A novel electron gun for a cyclotron wave protector

Abstract

The application discloses a novel electron gun for a cyclotron wave protector and relates to the technical field of vacuum electron devices. The electron gun comprises a cathode assembly, an anode assembly, a support assembly and a permanent magnet system. The cathode assembly adopts a planar cold cathode structure. The anode assembly comprises an anode main body and an electron beam channel in the anode main body. The cathode assembly and the anode assembly are fixedly connected through the support assembly. The permanent magnet system provides a uniform magnetic field. The cold cathode is adopted to replace a traditional hot cathode to generate a high-quality belt-shaped electron beam, and the electron gun has the advantages of simple structure, easy integration, rapid starting, long-term reliability, low consumption and energy saving.

Description

Technical Field

[0001] This invention relates to the field of vacuum electronic device technology, and specifically to a novel electron gun for cyclotron wave protectors. Background Technology

[0002] In radar, navigation, and communication receiving systems, cyclotron wave protectors play a crucial role as key receiver protection devices. They possess significant advantages such as high power capacity, short recovery time, no spike leakage, and high isolation, and are often used as primary front-end components in these systems. They effectively protect sensitive downstream receiving equipment from damage caused by high-power electromagnetic waves, ensuring stable and reliable system operation.

[0003] Currently, cyclotron wave protectors primarily rely on thermionic electron sources in practical applications. However, thermionic electron sources have several significant drawbacks: First, the complex electron gun structure not only increases the difficulty and cost of manufacturing processes but also makes equipment maintenance and repair more cumbersome; second, their large size occupies considerable space, hindering the miniaturization and integration of the system; third, their high power consumption undoubtedly increases the system's operating costs in today's energy-constrained environment; and fourth, their slow startup speed prevents them from providing timely and effective protection in applications requiring rapid response, thus limiting the system's performance.

[0004] Cold cathodes, as a novel cathode form distinct from traditional hot cathodes, operate on the principle of field-induced electron emission, fundamentally different from hot cathodes which rely on filament heating for electron emission. For example, in X-ray tubes, using a cold cathode instead of a traditional hot cathode eliminates the need for filament heating, enabling rapid start-up, significantly improving response speed, and offering low power consumption, meeting the energy-efficient requirements of modern electronic devices. However, this device requires the design of a grid and focusing electrode to control the electron emission from the cold cathode, resulting in structural complexity.

[0005] In summary, the advantages of cold cathodes in terms of performance and structure make them potential applications in vacuum electronic devices. However, there is currently no mature technical solution to effectively apply cold cathodes to cyclotron wave protectors. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a cold cathode electron gun for a cyclotron wave protector. This invention employs a carbon nanotube array as the cold cathode to generate a high-quality ribbon-shaped electron beam.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A novel electron gun for a cyclotron wave protector, characterized in that it comprises a cathode assembly, an anode assembly, a support assembly, and a permanent magnet system;

[0009] The cathode assembly includes a cathode substrate and a cathode emitter disposed on the surface of the cathode substrate; the cathode substrate and the cathode emitter are at the same negative potential;

[0010] The anode assembly includes an anode body and an electron beam channel disposed inside the anode body; the anode body is grounded and has a potential of 0.

[0011] The permanent magnet system is disposed outside the cathode assembly and the anode assembly to provide a uniform magnetic field;

[0012] The cathode substrate is a planar cathode substrate with a gap of the same width between it and the anode body to form a uniform longitudinal electric field. The two are connected and fixed by a support component.

[0013] The cathode emitter is a carbon nanotube array;

[0014] The centers of the cathode substrate, cathode emitter, anode body, and electron beam channel are all located on the same straight line.

[0015] Preferably, the gap width between the cathode substrate and the anode body is in the range of 0.38 to 0.4 mm.

[0016] Preferably, the cathode substrate is rectangular or cylindrical, and the planar dimensions adjacent to the anode body are such that the electron emission region has a uniform electric field.

[0017] Preferably, the anode body is a cylindrical structure, and the electron beam channel inside it is located on the central axis of the cylindrical structure.

[0018] Preferably, the support assembly includes an insulating ceramic ring and a metal base plate; the cathode substrate is fixed in the middle of the metal base plate; and the two ends of the insulating ceramic ring are welded and fixed to the anode body and the metal base plate, respectively.

[0019] Preferably, the electron beam channel is shaped to match the carbon nanotube array.

[0020] Preferably, the carbon nanotube array is a rectangular array of several carbon nanotubes arranged periodically; the electron beam channel is a rectangular channel with an aperture larger than the array size of the carbon nanotube array.

[0021] The principle and beneficial effects of this invention are as follows:

[0022] The novel electron gun of the cyclotron wave protector of this invention has a planar cathode substrate and anode, with the cathode emitter located on the cathode substrate. A negative potential is applied to both the cathode substrate and the cathode emitter, while the anode is grounded. By adjusting the dimensions of the cathode substrate, a uniform electric field is generated between the cathode substrate and the anode, ensuring that the cathode emitter can uniformly emit electrons. A permanent magnet system is externally provided to the high-frequency system of the cyclotron wave protector. Expanding the magnetic field range of this permanent magnet system provides a uniform and constant magnetic field for the electron gun of this invention, directly acting as a focusing agent and further reducing electron beam divergence, eliminating the need for a separate grid and focusing electrode, making the device simpler and more compact. Under the traction and acceleration of the electrostatic field and the constraint of the axial steady magnetic field, electrons undergo a small cyclotron motion from the cathode to the anode, and the final formed electron beam passes through the electron beam channel, thus achieving a strip-shaped output.

[0023] This invention uses a cold cathode instead of a traditional hot cathode, which has the advantages of simple structure, easy integration, fast start-up, long-term reliability, and low energy consumption. Attached Figure Description

[0024] Figure 1 A schematic diagram of the novel electron gun in the cyclotron wave protector of this invention.

[0025] Figure 2 Side view of the novel electron gun carbon nanotube array cathode of the cyclotron wave protector of this invention.

[0026] Figure 3 Top view of the novel electron gun carbon nanotube array cathode of the cyclotron wave protector of this invention.

[0027] Figure 4 A schematic diagram showing the distribution of the electric field between the anode and cathode of the novel electron gun in the cyclotron wave protector of this invention.

[0028] Figure 5 The magnetic system structure diagram of the novel electron gun in the cyclotron wave protector of this invention.

[0029] Figure 6 The focusing magnetic field distribution diagram of the novel electron gun in the cyclotron wave protector of this invention.

[0030] Figure 7 A schematic diagram of the electron emission of the novel electron gun in the cyclotron wave protector of this invention.

[0031] Figure 8 Electron distribution diagram at the output cross section of the novel electron gun in the cyclotron wave protector of this invention.

[0032] Explanation of reference numerals in the attached drawings: 1. Cathode emitter, 2. Cathode substrate, 3. Anode body, 4. Electron beam channel, 5. Permanent magnet system, 6. Insulating ceramic ring, 7. Metal base plate. Detailed Implementation

[0033] The invention will be further described in detail below with reference to a design example and accompanying drawings:

[0034] This embodiment provides a cold cathode electron gun for an X-band cyclotron wave protector, requiring the emission of a rectangular strip electron beam with an electron beam current of 1.25mA, a voltage of 150V, a thickness of 0.14mm, and a width of 1mm; its structure is as follows. Figure 1 As shown, it mainly includes a cathode assembly, an anode assembly, a support assembly, and a permanent magnet system.

[0035] The cathode assembly includes a cathode substrate and a cathode emitter disposed on the surface of the cathode substrate; the cathode substrate and the cathode emitter are both at a potential of -150V.

[0036] The anode assembly includes an anode body and an electron beam channel disposed inside the anode body; the anode body is grounded and has a potential of 0.

[0037] The cathode emitter uses a carbon nanotube array as the emitting material, fixed on the cathode substrate. The carbon nanotube array is a rectangular array of several periodically arranged carbon nanotubes. The dimensions of the rectangles are consistent with the required strip-shaped electron beam size, with a length and width of 1 mm and 0.14 mm, respectively. In the cold cathode simulation, the empirically selected linear and exponential factors for field emission are: a = 1.51 × 10⁻⁶. -4 b = 3.31 × 10 6 The side and top views of the novel electron gun carbon nanotube array cathode of the cyclotron wave protector of this invention are as follows: Figure 2 and Figure 3 As shown.

[0038] The anode body is a cylindrical structure, and the surface facing the cathode is a plane. The cylinder radius is 4mm.

[0039] The cathode substrate employs a planar structure. The cathode substrate is rectangular in shape, with both its long and short sides measuring 2 mm. The gap between the cathode substrate and the anode body is the same width, 0.39 mm, to ensure a uniform electric field is generated between the cathode and anode, thereby increasing the uniformity of cathode emission and reducing electron beam divergence. Figure 4 As shown, the electron gun creates a uniform longitudinal electric field between the anode and cathode.

[0040] The support assembly includes an insulating ceramic ring and a circular metal base plate; the cathode substrate is fixed in the middle of the circular metal base plate; the two ends of the insulating ceramic ring are welded and fixed to the anode body and the metal base plate, respectively.

[0041] The electron beam channel is located inside the anode cylinder and is used to transport the generated ribbon-shaped electron beam. The cross-sectional dimensions of the channel are required to be larger than the cross-sectional dimensions of the ribbon-shaped electron beam to ensure the complete transport of the electron beam. In this embodiment, the cross-section of the electron beam channel matches the shape of the carbon nanotube array, both being rectangular, with a height of 0.2 mm and a width of 1.2 mm, and a channel length of 5 mm.

[0042] In this embodiment, the centers of the cathode substrate, cathode emitter, anode body, and electron beam channel are all located on the same straight line.

[0043] In this embodiment, the electron gun operates within a longitudinally uniform magnetic field, which converges the diverging electron beam during movement, reducing divergence. The focusing magnetic field is generated by two external rectangular permanent magnets, and the uniform magnetic field strength is 0.356T. The structure and magnetic field distribution of the permanent magnet system are as follows: Figure 5 and Figure 6 As shown.

[0044] Figure 7 This is a schematic diagram of electron emission from an electron gun. It is observed that, under the traction and acceleration of the electrostatic field and the constraint of the axial steady magnetic field, electrons undergo a small cyclotron motion from the cathode to the anode, allowing the electron beam to pass completely through the electron beam channel for output. Figure 8 The electron distribution diagram at the end of the electron beam channel of the cold cathode electron gun is presented. The diagram shows that the shape of the ribbon-shaped electron beam changes very little during motion, remaining essentially rectangular. The entire ribbon-shaped electron beam rotates around its central axis at a certain azimuth angle. Calculations show that the deflection angle is approximately 0.57°, which has little impact on the overall shape. Simulations show that the electron beam current at the opening of the electron channel is 1.26 mA, consistent with the emission current. The electron beam can pass completely through the electron beam channel without emission collisions, and the electron beam flux is 100%, meeting the application requirements of the cyclotron wave protector electron beam.

Claims

1. A novel electron gun for cyclotron wave protectors, characterized in that, Includes cathode assembly, anode assembly, support assembly, and permanent magnet system; The cathode assembly includes a cathode substrate and a cathode emitter disposed on the surface of the cathode substrate; the cathode substrate and the cathode emitter are at the same negative potential; The anode assembly includes an anode body and an electron beam channel disposed inside the anode body; the anode body is a grounded cylindrical structure with a potential of 0, and the electron beam channel inside it is located on the central axis of the cylindrical structure; The permanent magnet system consists of two rectangular permanent magnets disposed outside the cathode assembly and the anode assembly to provide a uniform magnetic field; The cathode substrate is a planar cathode substrate, with a gap of the same width between the plane adjacent to the anode body and the anode body to form a uniform longitudinal electric field. The two are connected and fixed by a support component. The cathode emitter is a carbon nanotube array; The centers of the cathode substrate, cathode emitter, anode body, and electron beam channel are all located on the same straight line. The support assembly includes an insulating ceramic ring and a metal base plate; the cathode substrate is fixed in the middle of the metal base plate; the two ends of the insulating ceramic ring are welded and fixed to the anode body and the metal base plate, respectively.

2. The novel electron gun for a cyclotron wave protector as described in claim 1, characterized in that, The cathode substrate is rectangular or cylindrical, and its planar dimensions adjacent to the anode body are such that the electron emission region is a uniform electric field.

3. A novel electron gun for a cyclotron wave protector as described in claim 2, characterized in that, The gap width between the cathode substrate and the anode body ranges from 0.38 to 0.4 mm.

4. A novel electron gun for a cyclotron wave protector as described in claim 3, characterized in that, The electron beam channel is shaped to match the carbon nanotube array.

5. A novel electron gun for a cyclotron wave protector as described in claim 4, characterized in that, The carbon nanotube array is a rectangular array of several carbon nanotubes arranged periodically; the electron beam channel is a rectangular channel with an aperture larger than the array size of the carbon nanotube array.

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