Cathode and preparation method thereof

Abstract

The invention provides a cathode and a preparation method thereof, which can be applied to the technical field of microwave vacuum electronics. The preparation method comprises the steps that (CH3COO) 2Sr or Y (NO3) 3 is added into an initial emission material and treated, a target emission material is obtained, the target emission material comprises Ba2ScAlO5 and Ba3Al2O6, and the molar ratio of Ba2ScAlO5 to Ba3Al2O6 ranges from 1: 2 to 1: 1; dipping the sponge substrate in a target emission material; bombarding the surface of the impregnated sponge substrate by using an ion beam to remove residual oxide on the surface of the impregnated sponge substrate to obtain a textured layer; and depositing a metal film on the upper surface of the textured layer to obtain the target thermionic cathode.

Description

Technical Field

[0001] The present disclosure relates to the field of microwave vacuum electronic technology, and more specifically, to a cathode and a preparation method thereof. Background Art

[0002] Microwave vacuum electronic devices are used to output and convert electromagnetic waves, and have always played an important role in related fields. Among them, high-power microwave vacuum electronic devices are mainly used in radar, electron accelerators, free electron lasers and high-power microwave devices. The electromagnetic waves generated by high-frequency devices, especially terahertz devices, have unique advantages such as high communication speed and strong perspective ability. They have great scientific research value and broad application prospects in broadband communications, radar, electronic countermeasures, electromagnetic devices and medical imaging applications. The cathode is one of the core components of microwave vacuum electronic devices.

[0003] In the process of realizing the concept of the present disclosure, the inventors found that it is difficult for the cathode in the related art to simultaneously meet the requirements of low temperature, long pulse width, high emission current density and long service life. Summary of the invention

[0004] In view of this, the present disclosure provides a cathode and a method for preparing the same.

[0005] One aspect of the present disclosure provides a method for preparing a cathode, comprising:

[0006] Add (CH 3 COO 2 Sr or Y(NO 3 ) 3 and processed to obtain a target emission material, wherein the target emission material includes Ba in a molar ratio of 1:2 to 1:1. 2 ScAlO 5 and Ba 3 Al 2 O 6 ; Immerse the sponge matrix in the target emitting material; bombard the surface of the impregnated sponge matrix with an ion beam to remove the residual oxide on the surface of the impregnated sponge matrix to obtain a roughened layer; deposit a metal film on the upper surface of the roughened layer to obtain a target hot cathode.

[0007] According to an embodiment of the present disclosure, Ba in the target emission material 2 ScAlO 5 and Ba 3 Al 2 O 6 The total molar percentage is greater than 80%.

[0008] According to an embodiment of the present disclosure, the thickness of the metal film is 50 nm to 160 nm, and the material of the metal film includes one of the following: osmium, osmium-tungsten-rhenium alloy.

[0009] According to an embodiment of the present disclosure, the sponge matrix is ​​immersed in the target launch material for 1 to 2 minutes, and the immersion temperature is 1680 to 1730 degrees Celsius.

[0010] According to an embodiment of the present disclosure, the initial emission material includes: (CH 3 COO 2 Ba, (CH 3 COO 2 Ca、Al(NO 3 ) 3 Sc(NO 3 ) 3 , add (CH 3 COO 2 Sr or Y(NO 3 ) 3 And process to obtain the target launch material, including: (CH 3 COO 2 Sr or Y(NO 3 ) 3 Adding initial emission materials to promote Ba 2 ScAlO 5 and Ba 3 Al 2 O 6 The mixed initial launch material is freeze-dried and sintered to obtain the target launch material.

[0011] According to an embodiment of the present disclosure, an ion beam is used to bombard the surface of the impregnated sponge matrix to remove residual oxides on the surface of the impregnated sponge matrix to obtain a roughened layer, including: finishing the surface of the impregnated sponge matrix to clear the pores of the sponge matrix; bombarding the surface of the sponge matrix after finishing with an ion beam to obtain a roughened layer, wherein the ion beam is obtained by passing argon gas with a flow rate of 3.5 to 4 standard cubic centimeters per minute into an ion source.

[0012] According to an embodiment of the present disclosure, the screen voltage of the ion beam is 800 to 1000 volts, the current of the ion beam is 80 to 100 milliamperes, and the bombardment time of the ion beam is 40 to 60 minutes.

[0013] According to an embodiment of the present disclosure, a metal film is deposited on the upper surface of the roughened layer, including: bombarding a metal target material with an ion beam to obtain a metal film, wherein the ion beam includes argon gas with a flow rate of 4 to 5 standard cubic centimeters per minute, the screen voltage of the ion beam is 2500 to 2700 volts, and the current of the ion beam is 80 to 100 milliamperes; depositing the metal film on the upper surface of the roughened layer, wherein the deposition time is 0.5 to 1 hour.

[0014] Another aspect of the present disclosure provides a cathode, comprising:

[0015] The sponge matrix is ​​obtained by impregnating the target emission material, and the target emission material includes Ba in a molar ratio between 1:2 and 1:1. 2 ScAlO 5 and Ba 3 Al 2 O 6 ;

[0016] The hairy layer covers the upper surface of the sponge matrix;

[0017] The metal film covers the upper surface of the roughened layer.

[0018] According to an embodiment of the present disclosure, the sponge matrix includes a plurality of sponge cakes with a porosity of 22-25%, and the cathode further includes: a support tube connected to the sponge matrix via molybdenum-ruthenium solder; and a heater located inside the support tube.

[0019] According to an embodiment of the present disclosure, the sponge matrix is ​​impregnated with Ba in a molar ratio of 1:2 to 1:1. 2 ScAlO 5 and Ba 3 Al 2 O 6 In the target emission material, the surface of the sponge matrix after impregnation is bombarded with ion beams to remove the residual oxides to obtain a roughened layer, and a metal film is deposited on the surface of the roughened layer to improve the adhesion of the metal film. The metal film can protect the cathode and enhance the emission uniformity of the cathode surface. Therefore, with a relatively simple preparation process, the emission current density of the cathode at a long pulse width is increased, the cathode operating temperature is reduced, and the service life is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0021] Figure 1 A flow chart of a cathode preparation method according to an embodiment of the present disclosure is schematically shown.

[0022] Figure 2A cathode life curve diagram according to an embodiment of the present disclosure is schematically shown.

[0023] Figure 3 The cathode pulse voltammetric characteristic curve diagram according to the embodiment of the present disclosure is schematically shown with an operating temperature of 1000° C., a pulse width of 2 ms, and a working ratio of 5%.

[0024] Figure 4 The cathode pulse voltammetric characteristic curve diagram according to another embodiment of the present disclosure is schematically shown with an operating temperature of 1000° C., a pulse width of 2 ms, and a working ratio of 5%.

[0025] Figure 5 The cathode pulse voltammetric characteristic curve diagram according to another embodiment of the present disclosure is schematically shown with an operating temperature of 1000° C., a pulse width of 2 ms, and a working ratio of 5%.

[0026] Figure 6 The cathode pulse voltammetric characteristic curve diagram according to another embodiment of the present disclosure is schematically shown with an operating temperature of 1000° C., a pulse width of 2 ms, and a working ratio of 5%.

[0027] Figure 7 A schematic diagram of a cathode structure according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0029] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0030] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0031] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0032] With the development of high-power devices towards high reliability and long life, and the development of high-frequency devices towards high power, the requirements for the cathode's operating temperature, emission current density and ability to withstand long pulse width are increasing, that is, the operating temperature must be lower than 1050°C, the operating pulse width must be greater than 1ms, and the emission current density must be within 20A / cm 2 Above, and have the conditions of a lifespan of several thousand hours.

[0033] The emission current density of the high emission current density cathode in the related art, such as the scandium-containing diffused cathode, can reach 500A / cm in a narrow pulse of 5μs. 2 However, the cathode needs to work at a temperature above 1100°C, and its life is difficult to guarantee. At the same time, the cathode is weak in particle bombardment resistance, and there is almost no reported test data for pulse widths above 100μs. For ordinary impregnated barium tungsten cathodes, although the operating temperature can be below 1050°C and the pulse width is 4A / cm 2 The following DC also has a lifespan of tens of thousands of hours, but the emission current density is less than 20 A / cm when the pulse width is greater than 100 μs. 2 , and it is difficult to reach a lifespan of several thousand hours.

[0034] Therefore, the existing hot cathodes are difficult to meet the requirements of high-power devices and high-frequency devices.

[0035] In view of this, an embodiment of the present disclosure provides a method for preparing a cathode, comprising: adding (CH 3 COO 2 Sr or Y(NO 3 ) 3 and processed to obtain a target emission material, wherein the target emission material includes Ba in a molar ratio of 1:2 to 1:1. 2 ScAlO 5 and Ba 3 Al 2 O 6 ; Immerse the sponge matrix in the target emitting material; bombard the surface of the impregnated sponge matrix with an ion beam to remove the residual oxide on the surface of the impregnated sponge matrix to obtain a roughened layer; deposit a metal film on the upper surface of the roughened layer to obtain a target hot cathode.

[0036] Figure 1 A flow chart of a cathode preparation method according to an embodiment of the present disclosure is schematically shown.

[0037] like Figure 1 As shown, the method 100 includes operations S110 to S140.

[0038] In operation S110, (CH 3 COO 2 Sr or Y(NO 3 ) 3 And process it to obtain the target launch material.

[0039] In operation S120, the sponge matrix is ​​immersed in the target emission material.

[0040] In operation S130, the surface of the impregnated sponge matrix is ​​bombarded with an ion beam to remove residual oxides on the surface of the impregnated sponge matrix to obtain a roughened layer.

[0041] In operation S140, a metal film is deposited on the upper surface of the textured layer to obtain a target hot cathode.

[0042] According to an embodiment of the present disclosure, the sponge matrix may be a tungsten sponge matrix.

[0043] According to an embodiment of the present disclosure, the sponge matrix is ​​immersed in a high-emission target emission material, so that the sponge matrix fully absorbs the high-emission electron emission material, providing a basis for subsequent emission performance.

[0044] According to the embodiments of the present disclosure, by bombarding the surface of the impregnated sponge matrix with an ion beam of high-current gas, on the one hand, blocked channels on the surface of the sponge matrix can be opened, and on the other hand, residual oxides on the cathode surface can be bombarded off. In addition, by adjusting the size of the ion beam flow, an uneven roughened layer can be formed on the cathode surface to enhance the adhesion firmness of the metal film, thereby extending the service life of the cathode.

[0045] According to the embodiments of the present disclosure, when the cathode is working with long pulse width and high emission current density, a large number of barium and scandium atoms or barium and scandium ions will be generated in the tungsten sponge matrix, and these atoms or ions will diffuse along the channels in the tungsten sponge matrix to the emission surface of the cathode matrix. At the same time, when the cathode is working with long pulse width, the gas generated by the large amount of electron bombardment will be ionized under the action of the electric field, and the generated positive ions will move toward the cathode and directly bombard the emission surface of the cathode matrix, causing an imbalance in the barium-scandium ratio on the cathode surface, thereby reducing the cathode emission current and ending its service life. Therefore, by depositing a metal film that is beneficial to electron emission on the cathode surface, the technical effect of avoiding direct ion bombardment on the cathode matrix surface and enhancing the emission uniformity of the cathode surface can be achieved.

[0046] Figure 2 A cathode life curve diagram according to an embodiment of the present disclosure is schematically shown.

[0047] like Figure 2 As shown, the horizontal axis is the lifetime and the vertical axis is the working current. The emission current density is 25A / cm 2 , pulse width is 2ms, duty ratio is 5%, and operating temperature is 1000℃. The service life can reach more than 4000h. When the working time is 1149h, the current drops to 95.9% of the initial current; when the working time is 2053h, the current drops to 92.3% of the initial current; when the working time is 4021h, the current drops to 91.2% of the initial current.

[0048] It can be seen that the cathode of the embodiment of the present disclosure can simultaneously meet the requirements of high emission current density, long pulse width, low temperature operation and long service life of high power devices and high frequency devices.

[0049] According to an embodiment of the present disclosure, the sponge matrix is ​​impregnated with Ba in a molar ratio of 1:2 to 1:1. 2 ScAlO 5 and Ba 3 Al 2 O 6 In the target emitting material, the surface of the sponge matrix after impregnation is bombarded with ion beams to remove the residual oxides to obtain a roughened layer, and a metal film is deposited on the surface of the roughened layer to improve the adhesion firmness of the metal film. The metal film can protect the cathode and enhance the emission uniformity of the cathode surface. Therefore, with a relatively simple preparation process, the emission current density of the cathode at a long pulse width is increased, the cathode operating temperature is reduced, and the service life is increased, so that the prepared cathode can be applied to high-power devices and high-frequency devices in microwave vacuum electronic devices.

[0050] According to an embodiment of the present disclosure, Ba in the target emission material 2 ScAlO 5 and Ba 3 Al 2 O 6 The total molar percentage is greater than 80%.

[0051] According to the embodiments of the present disclosure, by limiting the content of the scandium-containing compound in the target emission material, stable high emission performance can be maintained under low temperature and long pulse width conditions.

[0052] According to an embodiment of the present disclosure, the thickness of the metal film is 50 nm to 160 nm, and the material of the metal film includes one of the following: osmium, osmium-tungsten-rhenium alloy.

[0053] According to the embodiments of the present disclosure, by depositing a metal film on the cathode surface, the cathode sponge substrate surface can be prevented from being directly bombarded by the ion beam, and the emission uniformity of the cathode surface can be enhanced. Since the diffusion rate of scandium or scandium ions in the metal film is relatively slow, in order to ensure that the barium-scandium ratio on the cathode surface is not mismatched during operation, the film thickness should not be too thick, and too thin will not protect the cathode, so the thickness can be between 50nm and 160nm, which is the best effect.

[0054] According to an embodiment of the present disclosure, the molar content of osmium in the metal film of the osmium-tungsten-rhenium alloy is not less than 50%, and the molar content of rhenium is not less than 20%.

[0055] According to an embodiment of the present disclosure, the initial emission material includes: (CH 3 COO 2 Ba, (CH 3 COO 2 Ca、Al(NO 3 ) 3 Sc(NO 3 ) 3 , add (CH 3 COO 2 Sr or Y(NO 3 ) 3 And process to obtain the target launch material, including: (CH 3 COO 2 Sr or Y(NO 3 ) 3 Adding initial emission materials to promote Ba 2 ScAlO 5 and Ba 3 Al 2 O 6 The mixed initial launch material is freeze-dried and sintered to obtain the target launch material.

[0056] According to the embodiments of the present disclosure, freeze drying can remove moisture from the mixed material, prevent unnecessary chemical reactions from occurring during the subsequent sintering process, and ensure the purity and uniformity of the target emission material.

[0057] According to an embodiment of the present disclosure, the sponge matrix is ​​immersed in the target launch material for 1 to 2 minutes, and the immersion temperature is 1680 to 1730 degrees Celsius.

[0058] According to the embodiments of the present disclosure, it is necessary to ensure appropriate immersion time and immersion temperature to ensure that the target launch material can fully penetrate into the pores of the sponge matrix and be evenly distributed.

[0059] According to an embodiment of the present disclosure, an ion beam is used to bombard the surface of the impregnated sponge matrix to remove residual oxides on the surface of the impregnated sponge matrix to obtain a roughened layer, including: finishing the surface of the impregnated sponge matrix to clear the pores of the sponge matrix; bombarding the surface of the sponge matrix after finishing with an ion beam to obtain a roughened layer, wherein the ion beam is obtained by passing argon gas with a flow rate of 3.5 to 4 standard cubic centimeters per minute into an ion source.

[0060] According to the embodiments of the present disclosure, the finishing process utilizes the high-speed rotation of the tool on the surface of the sponge matrix to remove the residues on the surface of the sponge matrix after impregnation and to unclog the pores of the sponge matrix, thereby preventing the active substances generated by the reaction of the target emission material in the sponge matrix with the sponge matrix from diffusing to the surface, thereby affecting the cathode emission performance.

[0061] According to an embodiment of the present disclosure, the screen voltage of the ion beam is 800 to 1000 volts, the current of the ion beam is 80 to 100 milliamperes, and the bombardment time of the ion beam is 40 to 60 minutes.

[0062] According to an embodiment of the present disclosure, a metal film is deposited on the upper surface of the roughened layer, including: bombarding a metal target material with an ion beam to obtain a metal film, wherein the ion beam includes argon gas with a flow rate of 4 to 5 standard cubic centimeters per minute, the screen voltage of the ion beam is 2500 to 2700 volts, and the current of the ion beam is 80 to 100 milliamperes; depositing the metal film on the upper surface of the roughened layer, wherein the deposition time is 0.5 to 1 hour.

[0063] According to the embodiments of the present disclosure, the metal film can be prepared by ion beam sputtering coating technology. Ion beam sputtering has the unique advantage of independently controlling ion energy, flux, and incident angle, and has a large control range, which is conducive to accurately controlling the thickness and uniformity of the metal film. At the same time, the metal film is deposited under high vacuum conditions to obtain a metal film with high purity, good density, and higher adhesion strength.

[0064] According to the embodiments of the present disclosure, the sponge matrix also needs to be welded to the molybdenum support barrel using high-temperature molybdenum-ruthenium solder, and a thermal subassembly is installed in the cathode molybdenum support cylinder.

[0065] According to an embodiment of the present disclosure, the cathode prepared as above is loaded into a cathode dynamic test system for degassing, activation and aging treatments, and then the cathode's volt-ampere characteristics are tested at a specific operating temperature, pulse width and working ratio to obtain a corresponding volt-ampere characteristic curve.

[0066] In order to better demonstrate that the cathode obtained by the above preparation method can simultaneously meet the conditions of low temperature operation, long pulse width and high emission current density, the following Figure 3~Figure 6 To give a hint.

[0067] Figure 3 The cathode pulse voltammetric characteristic curve diagram according to the embodiment of the present disclosure is schematically shown with an operating temperature of 1000° C., a pulse width of 2 ms, and a working ratio of 5%.

[0068] like Figure 3 As shown, the horizontal axis is the operating voltage, the vertical axis is the operating current, and the cathode emission current density is 60.6A / cm 2 , which exceeds 60 A / cm 2 .

[0069] According to an embodiment of the present disclosure, the sponge matrix of the cathode is impregnated with barium scandium aluminate (Ba 2 ScAlO 5 ) and barium aluminate (Ba 3 Al 2 O 6 ) is 87% by mole, and Ba 2 ScAlO 5 with Ba 3 Al 2 O 6 The molar ratio of is 1:1.6. The metal film deposition time is 0.5 hours, and the thickness of the metal film is 50nm to 80nm.

[0070] Figure 4 The cathode pulse voltammetric characteristic curve diagram according to another embodiment of the present disclosure is schematically shown with an operating temperature of 1000° C., a pulse width of 2 ms, and a working ratio of 5%.

[0071] like Figure 4 As shown, the horizontal axis is the operating voltage, the vertical axis is the operating current, and the cathode emission current density is 64.6A / cm 2 , which exceeds 60 A / cm 2 .

[0072] According to an embodiment of the present disclosure, the sponge matrix of the cathode is impregnated with barium scandium aluminate (Ba 2 ScAlO 5 ) and barium aluminate (Ba 3 Al 2 O 6 ) is 94% by mole, and Ba 2 ScAlO 5 with Ba 3 Al 2 O 6 The molar ratio of is 1:1.1. The metal film deposition time is 0.5 hours, and the thickness of the metal film is 50nm to 80nm.

[0073] contrast Figure 3 and Figure 4It can be seen that the emission current density can be increased by adjusting the total molar content and molar ratio of the two scandium-containing compounds in the target emission material.

[0074] Figure 5 The cathode pulse voltammetric characteristic curve diagram according to another embodiment of the present disclosure is schematically shown with an operating temperature of 1000° C., a pulse width of 2 ms, and a working ratio of 5%.

[0075] like Figure 5 As shown, the horizontal axis is the working voltage, the vertical axis is the working current, and the cathode emission current density is 60A / cm 2 , which reaches 60 A / cm 2 .

[0076] According to an embodiment of the present disclosure, the sponge matrix of the cathode is impregnated with barium scandium aluminate (Ba 2 ScAlO 5 ) and barium aluminate (Ba 3 Al 2 O 6 ) is 94% by mole, and Ba 2 ScAlO 5 with Ba 3 Al 2 O 6 The molar ratio of is 1:1.1. The metal film deposition time is 1 hour, and the thickness of the metal film is 100nm to 160nm.

[0077] contrast Figure 4 and Figure 5 It can be seen that the emission current density can be adjusted by changing the deposition time and thickness of the metal film.

[0078] Figure 6 The cathode pulse voltammetric characteristic curve diagram according to another embodiment of the present disclosure is schematically shown with an operating temperature of 1000° C., a pulse width of 2 ms, and a working ratio of 5%.

[0079] like Figure 6 As shown, the horizontal axis is the operating voltage, the vertical axis is the operating current, and the cathode emission current density is 61.3A / cm 2 , which exceeds 60 A / cm 2 .

[0080] According to an embodiment of the present disclosure, the sponge matrix of the cathode is impregnated with barium scandium aluminate (Ba 2 ScAlO 5 ) and barium aluminate (Ba 3 Al 2 O 6 ) is 91% by mole, and Ba 2ScAlO 5 with Ba 3 Al 2 O 6 The molar ratio of is 1: 2. The metal film deposition time is 0.5 hours, and the thickness of the metal film is 50nm to 80nm.

[0081] According to an embodiment of the present disclosure, Figure 3 The scandium compound in the target launch material is obtained by 9atom% (CH 3 COO 2 Sr promotes the generation of Figure 6 3atom% Y(NO 3 ) 3 Replaced 9atom% of (CH 3 COO 2 Sr.

[0082] According to the above preparation method, the present disclosure also provides a cathode, comprising: a sponge matrix, wherein the sponge matrix is ​​obtained by impregnating a target emission material, wherein the target emission material comprises Ba in a molar ratio between 1:2 and 1:1. 2 ScAlO 5 and Ba 3 Al 2 O 6 ; a hairy layer covering the upper surface of the sponge matrix; and a metal film covering the upper surface of the hairy layer.

[0083] Figure 7 A schematic diagram of a cathode structure according to an embodiment of the present disclosure is schematically shown.

[0084] like Figure 7 As shown, the cathode is composed of a metal film, a hairy layer, a sponge matrix, a support tube and a heater.

[0085] It should be noted that the cathode part in the embodiment of the present disclosure corresponds to the cathode preparation method part in the embodiment of the present disclosure. The description of the cathode part specifically refers to the cathode preparation method part, which will not be repeated here.

[0086] According to an embodiment of the present disclosure, the sponge matrix is ​​impregnated with Ba and 2 ScAlO 5 and Ba 3 Al 2 O 6In the target emission material, a roughened layer is provided on the surface of the sponge matrix, and a metal film is deposited on the surface of the roughened layer, which is beneficial to improving the adhesion firmness of the metal film. The metal film can protect the cathode and enhance the emission uniformity of the cathode surface. Therefore, the emission current density of the cathode at a long pulse width is increased, the cathode operating temperature is reduced, and the service life is increased. It can be applied to high-power devices and high-frequency devices in microwave vacuum electronic devices.

[0087] According to an embodiment of the present disclosure, the sponge matrix includes a plurality of sponge cakes with a porosity of 22-25%, and the cathode further includes: a support tube connected to the sponge matrix via molybdenum-ruthenium solder; and a heater located inside the support tube.

[0088] According to an embodiment of the present disclosure, the diameter of the sponge cake may be 1 mm, and channels may be formed between adjacent sponge cakes for impregnating the target emission material.

[0089] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functions and operations that may be implemented according to the structures and methods of various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they may sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It will be appreciated by those skilled in the art that the features recorded in the various embodiments of the present disclosure can be combined and / or combined in a variety of ways, even if such a combination or combination is not explicitly recorded in the present disclosure. In particular, without departing from the spirit and teaching of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0090] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A method for preparing a cathode, characterized in that: include: Adding (CH3COO)2Sr or Y(NO3)3 to the initial emission material and treating it to obtain a target emission material, wherein the target emission material includes Ba2ScAlO5 and Ba3Al2O6 in a molar ratio of 1:2 to 1:1; impregnating a sponge matrix into the target emission material; Bombarding the surface of the impregnated sponge matrix with an ion beam to remove residual oxides on the surface of the impregnated sponge matrix to obtain a roughened layer; A metal film is deposited on the upper surface of the textured layer to obtain a target hot cathode.

2. The method according to claim 1, characterized in that The total molar percentage of Ba2ScAlO5 and Ba3Al2O6 in the target emission material is greater than 80%.

3. The method according to claim 1, characterized in that The thickness of the metal film is 50nm-160nm, and the material of the metal film includes one of the following: osmium and osmium-tungsten-rhenium alloy.

4. The method according to claim 1, characterized in that: The sponge matrix is ​​immersed in the target launch material for 1 to 2 minutes at a temperature of 1680 to 1730 degrees Celsius.

5. The method according to claim 1, characterized in that The initial emission material includes: (CH3COO)2Ba, (CH3COO)2Ca, Al(NO3)3, Sc(NO3)3, and (CH3COO)2Sr or Y(NO3)3 is added to the initial emission material and processed to obtain the target emission material, including: Adding the (CH3COO)2Sr or Y(NO3)3 to the initial emission material to promote the formation of the Ba2ScAlO5 and the Ba3Al2O6; The mixed initial emission material is freeze-dried and sintered to obtain the target emission material.

6. The method according to claim 1, characterized in that The method of bombarding the surface of the impregnated sponge matrix with an ion beam to remove the residual oxide on the surface of the impregnated sponge matrix to obtain a roughened layer comprises: Performing a finishing process on the surface of the impregnated sponge matrix to dredge the pores of the sponge matrix; The surface of the sponge substrate after fine turning is bombarded with an ion beam to obtain a roughened layer, wherein the ion beam is obtained by passing argon gas with a flow rate of 3.5 to 4 standard cubic centimeters per minute into an ion source.

7. The method according to claim 6, characterized in that The plate voltage of the ion beam is 800-1000 volts, the current of the ion beam is 80-100 milliamperes, and the bombardment time of the ion beam is 40-60 minutes.

8. The method according to claim 1, characterized in that The step of depositing a metal film on the upper surface of the textured layer comprises: The metal film is obtained by bombarding a metal target with an ion beam, wherein the ion beam includes argon gas with a flow rate of 4 to 5 standard cubic centimeters per minute, the plate voltage of the ion beam is 2500 to 2700 volts, and the current of the ion beam is 80 to 100 milliamperes; The metal film is deposited on the upper surface of the textured layer, wherein the deposition time is 0.5 to 1 hour.

9. A cathode, characterized in that: include: A sponge matrix, wherein the sponge matrix is ​​obtained by being immersed in a target emission material, wherein the target emission material comprises Ba2ScAlO5 and Ba3Al2O6 in a molar ratio between 1:2 and 1:1; A hairy layer covering the upper surface of the sponge matrix; The metal film covers the upper surface of the hairy layer.

10. The cathode according to claim 9, characterized in that The sponge matrix includes a plurality of sponge cakes with a pore size of 22-25%, and the cathode further includes: A support tube connected to the sponge matrix via molybdenum-ruthenium solder; The heater is located inside the support tube.

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