Carbon nanotube cathode array

Abstract

The application provides a carbon nanotube cathode array, which comprises: a plurality of cathode elements, each of the cathode elements comprising a cathode substrate and an emitter located on one side of the cathode substrate; the plurality of cathode elements are arranged in an array in a first direction, each of the cathode elements extends in a second direction, the emitter comprises a carbon nanotube material; the first direction intersects the second direction; wherein the cathode elements are in the shape of a whole strip, the plurality of cathode elements are arranged at intervals in the first direction, and the ratio of the emission current of each of the cathode elements to the interval of the adjacent cathode elements in the first direction is greater than or equal to 1.67 mA / mm.

Description

Technical Field

[0001] This application relates to the fields of radiation technology and nanomaterials, and in particular to a carbon nanotube cathode array. Background Technology

[0002] Multi-beam klystrons are one of the more mature and important application areas of cathode array technology. The use of a multi-beam electron gun structure can effectively solve the technical contradictions of narrow bandwidth and high operating voltage in single-beam klystrons under high-power output conditions. Besides traditional applications such as military radar and satellite communication ground stations, large-scale scientific facilities such as particle accelerators in the L-band and microwave heating systems of nuclear fusion experimental devices (such as tokamak) also require a large number of such cathode arrays.

[0003] In recent years, cathode array technology has been successfully applied in distributed X-ray tubes, further promoting the innovation of X-ray sources and X-ray imaging technology. This cathode array can achieve rapid switching of multifocal electron beams through electronic control, without the need for mechanical moving parts, and can output pulsed high-precision X-rays, effectively eliminating dynamic imaging artifacts and significantly improving imaging resolution.

[0004] Cold cathode arrays are a novel type of electron emission device based on the field emission principle. Their working mechanism differs from the high-temperature emission mode of traditional hot cathodes. Cold cathode arrays offer advantages such as stable emission at room temperature, instantaneous response, high current density, long operating life, and ease of miniaturization and integration. Because cold cathode arrays can independently and controllably generate electron beams from multiple preset locations, they are currently used in core components of high-end equipment such as distributed X-ray sources, multi-beam electron beam additive manufacturing, high-power multi-beam klystrons, and advanced lithography sources.

[0005] The information disclosed in this section is only used to understand the background of the inventive concept of this application. Therefore, the above information may include information that does not constitute prior art. Summary of the Invention

[0006] To address at least one aspect of the above-mentioned problems, embodiments of this application provide a carbon nanotube cathode array.

[0007] One aspect of the embodiments of this application provides a carbon nanotube cathode array, the carbon nanotube cathode array comprising: a plurality of cathode elements, each cathode element comprising a cathode substrate and an emitter located on one side of the cathode substrate; the plurality of cathode elements are arranged in an array in a first direction, each cathode element extending in a second direction, the emitter comprising carbon nanotube material, the first direction intersecting the second direction; wherein, the cathode elements are generally strip-shaped, the plurality of cathode elements are spaced apart in the first direction, and the ratio of the emission current of each cathode element to the spacing between adjacent cathode elements in the first direction is greater than or equal to 1.67 mA / mm.

[0008] According to some exemplary embodiments, the ratio of the length of the cathode substrate in the second direction to the width of the cathode substrate in the first direction is greater than or equal to 5:1.

[0009] According to some exemplary embodiments, the width of the cathode substrate in the first direction is 0.5-10 mm; and / or the length of the cathode substrate in the second direction is greater than or equal to 20 mm; and / or the spacing between adjacent cathode substrates in the first direction is 1-10 mm.

[0010] According to some exemplary embodiments, the carbon nanotube cathode array further includes: a gate located on the side of the emitter away from the cathode substrate, the surface of the gate near the cathode substrate being spaced apart from the end of the emitter on the side away from the cathode substrate; a support portion including an insulating support base and a support column, the insulating support base being located on the side of the cathode substrate away from the emitter, and the support column being located between the insulating support base and the gate; a second distance of 70-500 μm is formed between the surface of the gate near the insulating support base and the end of the emitter on the side away from the insulating support base.

[0011] According to some exemplary embodiments, the height of the emitter in the third direction is 1-20 μm, and the difference in the second distance between different emitters and the gate is less than 30 μm.

[0012] According to some exemplary embodiments, the flatness error of the surface of the insulating support near the support post is less than or equal to 30 μm; and / or, the flatness error of the surface of the support post away from the insulating support is less than or equal to 30 μm; and / or, the flatness error of the surface of the gate near the support post is less than or equal to 30 μm.

[0013] According to some exemplary embodiments, the carbon nanotube cathode array further includes: a plurality of electron-permeable holes that penetrate the gate, wherein the orthographic projections of the plurality of electron-permeable holes on the insulating support at least partially overlap with the orthographic projections of the emitter on the insulating support.

[0014] According to some exemplary embodiments, the purity of the carbon nanotube material is greater than or equal to 90%, and the carbon nanotube is a few-walled carbon nanotube with a wall number of 2-5.

[0015] According to some exemplary embodiments, the gate is integrally disposed, and the orthographic projection of the gate on the insulating support covers the orthographic projection of the plurality of cathode elements on the insulating support; or the gate includes a plurality of sub-gates, and the orthographic projections of the plurality of emitters on the cathode substrate are respectively located within the orthographic projections of the plurality of sub-gates on the cathode substrate.

[0016] According to some exemplary embodiments, the gate has a first arc shape in a cross section perpendicular to the second direction, and the plurality of cathode elements have a second arc shape in a cross section perpendicular to the second direction, wherein the first arc shape and the second arc shape are concentric.

[0017] According to some exemplary embodiments, the plurality of cathode elements are controlled independently.

[0018] Another aspect of the embodiments of this application provides a carbon nanotube cathode array, the carbon nanotube cathode array comprising: a plurality of cathode elements, each cathode element comprising a cathode substrate and an emitter located on one side of the cathode substrate; the cathode substrate is integrally disposed, the plurality of emitters are arranged in an array in a first direction, each emitter extending in a second direction, the emitter comprising carbon nanotube material, the first direction intersecting the second direction; wherein, the orthographic projection of the emitter on the cathode substrate is strip-shaped, the plurality of emitters are spaced apart in the first direction, and the ratio of the emission current of each cathode element to the spacing between adjacent emitters in the first direction is greater than or equal to 1.67 mA / mm.

[0019] According to some exemplary embodiments, the carbon nanotube cathode array further includes: a gate located on the side of the emitter away from the cathode substrate, wherein the surface of the gate on the side near the cathode substrate is spaced apart from the end of the emitter on the side away from the cathode substrate; the gate includes a plurality of sub-gates, wherein the orthogonal projections of the plurality of emitters on the cathode substrate are respectively located within the orthogonal projections of the plurality of sub-gates on the cathode substrate.

[0020] In the embodiments of this application, the carbon nanotube cathode array adopts strip-shaped cathode elements. Multiple cathode elements are arranged in an array in the first direction and extend in the second direction. Compared with circular or square structures, it has a larger emission area under the same total area arrangement, which is beneficial to improve the emission current. At the same time, the strip structure makes the cathode elements occupy a smaller size in the first direction, providing a structural basis for small arrangement spacing, and taking into account the dual performance requirements of large current output and small arrangement spacing. Attached Figure Description

[0021] Other objects and advantages of this application will become apparent from the following description of the application with reference to the accompanying drawings, and will help to provide a comprehensive understanding of the application.

[0022] Figure 1 The illustration shows a three-dimensional schematic diagram of a carbon nanotube cathode array according to some exemplary embodiments of the present application;

[0023] Figure 2A The schematic diagram illustrates a cross-sectional schematic of a carbon nanotube cathode array according to some exemplary embodiments of this application;

[0024] Figure 2B The schematic diagram shows electron microscope images of cathode elements according to some exemplary embodiments of this application;

[0025] Figure 3A The schematic diagram illustrates a plurality of emitters projected onto an insulating support base according to some exemplary embodiments of this application;

[0026] Figures 3B-3C The schematic diagram illustrates a single emitter projected onto a cathode substrate according to some exemplary embodiments of this application;

[0027] Figure 4 The schematic diagram illustrates the orthographic projection of the gate and emitter onto an insulating support according to some exemplary embodiments of this application;

[0028] Figure 5 The illustration schematically shows a cross-sectional view of a carbon nanotube cathode array in a second direction according to some exemplary embodiments of the present application;

[0029] Figure 6A This schematic diagram illustrates a separate cathode substrate arrangement according to some exemplary embodiments of this application.

[0030] Figure 6B This schematically illustrates a structural diagram of a split gate arrangement according to some exemplary embodiments of this application;

[0031] Figure 6CThis schematically illustrates an electrical connection structure in which the gate and cathode substrate are separately arranged according to some exemplary embodiments of this application;

[0032] Figure 6D This schematically illustrates an electrical connection structure in which the cathode substrate is separately disposed according to some exemplary embodiments of this application;

[0033] Figure 6E This schematic diagram illustrates a gate and cathode element having an inner arc structure in some exemplary embodiments according to this application;

[0034] Figure 6F This schematic diagram illustrates a gate and cathode element having an outer arc structure in some exemplary embodiments according to this application;

[0035] Figure 7A The illustration shows a schematic diagram comparing the arrangement density of circular cathode elements and strip cathode elements in some exemplary embodiments according to this application;

[0036] Figures 7B-7C This schematic diagram illustrates a structure in which the cathode elements are arranged in a ring array according to some exemplary embodiments of this application;

[0037] Figure 8 The schematic diagram illustrates a structural schematic of an X-ray tube including a carbon nanotube cathode array according to some exemplary embodiments of this application;

[0038] Figure 9 The diagram illustrates the relationship between field voltage and emission current when a carbon nanotube cathode array is applied in an X-ray tube according to some exemplary embodiments of this application.

[0039] Figure 10 The illustration schematically shows a lifetime test diagram of a carbon nanotube cathode array applied to an X-ray tube according to some exemplary embodiments of this application.

[0040] It should be noted that, for clarity, the dimensions of layers, structures, or regions in the drawings used to describe embodiments of this application may be enlarged or reduced, i.e., these drawings are not drawn to actual scale. Detailed Implementation

[0041] The technical solution of this application will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of this application with reference to the accompanying drawings is intended to explain the overall inventive concept of this application and should not be construed as a limitation of this application.

[0042] Furthermore, in the following detailed description, numerous specific details are set forth for ease of explanation to provide a thorough understanding of the embodiments disclosed herein. However, it will be apparent that one or more embodiments may be practiced without these specific details.

[0043] It should be understood that although the terms first, second, etc., may be used herein to describe different elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0044] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “including” are used herein, it indicates the presence of the stated features, integrals, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof.

[0045] In cathode array applications, some scenarios prioritize high current output (e.g., emission current of a single emitter greater than or equal to 20 mA), while others prioritize small array spacing (e.g., spacing between adjacent emitters less than or equal to 12 mm). Most applications require both of these performance metrics. Especially in distributed X-ray tubes, where cathodes are required to achieve emission currents of tens or even hundreds of milliamps, the cathode array spacing has become an increasingly critical performance indicator. For example, static CT systems, relying on distributed X-ray array imaging technology, eliminate the mechanical scanning structure necessary for traditional equipment, achieving 3D imaging through multi-view projection data acquisition and reconstruction. In this technical architecture, the cathode array spacing directly determines the number of imaging angles, which in turn determines the dimensionality of the sampled information, thus becoming a core factor affecting the resolution and clarity of 3D image reconstruction. The denser the array arrangement, the more imaging angles, and the richer the dimensionality of the acquired sampled data, effectively filling imaging blind spots, significantly improving the resolution and stereoscopic realism of 3D images, and ultimately achieving high-precision, fast, and high-definition imaging.

[0046] Currently, distributed X-ray sources and their based static CT technology have achieved breakthroughs in principle verification and preliminary applications. Distributed X-ray sources have achieved cathode array integration, but the cathode spacing remains relatively large. While static CT based on distributed X-ray sources has achieved 3D imaging capabilities and is applied in fields with relatively low precision requirements, such as security inspection, it has not yet been effectively promoted in applications with stringent spatial resolution requirements, such as high-resolution medical imaging, chip inspection, and new energy battery inspection. One of the important reasons for these limitations is that the cathode array spacing urgently needs to be further reduced.

[0047] After reviewing and analyzing existing distributed X-ray source cathode technologies, their main technical approaches and existing shortcomings are as follows:

[0048] (1) Traditional hot cathode distributed X-ray source. This scheme adopts a filament emission structure and is equipped with a heat shielding component. The cathode unit is circular. Due to the constraints of structural heat dissipation and insulation design, the overall volume of the component is large, which makes it difficult to meet the requirements of high-density array integration. The cathode array spacing is usually not less than 20 mm, making it difficult to achieve high-definition X-ray imaging.

[0049] (2) Dot-matrix dense array cold cathode scheme. This scheme uses tiny circular or square cathode units arranged in a dense array. The carbon nanotube emission layer is prepared by screen printing, CVD in-situ growth or transfer method, which can meet the dense arrangement requirements. However, the area of ​​a single cathode unit in this scheme is small and the emission current is low. The current of a single cathode unit is about 1µA, and the total emission current is less than 1mA, which is difficult to meet the requirements of static CT high-definition rapid imaging for distributed X-ray source milliampere-level or even hundreds of milliampere-level beam current intensity.

[0050] (3) Linear / arc / circular cold cathode arrangement scheme. Currently, some cold cathodes have achieved linear, arc or circular arrays, but the size of a single cathode is large and the overall arrangement spacing is large, which makes it difficult to meet the application requirements of static CT in multi-view, high-precision, and high-frame-rate three-dimensional imaging, thus restricting the performance improvement and large-scale promotion of static CT equipment.

[0051] In summary, among the relevant cathode array technologies, schemes with higher emission current generally have larger cathode spacing (e.g., the cathode spacing of multi-beam klystrons is typically tens of millimeters), while schemes with smaller spacing generally have lower emission current (e.g., the spacing of micro-dot cold cathode arrays can be as small as hundreds of micrometers, but the current is only a few microamps). The current intensity of a single cathode fails to meet the requirements of practical applications such as industrial inspection, security inspection, and medical imaging. In other words, cathode arrays cannot simultaneously meet the dual performance requirements of high current output from a single cathode (e.g., the emission current of a single emitter is greater than or equal to 20 mA) and small spacing (e.g., the spacing between adjacent emitters is less than or equal to 12 mm).

[0052] To address at least one of the above problems, embodiments of this application provide a carbon nanotube cathode array.

[0053] Figure 1 The illustration shows a three-dimensional schematic diagram of a carbon nanotube cathode array according to some exemplary embodiments of the present application; Figure 2A The schematic diagram illustrates a cross-sectional schematic of a carbon nanotube cathode array according to some exemplary embodiments of this application; Figure 2B The diagram illustrates electron microscope images of cathode elements according to some exemplary embodiments of this application.

[0054] In some embodiments of this application, reference is made to Figure 1 and Figure 2A The carbon nanotube cathode array 100 may include a support portion 10, which may include an insulating support base 11 and a support pillar 12 located on one side of the insulating support base 11. The carbon nanotube cathode array 100 may include a plurality of cathode elements 20, with the cathode elements 20 and the support pillar 12 located on the same side of the insulating support base 11. Each cathode element 20 may include a cathode substrate 21 and an emitter 22 located on one side of the cathode substrate 21. The plurality of cathode elements 20 are arranged in an array in a first direction X, and each cathode element 20 extends in a second direction Y. The emitter 22 includes nanomaterial 221, and the first direction X intersects the second direction Y. The carbon nanotube cathode array 100 may also include a gate 30, located on the side of the support pillar 12 away from the insulating support base 11. The surface of the gate 30 near the insulating support base 11 is spaced apart from the end of the emitter 22 away from the insulating support base 11. In the embodiments of this application, the cathode element 20 is generally strip-shaped, and multiple cathode elements 20 are arranged at intervals in the first direction X. The ratio of the emission current of each cathode element 20 to the spacing between adjacent cathode elements 20 in the first direction X is greater than or equal to 1.67 mA / mm.

[0055] For example, the insulating support 11 can serve as a carrier substrate for the cathode element 20, providing a flat mounting surface for multiple cathode elements 20 and ensuring a high degree of consistency in the spatial arrangement of each cathode element 20. The support post 12 is disposed between the insulating support 11 and the gate 30, and can be used to precisely define the spatial position of the gate 30 relative to the cathode element 20, thereby controlling the inter-electrode distance between the emitting end face of the cathode element 20 and the lower surface of the gate 30 within a preset range. Precise control of this inter-electrode distance is crucial for the establishment and stabilization of the field emission electric field. If the distance is too small, breakdown discharge is likely to occur; if the distance is too large, a higher gate voltage must be applied to excite effective emission.

[0056] For example, multiple cathode elements 20 are arranged in an array along a first direction X, and each cathode element 20 extends along a second direction Y, forming a strip structure. When multiple cathode elements 20 are arranged in an array along one direction, the strip structure has a larger emission area for the same total area compared to a circular or square structure, which is beneficial for increasing the emission current. Simultaneously, the strip structure allows the cathode elements 20 to occupy a smaller dimension in the width direction (first direction X), providing a structural basis for a small arrangement spacing. Compared to the current of approximately 1µA in a single cathode unit in a micro-dot cold cathode array in related technologies, and the cathode spacing greater than or equal to 20 mm in a multi-beam klystron, the carbon nanotube cathode array 100 of this application can achieve an emission current of greater than or equal to 20 mA for the emitter 22 with a spacing less than or equal to 12 mm, i.e., the ratio of emission current to spacing is greater than or equal to 1.67 mA / mm, thus balancing the dual performance requirements of high current output and small arrangement spacing.

[0057] For example, the orthographic projection of the gate 30 on the insulating support 11 can cover the orthographic projections of multiple cathode elements 20, ensuring that the gate 30 can cover the emission region of the cathode elements 20, forming a uniform electric field coverage. The gate 30 can adopt an integral structure, which can build a high-intensity and uniformly distributed field emission electric field between the cathode elements 20 and the gate 30, enabling multiple cathode elements 20 to turn on synchronously and emit stably under the same gate voltage.

[0058] According to some exemplary embodiments, continue to refer to Figure 1 and Figure 2A The ratio of the length s of the cathode substrate 21 in the second direction Y to the width w of the cathode substrate 21 in the first direction X is greater than or equal to 5:1.

[0059] For example, by setting the aspect ratio (s / w) of the cathode substrate 21 to be greater than or equal to 5:1, it is ensured that a single cathode substrate 21 has a sufficiently long emission area to achieve high current output, and that each cathode substrate 21 can be compactly arranged in the width direction (i.e., the first direction X), thereby integrating more cathode elements 20 in a limited space and achieving the dual performance requirements of high current output and small arrangement spacing.

[0060] According to some exemplary embodiments, refer to Figure 1 , Figure 2A and Figure 3A The width w of the cathode substrate 21 in the first direction X is 0.5-10 mm; and / or the length s of the cathode substrate 21 in the second direction Y is greater than or equal to 20 mm; and / or the spacing d between adjacent cathode substrates 21 in the first direction X is 1-10 mm.

[0061] For example, the width w of the cathode substrate 21 is one of the key dimensions affecting the arrangement spacing. If the width w is less than 0.5 mm, the emission area of ​​the cathode element 20 will be too narrow. Under the same emission current density, the emission current of a single cathode element 20 will be reduced accordingly, making it difficult to meet the application requirements of high current output. If the width w is greater than 10 mm, within the limited array space, increasing the width w of the cathode substrate 21 will directly encroach on the arrangement space between adjacent elements, which is not conducive to achieving a small arrangement spacing. Therefore, setting the width w in the range of 0.5 to 10 mm can ensure that the cathode element 20 has a sufficient emission area while facilitating the array distribution of multiple cathode elements 20 with a small arrangement spacing.

[0062] For example, given a fixed width w, the emitting area of ​​the cathode element 20 is proportional to its length s. The larger the length s, the larger the emitting area, and the higher the emitting current can be obtained under the same field emission current density. In practical designs, the length s can be further increased according to the current requirements of specific application scenarios, such as 30mm, 50mm or even longer, to obtain a larger emitting current.

[0063] It should be noted that, referring to Figure 2B Each linear structure standing upright on the surface of the cathode substrate 21 can be a nanomaterial 221, and the nanomaterial 221 is densely arranged on the surface of the cathode substrate 21. Exemplarily, the extension direction of the nanomaterial 221 is substantially perpendicular to the upper surface of the cathode substrate 21, and the nanomaterial 221 is distributed at an angle of 75-90° to the upper surface; the height of the nanomaterial 221 is uniform, mainly distributed in the range of 1-20 μm; the density of the carbon nanotubes is high, reaching 100-200 nanotubes / μm. 2 The carbon nanotubes exhibit high uniformity, with a distribution non-uniformity of <20%. In the embodiments of this application, to illustrate the structure of the emitter 22 and its positional relationship with the cathode substrate 21, each emitter 22 represents a collection of all nanomaterials 221 located on a single cathode substrate 21 or a collection of all nanomaterials 221 located within a macroscopically distinguishable region on the cathode substrate 21. For example, referring to... Figure 2A The emitter 22 represents the collection of all nanomaterials 221 located on a single cathode substrate 21, and there are 7 emitters 22 corresponding to 7 single cathode substrates 21.

[0064] For example, the spacing d between adjacent cathode substrates 21 in the first direction X determines the array arrangement spacing, and also affects the electric field crosstalk and insulation reliability between adjacent cathode substrates 21. When the spacing d is greater than or equal to 1 mm, the withstand voltage exceeds 26 kV, ensuring that the voltage between adjacent cathode substrates 21 remains stable and does not arc within 3 kV. If the spacing d is too large (e.g., d is greater than 10 mm), the number of cathode elements 20 that can be arranged per unit length will decrease, which is not conducive to high current output.

[0065] Figure 3A The schematic diagram illustrates a plurality of emitters projected onto an insulating support base according to some exemplary embodiments of this application; Figures 3B-3C The schematic diagram illustrates a single emitter projected onto a cathode substrate as an orthographic projection according to some exemplary embodiments of this application.

[0066] According to some exemplary embodiments, in conjunction with reference to Figure 1 , Figure 2A and Figures 3A-3C The orthographic projection of the emitter 22 on the insulating support 11 is located within the orthographic projection of the cathode base 21 on the insulating support 11, and the orthographic projection of the emitter 22 on the cathode base 21 is strip-shaped.

[0067] For example, the cathode substrate 21 serves as both a carrier layer and a conductive layer, and the emitter 22 is located on the surface of the cathode substrate 21 away from the insulating support 11. The orthographic projection of the emitter 22 onto the insulating support 11 can be exactly the same as the orthographic projection of the cathode substrate 21 onto the insulating support 11 (e.g., Figure 3B (As shown), it can also be located within the orthographic projection of the cathode substrate 21 onto the insulating support 11 (e.g. Figure 3C As shown in the diagram, for example, the area of ​​the orthographic projection of the cathode substrate 21 onto the insulating support 11 is 2mm*20mm, and the area of ​​the orthographic projection of the emitter 22 onto the insulating support 11 is 1mm*18mm. The orthographic projection of the emitter 22 onto the cathode substrate 21 is strip-shaped, meaning that the emitter 22 extends continuously in its length direction and narrows into a long and narrow shape in its width direction. The strip-shaped outline of the emitter 22 can match the strip-shaped outline of the cathode substrate 21. For example, the strip-shaped dimensions of the emitter 22 and the strip-shaped dimensions of the cathode substrate 21 can be proportionally coordinated, and the aspect ratio of the emitter 22 can also be set to be greater than or equal to 5:1. The emitter 22 has sufficient extension dimensions in its length direction (second direction Y) to form a continuous large-area emission region. Compared to circular or square emitters of the same total area, the strip emitter 22 has a larger emission area, which is beneficial to increasing the emission current. At the same time, the narrower width of the strip emitter 22 reduces the space occupied by a single emitter 22 in the width direction, thereby leaving sufficient insulation spacing between adjacent emitters 22 to achieve a compact arrangement in the first direction X.

[0068] It should be noted that, in this application, "strip" refers to a narrow geometric shape in which the cathode element 20, cathode substrate 21, or emitter 22 appears as an elongated shape extending in the second direction Y (length direction) and narrowing in the first direction X (width direction) in its orthogonal projection onto the insulating support 11. Its length dimension is significantly larger than its width dimension, for example, an aspect ratio greater than 5:1. For example, the shape of the strip includes, but is not limited to, rectangles, racetracks, etc.

[0069] According to some exemplary embodiments, refer to Figure 1 and Figure 2A The surface of the gate 30 near the insulating support 11 has a second distance h2 between it and the end of the emitter 22 away from the insulating support 11. The second distance h2 is 70-500μm.

[0070] For example, a first distance h1 (i.e., the height of the support post 12) exists between the surface of the support post 12 near the insulating support base 11 and the surface of the support post 12 away from the insulating support base 11. A second distance h2 is equal to the difference between the first distance h1 and the height h3 of the cathode element 20 (the surface near the insulating support base 11 and the surface away from the insulating support base 11). In other words, the height of the support post 12 is set such that, after compensating for the height of the cathode element 20 itself, a 70-500 μm inter-electrode spacing is maintained between the lower surface of the gate 30 and the upper end of the emitter 22. This inter-electrode spacing facilitates the formation of a high-intensity, uniform field emission electric field between the cold cathode and the gate, significantly improving electron emission efficiency and stability, while avoiding the risk of breakdown and short circuits caused by excessively close spacing. For example, the spacing d can be greater than twice the second distance h2, which helps reduce electric field crosstalk and improve insulation reliability. For example, the second distance h2 can be 200 μm.

[0071] Figure 4 The schematic diagram illustrates a gate and emitter projected onto an insulating support base according to some exemplary embodiments of this application.

[0072] According to some exemplary embodiments, in conjunction with reference to Figure 1 and Figure 4 The carbon nanotube cathode array 100 may also include a plurality of electron-permeable holes 31 that penetrate the gate 30. The orthographic projections of the plurality of electron-permeable holes 31 on the insulating support 11 at least partially overlap with the orthographic projections of the emitter 22 on the insulating support 11. For example, the orthographic projections of the electron-permeable holes 31 on the insulating support 11 may include hexagons, circles, or rectangles.

[0073] For example, the opening area of ​​the electron through-hole 31 can completely cover the entire area of ​​the emitter 22, and can be slightly larger than the area of ​​the emitter 22, to form a sufficiently large electric field penetration window, so as to ensure that electrons escaping from each area of ​​the surface of the emitter 22 can pass through the gate 30 and enter the anode acceleration zone. The opening area being slightly larger than the area of ​​the emitter 22 is beneficial to making full use of the emission area of ​​the strip emitter 22 and increasing the emission current. The orthogonal projection of the electron through-hole 31 on the insulating support 11 can be hexagonal, that is, multiple electron through-holes 31 are arranged in a honeycomb array, and the supporting ribs 311 between adjacent electron through-holes 31 are evenly distributed and have good continuity. Under a certain opening area ratio, the hexagonal structure has better structural rigidity and deformation resistance, so that the gate 30 can maintain good flatness even under a large opening area ratio, and will not collapse or warp due to too many openings. The orthographic projection of the electron through-hole 31 onto the insulating support 11 can also be rectangular. The shape of the rectangular hole is highly matched with the outline of the strip cathode element 20 and the strip emitter 22, resulting in better space utilization.

[0074] According to some exemplary embodiments, the flatness error of the surface of the insulating support 11 near the support post 12 is less than or equal to 30 μm. The flatness error of the surface of the support post 12 away from the insulating support 11 is less than or equal to 30 μm. The flatness error of the surface of the gate 30 near the support post is less than or equal to 30 μm.

[0075] For example, the insulating support 11 serves as the fundamental load-bearing component of the entire carbon nanotube cathode array 100. Its surface near the support pillar 12 provides a common mounting reference for both the support pillar 12 and the cathode elements 20. The flatness error of this surface determines the consistency of the upper surfaces of all cathode elements 20 relative to this reference surface, and the basis for the parallelism of the lower surface of the gate 30 relative to this reference surface after the support pillar 12 is installed. Therefore, controlling the flatness error of the mounting surface of the insulating support 11 to within 30 μm ensures that the unevenness of the insulating support 11 itself is a reasonable proportion relative to the 70-500 μm inter-electrode spacing, and will not substantially affect the uniformity of the inter-electrode electric field. It should be noted that flatness refers to the degree of deviation of the surface of the insulating support 11 near the support pillar 12, the surface of the support pillar 12 away from the insulating support 11, or the surface of the gate 30 near the support pillar from an ideal plane. Flatness can be measured by finding the minimum distance between two parallel planes on the measured surface that can encompass all measurement points; this minimum distance is the flatness error.

[0076] For example, the support post 12 is located between the insulating support base 11 and the gate 30, and its top surface (i.e., the surface away from the insulating support base 11) is directly attached to the lower surface of the gate 30, serving as a key limiting surface that defines the height of the gate 30. The flatness error of this top surface directly affects the parallelism of the lower surface of the gate 30 relative to the upper surface of the cathode element 20, thereby determining the uniformity of the inter-electrode distance distribution across the entire area of ​​the cathode element 20 array. Therefore, controlling the flatness error of the upper surface of the support post 12 to within 30 μm is beneficial for controlling the consistency of the emission current of each cathode element 20 across the entire array.

[0077] For example, the insulating support 11 and the support column 12 can be made of high-insulation materials such as ceramics. These materials have excellent insulation properties, high structural stiffness, and low thermal deformation rate, which can maintain the structural dimensional stability and assembly accuracy for a long time, providing a reliable structural guarantee for the carbon nanotube cathode array 100 to achieve long-term stable and high-precision high-current emission.

[0078] For example, the flatness error of the gate 30 is less than or equal to 30 μm, which helps to improve the uniformity of the inter-electrode field strength distribution, thereby ensuring that the effective control voltage range of the gate 30 is stably maintained in a lower voltage range. Within this voltage range, the carbon nanotube cathode array 100 can achieve high current emission, thereby obtaining the operating characteristics of independent controllability of each cathode element 20 and excellent overall output current.

[0079] According to some exemplary embodiments, refer to Figure 2A The height h4 of the emitter 22 in the third direction Z is 1-20 μm, and the difference in the second distance h2 between the emitter 22 and the gate 30 in different cathode elements 20 is less than 30 μm.

[0080] For example, the inter-electrode spacing between the upper end of the emitter 22 and the lower surface of the gate 30 determines the surface electric field strength of the emitter 22. Under the same gate voltage, even a slight change in the inter-electrode spacing will lead to a corresponding change in the surface electric field strength of the emitter 22, thereby affecting the emission current density. Controlling the difference in inter-electrode spacing within 30 μm is beneficial to improving the uniformity of the emission current. For example, the height of the emitter 22 is 10 μm. It should be noted that the height of the emitter 22 refers to the average height of the corresponding nanomaterial 221, and the height of the nanomaterial 221 refers to the distance between the end of the nanomaterial 221 closest to the cathode substrate 21 and the end furthest from the cathode substrate 21 in the third direction Z.

[0081] According to some exemplary embodiments, nanomaterial 221 may include carbon nanotube material with a purity of ≥90%, and the carbon nanotube is a few-walled carbon nanotube with a wall number of 2-5.

[0082] For example, in carbon nanotube materials, the number of graphene layers and their nesting structure jointly determine the performance of the carbon nanotube material. A graphene layer count between 2 and 5 layers facilitates the fabrication of carbon nanotubes of a single type, avoiding the mixing of carbon nanotubes with different properties. Carbon nanotubes with a 2-5 layer structure exhibit excellent mechanical and electrical properties, better withstand high-current and high-energy electron emission processes, and maintain high stability, which helps extend the lifespan of the carbon nanotube cathode array 100. A carbon nanotube material purity of ≥90% is beneficial for improving electron emission performance, increasing emission current, and enhancing the output power and operating efficiency of the carbon nanotube cathode array 100.

[0083] For example, the nanomaterial 221 may also include ZnO nanowires. Carbon nanotube materials or ZnO nanowires can be prepared on the cathode substrate 21 by direct growth, electrophoretic deposition or coating; after preparation, the nanomaterial 221 is upright and uniformly distributed on the surface of the cathode substrate 21, and has excellent field emission performance.

[0084] Figure 5 The schematic diagram illustrates a cross-sectional view of a carbon nanotube cathode array in a second direction according to some exemplary embodiments of this application; for example, Figure 5 It can be a carbon nanotube cathode array along Figure 4 The cross-sectional view taken from line MM' in the diagram. Figure 6A The schematic diagram illustrates a separate cathode substrate arrangement in some exemplary embodiments according to this application, for example, Figure 6A It can be a carbon nanotube cathode array along Figure 4 A cross-sectional view of line NN' in the diagram; Figure 6B This schematically illustrates a structural diagram of a split gate arrangement according to some exemplary embodiments of this application; Figure 6C This schematically illustrates an electrical connection structure in which the gate and cathode substrate are separately arranged according to some exemplary embodiments of this application; Figure 6D This schematically illustrates an electrical connection structure in which the cathode substrate is separately disposed according to some exemplary embodiments of this application; Figure 6E This schematic diagram illustrates a gate and cathode element having an inner arc structure in some exemplary embodiments according to this application; Figure 6F The schematic diagram illustrates a gate and cathode element having an outer arc structure in some exemplary embodiments according to this application.

[0085] According to some exemplary embodiments, refer to Figure 2A , Figure 5 , Figure 6A , Figures 6C-6FThe gate 30 can be integrally formed, and the orthogonal projection of the gate 30 on the insulating support 11 can cover the orthogonal projection of the multiple cathode elements 20 on the insulating support 11; or the gate 30 includes multiple sub-gates 32, and the orthogonal projections of the multiple emitters 22 on the cathode substrate 21 can be respectively located within the orthogonal projections of the multiple sub-gates 32 on the cathode substrate 21.

[0086] Reference Figure 5 and Figure 6A The cathode substrates 21 of different cathode elements 20 can be separately configured, and the emitters 22 can be individually controlled, meaning that each cathode element 20 has an independent cathode substrate 21. Each cathode substrate 21 is connected to the driving circuit via an independent lead electrode, thereby enabling independent supply and control of the emission current of each cathode element 20. This discrete substrate physically breaks off the conductive path formed between the units through the substrate, improving the crosstalk immunity of the carbon nanotube cathode array 100.

[0087] Reference Figure 6C Both the gate 30 and the cathode substrate 21 can be separately configured. The gate 30 includes multiple sub-gates 32, each sub-gate 32 being connected to the driving circuit via an independent lead electrode. The cathode substrate 21 includes multiple sub-substrates 211, each sub-substrate 211 being connected to the driving circuit via an independent lead electrode. For example, each gate 30 is independently connected to a potential U. a1 U a2 U a3 U a4 U a5 Each cathode substrate 21 is independently connected to potentials U0, U1, U2, U3, U4, U5, U6, ... . When the potential of the cathode substrate 21 is negative relative to the potential of the corresponding gate 30, and the negative value exceeds a certain threshold, the emitting material on the cathode substrate 21 emits an electron beam. Potential U a1 U a2 U a3 U a4 U a5 The potentials U0, U1, U2, U3, U4, U5, U6, ... can be equal or unequal.

[0088] Reference Figure 6DThe cathode substrate 21 can be a separate unit, while the gate 30 can be a single unit. The cathode substrate 21 includes multiple sub-substrates 211, each connected to the driving circuit via an independent lead electrode. For example, each cathode substrate 21 is independently connected to potentials U1, U2, U3, U4, U5, U6, U7, ..., and the gate 30 is connected to potential U0. When the potential of the cathode substrate 21 is negative relative to the potential U0 of the corresponding gate 30, and the negative value exceeds a certain threshold, the emitting material on the cathode substrate 21 emits an electron beam. Potentials U1, U2, U3, U4, U5, U6, U7, ... can be equal or unequal.

[0089] According to some exemplary embodiments, the gate 30 has a first arc shape in a cross section perpendicular to the second direction Y, and the plurality of cathode elements 20 have a second arc shape in a cross section perpendicular to the second direction Y, wherein the first arc shape and the second arc shape are concentric.

[0090] Reference Figure 6E The gate 30 can have an inner arc shape, and multiple cathode substrates 21 can also have an inner arc shape. The two inner arc shapes share a common center, and the emission direction of the electron beam points to this center.

[0091] Reference Figure 6F The gate 30 may have an outer arc shape, and the multiple cathode substrates 21 may also have an outer arc shape. The two inner arc shapes share a common center, and the emission direction of the electron beam is away from this center. For example, the structure of the inner and outer arc shapes can be used as a core component of equipment such as multi-beam electron beam additive manufacturing equipment, high-power multi-beam klystrons, and advanced lithography sources.

[0092] According to some exemplary embodiments, in conjunction with reference to Figure 2A and Figure 6BThe carbon nanotube cathode array 100 includes multiple cathode elements 20, each cathode element 20 including a cathode substrate 21 and an emitter 22 located on one side of the cathode substrate 21; the cathode substrate 21 is integrally formed, the multiple emitters 11 are arranged in an array in a first direction X, and each emitter 22 extends in a second direction Y. The emitter 22 includes carbon nanotube material 221, and the first direction X and the second direction Y intersect; wherein, the orthographic projection of the emitter 22 on the cathode substrate 21 is strip-shaped, the multiple emitters 22 are arranged at intervals in the first direction X, and the ratio of the emission current of each cathode element 20 to the spacing of the adjacent emitter 22 in the first direction X is greater than or equal to 1.67 mA / mm. The carbon nanotube cathode array 100 also includes a gate 30, which is located on the side of the emitter 22 away from the cathode substrate 21. The surface of the gate 30 near the cathode substrate 21 is spaced apart from the end of the emitter 22 away from the cathode substrate 21. The gate 30 includes a plurality of sub-gates 32, and the orthogonal projections of the plurality of emitters 22 on the cathode substrate 21 are respectively located within the orthogonal projections of the plurality of sub-gates 32 on the cathode substrate 21.

[0093] For example, the gate 30 can be separately configured, the cathode substrate 21 can be integrally configured, and the emitter 22 can be individually controlled, that is, each cathode element 20 corresponds to an independent gate 30. Each gate 30 is connected to the driving circuit through an independent lead electrode, thereby realizing the independent supply and regulation of the emission current of each cathode element 20.

[0094] Figure 7A The illustration shows a schematic comparison of the arrangement spacing of circular cathode elements and strip cathode elements in some exemplary embodiments according to this application.

[0095] For example, refer to Figure 7AThe circular cathode elements 40 and the strip cathode elements 20 are arranged within the same defined area. For example, with the first direction X perpendicular to the second direction Y, the circular cathode elements 40 are arranged in 2 rows in the first direction X and 6 columns in the second direction Y, for a total of 12 circular cathode elements 40; the strip cathode elements 20 are arranged in 12 rows in the first direction X and 1 column in the second direction Y, for a total of 12 strip cathode elements 20. Because a large insulation gap must be reserved between adjacent circular cathode elements 20, the area of ​​their spacing region is significantly increased; while the strip cathode elements 20, due to their extended length in the first direction X and their compact arrangement in the second direction Y, require a relatively smaller insulation gap between units. Therefore, within the same arrangement area, the spacing area of ​​the circular cathode element 40 is larger, the emission area of ​​a single circular cathode element 40 is smaller than that of a single strip cathode element 20, and the array spacing of the strip cathode elements 20 is smaller than that of the array spacing of the circular cathode elements 40. Thus, under the same array area, the strip cold cathode scheme can achieve higher unit integration density and larger total emission current.

[0096] In some embodiments of this application, high emission density techniques are utilized, such as a current emission density stabilized at 7777.8 mA / cm². 2 Each emitter 22 is 20mm long and 1mm wide, with a launch area of ​​1mm * 20mm = 0.2cm. 2 The current in each cathode can reach up to 1555.6 mA (calculation process: 0.2 cm). 2 ×7777.8mA / cm 2 =1555.6mA), and operates stably. This value is much higher than that of conventional cold cathode radiation sources, and in high-current operation mode, the cathode emission is uniform, has good thermal stability, and has a long service life.

[0097] Figures 7B-7C The schematic diagram illustrates a structure in which the cathode elements are arranged in a ring array according to some exemplary embodiments of this application.

[0098] Reference Figures 7B-7CMultiple cathode elements 20 are arranged in a concentric ring array along an arc trajectory. For example, the first direction X is the direction of arc extension, and the second direction Y is the radial direction pointing from a point on the arc to the center O. Each cathode element 20 extends in the radial direction of the circle, and the length direction of each cathode element 20 points to the center O, forming a concentric radial arrangement. In this ring array structure, the multiple cathode elements 20 can be arranged at equal intervals along the arc direction, and the tangential spacing between adjacent cathode elements 20 along the arc direction also meets the aforementioned range of 0.5-10mm, thereby achieving high-density integration within the ring structure. The length of each cathode element 20 extending in the radial direction can be set according to the radial dimension of the ring structure and application requirements, while maintaining an aspect ratio greater than 5:1 to ensure that each cathode element 20 has a large emission area.

[0099] Figure 8 The schematic diagram illustrates a structural schematic of an X-ray tube including a carbon nanotube cathode array according to some exemplary embodiments of this application.

[0100] Embodiments of this application also provide an X-ray tube 1000, which includes the carbon nanotube cathode array 100 as described above.

[0101] Reference Figure 8 The X-ray tube 1000 may include a support portion 10, a cathode element 20, and a grid 30 as described above. The cathode element 20 is located on the support portion 10 and forms a triode electron gun structure with the grid 30 and the anode 83. For example, the distance between the grid 30 and the cathode element 20 is 150-500 μm. A certain voltage value (0-3 kV) is applied to the grid 30 to form a first electric field E1, the magnitude of which is 1-20 V / μm. When the voltage of the grid 30 generates an electric field threshold value greater than the threshold value for field emission, the cathode element 20 emits electrons 811. A certain voltage value is applied to the anode 83 to form a second electric field E2. The emitted electrons 811 are accelerated under the action of the second electric field E2 and bombard the anode target 84 to generate X-rays 812. The X-rays 812 are received by the detector 86 after passing through the beryllium window 85, and then processed and analyzed by devices such as the amplifier 87, oscilloscope 88, and computer 89 to achieve imaging or detection of objects.

[0102] In some embodiments of this application, based on Figure 8 Actual testing of the X-ray tube with carbon nanotube cathode array shows that when the distance between the cathode element 20 and the gate 30 is 215 μm, the X-ray tube is configured such that, in response to the control voltage of the gate 30 being 1600 V, the emission current of the carbon nanotube cathode array is greater than or equal to 350 mA; and the performance is stable with a lifespan exceeding 276,000 cycles per second.

[0103] Figure 9The diagram illustrates the relationship between field voltage and emission current when a carbon nanotube cathode array is applied in an X-ray tube according to some exemplary embodiments of this application. Figure 10 The illustration schematically shows a lifetime test diagram of a carbon nanotube cathode array applied to an X-ray tube according to some exemplary embodiments of this application.

[0104] Reference Figure 9 By measuring the emission current under different field voltages, it can be seen that the carbon nanotube cathode array obtained in the embodiments of this application, with a cathode-gate spacing of 215µm and a gate voltage of 1388V, can achieve a maximum emission current of 350mA, corresponding to an emission current density of approximately 7777.8mA / cm². 2 Furthermore, increasing the gate voltage can further increase the emission current, indicating that it has excellent field emission performance. The field emission performance of commercially available carbon nanotubes is relatively poor. The operating current of carbon nanotube cathode arrays used in X-ray tubes is generally from a few mA to tens of mA, while the maximum short-time pulse emission current disclosed in existing technology is only 200 mA, but the gate control voltage is as high as 1700V or more.

[0105] Reference Figure 10 Under operating conditions of 200 mA cathode current, 1 ms current pulse width, and 0.3% duty cycle, after long-term electron emission tests exceeding 5 million cycles, it can be seen that the carbon nanotube cathode array obtained in the embodiments of this application only increased its voltage from 1342 V to 1372 V during more than 5 million electron emission cycles, an increase of only 30 V. This leaves a growth potential of 1628 V to the allowable gate control voltage of 3000 V. If the gate control voltage maintains the current growth rate in subsequent operations, the number of operating pulses for this cathode can be estimated to reach 2.76 × 10⁻⁶. 8 The total operating time can reach 276,000 seconds (2.76 × 10⁻⁶) times (1628V ÷ 30V × 500 + 5 million times). 8 (Times × 1 millisecond), meeting the 200,000 seconds lifespan requirement for medical CT tube registration certification, indicating that the carbon nanotube cathode of this application has stable emission performance and a long service life, and can meet relevant usage requirements in future practical applications.

[0106] In the embodiments of this application, the carbon nanotube cathode array 100 features a large emission current and a small spacing between its cells, which significantly improves the performance of the X-ray tube 1000. For example, the operating current of this X-ray tube 1000 is at least an order of magnitude higher than that of similar technologies, while also exhibiting high stability and long lifespan. These advantages enable the X-ray tube 1000 to successfully transition from the laboratory research stage to large-scale commercial applications, demonstrating enormous potential and value in multiple application areas.

[0107] The X-ray tube 1000 has a wide range of applications. For example, it can be used in medical imaging as a cathode material in X-ray generators for CT scans and radiotherapy. In scientific research equipment, it can serve as an electron source in electron microscopes, providing high-resolution imaging capabilities. In industrial inspection, it can be used in non-destructive testing equipment for examining the internal structure of materials. Finally, it can be used in flat panel displays as an electron source in field emission displays, achieving high brightness and high contrast.

[0108] It should be understood that the X-ray tube 1000 according to some exemplary embodiments of this application has all the features and advantages of the carbon nanotube cathode array 100 described above, which can be referred to in the above description of the carbon nanotube cathode array 100 and will not be repeated here.

[0109] The carbon nanotube cathode array in some exemplary embodiments of this application is suitable for static CT systems. Its small spacing allows for a large number of emitters 22 per unit length, resulting in high density. This high-density focal arrangement significantly increases the imaging field of view and enriches the dimensions of sampling information, thereby greatly improving imaging resolution and image clarity. This meets the high-precision detection requirements for fine lesions and defects, effectively broadening the application scenarios of static CT in medical imaging and industrial non-destructive testing. Simultaneously, the carbon nanotube cathode array has a high current output capability, which increases the beam power and penetration of the X-ray tube, enabling effective detection of thick workpieces and high-density tissues. It also shortens imaging exposure time, reduces motion artifacts, and improves scanning efficiency, fully meeting the actual needs of high-load commercial applications such as industrial flaw detection and medical static CT, further expanding the key indicators and application scope of distributed X-ray sources. Furthermore, the cathode array adopts a modular assembly design, resulting in a simplified overall structure, convenient assembly, and controllable production costs, demonstrating good adaptability for large-scale mass production.

[0110] The carbon nanotube cathode array in the exemplary embodiments of this application has been used to fabricate multifocal X-ray tubes. Compared with traditional hot cathode and ordinary cold cathode X-ray sources, this multifocal X-ray tube exhibits significant improvements in electron emission capability, array spacing, lifespan, and imaging quality. Specifically, the maximum emission current of a single cathode unit can reach 350 mA, and its lifespan is excellent. Furthermore, through further refined design of the cathode dimensions and unit spacing, this application achieves an ultra-high density cathode array layout, with an array spacing of up to 500 units / meter in the first direction.

[0111] This multifocal X-ray tube can be applied to security inspection and industrial precision non-destructive testing scenarios. In typical security inspection applications, the tube voltage is 150kV–180kV, the operating current is 15mA–25mA, and the number of circumferential focal points is 250–900. With its high-density focal array, this X-ray tube can perform rapid full-area scanning, effectively improving the equipment's scanning frame rate and enhancing its ability to identify small foreign objects and hidden defects, making it suitable for high-volume, high-efficiency inspection operations.

[0112] In medical imaging scenarios, this X-ray tube combines the advantages of high output current, small focal spot size, and small array spacing, effectively improving the spatial resolution of CT images and reducing imaging artifacts, fully meeting the technological upgrade requirements of next-generation static CT equipment. In comparison, existing research reports that static CT equipment can only arrange 24 X-ray focal spots on a circumference, while this application can arrange up to 2000 focal spots within a 4-meter diameter annular structure, a total number of focal spots 83 times that of existing similar equipment. Both the array spacing and imaging sampling dimension represent a significant leap forward.

[0113] In summary, thanks to the dual technological advantages of high-current output and high-density focal array, this application enables multi-angle, high-density projection imaging, significantly improving the temporal and spatial resolution of the equipment. This technical solution boasts outstanding comprehensive performance advantages and possesses high engineering transformation value and broad market application prospects in fields such as high-end medical CT, precision industrial flaw detection, and intelligent security imaging.

[0114] While some embodiments based on the overall inventive concept of this application have been illustrated and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the overall inventive concept of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A carbon nanotube cathode array, characterized in that, The carbon nanotube cathode array includes: Multiple cathode elements, each cathode element including a cathode substrate and an emitter located on one side of the cathode substrate; the multiple cathode elements are arranged in an array in a first direction, each cathode element extends in a second direction, the emitter includes a carbon nanotube material, and the first direction intersects the second direction; The cathode element is generally strip-shaped, and multiple cathode elements are arranged at intervals in the first direction. The ratio of the emission current of each cathode element to the spacing between adjacent cathode elements in the first direction is greater than or equal to 1.67 mA / mm.

2. The carbon nanotube cathode array according to claim 1, characterized in that, The ratio of the length of the cathode substrate in the second direction to the width of the cathode substrate in the first direction is greater than or equal to 5:

1.

3. The carbon nanotube cathode array according to claim 2, characterized in that, The width of the cathode substrate in the first direction is 0.5-10 mm; and / or The length of the cathode substrate in the second direction is greater than or equal to 20 mm; and / or The spacing between adjacent cathode substrates in the first direction is 1-10 mm.

4. The carbon nanotube cathode array according to any one of claims 1-3, characterized in that, The carbon nanotube cathode array also includes: A gate is located on the side of the emitter away from the cathode substrate, and the surface of the gate near the cathode substrate is spaced apart from the end of the emitter away from the cathode substrate. The support portion includes an insulating support base and a support column. The insulating support base is located on the side of the cathode substrate away from the emitter, and the support column is located between the insulating support base and the gate. A second distance of 70-500 μm is formed between the surface of the gate near the insulating support base and the end of the emitter away from the insulating support base.

5. The carbon nanotube cathode array according to claim 4, characterized in that, The height of the emitter in the third direction is 1-20 μm, and the difference in the second distance between different emitters and the gate is less than 30 μm.

6. The carbon nanotube cathode array according to claim 4, characterized in that, The flatness error of the surface of the insulating support base near the support post is less than or equal to 30 μm; and / or, the flatness error of the surface of the support post away from the insulating support base is less than or equal to 30 μm; and / or, the flatness error of the surface of the gate near the support post is less than or equal to 30 μm.

7. The carbon nanotube cathode array according to claim 4, characterized in that, The carbon nanotube cathode array also includes: Multiple electron through-holes penetrate the gate, and the orthographic projections of the multiple electron through-holes on the insulating support at least partially overlap with the orthographic projections of the emitter on the insulating support.

8. The carbon nanotube cathode array according to claim 1, characterized in that, The purity of the carbon nanotube material is greater than or equal to 90%, and the carbon nanotubes are low-walled carbon nanotubes with a wall number of 2-5.

9. The carbon nanotube cathode array according to claim 4, characterized in that, The gate is integrally formed, and the orthographic projection of the gate on the insulating support covers the orthographic projection of the plurality of cathode elements on the insulating support; or The gate includes a plurality of sub-gates, and the orthogonal projections of the plurality of emitters on the cathode substrate are respectively located within the orthogonal projections of the plurality of sub-gates on the cathode substrate.

10. The carbon nanotube cathode array according to claim 4, characterized in that, The gate has a first arc shape in a cross section perpendicular to the second direction, and the plurality of cathode elements have a second arc shape in a cross section perpendicular to the second direction, wherein the first arc shape and the second arc shape share the same center.

11. The carbon nanotube cathode array according to claim 1, characterized in that, The multiple cathode elements are controlled independently.

12. A carbon nanotube cathode array, characterized in that, The carbon nanotube cathode array includes: Multiple cathode elements are provided, each of which includes a cathode substrate and an emitter located on one side of the cathode substrate; the cathode substrate is integrally formed, the multiple emitters are arranged in an array in a first direction, each emitter extends in a second direction, the emitter includes carbon nanotube material, and the first direction intersects the second direction; The emitter has a strip-shaped orthographic projection on the cathode substrate, and multiple emitters are arranged at intervals in the first direction. The ratio of the emission current of each cathode element to the spacing between adjacent emitters in the first direction is greater than or equal to 1.67 mA / mm.

13. The carbon nanotube cathode array according to claim 12, characterized in that, The carbon nanotube cathode array also includes: A gate is located on the side of the emitter away from the cathode substrate, and the surface of the gate near the cathode substrate is spaced apart from the end of the emitter away from the cathode substrate. The gate includes a plurality of sub-gates, and the orthogonal projections of the plurality of emitters on the cathode substrate are respectively located within the orthogonal projections of the plurality of sub-gates on the cathode substrate.

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