and collector electrode 30. It is understood that the titanium pump 50 is used to maintain the vacuum atmosphere of the TWT. The uniform permanent magnet focusing system includes a ring magnet 40.

[0039] In summary, this invention provides an electron gun for a terahertz traveling wave tube, comprising an anode; a focusing electrode located inside the anode; an outer insulating ceramic ring located between the anode and the focusing electrode; a cathode located inside the focusing electrode; and an inner insulating ceramic ring located between the cathode and the focusing electrode to fix them relatively in place. The anode, focusing electrode, and cathode are all made of non-magnetic metal. Stress relief structures are formed at the sealing points of the focusing electrode and the outer insulating ceramic ring, and at the sealing points of the cathode and the inner insulating ceramic ring. These stress relief structures are configured to release tensile stress generated during the sealing process due to differences in the thermal expansion coefficients of the different materials by changing the geometry of the corresponding sealing points. The core advantage of this invention lies in the fact that by collaboratively designing the sealing interfaces of the inner and outer insulating ceramic rings with the non-magnetic metal focusing electrode and cathode to form stress relief structures, tensile stress generated during the sealing process due to differences in the thermal expansion coefficients of the different materials is released by changing the geometry of the corresponding sealing interfaces, without altering the performance of the electron gun. This invention successfully resolved the core contradiction between the stringent requirements of immersion flow electron optics systems for a non-magnetic environment and the mismatch in the thermal expansion coefficients of materials. This made the manufacture of high-performance, high-reliability non-magnetic electron guns a reality, ensuring that the magnetic flux density and electron beam focusing ability of the traveling wave tube (TWT) magnetic focusing system remained unaffected, thereby increasing the TWT's output power. The electron gun of this invention has strong versatility, applicable not only to various TWTs employing immersion flow systems but also to all high-power microwave devices sensitive to magnetization and requiring electron guns, greatly expanding its applicability.

[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. An electron gun for a terahertz traveling wave tube, characterized in that, include: Anode components; A focusing electrode located inside the anode component; The outer insulating ceramic ring is located between the anode and the focusing electrode; The cathode element located inside the focusing electrode; And the inner insulating ceramic ring located between the cathode and the focusing electrode; The anode, focusing electrode, and cathode are all made of non-magnetic metal materials. The sealing joints between the focusing electrode and the outer insulating ceramic ring, and between the cathode and the inner insulating ceramic ring, are all equipped with stress-relieving structures. The stress relief structure is configured to release tensile stress formed during the sealing process due to the difference in thermal expansion coefficients of different materials by changing the geometry of the corresponding sealing joint.

2. The electron gun for a terahertz traveling wave tube according to claim 1, characterized in that, The stress relief structure includes a first stress relief structure formed at the seal between the focusing electrode and the outer insulating ceramic ring, and a second stress relief structure formed at the seal between the cathode and the inner insulating ceramic ring.

3. The electron gun for a terahertz traveling wave tube according to claim 2, characterized in that, The outer insulating ceramic ring has a first chamfer formed on the inner circumferential edge of the outer insulating ceramic ring, which is coaxial with the outer insulating ceramic ring. The first chamfer is symmetrically formed at both ends of the outer insulating ceramic ring along the electron beam transmission direction. The outer circumferential surface of the focusing electrode has a first annular boss that corresponds to and mates with the inner circumferential surface of the outer insulating ceramic ring. The inner circumferential surface of the outer insulating ceramic ring and the first annular boss mate to form a first stress relief structure. The inner circumferential surface of the inner insulating ceramic ring has a second chamfer that is annular and coaxially arranged with the inner insulating ceramic ring. The second chamfer is symmetrically formed at both ends of the inner insulating ceramic ring along the electron beam transmission direction. The outer circumferential surface of the cathode has a second annular boss that corresponds to and mates with the inner circumferential surface of the inner insulating ceramic ring. The inner circumferential surface of the inner insulating ceramic ring and the second annular boss mate to form a second stress relief structure.

4. The electron gun for a terahertz traveling wave tube according to claim 3, characterized in that... The inner circumferential surface of the outer insulating ceramic ring is fitted and sealed to the outer circumferential surface of the first annular protrusion, and the length of the inner circumferential surface of the outer insulating ceramic ring in the electron beam transmission direction is less than that of the outer circumferential surface; the inner circumferential surface of the inner insulating ceramic ring is fitted and sealed to the outer circumferential surface of the second annular protrusion, and the length of the inner circumferential surface of the inner insulating ceramic ring in the electron beam transmission direction is less than that of the outer circumferential surface.

5. The electron gun for a terahertz traveling wave tube according to claim 3, characterized in that, The first chamfer and the second chamfer are both inclined surfaces that form a 45-degree angle with the surface of the corresponding insulating ceramic ring, and the cross-sections of the first annular boss and the second annular boss are both rectangular.

6. The electron gun for a terahertz traveling wave tube according to claim 4, characterized in that, The length of the inner circumferential surface of the outer insulating ceramic ring in the electron beam transmission direction is equal to the length of the first annular protrusion in the electron beam transmission direction; the length of the inner circumferential surface of the inner insulating ceramic ring in the electron beam transmission direction is equal to the length of the second annular protrusion in the electron beam transmission direction.

7. The electron gun for a terahertz traveling wave tube according to claim 5, characterized in that, In the direction perpendicular to the electron beam transmission direction, the thickness of the first annular boss and the second annular boss both range from 0.25 to 0.42 mm, and the length of the hypotenuse corresponding to the first chamfer and the second chamfer both range from 1.06 to 1.77 mm.

8. The electron gun for a terahertz traveling wave tube according to claim 7, characterized in that, For the same stress-relief structure, the length of the bevel corresponding to the chamfer is 4.24 times the thickness of the annular boss.

9. A traveling wave tube, characterized in that, The traveling wave tube includes an electron gun as described in any one of claims 1-8.

10. The traveling wave tube according to claim 9, characterized in that, The operating frequency range of the traveling wave tube is above 0.1THz; the traveling wave tube also includes a slow wave circuit, a collecting electrode, a uniform permanent magnet focusing system and a titanium pump. The electron gun, the slow wave circuit, the collecting electrode and the titanium pump are arranged sequentially along the axial direction of the uniform permanent magnet focusing system, which is arranged around the electron gun, the slow wave circuit and the collecting electrode.

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