Cathode with long service life and high stability for electron emission device and preparation method thereof

Abstract

The invention relates to a cathode for an electron emission device and a preparation method thereof, in particular to a long-service-life high-stability cathode for an electron emission device and a preparation method thereof, and solves the technical problem that the existing cathode for the electron emission device is difficult to meet the requirements of long service life and stable discharge at the same time. According to the invention, the doping material is added into the matrix, so that a stable and easy-to-discharge interface is formed between the matrix and the doping material, and discharge can be carried out before field enhancement points and medium micro-points on the cathode discharge surface non-uniformly distributed on the cathode discharge surface to replace unstable breakdown induced by the field enhancement points and the medium micro-points; along with the continuous work of the electron emission device, no matter how the state of the cathode discharge surface changes, the stability of the breakdown voltage is not influenced, the discharge voltage is stable, and the dispersity is low; after the electron emission device is broken down, the new surface exposed after the discharge surface of the cathode is locally ablated keeps the same electron emission property as the original surface, and the electron emission device has relatively long service life and discharge stability.

Description

Technical Field

[0001] The present invention relates to a cathode for an electron emission device and a method for preparing the same, and particularly to a long-life and high-stability cathode for an electron emission device and a method for preparing the same. Background Art

[0002] High-voltage pulse power systems generally select electron emission devices such as gas switches to connect energy storage and loads. Through the breakdown of the electron emission device, energy is compressed on the time scale and output to the load, and it is widely used in large-scale devices such as high-energy particle accelerators and nuclear fusion. These large-scale devices usually require the breakdown voltage of the electron emission device to be stable, with small dispersion, stable working performance, and long life. The breakdown of the electron emission device is generally induced by field-emitted electrons at the field enhancement points and dielectric micro-points on the cathode discharge surface. The number of field-emitted electrons is directly related to the breakdown voltage of the electron emission device, and its stability is the determining factor for the breakdown voltage stability of the electron emission device.

[0003] As Figure 1 shown, non-ideal cathode discharge surfaces often have field enhancement points 01 composed of tips or micro-protrusions or dielectric micro-points 02 composed of surface impurities, defects, etc. Such inherent native defects existing on the cathode discharge surface are in a high-energy state and are generally considered to be the starting points of field-emission current. The non-uniform distribution of inherent native defects such as field enhancement points 01 and dielectric micro-points 02 on the cathode discharge surface restricts the stability of cathode electron emission, thereby affecting the breakdown stability of the electron emission device, which is the root cause of the poor breakdown stability of the electron emission device. On the other hand, since the discharge plasma formed during the breakdown process of the electron emission device will ablate and damage the cathode discharge surface, the state of the cathode discharge surface continuously changes during the discharge process, resulting in unstable cathode field-emission current, and then causing the dispersion of the gas breakdown voltage to gradually increase, making it difficult to meet the requirements of the electron emission device for breakdown voltage stability, affecting the normal operation of the high-voltage pulse power system, and becoming a bottleneck problem in the high-voltage pulse power field.

[0004] To obtain a stable electron emission device, researchers have analyzed various factors such as the cathode material, cathode structure, and gas composition of the electron emission device. For example, articles such as

Luo Weixi, Cong Peitian, Sun Tieping, et al. Influence of cathode materials on the static performance of gas switches [J]. High Power Laser and Particle Beams, 2016, 28(1): 015022-1-5.

Guo Liangfu, Li Li, Lai Guiyou, et al. Graphite-type high-energy two-cathode gas switches [J]. High Power Laser and Particle Beams, 2010, 22(12): 3034-3038.

[0005] Based on the above research results, the paper "[Wang Gang, Su Jiancang, Liu Wenyuan, et al. Research on the breakdown characteristics of a micro-grooved graphite cathode gas switch [C]. National Conference on High Voltage and Discharge Plasma, Nanjing, 2018]" proposed a micro-grooved graphite cathode structure, which can effectively improve the stability of cathode discharge and reduce the fluctuation of discharge voltage. The Chinese patent with the publication number CN113594873A discloses an electrode with a metal micro-column array on its surface and a preparation method thereof. It prepares a metal micro-column array by electroplating, and uses metal micro-columns with better toughness to replace graphite micro-columns, effectively improving the life and discharge stability of the electrode. The above two solutions both achieve the effect of stable discharge by constructing the structure of the cathode discharge surface and replacing the unstable discharge factors on the cathode discharge surface. However, due to the ablation of the cathode discharge surface during continuous discharge, the constructed cathode discharge surface structure will be gradually damaged and ablated, making it difficult to maintain a long life. Summary of the Invention

[0006] The object of the present invention is to solve the technical problem that the existing cathodes for electron emission devices are difficult to simultaneously meet the requirements of long life and stable discharge, and to provide a long-life and high-stability cathode for electron emission devices and a preparation method thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A long-life and high-stability cathode for an electron emission device, characterized in that: it includes a matrix and doping materials distributed in the matrix, wherein the doping materials are a number of doping rods;

[0009] The doping rods are all arranged perpendicular to the discharge surface of the cathode and are arranged in an array in the matrix. The interface between the matrix and the doping rods is used for electron emission;

[0010] The total area ratio of the doping rods to the matrix on the cathode discharge surface is 5-50:95-50, and the melting point of the doping rods is higher than that of the matrix;

[0011] The diameter of the doping rods is 1 μm - 200 μm, and the distribution period in the matrix is greater than 200 μm.

[0012] Furthermore, the doping rods are only arranged in an array in the matrix in the working area of the cathode.

[0013] Furthermore, the doping rods are non-metallic materials or conductive materials;

[0014] The matrix is a metal material or a conductive material.

[0015] Furthermore, when the doping rods are non-metallic materials, silicon carbide, titanium carbide or alumina are used; when the doping rods are conductive materials, graphite or carbon fiber are used;

[0016] When the substrate is a metal material, copper, aluminum, iron or stainless steel is used; when the substrate is a conductive material, graphite is used.

[0017] The present invention also provides a preparation method of the above-mentioned long-life and high-stability cathode for an electron emission device, which is characterized in that it includes the following steps:

[0018] Step A1: Select a number of doping rods with a diameter of 1 μm to 200 μm, cut them to the same length, and then insert both ends of the doping rods into the corresponding array holes of two sheet molds for fixation; the total area ratio of the array holes on the sheet mold is 5% to 50%;

[0019] Step A2: Fix the sheet mold in a casting mold so that a number of doping rods are straightened and parallel to each other;

[0020] Step A3: Make the melted substrate and the doping rods combine with each other in the casting mold to obtain a cathode blank with the doping rod array distributed in the substrate;

[0021] Step A4: Perform machining on the cathode blank, and use the cross-section perpendicular to the doping rod as the discharge surface of the cathode to obtain a long-life and high-stability cathode for an electron emission device.

[0022] Further, step A3 is specifically:

[0023] Pour the melted substrate into the casting mold and cool it naturally to make the substrate and the doping rods combine with each other to obtain a cathode blank with the doping rod array distributed in the substrate;

[0024] Or, fill the casting mold with the granular material of the substrate, then heat it in an atmosphere furnace to melt the granular material of the substrate, combine it with the doping rods, and cool it naturally to obtain a cathode blank with the doping rod array distributed in the substrate.

[0025] The present invention also provides another preparation method of the above-mentioned long-life and high-stability cathode for an electron emission device, which is characterized in that it includes the following steps:

[0026] Step B1: Select a number of doping rods with a diameter of 1 μm to 200 μm and cut them to the same length;

[0027] Step B2: Perform electroplating or electroless plating on the doping rods to uniformly grow a substrate coating on their surfaces to obtain doping rods with a substrate coating;

[0028] Step B3: Arrange the doping rods with a substrate coating evenly and then bundle them into a rod material;

[0029] Step B4: Sinter the matrix coating by hot pressing method to tightly bond the matrix coatings of each doping rod, obtaining a cathode blank with doping rods arrayed in the matrix;

[0030] Step B5: Machine the cathode blank, using the cross-section perpendicular to the doping rod as the discharge surface of the cathode, obtaining a long-life and high-stability cathode for electron emission devices.

[0031] The present invention also provides another long-life and high-stability cathode for electron emission devices, which is characterized in that: it includes a matrix and doping materials distributed in the matrix, wherein the doping materials are doping particles;

[0032] The doping particles are evenly distributed in the matrix;

[0033] The mass ratio of the doping particles to the matrix is 5 - 50:95 - 50;

[0034] The diameter of the doping particles is 1μm - 200μm, and their melting point is higher than that of the matrix.

[0035] Further, the doping particles are non-metallic materials or conductive materials;

[0036] The matrix uses a fusible metal material.

[0037] The present invention also provides a preparation method for the above-mentioned long-life and high-stability cathode for electron emission devices, which is characterized in that it includes the following steps:

[0038] Step 1: Weigh the particulate materials of the doping particles and the matrix respectively according to the mass ratio of 5 - 50:95 - 50;

[0039] Step 2: Mix the particulate materials of the doping particles and the matrix evenly, and then sinter them by hot pressing method to tightly bond the particulate materials of the matrix, obtaining a cathode blank with doping particles evenly distributed in the matrix;

[0040] Step 3: Machine the cathode blank to obtain a long-life and high-stability cathode for electron emission devices.

[0041] Compared with the prior art, the present invention has the following beneficial technical effects:

[0042] 1. For the long-life and high-stability cathode for electron emission devices provided by the present invention, doping materials are added to the matrix, and a stable and easily dischargeable interface is formed between the matrix and the doping materials, which can discharge prior to the field enhancement points and dielectric micro-points on the cathode discharge surface, replacing the unstable breakdown induced by non-uniformly distributed inherent impurity defects. And with the continuous operation of the electron emission device, no matter how the state of the cathode discharge surface changes, it will not affect the breakdown voltage stability, and the discharge voltage is stable and has low dispersion;

[0043] 2. The long - life and high - stability cathode for an electron - emitting device provided by the present invention, after the electron - emitting device breaks down, the new interface exposed after the local interface is ablated as a whole maintains the same electron - emission property as the original interface, and has a relatively high life and discharge stability.

[0044] 3. The long - life and high - stability cathode for an electron - emitting device provided by the present invention, the doped rods are only located in the working area of the cathode, which can form a stable and low - threshold electron - emission area, facilitating the stable breakdown of the electron - emitting device; while the non - working area of the cathode only contains the matrix, with a high emission threshold, which can inhibit the cathode from emitting electrons in an undesired direction, avoiding the phenomenon of insulation failure or increased loss.

[0045] 4. The long - life and high - stability cathode for an electron - emitting device provided by the present invention, the materials of the matrix and the doped rods have a wide range of options, and the forming process requirements are low. The doped rods can be combined with the matrix by casting or sintering after being fixed by a mold, or can be first combined with the matrix by electroplating and then sintered after being arranged evenly. Description of the Drawings

[0046] Figure 1 is a schematic structural diagram of an existing cathode;

[0047] Figure 2 is a schematic cross - sectional structural diagram of the first embodiment of the long - life and high - stability cathode for an electron - emitting device of the present invention;

[0048] The descriptions of the reference numerals in the drawings are as follows:

[0049] 01 - field - enhancement point, 02 - dielectric micro - point;

[0050] 1 - matrix, 2 - doped rod, 3 - interface, 4 - non - working area of the cathode, 5 - working area of the cathode. Detailed Embodiments

[0051] The following further elaborates in detail on the long - life and high - stability cathode for an electron - emitting device and its preparation method proposed by the present invention in conjunction with the drawings and specific embodiments. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention, and the purpose is not to limit the protection scope of the present invention.

[0052] Embodiment 1

[0053] A long - life and high - stability cathode for an electron - emitting device, as Figure 2As shown, it includes a matrix 1 and doping materials distributed in the matrix 1, where the doping materials are several doping rods 2. The doping rods 2 are all arranged perpendicular to the discharge surface of the cathode and are arranged in an array within the matrix 1. The interface 3 between the matrix 1 and the doping rods 2 is used for electron emission. The total area ratio of the doping rods 2 to the matrix 1 on the cathode discharge surface is 5 - 50:95 - 50, and the melting point of the doping rods 2 is higher than that of the matrix 1 to avoid changes in the doping rods 2 during the preparation process. The diameter D of the doping rods 2 is 1 μm - 200 μm, and the distance between the central axes of two adjacent doping rods 2 is greater than 200 μm. The doping rods 2 are only arranged in an array within the matrix 1 in the cathode working area 5. The cathode working area 5 is located in the central area of the cathode, and the discharge surface of the cathode is the surface of the cathode working area 5. The cathode non-working area 4 is located on the periphery of the cathode working area 5.

[0054] The discharge channel diameter at the breakdown of the electron emission device is usually less than 200 μm. To reduce the manufacturing cost, the diameter of the doping rods 2 needs to be less than or equal to 200 μm. The area ratio of the doping rods 2 on the cathode discharge surface is less than 50%, which can ensure the mechanical strength of the cathode; the area ratio is greater than 5%, which can ensure the service life of the cathode. The service life is estimated by the following method: Assuming that one doping rod 2 is consumed per discharge, the life is determined by the number N of the doping rods 2. Let the total area ratio of the doping rods 2 to the matrix 1 on the cathode discharge surface be w and the area of the cathode discharge surface be S, then N = S*w / (π(D / 2)^2). Furthermore, it can be calculated that for a cathode with a diameter of 100 mm, when the total area ratio of the doping rods 2 to the matrix 1 on the cathode discharge surface is 5%, the service life can exceed 10,000 pulses.

[0055] In this embodiment, the doping rods 2 are non-metallic materials or conductive materials. When the doping rods 2 are non-metallic materials, silicon carbide, titanium carbide or alumina are used; when the doping rods 2 are conductive materials, graphite or carbon fiber are used. The matrix 1 is a metallic material or a conductive material. When the matrix 1 is a metallic material, copper, aluminum, iron or stainless steel are used; when the matrix 1 is a conductive material, graphite is used.

[0056] This embodiment also provides a preparation method for the long-life and high-stability cathode for an electron emission device as described above, including the following steps:

[0057] Step A1: Select several doping rods 2 with a diameter of 1 μm - 200 μm, cut them to the same length, and then insert the two ends of the doping rods 2 into the corresponding array holes of two sheet molds for fixation; where the total area ratio of the array holes on the sheet mold is 5% - 50%;

[0058] Step A2: Fix the sheet mold in a casting mold so that several doping rods 2 are straightened and parallel to each other;

[0059] Step A3: Combine the melted matrix 1 and the doping rod 2 in a casting mold to obtain a cathode blank with the doping rods 2 distributed in an array within the matrix 1;

[0060] Step A4: Machine the cathode blank, and use the cross-section perpendicular to the doping rod 2 as the discharge surface of the cathode to obtain a long-life and high-stability cathode for an electron emission device. In this step, the machining operations are conventional turning, milling, and polishing.

[0061] Among them, Step A3 is specifically as follows:

[0062] Pour the melted matrix 1 into a casting mold and let it cool naturally to combine the matrix 1 and the doping rod 2, obtaining a cathode blank with the doping rods 2 distributed in an array within the matrix 1;

[0063] Alternatively, fill the casting mold with particulate material of the matrix 1, then heat it in an atmosphere furnace to melt the particulate material of the matrix 1, combine it with the doping rod 2, and let it cool naturally to obtain a cathode blank with the doping rods 2 distributed in an array within the matrix 1.

[0064] In the above method, by adjusting the parameters of the array holes on the sheet mold or the mass ratio of the doping rod 2 to the matrix 1, the adjustment of the total area ratio of the doping rod 2 to the matrix 1 on the cathode discharge surface can be achieved.

[0065] This embodiment also provides another preparation method for the above-mentioned long-life and high-stability cathode for an electron emission device, including the following steps:

[0066] Step B1: Select several doping rods 2 with a diameter of 1 μm to 200 μm and cut them to the same length;

[0067] Step B2: Electroplate or electroless plate the doping rod 2 to uniformly grow a matrix coating on its surface to obtain a doping rod 2 with a matrix coating;

[0068] Step B3: Arrange the doping rods 2 with matrix coatings evenly and then bundle them into a rod stock;

[0069] Step B4: Sinter the matrix coatings by hot pressing to closely combine the matrix coatings of each doping rod 2 to obtain a cathode blank with the doping rods 2 distributed in an array within the matrix 1;

[0070] Step B5: Machine the cathode blank, and use the cross-section perpendicular to the doping rod 2 as the discharge surface of the cathode to obtain a long-life and high-stability cathode for an electron emission device. In this step, the machining operations are conventional turning, milling, and polishing.

[0071] The long-life and high-stability cathode for an electron emission device proposed in this embodiment adds doping rods 2 with an array distribution in the cathode working area 5 to the matrix 1. In this structure, the interfacial energy of the interface 3 between the matrix 1 and the doping rods 2 is relatively high, in a high-energy state, and electrons are extremely easy to emit under the action of a strong electric field, thus replacing the electron emission at the field enhancement points 01 or dielectric micro-points 02 on the discharge surface of the existing cathode. That is, the interface 3 between the matrix and the doping rods starts electron emission at a relatively low voltage and triggers the subsequent breakdown process. Since the field enhancement points and dielectric micro-points on the cathode discharge surface have insufficient emission current and are not enough to cause the switching gap, it replaces the unstable breakdown induced by non-uniformly distributed inherent impurity defects. In this embodiment, a material interface with a stable electron emission state is used to replace the field enhancement points 01 and dielectric micro-points 02 with an unstable electron emission state, thereby improving the working stability of the electron device.

[0072] After completing the replacement of the unstable breakdown induced by the field enhancement points and dielectric micro-points on the cathode discharge surface, the breakdown voltage and the stability of the breakdown voltage of the electron emission device are determined by the state of the interface 3 between the matrix 1 and the doping rods 2. The state of the interface 3 is determined by the physical and chemical properties of the materials of the matrix 1 and the doping rods 2. After the materials are selected, the interface is basically in a fixed state. After the applied electric field reaches a certain value, the interfaces in this embodiment can all stably emit electrons and induce the breakdown of the electron emission device, so it has high breakdown stability.

[0073] At the same time, since the doping rods 2 are arrayed in the cathode working area 5, a stable and low-threshold electron emission area is formed, which is beneficial to providing stable field emission electrons and enabling the electron emission device to break down stably. The non-working area 4 of the cathode only contains the matrix 1, and the electron emission threshold is high, which inhibits the electron emission of the cathode along the non-expected direction and avoids the phenomena of insulation failure or increased loss.

[0074] In addition, this embodiment also has the characteristic of a long service life. After the switch breaks down, the exposed interface after the local interface of the cathode is ablated by several micrometers as a whole still maintains the same electron emission property as the original interface, so it has high life and discharge stability.

[0075] Generally speaking, for the long-life and high-stability cathode for an electron emission device proposed in this embodiment, the doped rod 2 and the matrix 1 are used to form a stable and easily electron-emitting high-energy state interface, which causes field emission prior to the field enhancement points and dielectric micro-points on the cathode discharge surface, etc., forming a shielding effect on the native defects of the cathode discharge surface, further suppressing the breakdown voltage fluctuations caused by the continuously changing surface structure during the discharge process, and improving the stability of the discharge voltage. At the same time, since the doped rod 2 is arrayed in the cathode working area 5, a stable and low-threshold electron emission area is formed, which is conducive to the stable breakdown of the electron emission device. And the cathode non-working area 4 is the matrix 1 with a higher emission threshold, which inhibits the cathode from emitting electrons in an undesired direction and avoids the phenomenon of insulation failure or increased loss. When the electron emission device operates continuously, the bare interface after the high-energy interface in this embodiment is integrally ablated by several micrometers maintains the same electron emission properties as the original interface, having a high service life and discharge stability.

[0076] Embodiment 2

[0077] The working principle of this embodiment is the same as that of Embodiment 1, the difference lies in the shape of the doping material and its distribution mode in the matrix 1.

[0078] A long-life and high-stability cathode for an electron emission device, comprising a matrix 1 and a doping material distributed in the matrix 1. Among them, the doping material is doping particles. The doping particles are evenly distributed in the matrix 1. The mass ratio of the doping particles to the matrix 1 is 5-50:95-50, the diameter of the doping particles is 1 μm-200 μm, and its melting point is higher than that of the matrix material. The doping particles are non-metallic materials or conductive materials, and the matrix 1 uses a fusible metal material.

[0079] This embodiment also provides a preparation method for the above-mentioned long-life and high-stability cathode for an electron emission device, comprising the following steps:

[0080] Step 1: Weigh the particulate materials of the doping particles and the matrix 1 respectively according to the mass ratio of 5-50:95-50;

[0081] Step 2: Mix the particulate materials of the doping particles and the matrix 1 evenly, and then sinter them by hot pressing to make the particulate materials of the matrix 1 tightly combined with each other, obtaining a cathode blank with the doping particles evenly distributed in the matrix 1;

[0082] Step 3: Perform machining on the cathode blank to obtain a long-life and high-stability cathode for an electron emission device. In this step, the machining is conventional operations such as turning, milling, and polishing.

Claims

1. A long-life, high-stability cathode for an electron-emitting device, characterized in that: It comprises a matrix (1) and a doping material distributed in the matrix (1), wherein the doping material is a plurality of doping rods (2); The doping rods (2) are arranged perpendicular to the discharge surface of the cathode and are distributed in an array in the matrix 1. The interface (3) between the matrix (1) and the doping rods (2) is used to emit electrons. The total area ratio of the doping rod (2) to the matrix (1) on the cathode discharge surface is 5-50:95-50, and the melting point of the doping rod (2) is higher than that of the matrix (1); The diameter of the doping rod (2) is 1 μm to 200 μm, and the distance between the central axes of two adjacent doping rods (2) is greater than 200 μm.

2. The long-life high-stability cathode for an electron-emitting device according to claim 1, characterized in that: The doping rods (2) are distributed in an array only in the matrix (1) in the cathode working area (5).

3. The long-life high-stability cathode for an electron-emitting device according to claim 1 or 2, characterized in that: The doping rod (2) is made of non-metallic material or conductive material; The substrate (1) is a metal material or a conductive material.

4. The long-life high-stability cathode for an electron-emitting device according to claim 3, characterized in that: When the doping rod (2) is made of a non-metallic material, silicon carbide, titanium carbide or aluminum oxide is used; when the doping rod (2) is made of a conductive material, graphite or carbon fiber is used; When the matrix (1) is a metal material, copper, aluminum, iron or stainless steel is used; when the matrix (1) is a conductive material, graphite is used.

5. A method for preparing a long-life high-stability cathode for an electron emission device according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step A1, selecting a plurality of doping rods (2) with a diameter of 1 μm to 200 μm, cutting them to the same length, and then inserting the two ends of the doping rods (2) into the corresponding array holes of two sheet molds for fixing; the total area of ​​the array holes on the sheet mold accounts for 5% to 50%; Step A2, fixing the sheet mold in the casting mold so that a plurality of doping rods (2) are straightened and parallel to each other; Step A3, combining the melted matrix (1) and the doping rods (2) in a casting mold to obtain a cathode blank in which the doping rods (2) are distributed in an array in the matrix (1); Step A4: Mechanically process the cathode blank, and use the section perpendicular to the doping rod (2) as the discharge surface of the cathode, so as to obtain a cathode with long life and high stability for the electron emission device.

6. The method for preparing a long-life high-stability cathode for an electron emission device according to claim 5, characterized in that: Step A3 is specifically as follows: The matrix (1) is melted and poured into a casting mold, and cooled naturally to allow the matrix (1) and the doping rods (2) to be combined with each other, thereby obtaining a cathode blank in which the doping rods (2) are distributed in an array in the matrix (1); Alternatively, a casting mold is filled with particles of the matrix (1), which are then heated in an atmosphere furnace to melt the particles of the matrix (1) and combine with the doping rods (2), and then cooled naturally to obtain a cathode blank with an array of doping rods (2) distributed in the matrix (1).

7. A method for preparing a long-life high-stability cathode for an electron emission device according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step B1, selecting a plurality of doping rods (2) with a diameter of 1 μm to 200 μm, and cutting them to a uniform length; Step B2, electroplating or chemically plating the doping rod (2) to uniformly grow a matrix coating on the surface of the doping rod (2), thereby obtaining a doping rod (2) having a matrix coating; Step B3, arranging the doped rods (2) with the matrix coating evenly and then bundling them into rods; Step B4, sintering the matrix coating by hot pressing so that the matrix coating of each doping rod (2) is tightly bonded to each other, thereby obtaining a cathode blank in which the doping rods (2) are arrayed and distributed in the matrix (1); Step B5, mechanically processing the cathode blank, using the cross section perpendicular to the doping rod (2) as the discharge surface of the cathode, and obtaining a cathode with a long life and high stability for an electron emission device.

8. A long-life, high-stability cathode for an electron-emitting device, characterized in that: It comprises a matrix (1) and a doping material distributed in the matrix (1), wherein the doping material is doping particles; The doped particles are uniformly distributed in the matrix (1); The mass ratio of the doped particles to the matrix (1) is 5-50:95-50; The diameter of the doped particles is 1 μm to 200 μm, and the melting point is higher than that of the matrix (1).

9. The long-life high-stability cathode for an electron-emitting device according to claim 8, characterized in that: The doped particles are non-metallic materials or conductive materials; The matrix (1) is made of a fusible metal material.

10. A method for preparing a long-life high-stability cathode for an electron-emitting device according to claim 8 or 9, characterized in that: The following steps are involved: Step 1, weighing the doped particles and the matrix (1) particles in a mass ratio of 5-50:95-50 respectively; Step 2, uniformly mixing the doped particles with the particles of the matrix (1), and then sintering them by hot pressing so that the particles of the matrix (1) are tightly combined to obtain a cathode blank in which the doped particles are uniformly distributed in the matrix (1); Step 3: Mechanically process the cathode blank to obtain a cathode with long life and high stability for electron emission devices.

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