阅读说明：本技术 分段式复合结构磁等离子体动力推力器阴极及其制备方法 (Segmented composite structure magnetic plasma power thruster cathode and preparation method thereof ) 是由 王戈 周成 李永 杨志懋 魏延明 丁凤林 宋飞 孔春才 丛云天 王宝军 张晓晶 于 2020-05-12 设计创作，主要内容包括：本发明涉及分段式复合结构磁等离子体动力推力器阴极及其制备方法。所述阴极包括导热段、过渡段、发射段、进气缓冲腔体、多孔导流通道,导流通道均匀分布并贯穿导热段、过渡段和发射段,与进气缓冲腔体相通,等离子体通过进气缓冲腔体进入阴极并使气体均匀的进入多孔导流通道进行工质输送,阴极由铜或铜合金制成的导热段、连接导热段和发射段的过渡段与钨基复合氧化物复合材料制成的发射段组成,实现了促进发射段的导热,增加温度梯度,从而增加钨基阴极的散热,降低阴极表面温度,减轻阴极的烧蚀。(The invention relates to a segmented composite structure magnetic plasma power thruster cathode and a preparation method thereof. The cathode comprises a heat conduction section, a transition section, an emission section, an air inlet buffer cavity and a porous flow guide channel, wherein the flow guide channel is uniformly distributed and penetrates through the heat conduction section, the transition section and the emission section and is communicated with the air inlet buffer cavity, plasma enters the cathode through the air inlet buffer cavity and enables gas to uniformly enter the porous flow guide channel for conveying working media, the cathode consists of the heat conduction section made of copper or copper alloy, the transition section connecting the heat conduction section and the emission section made of tungsten-based composite oxide composite materials, heat conduction of the emission section is promoted, temperature gradient is increased, heat dissipation of the tungsten-based cathode is increased, surface temperature of the cathode is reduced, and ablation of the cathode is relieved.)

1. A segmented composite structure magnetic plasma dynamic thruster cathode is characterized by comprising a heat conduction section (1), a transition section (2) and an emission section (3);

the heat conduction section (1) of the cathode is hermetically connected with a cathode water-cooling cylinder sleeve surrounding the outside of the thruster by adopting a conical surface, the transition section (2) is used for connecting the emission section (3) and the heat conduction section (1), an air inlet buffer cavity (4) is arranged inside the heat conduction section (1), porous flow guide channels (5) which are communicated with each other are arranged inside the transition section (2) and the emission section (3), the air inlet buffer cavity (4) is communicated with the porous flow guide channels (5), plasma enters the porous flow guide channels (5) through the air inlet buffer cavity (4) and is transmitted to the emission section (3) through the porous flow guide channels (5), and electrons emitted by the emission section (3) ionize working media into plasma; a large amount of surplus heat can be produced when emission section (3) launches the electron, through changeover portion (2) with emission section (3) production heat conduction to heat conduction section (1), the heat dissipation of rethread negative pole water-cooling sleeve reduces the surface temperature of emission section (3), prevents the ablation of emission section (3).

2. A segmented composite structure magnetic plasma dynamic thruster cathode according to claim 1, characterized in that the heat conducting segment (1) is made of metal material consistent with cathode water cooling sleeve material, such as: copper alloy or copper.

3. The segmented composite structure magnetic plasma dynamic thruster cathode of claim 1, wherein the length of the heat conducting segment (1) is the same as the length of the surrounding cathode water cooling cylinder sleeve conical surface, so as to carry out sufficient heat exchange and transfer the heat generated when the cathode emits electrons, and the length is 30 mm.

4. The segmented composite structure magnetic plasma dynamic thruster cathode according to claim 3, characterized in that the length of the emission segment (3) is 10-20 mm.

5. A segmented composite structure magnetic plasma dynamic thruster cathode according to claim 4, characterized in that the length of the transition section (2) satisfies the following relation: the length of the transition section is equal to the length of the cathode, the length of the emission section and the length of the heat conduction section, and the length of the cathode is 60-68 mm.

6. The segmented composite structure magnetic plasma dynamic thruster cathode according to claim 1, characterized in that the transition section (2) is composed of a skeleton and a coating, the skeleton is made of the same material as the emission section (3), and the coating is made of the same material as the heat conduction section (1).

7. The segmented composite structure magnetic plasma power thruster cathode according to any one of claims 1 to 6, wherein: the heat conduction section (1) and the transition section (2) are connected by adopting an integrated infiltration forming process or a welding mode.

8. The segmented composite structure magnetic plasma power thruster cathode according to any one of claims 1 to 6, wherein: the transition section (2) and the emission section (3) are connected in a welding mode.

9. A segmented composite structure magnetic plasma power thruster cathode as claimed in claims 1-6, characterized in that the material of the emitter segment (3) is a tungsten based oxide composite material, such as yttrium oxide, lanthanum oxide, cerium oxide.

10. The sectional composite structure magnetic plasma dynamic thruster cathode according to the claims 1 to 6, characterized in that the outer surface of the heat conducting section (1) is a conical surface and is connected with a cathode water cooling sleeve structure in a conical manner.

11. A preparation method of a cathode of a magnetic plasma power thruster with a sectional composite structure is characterized by comprising the following steps:

(1) preparing a rough blank of the emission section (3);

(2) the porous framework is made of the same material as the rough blank of the emission section (3) and is used as the framework of the transition section (2);

(3) welding the framework of the transition section (2) and the emission section (3);

(4) placing the porous framework welded with the emission section (3) into a transition section (2) mould, and carrying out copper infiltration casting in an H2 atmosphere furnace to ensure that molten copper is infiltrated into the porous framework and redundant copper is attached to the surface of the transition section (2);

(5) welding the cathode heat conduction section (1) and the transition section (2) together;

(6) and (3) machining an air inlet buffer cavity (4) and a porous flow guide channel (5) on the rough blank machined in the step (5) through machining.

12. The method for preparing the cathode of the segmented composite structure magnetic plasma dynamic thruster, according to the claim 11, is characterized in that the transition section (1) is made of a mixed material of tungsten-based oxide and copper.

Technical Field

The invention relates to a segmented composite structure magnetic plasma power thruster cathode and a preparation method thereof, belonging to the field of magnetic power.

Background

With the requirements of applying an electric propulsion platform and a deep space exploration task to a spacecraft, various electric propulsion technical researches are developed in China and make great progress, but in view of the fact that the high-power space power supply technology of China is still in the development stage, the research on the high-power MPDT in China is started later. The magnetic power plasma thruster has the working principle that electric arcs are formed by discharging between a cathode and an anode, high current passes through high-temperature plasma formed by the propellant, and axial Lorentz force is generated by interaction of a current induced magnetic field, an additional magnetic field and the current, so that the propellant is accelerated to be discharged to generate thrust. The problem of cathode life of the high-power MPD thruster is always a bottleneck limiting the wide application of the high-power MPD thruster. When the MPD thruster works in a steady state, the temperature of the cathode emission surface can reach 3000 ℃, and because the cathode of the traditional MPD thruster is made of tungsten oxide materials, the heat conductivity coefficient of the tungsten oxide composite material is low and is only 150W/mK, the heat transmission in the working process is greatly limited.

The cathode of the existing MPD thruster mostly adopts an integrated tungsten oxide composite material, and because the heat conductivity coefficient is only 150W/mK, the heat of the cathode in a working medium ionization region can not be quickly discharged, so that the cathode melting ablation rate is high.

Disclosure of Invention

The technical problem solved by the invention is as follows: aiming at the problem of cathode fusion ablation caused by poor heat conduction performance of the cathode of the traditional MPD thruster in the prior art, the cathode of the magnetic plasma power thruster with the sectional type composite structure and the preparation method thereof are provided, and the heat dissipation capability and the ablation resistance capability of the cathode are ensured.

The technical solution of the invention is as follows: a magnetic plasma power thruster cathode with a sectional composite structure comprises a heat conduction section, a transition section and an emission section;

the heat conduction section of the cathode is hermetically connected with a cathode water cooling cylinder sleeve surrounding the outside of the thruster by adopting a conical surface, the transition section is used for connecting the emission section and the heat conduction section, an air inlet buffer cavity is arranged in the heat conduction section, porous flow guide channels which are communicated with each other are arranged in the transition section and the emission section, the air inlet buffer cavity is communicated with the porous flow guide channels, plasma enters the porous flow guide channels through the air inlet buffer cavity and is transmitted to the emission section through the porous flow guide channels, and the emission section emits electrons to ionize working media into the plasma; a large amount of redundant heat can be generated when the emission section emits electrons, the emission section generates heat through the transition section and conducts the heat to the heat conduction section, and then the heat is dissipated through the cathode water-cooling sleeve, so that the surface temperature of the emission section is reduced, and the ablation of the emission section is prevented.

The heat conducting section is made of metal materials consistent with the cathode water-cooling sleeve, such as: copper alloy or copper.

The length of the heat conduction section is consistent with the length of the conical surface of the surrounding cathode water-cooling cylinder sleeve, so that sufficient heat exchange is carried out, heat generated when the cathode emits electrons is transmitted out, and the length is 30 mm.

The length of the transmitting section is 10-20 mm.

The length of the transition section satisfies the following relation: the length of the transition section is equal to the length of the cathode, the length of the emission section and the length of the heat conduction section, and the length of the cathode is 60-68 mm.

The transition section is composed of a framework and a coating, the framework is made of materials identical to those of the emission section, and the coating is made of materials identical to those of the heat conduction section.

The heat conduction section and the transition section are connected by adopting an integrated infiltration forming process or a welding mode.

The transition section is connected with the emission section in a welding mode.

The material of the emission section is a tungsten-based oxide composite material, such as yttrium oxide, lanthanum oxide and cerium oxide.

The outer surface of the cathode heat conduction section is a conical surface and is in conical connection with the cathode water cooling sleeve structure.

The other technical solution of the invention is as follows: a preparation method of a cathode of a magnetic plasma power thruster with a sectional composite structure comprises the following steps:

(1) preparing a rough blank of an emission section;

(2) preparing a porous framework from the same material as the emission section rough blank, and taking the porous framework as a framework of the transition section;

(3) welding the framework of the transition section and the emission section;

(4) placing the porous framework welded with the emission section into a transition section mould, and carrying out copper infiltration casting in an H2 atmosphere furnace to ensure that molten copper is infiltrated into the porous framework and redundant copper is attached to the surface of the transition section;

(5) welding the cathode heat conduction section and the transition section together;

(6) and machining an air inlet buffer cavity and a porous flow guide channel on the rough blank machined in the step.

The transition section (1) is made of a mixed material of tungsten-based oxide and copper.

Compared with the prior art, the invention has the advantages that:

(1) the novel sectional type composite structure cathode structure provided by the invention is respectively composed of the emission section, the transition section and the heat conduction section, promotes the heat conduction of the emission section on the premise of not influencing the electron emission capability of the cathode, and increases the temperature gradient, thereby increasing the heat dissipation of the tungsten cathode, reducing the surface temperature of the cathode and lightening the ablation of the cathode.

(2) The tungsten-copper welding process adopted by the transition section is reliable and high-temperature resistant, and can be used for a long time in the working environment of a magnetic plasma power (MPD) thruster;

(3) the heat conducting section of the invention adopts high heat conducting metal which is consistent with the material of the cathode water cooling sleeve, thereby effectively improving the heat exchange effect.

Drawings

Fig. 1 is a structural diagram of a cathode provided in an embodiment of the invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and examples.

As shown in fig. 1, the present invention provides a segmented composite structure magnetic plasma power (MPD) thruster cathode, which includes a heat conducting segment 1, a transition segment 2 and an emission segment 3;

the heat conducting section 1 of the cathode is hermetically connected with a cathode water-cooling cylinder sleeve surrounding the outside of the device by adopting a conical surface, the transition section 2 is used for connecting the emission section 3 with the heat conducting section 1, an air inlet buffer cavity 4 is arranged inside the heat conducting section 1, porous flow guide channels 5 which are mutually communicated are arranged inside the transition section 2 and the emission section 3, the air inlet buffer cavity 4 is communicated with the porous flow guide channels 5, the air inlet buffer cavity 4 is positioned at the center of the cathode heat conducting section 1, plasma uniformly enters the porous flow guide channels 5 through the air inlet buffer cavity 4 and is transmitted to the emission section 3 through the porous flow guide channels 5, and electrons emitted by the emission section 3 ionize working media into plasma; a large amount of redundant heat can be generated when the emission section 3 emits electrons, the emission section 3 generates heat to be conducted to the heat conduction section 1 through the transition section 2, and then the surface temperature of the emission section 3 is reduced through heat dissipation of the cathode water-cooling sleeve, so that ablation of the emission section 3 is prevented. The porous flow guide channel 5 is positioned at the center of the transition section 2 and the emission section 3 and is communicated with the transition section and the emission section to provide a sufficient electron emission section for the cathode.

Preferably, the heat conducting section 1 is made of a metal material consistent with the material of the cathode water-cooling sleeve,

preferably, the length of the heat conducting section 1 is consistent with the length of the conical surface of the surrounding cathode water-cooling cylinder sleeve, so that sufficient heat exchange can be carried out, and the heat generated when the cathode emits electrons is transferred, and the length is 30 mm.

Preferably, the invention adopts a sectional variable temperature gradient structure, the length of the cathode transition section is 15-22 mm, the length of the cathode emission section is 10-20 mm, and the length of the transition section satisfies the following relation: the length of the transition section is equal to the length of a cathode, the length of an emission section and the length of a heat conduction section, the length of the cathode is 60-68 mm, the outer surface of the cathode heat conduction section is a conical surface, and the outer surface of the cathode heat conduction section is in conical connection with a cathode water cooling sleeve structure.

Preferably, the transition section 2 consists of a framework and a coating, the framework is made of the material of the emission section (3), and the coating is made of the same material as the heat conduction section 1.

Preferably, the heat conducting section 1 and the transition section 2 are connected by adopting an integrated infiltration forming process or a welding mode.

Preferably, the transition section 2 and the emission section 3 are connected by welding.

Preferably, the outer surface of the cathode heat conduction section 1 is a conical surface and is in conical connection with the cathode water cooling sleeve structure, so that sufficient heat exchange contact and clamping can be guaranteed, and the cathode heat conduction section can be rapidly detached.

Preferably, the heat conducting section 1 is made of copper alloy or copper, the heat conductivity coefficient is 401W/mK, and the heat exchange capacity is ensured.

Preferably, the transition section (1) is made of a mixed material of tungsten-based oxide and copper, and the volume ratio of mixed tungsten and copper is 1: 8.

preferably, the framework material of the transition section 2 is a copper-tungsten oxide composite material, and the thermal conductivity is 195W/mK. The transition section 2 can ensure the uniform change of the temperature gradient, improve the heat exchange capability of the cathode and reduce the difficulty of the welding process of connection.

Preferably, the material of the emission section 3 is a tungsten oxide composite material, such as yttrium oxide, lanthanum oxide and cerium oxide, which can maintain the emission capability of electrons and control the temperature not to exceed 3000 ℃.

The invention also provides a preparation method of the segmented composite structure MPD thruster cathode, which comprises the following steps:

(1) preparing a rough blank of the emission section 3;

(2) preparing a porous framework from the same material as the emission section 3 coarse blank, and taking the porous framework as the framework of the transition section 2;

(3) welding the framework of the transition section 2 and the emission section 3;

(4) placing the porous framework welded with the emission section 3 into a transition section 2 mould, and carrying out copper infiltration casting in an H2 atmosphere furnace to ensure that molten copper is infiltrated into the porous framework and redundant copper is attached to the surface of the transition section 2;

(5) welding the cathode heat conduction section 1 and the transition section 2 together;

(6) and machining an air inlet buffer cavity 4 and a porous flow guide channel 5 on the rough blank machined in the step 5 through machining.

On one hand, the preparation method can improve the heat conduction performance of the emission section 3, increase the temperature gradient and reduce the ablation of the cathode; on the other hand, the electron emission capability of the cathode can be maintained, and the engine performance is maintained unchanged.

Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.