CN217239379U - X-ray source and horizontal field emission structure thereof - Google Patents
X-ray source and horizontal field emission structure thereof Download PDFInfo
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- CN217239379U CN217239379U CN202221241088.2U CN202221241088U CN217239379U CN 217239379 U CN217239379 U CN 217239379U CN 202221241088 U CN202221241088 U CN 202221241088U CN 217239379 U CN217239379 U CN 217239379U
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Abstract
The utility model discloses an X-ray source and a horizontal field emission structure thereof, wherein the horizontal field emission structure comprises a base body, a cathode and a grid; the cathode and the grid are arranged on the same surface of the substrate to form a cathode-grid pair; the grid is used for converting electrons emitted by the cathode into secondary electrons. Compare in current vertical field emission structure, the utility model discloses a negative pole-grid is to horizontal arrangement and secondary electron effect, can obtain the field emission negative pole that preparation simple process, tolerant ion bombardment.
Description
Technical Field
The utility model belongs to the technical field of X ray source, concretely relates to X ray source and horizontal field emission structure thereof.
Background
The X-ray source has wide application in the fields of industrial detection, scientific instruments, medical imaging, treatment and the like. In an X-ray source, an electron gun is required to generate electrons. The electron gun is called a cathode, and the cathode is classified into a hot cathode, a field cathode, a photocathode, a plasma cathode, a secondary electron cathode, and the like according to the operation mode. At present, the cathode widely used in the X-ray source is mainly a hot cathode, and the hot cathode has the advantages of simple structure, stable work and large emission current. However, hot cathodes have some limitations, such as: before the hot cathode works normally to emit electrons, the hot cathode must be heated to a proper working temperature, and the process usually needs several seconds to tens of seconds, so that the quick start and the short-pulse type work of the device are not facilitated; the continuous heating of the hot cathode during the preheating and the work intermission period leads to higher temperature of the device, more obvious heat power consumption and difficult bearing for small devices; for small devices, and to reduce power consumption, the hot cathode is usually very small, resulting in complex manufacturing process and poor product reliability.
To solve these problems, in some X-ray tubes, which require less current, field emission cathodes are used to generate electrons. These X-ray tubes are generally used in the field of precision nondestructive testing of semiconductors, batteries, and the like. The field emission cathodes used in X-ray tubes at present are all designed in a vertically led structure, i.e. a cathode emission array is arranged on a plane perpendicular to a cathode substrate, and electrons are generated in an axial emission manner, as shown in fig. 1-2.
In these field emission cathodes and X-ray sources, a vertically arranged carbon nanotube array, a graphene array or a metal pointed cone is usually adopted, and an electric field is applied between the field emission cathode and a gate electrode, so that electrons are emitted from the surface of the cathode and are extracted by the gate electrode.
Such a field emission electron generation method has some problems, for example: when an independent grid is adopted, the grid and the emitter are two independent parts, and precise assembly is difficult to realize. For a semiconductor or a metal pointed cone array prepared by a semiconductor process, a miniature insulation and gate control structure needs to be prepared step by step, and the preparation process is complex; moreover, passivation is easily caused in the emission process of the pointed cone due to reverse ion bombardment, so that the distance between the pointed cone and the grid control ring is increased, the electric field on the surface of the pointed cone is reduced, and the emission density is reduced.
SUMMERY OF THE UTILITY MODEL
In order to solve the current field emission electron technology preparation technology complicacy, and the passivation appears easily in the negative pole pointed cone and leads to pointed cone surface electric field to descend, the low scheduling problem of emission density, the utility model provides an X ray source and horizontal field emission structure thereof. The utility model discloses a field electron emission structure of horizontal arrangement negative-grid electrode pair, simple process can once only realize the controllable ideal emission structure preparation of space density, simultaneously because the negative pole awl is horizontal arrangement, therefore the particle of anti-bombing can not show the corruption awl.
The utility model discloses a following technical scheme realizes:
an X-ray source and a horizontal field emission structure thereof comprise a substrate, a cathode and a grid; the cathode and the grid are arranged on the same surface of the substrate to form a cathode-grid pair;
the grid is used for converting electrons emitted by the cathode into secondary electrons.
Compare in current vertical field emission structure, the utility model discloses a negative pole-grid is to horizontal arrangement and secondary electron effect, can obtain the field emission negative pole that preparation simple process, tolerant ion bombardment.
As a preferred embodiment, the same surface of the substrate of the present invention is provided with an array of cathode-gate pairs. The utility model discloses a mode that the array set up has realized the horizontal field emission cathode assembly of great area.
As a preferred embodiment, the same surface of the matrix of the present invention is provided with a multi-layer nested array of cathode-gate pairs. The utility model discloses a mode that the multilayer was nested sets up has further improved electronic power.
As a preferred embodiment, the distance between the cathode and the grid of the present invention is 100nm to 5 μm.
As a preferred embodiment, the cathode of the utility model is at a negative potential relative to the grid, and the voltage difference between the cathode and the grid is 10V-1000V.
In a preferred embodiment, the cathode and the gate of the present invention are made of silicon, molybdenum, tungsten or copper.
In a preferred embodiment, the surface of the cathode and the gate of the present invention is covered with a low work function film.
In a preferred embodiment, the cathode and the gate of the present invention are covered with a diamond-like film.
In a preferred embodiment, the area of the gate electrode of the present invention is larger than the area of the cathode electrode. Because heat dissipation is deposited on the grid electrode, the area of the grid electrode is larger than that of the cathode electrode, so that the heat dissipation of the grid electrode is promoted.
In a second aspect, the present invention provides an X-ray source, comprising the horizontal field emission structure, an extraction electrode and an anode of the present invention;
the cathode is used for emitting electrons, one part of the electrons is directly led out by an electric field between the base body and the leading-out electrode, the other part of the electrons bombards the grid to generate secondary electrons, and the secondary electrons are led out by the electric field between the base body and the leading-out electrode;
the extracted electrons are accelerated under the action of an accelerating electric field between the extraction electrode and the anode and bombard the anode target surface to generate X rays.
The utility model discloses following advantage and beneficial effect have:
the utility model provides a field electron emission structure of negative pole-gate electrode to horizontal arrangement for perpendicular field emission structure, can accomplish through the synchronous preparation of technology in proper order on stratum basale material plane, simple process is reliable, because the negative pole awl is horizontal arrangement, consequently the ion of anti-bombing can not show the corrosion pointed end, therefore horizontal field emission cathode structure can be able to bear or endure the ion bombardment.
The utility model provides an X ray source adopts the field electron emission structure of negative-gate electrode to horizontal arrangement, possesses the resistant ion bombardment performance good, and emission density is controllable, dispel the heat advantage such as good.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
fig. 1 is a schematic view of a conventional vertical field emission structure.
Fig. 2 is a schematic view of the operating principle of an X-ray source employing the vertical field emission structure shown in fig. 1.
Fig. 3 is a schematic diagram comparing the principle of the prior vertical field emission structure with the horizontal field emission structure of the present invention. Wherein, the left picture is current vertical field emission structure, the right picture is the utility model discloses a horizontal field emission structure.
Fig. 4 is a schematic view of a horizontal field emission structure according to a first embodiment of the present invention.
Fig. 5 is a schematic view of a horizontal field emission structure according to a second embodiment of the present invention.
Fig. 6 is a schematic diagram of an X-ray source employing a horizontal field emission structure according to an embodiment of the present invention.
Reference numbers and corresponding part names in the drawings:
1-substrate, 2-cathode, 3-grid, 4-extraction electrode, 5-anode, 61-primary electron, 62-secondary electron, 7-electron beam, 8-X ray.
Detailed Description
Hereinafter, the terms "include" or "may include" used in various embodiments of the present invention indicate the existence of the functions, operations or elements of the present invention, and do not limit the addition of one or more functions, operations or elements. Furthermore, as used in various embodiments of the present invention, the terms "comprises," "comprising," "includes," "including," "has," "having" and their derivatives are intended to refer only to the particular feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as first excluding the existence of, or adding to, one or more other features, numbers, steps, operations, elements, components, or combination of the foregoing.
In various embodiments of the present invention, the expression "or" at least one of a or/and B "includes any or all combinations of the words listed simultaneously. For example, the expression "a or B" or "at least one of a or/and B" may include a, may include B, or may include both a and B.
Expressions (such as "first", "second", and the like) used in various embodiments of the present invention may modify various constituent elements in various embodiments, but may not limit the respective constituent elements. For example, the above description does not limit the order and/or importance of the elements described. The foregoing description is for the purpose of distinguishing one element from another. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of various embodiments of the present invention.
It should be noted that: if it is described that one constituent element is "connected" to another constituent element, the first constituent element may be directly connected to the second constituent element, and a third constituent element may be "connected" between the first constituent element and the second constituent element. In contrast, when one constituent element is "directly connected" to another constituent element, it is understood that there is no third constituent element between the first constituent element and the second constituent element.
The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the various embodiments of the invention. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the present invention belong. The terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning that is consistent with their contextual meaning in the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in various embodiments of the present invention.
To make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the following examples and drawings, and the exemplary embodiments and descriptions thereof of the present invention are only used for explaining the present invention, and are not intended as limitations of the present invention.
Examples
The existing vertical field emission structure needs to prepare a miniature insulation and gate control structure step by step for a semiconductor or a metal pointed cone array prepared by a semiconductor process, the preparation process is complex, and the ion bombardment resistance of an emission tip is poor. Based on this, the present embodiment provides a horizontal field emission structure, and compared with a vertical field emission structure, the horizontal field emission structure of the present embodiment can be synchronously fabricated on the plane of the base layer material by one process, and the process is simple and reliable, as shown in fig. 3.
In this embodiment, a horizontal field emission structure is illustrated by taking a single cathode-gate pair as an example, as shown in fig. 4, the horizontal field emission structure of this embodiment includes a cathode 2 and a gate 3, and the cathode and the gate are disposed on the same surface of a substrate 1, and specifically, the cathode 2 and the gate 3 can be prepared on the substrate 1 at one time through photolithography and etching processes.
The cathode of the present embodiment is at a negative potential with respect to the gate, the distance between the cathode and the gate is 100nm-5 μm, and the voltage difference is 10V-1000V.
The cathode and the gate of the present embodiment are made of materials including, but not limited to, silicon, molybdenum, tungsten, or copper.
The cathode and gate surfaces of this embodiment are covered with low work function films, but are not limited to diamond-like carbon films.
Since the current emitted from a single cathode is limited, in another preferred embodiment, a horizontal field emission cathode assembly with a large area can be realized by fabricating an array of cathode-gate pairs by a semiconductor process, as shown in fig. 5, the horizontal field emission structure includes forming the array of cathode-gate pairs on the same substrate 1, and the area of the gate electrode is significantly larger than that of the cathode electrode due to the heat deposition on the gate electrode, so as to promote the heat dissipation of the gate electrode.
In a further preferred embodiment, it is also possible to form an array of nested cathode-gate pairs in multiple layers on the same substrate 1 for generating an electron beam of greater current intensity.
The present embodiment also proposes an X-ray source based on the above horizontal field emission structure, comprising a horizontal field emission structure, an extraction (focusing) electrode 4, an anode assembly and an insulating assembly.
Wherein, the horizontal field emission structure is used for generating electrons, and the extraction electrode (focusing electrode) is used for extracting the electrons generated by the horizontal field emission structure and leading the electrons to bombard the anode target surface of the anode assembly, thereby generating X rays. The insulating assembly is used for providing structural support and insulation function of the X-ray source, and the insulating assembly adopts the existing insulating assembly structure, so that the detailed description is omitted.
As shown in fig. 6, the specific working process of the X-ray source is as follows:
when a certain voltage is applied to the two ends of the cathode 2 and the grid 3, the cathode is relatively in negative potential, the tip of the cathode emits electrons, a part of the electrons (namely primary electrons 61) are directly led out by an electric field between the matrix 1 and the leading-out electrode 4, most of the electrons bombard the grid 3 to generate secondary electrons 62, and the secondary electrons are led out by the electric field between the matrix 1 and the leading-out electrode 4.
The extracted electron beam 7 is accelerated and bombarded on the anode target surface under the action of an accelerating electric field between the extraction electrode 4 and the anode 5, and X-rays 8 are generated.
The above-mentioned embodiments, further detailed description of the objects, technical solutions and advantages of the present invention, it should be understood that the above description is only the embodiments of the present invention, and is not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A horizontal field emission structure comprises a substrate (1), a cathode (2) and a grid (3); the device is characterized in that the cathode (2) and the grid (3) are arranged on the same surface of the substrate (1) to form a cathode-grid pair;
the grid (3) is used for converting electrons emitted by the cathode (2) into secondary electrons.
2. A horizontal field emission structure according to claim 1, wherein the same surface of the substrate (1) is provided with an array of cathode-gate pairs.
3. A horizontal field emission structure according to claim 1, wherein the same surface of the substrate (1) is provided with an array of nested cathode-gate pairs in a plurality of layers.
4. A horizontal field emission structure according to any of claims 1 to 3, wherein the spacing between the cathode (2) and the gate (3) is in the range of 100nm to 5 μm.
5. A horizontal field emission structure according to any of claims 1 to 3, wherein the cathode (2) is at a negative potential with respect to the gate (3), and the voltage difference between the cathode (2) and the gate (3) is in the range of 10V to 1000V.
6. A horizontal field emission structure according to any of claims 1 to 3, wherein the cathode (2) and the gate (3) are made of silicon, molybdenum, tungsten or copper.
7. A horizontal field emission structure according to any of claims 1 to 3, wherein the surfaces of the cathode (2) and the gate (3) are covered with a low work function film.
8. A horizontal field emission structure according to any of claims 1 to 3, wherein the cathode (2) and gate (3) surfaces are covered with a diamond-like film.
9. A horizontal field emission structure according to any of claims 1 to 3, wherein the area of the gate (3) is larger than the area of the cathode (2).
10. An X-ray source, characterized by comprising a horizontal field emission structure according to any of claims 1-9, an extraction electrode (4) and an anode (5);
the cathode (2) is used for emitting electrons, one part of the electrons is directly extracted by an electric field between the base body (1) and the extraction electrode (4), the other part of the electrons bombards the grid electrode (3) to generate secondary electrons, and the secondary electrons are extracted by the electric field between the base body (1) and the extraction electrode (4);
the extracted electrons are accelerated under the action of an accelerating electric field between the extraction electrode (4) and the anode (5) and bombard the anode target surface to generate X-rays.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202221241088.2U CN217239379U (en) | 2022-05-23 | 2022-05-23 | X-ray source and horizontal field emission structure thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202221241088.2U CN217239379U (en) | 2022-05-23 | 2022-05-23 | X-ray source and horizontal field emission structure thereof |
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| CN217239379U true CN217239379U (en) | 2022-08-19 |
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| CN202221241088.2U Active CN217239379U (en) | 2022-05-23 | 2022-05-23 | X-ray source and horizontal field emission structure thereof |
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