Pulse electron gun for microwave emission system and microwave emission device thereof

Abstract

The invention relates to the technical field of electron emission and microwave emission, and provides a pulse electron gun for a microwave emission system and a microwave emission device thereof, and the pulse electron gun comprises a pulse high-voltage power supply, a cathode rod, a first electric field, a field emission cathode, an electron multiplication medium, a second electric field and a third electric field. Under the action of a high-voltage pulse power supply, an electric field is formed between the cathode rod and the anode cylinder, the initial emission cathode emits electrons under the driving of the electric field, and the electrons are multiplied and amplified by the electron multiplication module to form electron beams to meet the requirements of a microwave emission system. By optimizing the cathode structure, the diode type pulse electron gun is designed, the voltage applying mode is simplified, and the stray capacitance influence is effectively reduced. The specific material is selected to construct the electron multiplication channels and the number of the electron multiplication channels is increased, so that the total output current is remarkably improved, the ignition risk is reduced, the service life of the cathode is remarkably prolonged, the working stability of the cathode is remarkably improved, stable pulse high-current output can be realized, and the requirements of a high-power microwave emission system are met.

Description

Technical Field

[0001] The present application relates to the technical field of electron emission and microwave emission, and in particular to a pulse electron gun and a microwave emission device thereof for a microwave emission system. Background Art

[0002] The contents of this section merely provide background information related to the present application and may not constitute prior art.

[0003] In high-power microwave emission systems, one of the core challenges is how to achieve a high emission current density, long life and stable electron beam source. In the prior art, Song Falun [Song Falun, Jin Xiao, Zhang Yonghui, et al. Research progress on explosive emission cathode characteristics, Physics, 2007, 36 (3): 241-246] et al. used explosive emission cathodes, which are considered to be a technology option with great potential because they can generate extremely high current density (up to the order of kA / cm2). This cathode theoretically has almost unlimited emission capabilities. However, in practical applications, the performance of explosive emission cathodes decreases rapidly, and the working life is usually limited to tens of thousands of pulses, which is mainly attributed to plasma expansion and ablation loss of emission sites. These limitations seriously affect the stability of electronic devices and even the entire system.

[0004] Another existing technology is the field emission cathode [Chen Zexiang, Cao Guichuan, Zhang Qiang, et al. Development of high current density carbon nanotube field emission array, High Power Laser and Particle Beam, 2006, 18 (12): 2070-2073]. Although it can also provide a high emission current density, it is limited by the effective area of ​​the emitter, and its total emission current is not ideal. In contrast, secondary electron emission, as an emerging technology, amplifies current by releasing internal electrons through the interaction between primary electrons and solid surfaces. For example, photomultiplier tubes use this principle, but they are limited to low current environments. Dong Ye [Dong Ye. Theoretical and numerical simulation study on secondary electron multiplication suppression and enhancement [D]. Sichuan: Southwest Jiaotong University, 2019.] combines field emission with secondary electron multiplication. Although a high current density is achieved, the space charge field caused by the positive charge deposition in the secondary electron multiplication process leads to multiplication saturation, while increasing the field strength of field emission, which may induce explosive emission, thereby shortening the cathode life.

[0005] At the same time, secondary electron emission is applied to accelerators. Liao Lang [Liao Lang. Research and Design of Microwave Micropulse Electron Gun [J]. Graduate School of the Chinese Academy of Sciences (Shanghai Institute of Applied Physics), 2015] uses a bilateral secondary electron multiplication mechanism under radio frequency field to achieve a high-quality electron beam with a duration of several microseconds, low energy dispersion, and low emissivity. However, it still faces the limitations of beam quality degradation caused by space charge effect, strict resonance conditions, high material requirements, and short pulse duration. Although the microchannel plate (MCP) [Hirshfield J L. HIGH-CURRENT COLD CATHODE FIELD EMISSION ARRAY FORELECTRON LENS APPLICATION [R]. Omega-P, Inc., 2012.] can output a higher current density, it is also easy to saturate when working at a large current, making it difficult to output continuously and stably, and it is difficult to meet the needs of high-power microwave sources. In order to overcome the saturation problem in the secondary electron multiplication process, Tang Yongliang [L.Wang, Y.Hao, W.Lv, D.Wang, Y.Zhang, Y.Lu, Q.Liu, J.Luo, and Y.Tang, "A comprehensive study of pulsed high-current secondary electron emission cathode," Journal of Applied Physics, vol.136, no.4, 2024.] et al. used SnO with high secondary electron emission coefficient and high conductivity. 2 The material combines field emission with secondary electron multiplication to achieve a high-current secondary electron multiplication emission cathode with an output current density of 100 A / cm2. Although this breakthrough has improved the secondary electron emission performance, the multi-pole pressure application method is not only easy to introduce a large amount of stray capacitance in the experiment, but also requires a complex power supply system support, so it is difficult to meet the actual needs of high-power microwave systems.

[0006] In view of the above problems, there is an urgent need for a pulsed electron gun for microwave emission systems to overcome the technical challenges of low emission current density, short life and complex pressure application of cold cathode electron beam diodes. Summary of the invention

[0007] In order to solve the above technical problems, the purpose of the present application is to provide a pulse electron gun for a microwave transmission system, which simplifies the voltage application method by redesigning the cathode structure and makes it suitable for high-power microwave systems; selects materials with high conductivity, high breakdown threshold, and high secondary electron multiplication coefficient (such as ZnO, SnO 2The electron multiplication channel is constructed by using a plurality of channels (such as quartz crystals, nanostructured carbon nanotubes, etc.). The positive charge deposited on the channel surface during the high-current electron emission process can be effectively neutralized by the channel conduction current, thereby suppressing the saturation effect of the secondary electron multiplication. The total channel area can be increased by further increasing the number of electron multiplication channels, thereby solving the problem of low emission current density of cold cathode electron beam diodes, reducing the ignition probability, improving the life and stability of the cathode, and ultimately achieving stable pulsed high-current output.

[0008] The purpose of this application is achieved through the following technical solutions:

[0009] The present invention provides a pulse electron gun for a microwave emission system, comprising:

[0010] An electron gun, the electron gun comprises a high-voltage pulse power supply, a cathode rod, an initial emission cathode, an electron multiplication module and an anode tube, the negative electrode of the high-voltage pulse power supply is electrically connected to the cathode rod, and the positive electrode of the high-voltage pulse power supply is electrically connected to the anode tube; the electric field formed by the cathode rod and the anode tube covers the initial emission cathode and the electron multiplication module; a placement cavity is provided on the cathode rod, the placement cavity is provided with an opening, and the opening faces the electron output channel in the anode tube; the initial emission cathode is arranged on one end of the placement cavity away from the opening; the electron multiplication module comprises a multiplication medium and a plurality of electron multiplication channels penetrating the multiplication medium, the side wall of the multiplication medium maintains good electrical connection with the side wall of the opening, each electron multiplication channel is arranged vertically to the initial emission cathode, and a secondary electron multiplication material coating is provided on the inner wall of each electron multiplication channel;

[0011] Furthermore, a circular ring-shaped metal gasket is provided between the multiplication medium and the initial emission cathode, and the metal gasket separates an isolation space between the multiplication medium and the initial emission cathode.

[0012] Furthermore, the electric field includes a first electric field located in the isolation space, a second electric field located in the electron multiplier module, and a third electric field located between one side of the cathode rod with an opening and the anode cylinder, and the first electric field, the second electric field and the third electric field are all axisymmetric electric fields.

[0013] Furthermore, it also includes a focusing device, which is arranged around the anode cylinder at the position of the third electric field, and the focusing device focuses the electron beam in the third electric field through a focusing magnetic field.

[0014] Furthermore, the thickness of the metal gasket is 0.1-1 mm.

[0015] Furthermore, the initial emission cathode adopts at least one of an array consisting of metal tungsten or molybdenum needle tips, carbon nanotubes, graphene, carbon fibers, or an array consisting of metal nanorods.

[0016] Furthermore, an annular protrusion is provided on the anode cylinder near the opening of the placement cavity.

[0017] Furthermore, the inner diameter of the annular protrusion is larger than the outer diameter of the electron multiplier module, and the difference between the inner diameter and the outer diameter is in the range of 0-10 mm.

[0018] Furthermore, rounded corners are provided on both the outer circumference and the inner circumference of the protrusion. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of a pulse electron gun suitable for a microwave transmitting system provided by the present invention;

[0020] Figure 2 It is a schematic diagram of the structure of the multiplication medium in the multiplication module;

[0021] Figure 3 A schematic diagram of the system structure of a microwave transmitting device driven by a pulse electron gun;

[0022] Icons: 1. Microwave signal generator; 2. Electron gun; 21. High-voltage pulse power supply; 22. Cathode rod; 23. Anode cylinder; 231. Protrusion; 24. Initial emission cathode; 25. Metal gasket; 26. Electron multiplier module; 261. Electron multiplier channel; 262. Multiplication medium; 3. Electron motion tube; 31. Drift tube; 32. Input cavity; 321. Input gap; 322. First coupling hole; 33. Output cavity; 331. Output gap; 332. Second coupling hole; 34. Collector; 4. Antenna; 5. Electron beam; 6. Electron cluster; 7. First focusing device, 8. Second focusing device. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Example 1

[0025] A pulse electron gun for a microwave emission system proposed in an embodiment of the present application comprises a high-voltage pulse power supply 21, a cathode rod 22, an initial emission cathode 24, an electron multiplication module 26 and an anode cylinder 23. The high-voltage pulse power supply 21 provides the necessary voltage difference for the electron gun 2, the negative electrode of the high-voltage pulse power supply 21 is connected to the cathode rod 22, the positive electrode of the high-voltage pulse power supply 21 is connected to the anode cylinder 23, and a placement cavity is provided on the cathode rod 22, and the placement cavity is provided with an opening, which faces the channel in the anode cylinder 23, so as to form an electric field between the two.

[0026] The cathode rod 22 is the starting point of electron emission, and is provided with a special structure, that is, the cathode rod 22 is provided with a placement cavity for accommodating the initial emission cathode 24 and the electron multiplier module 26, and the placement cavity is provided with an opening, and the opening faces the channel in the anode cylinder 23, so that the electric field covers the entire placement cavity (that is, the electric field covers the initial emission cathode 24 and the electron multiplier module 26), and the electron beam 5 can smoothly emit the initial electrons from the initial emission cathode 24, and after being multiplied by the electron multiplier module 26, enter the channel in the anode cylinder 23 and then output. The electric field coincides with the axis of the electron multiplier module 26.

[0027] In addition, the initial emission cathode 24 is provided as an initial electron source at one end of the placement cavity away from the opening, and emits initial electrons under the action of the electric field. These electrons then enter the electron multiplication module 26 for multiplication and amplification. The electron multiplication module 26 includes a multiplication medium 262 and a plurality of electron multiplication channels 261 that penetrate the multiplication medium 262, such as Figure 3 As shown, the side wall of the multiplication medium 262 maintains good electrical connection with the side wall of the opening, each electron multiplication channel 261 is arranged vertically with the initial emission cathode 24, and a secondary electron multiplication material coating is arranged on the inner wall of each electron multiplication channel 261. Figure 2 As shown, the multiplication medium 262 is preferably made of GaAs, GaN, SiC, Al 2 O 3 、SiO 2 、ZrO 2 At least one of the electron multiplication channels 261 in the multiplication medium 262 is perpendicular to the initial emission cathode 24. The number of electron multiplication channels 261 is determined by the current that a single channel can withstand. For example, the surface stable secondary electron current density in the multiplication medium 262 can reach hundreds of mA / mm. Under the premise of controlling the current density to hundreds of mA / mm, by increasing the number of electron multiplication channels 261 to 10 2 -10 6 Pieces / cm 2 , to increase the total channel area and thus increase the total emission current.

[0028] The electron multiplying module 26 multiplies and amplifies the initial electrons entering the electron multiplying channel 261 under the action of the electric field to form a strong current electron beam 5, ensuring that there are enough electrons to participate in the subsequent microwave generation. Among them, since the diameter of the electron multiplying channel 261 will affect the degree of electron multiplication, if the spacing of the electron multiplying channel 261 is too large, the number of times the electrons collide with the surface of the electron multiplying channel 261 will decrease; if the channel diameter is too small, the incident energy of the electrons colliding with the surface of the electron multiplying channel 261 is too small and the electrons cannot be pulled out; therefore, in order to achieve efficient electron multiplication, the present invention preferably uses an electron multiplying channel 261 with an aspect ratio of 20-100, and the diameter of the electron multiplying channel 261 is preferably 5-300μm. The length of the electron multiplying channel 261 will also affect the intensity of the final output current; when the secondary electrons are multiplied at the selected conductivity, if the length of the electron multiplying channel 261 is appropriate, the output of a large current can be effectively achieved; if the length of the electron multiplying channel 261 is too long, the number of collisions of electrons therein will increase, resulting in insufficient incident energy for subsequent collisions with the surface of the electron multiplying channel 261, making it difficult to effectively pull out electrons. Therefore, the preferred length of the electron multiplying channel 261 of the present invention is 200-20000 μm.

[0029] It should be noted that in the present invention, a secondary electron multiplication material coating is provided on the inner wall of the electron multiplication channel 261. The resistivity of the secondary electron multiplication material coating is 10 -8 -10 12 Ω·m, preferably Cu, SiO 2 、Al 2 O 3 、ZnO、SnO、MgO、BeO 2 , BaO. The initial emission cathode 24 uses a nanomaterial with a low work function, preferably a nanomaterial with a work function of 3-5 eV. In practical applications, at least one nanomaterial selected from an array of metal tungsten or molybdenum needle tips, carbon nanotubes, graphene, carbon fibers, and an array of metal nanorods (wires) can be used as the initial emission cathode 24. By using a nanomaterial with a low work function as the initial emission cathode 24, the initial emission cathode 24 can emit electrons under a relatively low electric field.

[0030] Furthermore, a circular ring-shaped metal gasket 25 is provided between the multiplication medium 262 and the initial emission cathode 24 , and the metal gasket 25 separates an isolation space between the multiplication medium 262 and the initial emission cathode 24 .

[0031] Specifically, by adjusting the thickness of the metal gasket 25, the physical distance between the initial emission cathode 24 and the multiplication medium 262 can be accurately controlled. This spacing has an important influence on the initial emission electron emission performance, because the process of electron emission from the cathode to the multiplication channel is highly dependent on the electric field strength formed between them. The greater the electric field strength, the stronger the driving force on the electrons, so that the emission threshold can be overcome more effectively and efficient emission can be achieved. However, excessively high electric field strength can also lead to the breakdown of the initial emission cathode 24. Therefore, in order to achieve efficient electron emission, the present invention preferably uses a metal gasket 25 with a thickness of 0.1-1mm, an outer diameter of 5-15mm, and a difference between the inner diameter and the outer diameter of 1-2mm.

[0032] In addition, according to the preferred design of the present invention, the outer diameter of the cathode rod 22 is 15-50mm, the thickness of the cavity in which it is placed is 5-10mm, the radius is 5-15mm, the outer diameter of the anode cylinder 23 sleeved on the upper part of the cathode rod 22 is 40-100mm, the radius of the part of the anode cylinder 23 facing the cathode rod 22 is 20-50mm, the outer diameter of the initial emission cathode 24 is 5-15mm, the length of the electron multiplier module 26 is 5-10mm, the outer diameter is 5-15mm, the distance between the cathode rod 22 and the anode cylinder 23 is 20-40mm, and the thickness of the metal gasket 25 is preferably 0.1-1mm. Based on the setting of the above parameters, it can be beneficial for the electric field at each location to have a suitable field strength, and can be used to generate, form and accelerate a high-current electron beam.

[0033] After the above settings, the electric field is divided into a plurality of different regions, namely, the first electric field located in the isolation space, the second electric field located in the electron multiplier module 26, and the third electric field located between the opening of the cathode rod 22 and the anode cylinder 23. The first electric field, the second electric field, and the third electric field are all axisymmetric electric fields. The first electric field is used to provide emission conditions for the initial emission cathode 24, and drive the initial electrons to drift toward the electron multiplier module 26. The electron multiplier module 26 is located in the second electric field. The electron multiplier module 26 includes uniformly arranged electron multiplier channels 261. The electron multiplier channel 261 and the second electric field are used to multiply and amplify the initial emission electrons entering the electron multiplier channel 261 to obtain the amplified electron beam 5, and finally enter the channel in the anode cylinder 23 under the acceleration of the third electric field and the constraint of the magnetic field and then output. Among them, the electric field strength of the first electric field is 1-10MV / m, the electric field strength of the second electric field is 0.1-10MV / m, and the electric field strength of the third electric field is 1-20MV / m. Among them, the axisymmetric electric field can ensure that the electron beam 5 is subjected to a uniform and stable electric field force during the transmission process. At the same time, under the constraint of the focusing magnetic field, the electron beam 5 will not diffuse during the forward process, thereby ensuring the stability of the electron beam 5 and further improving the energy conversion efficiency of the system.

[0034] Furthermore, an annular protrusion 231 is provided on the anode cylinder 23 near the opening of the placement cavity. The setting of the protrusion 231 can form the required electric field strength with the cathode rod 22 at a closer distance, and can perform preliminary focusing on the electron beam 5. In addition, the inner diameter of the annular protrusion 231 is larger than the outer diameter of the electron multiplier module 26, and the difference between the inner diameter and the outer diameter ranges from 0 to 10 mm. That is, by setting the inner diameter of the anode cylinder 23 to be slightly larger than the outer diameter of the electron multiplier module 26, the anode cylinder 23 can wrap the electron beam 5 transmitted from the electron multiplier module 26, thereby ensuring the stability of the electrons during movement.

[0035] Furthermore, rounded corners are provided on the outer circumference and the inner circumference of the protrusion 231. The rounded corner design disperses the high-intensity electric field area that may be formed by sharp corners, reduces the electric field intensity in the area, and thus reduces the risk of the electric field reaching the breakdown threshold at the area, thereby improving the durability and reliability of the protrusion 231.

[0036] Furthermore, it also includes a focusing device, wherein a plurality of the first focusing devices are arranged around the anode cylinder at the position of the third electric field, and each of the first focusing devices focuses the electron beam in the third electric field through a focusing magnetic field;

[0037] Specifically, in order to improve the trajectory stability and transmission efficiency of the electron beam 5, a first focusing device is arranged around the anode cylinder at the position of the third electric field. By generating a focusing magnetic field with adjustable strength through an electromagnetic coil, these devices precisely control the movement trajectory of the electron beam 5, focus it to a smaller area, reduce scattering and maintain energy and shape stability. That is, the first focusing device 7 is used to focus the electron beam 5 in the third electric field through the focusing magnetic field, so that the electron beam 5 is constantly constrained and adjusted during the transmission process, and finally reaches the target area with a stable trajectory and high electron density.

[0038] In an embodiment of the present invention, the electron gun 2 forms an electric field between the cathode rod 22 and the anode cylinder 23 under the action of the high-voltage pulse power supply 21, and the initial emission cathode 24 emits electrons under the action of the electric field. The electrons enter the electron multiplication module 26 made of materials such as GaAs for multiplication to form a high-energy electron beam 5. The aspect ratio, diameter and length of the electron multiplication channel 261 are optimized to improve the electron multiplication efficiency and output current intensity. At the same time, the metal gasket 25 optimizes the initial electron emission performance, the electron multiplication module 26 increases the total output electrons of the electron beam 5, and the focusing device focuses the electron beam 5 through the focusing magnetic field to improve the accuracy and system efficiency of the electron beam 5.

[0039] Example 2

[0040] Based on the same concept, the present invention provides an electron beam microwave emitting device based on electron multiplication.

[0041] Specifically, the microwave signal generator 1 converts ordinary electrical signals into signals in the microwave frequency band, providing necessary support for wireless communication. Subsequently, the electron gun 2 generates and accelerates the electron beam 5, wherein the initial emission cathode 24 emits electrons under the action of the electric field, and these electrons are multiplied by the electron multiplier module 26 to form a high-energy electron beam 5. In this process, the optimization of the parameters such as the aspect ratio, diameter and length of the electron multiplier channel 261 ensures that the electrons can be efficiently multiplied, thereby increasing the total emission current and providing a sufficient electron source for subsequent microwave generation. The electron motion tube 3 is responsible for speed modulating the electron beam 5 generated by the electron gun 2 and converting the energy of the electron beam 5 into a microwave signal. In the input cavity 32, the microwave signal emitted by the microwave signal generator 1 establishes a high-frequency electric field to speed modulate the electron beam 5. The speed-modulated electron beam 5 decelerates in the output cavity 33 and efficiently converts the energy into a microwave signal. This conversion process not only improves the generation efficiency of the microwave signal, but also ensures the stability and quality of the microwave signal.

[0042] The antenna 4 receives and concentrates the output microwave energy, and then radiates the microwave signal into space with its specific radiation mode, thus realizing wireless communication between the microwave transmission system and the mobile device. In addition, the setting of the metal gasket 25 optimizes the emission performance of the initial electrons, and the preferred electron multiplication material improves the multiplication characteristics of the multiplication medium 262, ensuring the output performance of the electron beam 5 and further improving the energy conversion efficiency.

[0043] The microwave signal transmitting device also focuses the electron beam 5 through a plurality of first and second focusing devices. A plurality of second focusing devices 8 are arranged around the electron motion tube 3. Each second focusing device 8 focuses the electron beam in the electron motion tube through a focusing magnetic field, thereby improving the accuracy of the electron beam 5 and the working efficiency of the system. The magnetic field generated by these focusing devices can finely control the motion trajectory of the electron beam 5, tightly constrain it together, and reduce the scattering of the electron beam 5. This not only ensures that the electron beam 5 can reach the target area with extremely high accuracy, but also improves the focusing effect of the electron beam 5, thereby enhancing the transmission capability and coverage of microwave signals in the system.

[0044] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pulse electron gun for a microwave transmission system, characterized in that: It comprises a high-voltage pulse power supply, a cathode rod, an initial emission cathode, an electron multiplier module and an anode cylinder, wherein the negative electrode of the high-voltage pulse power supply is electrically connected to the cathode rod, and the positive electrode of the high-voltage pulse power supply is electrically connected to the anode cylinder; the electric field formed by the cathode rod and the anode cylinder covers the initial emission cathode and the electron multiplier module; the cathode rod is provided with a placement cavity, and the placement cavity is provided with an opening, and the opening faces the electron output channel in the anode cylinder; The initial emission cathode is arranged on one end of the placement cavity away from the opening; the electron multiplication module includes a multiplication medium and a plurality of electron multiplication channels penetrating the multiplication medium, the side wall of the multiplication medium maintains good electrical connection with the side wall of the opening, each of the electron multiplication channels is arranged vertically to the initial emission cathode, and a secondary electron multiplication material coating is provided on the inner wall of each of the electron multiplication channels.

2. The pulse electron gun for a microwave transmitting system according to claim 1, characterized in that: A circular metal gasket is arranged between the multiplication medium and the initial emission cathode, and the metal gasket separates an isolation space between the multiplication medium and the initial emission cathode.

3. The pulse electron gun for a microwave transmitting system according to claim 2, characterized in that: The electric field includes a first electric field located in the isolation space, a second electric field located in the electron multiplier module, and a third electric field located between a side of the cathode rod with an opening and the anode cylinder. The first electric field, the second electric field and the third electric field are all axisymmetric electric fields.

4. The pulse electron gun for a microwave transmitting system according to claim 3, characterized in that: It also includes a focusing device, wherein the first focusing device is arranged around the anode cylinder at the position of the third electric field, and the first focusing device focuses the electron beam in the third electric field through a focusing magnetic field.

5. The pulse electron gun for a microwave transmitting system according to claim 2, characterized in that: The thickness of the metal gasket is 0.1-1 mm.

6. The pulse electron gun for a microwave transmitting system according to claim 1, characterized in that: The initial emission cathode is at least one of an array consisting of metal tungsten or molybdenum needle tips, carbon nanotubes, graphene, carbon fibers, or an array consisting of metal nanorods.

7. The pulse electron gun for a microwave transmitting system according to claim 1, characterized in that: An annular protrusion is provided on the anode cylinder near the opening of the placement cavity.

8. The pulse electron gun for a microwave transmitting system according to claim 7, characterized in that: The inner diameter of the annular protrusion is greater than the outer diameter of the electron multiplier module, and the difference between the inner diameter and the outer diameter is in the range of 0-10 mm.

9. The pulse electron gun for a microwave transmitting system according to claim 8, characterized in that: The outer circumference and the inner circumference of the protrusion are both provided with rounded corners.

10. An electron beam microwave emitting device based on electron multiplication, characterized in that: It comprises a pulse electron gun suitable for a microwave emission system as described in any one of claims 1 to 9.

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