CN115875223A - Hollow cathode sealing structure of electric propulsion system and inspection method of airtightness of hollow cathode - Google Patents

Abstract

The invention provides a hollow cathode sealing structure of an electric propulsion system and a method for testing the airtightness of the hollow cathode. The hollow cathode sealing structure of an electric propulsion system includes a hollow cathode casing, a compression cover and a rubber gasket, the compression cover is detachably mounted on one end of the hollow cathode casing, and the hollow cathode casing It is connected with the compression cover through a threaded structure. One end of the hollow cathode casing is provided with a top hole. The compression cover includes a cover body and a connecting portion, the cover body is provided with a groove structure, the rubber gasket is installed in the groove structure, and the thickness of the rubber gasket is greater than that of the groove structure depth. The invention can seal and protect the hollow cathode, prevent the emitter from reacting with water and oxygen in the ambient atmosphere, play an anti-poisoning role, and at the same time prevent dust and excess, prolong the life of the hollow cathode, and facilitate the realization of an electric propulsion system long life and high reliability.

Description

Hollow cathode sealing structure of electric propulsion system and inspection method of airtightness of hollow cathode

technical field

The present invention relates to the field of aerospace propulsion technology, in particular to a hollow cathode anti-poisoning multifunctional sealing structure design for aerospace electric propulsion systems, especially suitable for hollow cathodes used in Hall, ion, microwave and other electric propulsion systems, which can reduce hollow cathodes. The cathode reacts after being in contact with water and oxygen impurities in the environment, effectively prolonging the service life of the hollow cathode. In particular, it relates to a hollow cathode sealing structure of an electric propulsion system and a method for testing the airtightness of the hollow cathode.

Background technique

Compared with chemical propulsion, electric propulsion has a significant characteristic of higher specific impulse. All space powers regard electric propulsion technology as the key technology of future spacecraft, which can be widely used in spacecraft orbit transfer, orbit maintenance, attitude control, dragless control, deep space Missions such as exploration of main propulsion can provide significant savings in propellant, increase spacecraft life, or reduce delivery requirements.

Electric thrusters such as Hall, ion, microwave plasma, and field emission are the types of thrusters that are widely used in space and researched more. Their working principles are similar. They all ionize the propellant into ions first, and then accelerate the ions through a high-voltage electric field to eject them at high speed to generate a reaction force. The current is electrically neutral to avoid electrification of the spacecraft. The role of the hollow cathode is to provide high-energy particles and neutralize the ion plume for the ionization of the propellant. The interior of the hollow cathode uses high-temperature vacuum electron emission functional materials, which are easily polluted by harmful impurities such as water and oxygen in the environment. Exposure to the atmosphere for a long time will cause the emitter material to react with water and oxygen in the air, thereby degrading its performance. Severe cases may even lead to the failure of the projectile poisoning and the end of the life of the hollow cathode, which directly affects the life and reliability of the electric propulsion system and electric thruster.

During the satellite AIT stage, the assembly, final assembly and test last for several weeks or even months. The atmospheric environment in the final assembly plant is usually an atmosphere with a humidity range of 30% to 60%, and an oxygen content of about 21%. The hollow cathode has been exposed to this environment for a long time Under such conditions, it is very easy to cause poisoning of the emitter, the failure of the hollow cathode, and the inability of the electric propulsion system to work.

Hollow cathodes require high air tightness, and air leakage may cause ignition at abnormal parts and affect product insulation. The airtightness test shall be carried out during the delivery and acceptance of the product. During the airtightness test, it is required to seal the hollow cathode and be able to withstand a certain degree of positive pressure.

The long-term storage of hollow cathodes on the ground requires storage in a drying cabinet with a certain temperature and humidity. There are also strict temperature and humidity requirements during the circulation and ground inspection process, and the sensitivity of storage and transfer is low.

Therefore, there is an urgent need for a hollow cathode sealing structure that can not only make the hollow cathode meet the sealing requirements of the airtightness test, but also facilitate the hollow cathode to meet the requirements of ground moisture and moisture resistance during long-term storage on the ground.

Contents of the invention

In view of the deficiencies in the prior art, the object of the present invention is to provide a hollow cathode sealing structure of an electric propulsion system and a method for testing the airtightness of the hollow cathode.

A hollow cathode sealing structure for an electric propulsion system according to the present invention includes a hollow cathode casing and a compression cover, and the detachable cover of the compression cover is mounted on one end of the hollow cathode casing, and the hollow cathode casing The other end of the tube is provided with a pipe connection port, and the hollow cathode casing and the compression cover are connected to each other through a threaded structure.

Preferably, one end of the hollow cathode casing is provided with a top hole.

Preferably, the compression cover includes a cover body and a connection part, the connection part is circumferentially arranged on the cover body, the cover body is used to seal one end of the hollow cathode casing, and the connection part is used to connect the cover body with hollow cathode casing.

Preferably, the cover body is provided with a groove structure, the groove structure is arranged in a ring shape on the side of the cover body close to the hollow cathode casing, and the radius of the groove structure is larger than the radius of the top hole.

Preferably, a rubber gasket is further included, the rubber gasket is installed in the groove structure, and the thickness of the rubber gasket is greater than the depth of the groove structure.

Preferably, the hollow cathode casing is provided with a first thread, and the connecting part is provided with a second thread, and the first thread matches the second thread.

Preferably, the pressing cover, the groove structure, the hollow cathode casing and the top hole are coaxially arranged.

Preferably, the groove structure is any of the following:

rectangular slot;

Trapezoidal groove;

Dovetail groove;

semicircular groove.

Preferably, the compression cover is designed with a non-slip structure, which is convenient for the operator to manually tighten the compression cover.

The present invention also provides a method for testing the airtightness of the hollow cathode, which adopts the hollow cathode sealing structure of the electric propulsion system, and further includes the following steps:

S1. Tighten the compression cover with the rubber gasket installed to the hollow cathode casing to realize the sealing of the hollow cathode;

S2. Put the hollow cathode into the vacuum tank, and connect the pipe connection port of the hollow cathode shell with the helium-filled pipeline of the helium mass spectrometer leak detector through the vacuum tank body;

The end of the helium-filled pipeline of the helium mass spectrometer leak detector is connected to a helium source, and the gas distribution platform is installed on the helium-filled pipeline, and is located between the pipeline connection port and the helium source;

The inner space of the vacuum tank is connected with the vacuum pump and the vacuum valve through the vacuum tank vacuum pipeline;

S3, vacuumize the inside of the vacuum tank through a vacuum pump and a vacuum valve;

S4. Fill helium at a specified pressure into the inspected hollow cathode through the helium source and gas distribution platform, and read the leak rate of the inspected hollow cathode through the helium mass spectrometer leak detector.

Compared with the prior art, the present invention has the following beneficial effects:

1. Through the detachable design of the compression cover, the present invention can seal and protect the hollow cathode, avoid the reaction of the emitter with water and oxygen in the ambient atmosphere, play an anti-poisoning role, and at the same time prevent dust and excess, and can Prolonging the life of the hollow cathode is conducive to realizing the long life and high reliability of the electric propulsion system.

2. The present invention can be used in the process of ground storage, transfer and inspection of aerospace electric propulsion systems to reduce the contact with ambient gas and reduce the difficulty of storage.

3. The present invention can be used for air tightness inspection of hollow cathodes in the ground inspection stage.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is a schematic diagram of the structure of the present invention when it can be used in the satellite AIT stage.

Fig. 3 is a schematic diagram of applying helium by the helium mass spectrometry pressure vacuum leak detection method when the airtightness test of the hollow cathode is carried out in the present invention.

Fig. 4 is a schematic structural view of the present invention in the stage of storage, circulation or inspection and testing of ground components.

Fig. 5 is a structural schematic view of the present invention when the groove structure of the compression cover is a rectangular groove.

Fig. 6 is a structural schematic diagram of the present invention when the groove structure of the compression cover is a trapezoidal groove.

Fig. 7 is a schematic structural view of the rubber gasket in the present invention.

The figure shows:

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

The present invention provides a hollow cathode sealing structure for an electric propulsion system, as shown in FIG. One end of the hollow cathode casing 3 is provided with a pipe connection port 105 on the other end of the hollow cathode casing 3 , and the hollow cathode casing 3 and the compression cover 1 are connected to each other through a threaded structure 5 .

One end of the hollow cathode casing 3 is provided with a top hole 4 .

The compression cover 1 includes a cover body 101 and a connecting portion 102, the connecting portion 102 is circumferentially arranged on the cover body 101, the cover body 101 is used to seal one end of the hollow cathode casing 3, and the connecting portion 102 Used to connect the cover body 101 and the hollow cathode casing 3 . In a preferred example, the hollow cathode casing 3 is provided with a first thread, and the connecting portion 102 is provided with a second thread, and the first thread matches the second thread. Preferably, the first thread One thread is an external thread, and the second thread is an internal thread. In a preferred example, the cover body 101 is integrally connected with the connecting portion 102 .

The cover body 101 is provided with a groove structure, as shown in FIG. 5 and FIG. 6 , the groove structure is any one of the following: rectangular grooves; trapezoidal grooves; dovetail grooves; semicircular grooves. The groove structure is arranged in a ring shape on the side of the cover body 101 close to the hollow cathode casing 3, and the radius of the groove structure is larger than the radius of the top hole 4, specifically, in the ring groove, the radius of the ring is greater than the radius of the top hole 4 . As shown in Figure 7, Figure 7 is a schematic structural view of the rubber gasket 2, the rubber gasket 2 is installed in the groove structure, and the thickness of the rubber gasket 2 is greater than the depth of the groove structure, in addition , the cross-sectional area of the groove structure is slightly larger than the cross-sectional area of the rubber sealing ring 2. The rubber gasket 2 preferably selects a trapezoidal groove, which is convenient for sealing and fixing, and the sealing ring is not easy to run out of the groove, so it is easy to install.

The pressing cover 1, the groove structure, the hollow cathode casing 3 and the top hole 4 are coaxially arranged.

In a preferred example, the hollow cathode casing 3 is a holding electrode casing, and the compression cover 1 is designed with a non-slip structure, which is convenient for the operator to tighten the compression cover 1 manually, and the anti-slip structure is a knurled structure.

When in use, the rubber gasket 2 corresponds to the outside of the top hole 4, and the rubber gasket 2 is compressed by tightening the first thread and the second thread, so that the interior of the hollow cathode casing 3 is airtightly isolated from the external environment, and plays a sealing role.

As shown in Figure 2, the present invention can be used in the satellite AIT stage. By using the present invention, the reaction between the hollow cathode and the water and oxygen in the ambient atmosphere can be avoided, and at the same time, it can prevent dust. Specifically, in the hollow cathode shell The pipe connection port 105 of the body 3 is connected to a pipe, and the two ends of the pipe are respectively provided with a discharge valve 103 and an air intake valve 104. Inert gas is filled after vacuuming or replacement through the adding and discharging valve 103, thereby isolating the atmosphere in the assembly plant, preventing the emitter from reacting with water and oxygen in the ambient atmosphere, and at the same time playing a dustproof role.

As shown in Fig. 3, the present invention can be used in the airtightness test of the hollow cathode. Due to the high air tightness requirements of the hollow cathode, air leakage may cause ignition at abnormal parts and affect the insulation of the product. Therefore, air tightness inspection is required during the delivery or acceptance inspection of the hollow cathode assembly. Helium mass spectrometry is usually used for leak detection, specifically including various helium mass spectrometry leak detection methods such as jet leak detection, helium cover leak detection, and pressure vacuum leak detection, all of which require the hollow cathode to be sealed. The total leak rate of the tested hollow cathode product, and the leak detection process is closer to the actual working pressure of the hollow cathode.

Taking the helium mass spectrometry pressure vacuum leak detection method as an example, the present invention also provides a hollow cathode airtightness inspection method, which adopts the hollow cathode sealing structure of the electric propulsion system, and further includes the following steps:

S1. Tighten the compression cover 1 with the rubber gasket 2 installed on the hollow cathode casing 3 to realize the sealing of the hollow cathode;

As shown in Figure 3, S2, put the hollow cathode into the inside of the vacuum tank 16, pass the pipeline connection port 6 of the hollow cathode housing 3 and the helium-filled pipeline 7 of the helium mass spectrometer leak detector through the vacuum tank The body is connected inside and outside; wherein, the end of the helium-filled pipeline 7 of the helium mass spectrometer leak detector is connected with a helium source 9, and the gas distribution platform 10 is installed on the helium-filled pipeline 7, and is located between the pipeline connection port 6 and the Between the helium source 9; the inner space of the vacuum tank 16 is connected with the vacuum pump 12 and the vacuum valve 11 through the vacuum tank evacuation pipeline 8;

S3, vacuumize the vacuum tank by the vacuum pump 12 and the vacuum valve 11;

S4. After the leak detection system enters the leak detection state, and completes the effective minimum detectable leak rate test and the reaction time test of the system, fill the hollow cathode with specified pressure helium gas through the helium gas source 9 and the gas distribution platform 10 , through the helium mass spectrometer leak detector to display and read the leak rate of the tested hollow cathode.

As shown in Figure 4, the present invention can be used in the storage, circulation or inspection and testing stages of ground components, specifically, it also includes an outer casing nut 13, a spherical joint 14, and a blocking cover 15; the air inlet pipe 6 is connected to the pipe connection port 105 connection, the outer sleeve nut 13 is sleeved on the intake pipe 6; one end of the ball joint 14 is spherical, and the other end is welded on the end of the intake pipe 6. The plugging cap 15 has an external thread at one end and a closed end at the other end, and the threaded end of the plugging cap 15 is threadedly connected with the outer nut 13 . In the stage of storage, circulation or inspection and testing of ground components, the compression cover, rubber gasket, and hollow cathode casing 3 work together to seal and protect the downstream of the hollow cathode, and the outer casing nut, ball joint, and blocking cover work together to seal and protect the upstream of the hollow cathode , play a certain waterproof oxygen, dustproof effect.

The invention has a simple and reliable structure, can seal and protect the hollow cathode without changing the interface and function, is easy to use, and can seal and protect the hollow cathode. This structure can seal the hollow cathode, reduce contact with ambient gas, and reduce the risk of projectile poisoning during the satellite assembly process. At the same time, it can be used as an airtight inspection tool, and can also reduce the difficulty of daily storage and operation, effectively extending the life of the hollow cathode. Improve system reliability.

In the satellite AIT stage, the present invention seals and protects the hollow cathode, vacuumizes or replaces the hollow cathode with an exhaust valve upstream of the hollow cathode, and then fills it with inert gas, thereby isolating the atmosphere in the assembly plant and avoiding the water in the emitter and the ambient atmosphere. , Oxygen reacts, and at the same time plays a dustproof role. The invention can prevent dust and reduce contact with the atmosphere in the ground inspection stage; especially in the air tightness inspection, the structure can seal the hollow cathode and perform helium mass spectrometry leak detection. The present invention can prevent dust and reduce contact with the atmosphere during ground storage and transfer stages.

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", The orientation or positional relationship indicated by "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, rather than indicating or implying the referred device Or elements must have a certain orientation, be constructed and operate in a certain orientation, and thus should not be construed as limiting the application.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims (10)

1. The utility model provides an electric propulsion system hollow cathode seal structure, its characterized in that includes hollow cathode casing (3), compresses tightly lid (1), compress tightly lid (1) detachable lid dress and be in hollow cathode casing (3) one end, be provided with pipeline connector (105) on the other end of hollow cathode casing (3), hollow cathode casing (3) and compress tightly lid (1) through helicitic texture (5) interconnect.

2. An electric propulsion system hollow cathode sealing structure according to claim 1, characterized in that one end of the hollow cathode housing (3) is provided with a top hole (4).

3. An electric propulsion system hollow cathode sealing structure according to claim 2, characterized in that the hold-down cap (1) comprises a cap body (101) and a connecting portion (102), the connecting portion (102) being circumferentially arranged on the cap body (101), the cap body (101) being adapted to seal one end of the hollow cathode casing (3), the connecting portion (102) being adapted to connect the cap body (101) with the hollow cathode casing (3).

4. An electric propulsion system hollow cathode sealing structure according to claim 3, characterized in that the cover body (101) is provided with a groove structure, the groove structure is annularly arranged on one side of the cover body (101) close to the hollow cathode shell (3), and the radius of the groove structure is larger than that of the top hole (4).

5. An electric propulsion system hollow cathode sealing structure according to claim 4, characterized in that it further comprises a rubber gasket (2), said rubber gasket (2) being mounted within said groove structure, and the thickness of said rubber gasket (2) being greater than the depth of said groove structure.

6. An electric propulsion system hollow cathode sealing structure according to claim 1, characterized in that the hollow cathode housing (3) is provided with a first thread and the connection portion (102) is provided with a second thread, the first thread matching the second thread.

7. An electric propulsion system hollow cathode sealing structure according to claim 4, characterized in that the hold-down cap (1), the groove structure, the hollow cathode housing (3) and the top aperture (4) are coaxially arranged.

8. An electric propulsion system hollow cathode sealing structure according to claim 1, characterized in that the groove structure is any one of the following:

a rectangular groove;

a trapezoidal groove;

a dovetail groove;

a semicircular groove.

9. The electric propulsion system hollow cathode sealing structure according to claim 1, characterized in that the compressing cover (1) is designed with an anti-slip structure to facilitate manual tightening of the compressing cover (1) by an operator.

10. A method for testing the air tightness of a hollow cathode, which is characterized in that the hollow cathode sealing structure of the electric propulsion system according to any one of claims 1 to 9 is adopted, and the method further comprises the following steps:

s1, screwing a compression cover (1) provided with a rubber gasket (2) to a hollow cathode shell (3) to seal the hollow cathode;

s2, placing the hollow cathode into a vacuum tank (16), and connecting a pipeline connecting port (6) of a hollow cathode shell (3) with a helium filling pipeline (7) of the helium mass spectrometer leak detector inside and outside through a vacuum tank body;

the end part of a helium filling pipeline (7) of the helium mass spectrometer leak detector is connected with a helium source (9), and a gas distribution table (10) is arranged on the helium filling pipeline (7) and is positioned between a pipeline connecting port (6) and the helium source (9);

the inner space of the vacuum tank (16) is connected with a vacuum pump (12) and a vacuum valve (11) through a vacuum tank vacuum-pumping pipeline (8);

s3, vacuumizing the vacuum tank through a vacuum pump (12) and a vacuumizing valve (11);

and S4, filling helium gas with specified pressure into the hollow cathode to be detected through a helium gas source (9) and a gas distribution table (10), and displaying and reading the leakage rate condition of the hollow cathode to be detected through a helium mass spectrometer leak detector.

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