A large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun

Abstract

This application relates to the field of vacuum electronics technology, specifically to a large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun, comprising a cover plate, a shell, a base, a focusing electrode, a large-area cathode assembly, and electrode posts. The cover plate is fixed to the top of the shell, and the bottom of the shell is fixed to the base. The focusing electrode is disposed inside the shell and includes a first focusing electrode, a decelerating electrode, and a second focusing electrode. The large-area cathode assembly is disposed inside the shell and is fixedly connected to the first focusing electrode via a ceramic insulating gasket and a connector insulating bushing. The electrode posts are fixed to the base via the connector insulating bushing. This application employs a five-electrode structure consisting of a large-area carbon nanotube cathode, a grid, a first focusing electrode, a decelerating electrode, and a second focusing electrode. The cathode-grid structure composed of the large-area carbon nanotube cathode and the grid can emit a stable, high-intensity electron beam.

Description

Technical Field

[0001] This application relates to the field of vacuum electronics technology, and more specifically, to a large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun. Background Technology

[0002] Large-area wide-beam cold cathode electron guns are widely used in surface treatment, materials processing, microelectronics manufacturing, electron microscopy, ultra-low energy wide-beam ion sources, etc. However, they still have significant defects in key performance aspects such as electron beam energy, energy distribution, beam current uniformity and beam current intensity, which limits their further application in high-precision and large-area processing.

[0003] Currently, large-area wide-beam cold cathode electron guns primarily rely on field emission to generate electron beams. The emitted electron beams have high energies, typically above 100 eV, and this emission mechanism results in a wide energy distribution. Due to the non-uniformity of electron energy in field emission, precise control is difficult in the low-energy range (e.g., tens to hundreds of eV), leading to significant energy divergence and impacting energy control requirements in precision machining processes. Furthermore, because cold cathode emission is concentrated at local emission points, beam uniformity is poor, especially in large-area wide-beam applications, where significant differences in electron density between the beam center and edges cause uneven electron beam bombardment intensity on the machining surface, ultimately affecting process performance.

[0004] Meanwhile, insufficient and fluctuating beam current intensity is also one of the challenges faced by cold cathode electron guns. Field emission is extremely sensitive to operating conditions such as electric field strength and vacuum level, making it difficult to maintain a stable beam current intensity and resulting in low electron emission efficiency. Especially in applications requiring high current density, the beam current intensity often fails to meet process requirements. These shortcomings limit the performance and reliability of cold cathode electron guns in some high-precision, high-power applications, hindering their use in processes requiring long-term continuous operation. Summary of the Invention

[0005] This application provides a large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun with low electron beam energy, high beam current intensity, and small electron beam divergence angle, which can meet the needs of high precision and large-area applications.

[0006] To achieve the above objectives, this application provides a large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun, comprising a cover plate, a shell, a base, a focusing electrode, a large-area cathode assembly, and electrode posts, wherein: the cover plate is fixed to the top of the shell, and the bottom of the shell is fixed to the base; the focusing electrode is disposed inside the shell, including a first focusing electrode, a decelerating electrode, and a second focusing electrode, the second focusing electrode being fixed below the cover plate by a ceramic insulating gasket and a connector insulating bushing, the decelerating electrode being fixedly connected to the second focusing electrode by a ceramic insulating gasket and a connector insulating bushing; the first focusing electrode being fixedly connected to the decelerating electrode by a ceramic insulating gasket and a connector insulating bushing; the large-area cathode assembly is disposed inside the shell and is fixedly connected to the first focusing electrode by a ceramic insulating gasket and a connector insulating bushing; the electrode posts are fixed to the base by connector insulating bushings, with one end exposed outside the base.

[0007] Furthermore, the large-area cathode assembly includes a cathode, a grid, a cathode ceramic base, a first fixing member, a second fixing member, and a grid clamping ring, wherein: both sides of the cathode are fixed to the cathode ceramic base by threaded connection; the first fixing member and the second fixing member are sequentially fixed to the cathode ceramic base by threaded connection; the grid is disposed above the cathode and fixed to the second fixing member by the grid clamping ring.

[0008] Furthermore, the cathode is a large-area carbon nanotube cathode with a diameter of 30 mm.

[0009] Furthermore, the distance between the cathode and the gate is 200 μm.

[0010] Furthermore, the focusing electrode has a conical structure, with the first focusing electrode having a taper of 3° and the second focusing electrode having a taper of 14°.

[0011] Furthermore, the lengths of the first focusing electrode, the decelerating electrode, and the second focusing electrode are equal to the diameter of the cathode, and the inner diameter of the decelerating electrode is 1.5 times the diameter of the cathode.

[0012] Furthermore, the cathode, grid, first focusing electrode, deceleration electrode, and second focusing electrode are connected to various power supplies via electrode posts, wherein: the outer casing is grounded; the cathode is connected to a negative voltage of 60-70V; the grid is connected to a positive voltage of 1000V; the first focusing electrode is connected to a positive voltage of 1200-1300V; the deceleration electrode is connected to a positive voltage of 400V; and the second focusing electrode is connected to a positive voltage of 10V.

[0013] Furthermore, the electron beam divergence angle is less than 10°, the electron beam waist diameter is 30 mm, and the electron beam energy is 75 eV.

[0014] The large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun provided in this application has the following beneficial effects:

[0015] This application employs a five-electrode structure consisting of a large-area carbon nanotube cathode, a grid, a first focusing electrode, a decelerating electrode, and a second focusing electrode. The cathode-grid structure composed of the large-area carbon nanotube cathode and the grid can emit a stable, high-intensity electron beam. The electrostatic lens system composed of the first focusing electrode, the decelerating electrode, and the second focusing electrode can effectively confine the electrons, resulting in an electron beam with high beam intensity, low and singular electron beam energy, small divergence angle, and wide and uniform beam distribution. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings:

[0017] Figure 1 This is a schematic diagram of the internal structure of a large-area, low-energy carbon nanotube cold cathode electron gun according to an embodiment of this application.

[0018] Figure 2 This is a schematic diagram of an angle of the large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun provided in an embodiment of this application;

[0019] Figure 3 This is a schematic diagram from another angle of the large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun provided in the embodiments of this application;

[0020] Figure 4 This is a schematic diagram of a large-area cathode assembly provided in an embodiment of this application;

[0021] In the figure: 1-base, 2-outer shell, 3-cover plate, 4-ceramic insulating gasket, 5-second focusing electrode, 6-deceleration electrode, 7-first focusing electrode, 8-gate retaining ring, 9-second fixing component, 10-first fixing component, 11-cathode ceramic seat, 12-cathode, 13-gate, 14-connector insulating bushing, 15-electrode post. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0025] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0026] In addition, the term "multiple" should mean two or more.

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] like Figure 1-3As shown, this application provides a large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun, including a cover plate 3, a shell 2, a base 1, a focusing electrode, a large-area cathode assembly, and an electrode post 15. The cover plate 3 is fixed to the top of the shell 2, and the bottom of the shell 2 is fixed to the base 1. The focusing electrode is disposed inside the shell 2, including a first focusing electrode 7, a decelerating electrode 6, and a second focusing electrode 5. The second focusing electrode 5 is fixed below the cover plate 3 by a ceramic insulating gasket 4 and a connector insulating bushing 14. The decelerating electrode 6 is fixedly connected to the second focusing electrode 5 by the ceramic insulating gasket 4 and the connector insulating bushing 14. The first focusing electrode 7 is fixedly connected to the decelerating electrode 6 by the ceramic insulating gasket 4 and the connector insulating bushing 14. The large-area cathode assembly is disposed inside the shell 2 and is fixedly connected to the first focusing electrode 7 by the ceramic insulating gasket 4 and the connector insulating bushing 14. The electrode post 15 is fixed to the base 1 by the connector insulating bushing 14, with one end exposed outside the base 1.

[0029] Specifically, the large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun provided in this application embodiment is based on a large-area carbon nanotube cathode. By optimizing the electric field design and improving beam stability, it enhances the precision of electron beam energy control, improves beam uniformity, and strengthens beam intensity, thereby meeting the needs of high-precision and large-area applications. The electron gun consists of a cover plate 3, a housing 2, and a base 1. The cover plate 3 is fixed to the top of the housing 2 via a threaded hole, and the bottom of the housing 2 is fixed to the base 1 via a threaded hole. The large-area cathode assembly is located inside the housing 2 and is used to emit the electron beam. The focusing electrode is located at the front end of the large-area cathode assembly and is used to focus and constrain the electron beam to ensure the emission of a stable and high-intensity electron beam. The distance between the first focusing electrode 7 and the deceleration electrode 6, and between the deceleration electrode 6 and the second focusing electrode 5, is preferably controlled by a ceramic insulating gasket 4, with a distance of 1 mm. The ceramic insulating gasket 4 and the connector insulating bushing 14 are used for insulation during the connection process. The electrode post 15 is located on the base 1, passes through the base 1, and is connected to the power supply at one end and to the cathode assembly and the focusing electrode at the other end. The assembled electron gun is fixed and connected by the base flange.

[0030] Furthermore, such as Figure 4 The large-area cathode assembly includes a cathode 12, a grid 13, a cathode ceramic base 11, a first fixing member 10, a second fixing member 9, and a grid retaining ring 8. The cathode 12 is fixed to the cathode ceramic base 11 via threaded connections on both sides. The first fixing member 10 and the second fixing member 9 are sequentially fixed to the cathode ceramic base 11 via threaded connections. The grid 13 is positioned above the cathode 12 and is fixed to the second fixing member 9 via the grid retaining ring 8. The cathode 12 is mounted on the cathode ceramic base 11 using bolts and nuts. The grid 13 is positioned above the cathode 12 via the grid retaining ring 8 and is fixedly isolated from the cathode 12 by the first fixing member 10 and the second fixing member 9.

[0031] Furthermore, cathode 12 is a large-area carbon nanotube cathode with a diameter of 30 mm.

[0032] Furthermore, the distance between the cathode 12 and the gate 13 is 200 μm.

[0033] Specifically, in the embodiments of this application, the cathode 12 is preferably made of large-area carbon nanotubes with a diameter of 30 mm, and the distance between the cathode 12 and the gate 13 is preferably 200 μm.

[0034] Furthermore, the focusing electrode has a conical structure, with the first focusing electrode 7 having a taper of 3° and the second focusing electrode 5 having a taper of 14°. The focusing electrode adopts a simple conical structure, which is simple in structure, convenient in installation, and clear in principle. Both the first focusing electrode 7 and the second focusing electrode 5 are conical structures with tapers of 3° and 14°, respectively.

[0035] Furthermore, the lengths of the first focusing electrode 7, the decelerating electrode 6, and the second focusing electrode 5 are equal to the diameter of the cathode 12, and the inner diameter of the decelerating electrode 6 is 1.5 times the diameter of the cathode 12.

[0036] Furthermore, the cathode 12, grid 13, first focusing electrode 7, deceleration electrode 6, and second focusing electrode 5 are connected to various power supplies via electrode posts 15, wherein: the outer casing 2 is grounded; the cathode 12 is connected to a negative voltage of 60-70V; the grid 13 is connected to a positive voltage of 1000V; the first focusing electrode 7 is connected to a positive voltage of 1200-1300V; the deceleration electrode 6 is connected to a positive voltage of 400V; and the second focusing electrode 5 is connected to a positive voltage of 10V.

[0037] Furthermore, the electron beam divergence angle is less than 10°, the electron beam waist diameter is 30 mm, and the electron beam energy is 75 eV.

[0038] Specifically, in this embodiment, after the overall structure is assembled, simulation optimization is performed using the CST particle studio based on actual conditions. The electron gun is modeled using the CST particle studio, and the dimensions of the first focusing electrode 7, the decelerating electrode 6, and the second focusing electrode 5, the spacing between the cathode 12 and the gate 13, and the voltage of each electrode are changed to obtain an electron gun model that meets the simulation requirements. The electron gun simulation performance is: electron beam divergence angle less than 10°, electron beam waist diameter of 30 mm, and a single electron beam energy of 75 eV. The electron beam emitted using this embodiment has advantages such as high current intensity, single beam energy, low energy, large beam spot size, small divergence angle, and uniform spatial distribution, and can be widely used in ultra-low energy wide-beam ion sources.

[0039] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun, characterized in that, Includes a cover plate, housing, base, focusing electrode, large-area cathode assembly, and electrode posts, wherein: The cover plate is fixed to the top of the outer casing, and the bottom of the outer casing is fixed to the base; The focusing electrode is disposed inside the housing and includes a first focusing electrode, a deceleration electrode, and a second focusing electrode. The second focusing electrode is fixed below the cover plate by a ceramic insulating gasket and a connector insulating bushing. The deceleration electrode is fixedly connected to the second focusing electrode by a ceramic insulating gasket and a connector insulating bushing. The first focusing electrode is fixedly connected to the deceleration electrode by a ceramic insulating gasket and a connector insulating bushing. The large-area cathode assembly is located inside the housing and is fixedly connected to the first focusing electrode via ceramic insulating gaskets and connector insulating bushings. The electrode post is fixed to the base by a connector insulating bushing, with one end exposed outside the base; The large-area cathode assembly includes a cathode, a grid, a cathode ceramic base, a first fixing member, a second fixing member, and a grid retaining ring, wherein: The two sides of the cathode are fixed to the cathode ceramic base by threaded connection; The first fixing member and the second fixing member are sequentially fixed to the cathode ceramic seat by threaded connection; The gate is disposed above the cathode and is fixed to the second fixing member by a gate clamping ring.

2. The large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun according to claim 1, characterized in that, The cathode is a large-area carbon nanotube cathode with a diameter of 30 mm.

3. The large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun according to claim 2, characterized in that, The distance between the cathode and the gate is 200 μm.

4. The large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun according to claim 3, characterized in that, The focusing electrode has a conical structure, with the first focusing electrode having a taper of 3° and the second focusing electrode having a taper of 14°.

5. The large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun according to claim 4, characterized in that, The lengths of the first focusing electrode, the decelerating electrode, and the second focusing electrode are equal to the diameter of the cathode, and the inner diameter of the decelerating electrode is 1.5 times the diameter of the cathode.

6. The large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun according to claim 5, characterized in that, The cathode, the gate, the first focusing electrode, the decelerating electrode, and the second focusing electrode are connected to the respective power supplies via the electrode posts, wherein: The outer casing is grounded; The cathode is connected to a negative voltage of 60-70V; The gate is connected to a positive voltage of 1000V; The first focusing electrode is connected to a positive voltage of 1200-1300V; The deceleration pole is connected to a positive voltage of 400V; The second focusing electrode is connected to a positive voltage of 10V.

7. The large-area, wide-beam, low-energy carbon nanotube cold cathode electron gun according to claim 6, characterized in that, The electron beam divergence angle is less than 10°, the electron beam waist diameter is 30 mm, and the electron beam energy is 75 eV.

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