A coaxial type pulse plasma thruster with a magnet as an outer electrode

Abstract

The application discloses a coaxial pulse plasma thruster with a magnet as an outer electrode, and belongs to the technical field of microsatellite aerospace propulsion. The coaxial pulse plasma thruster with a magnet as an outer electrode mainly comprises an anode, a magnet cathode, a metal cathode, a propellant, an insulating outer shell, an insulating base, a supply spring and a spark plug. The metal cathode is divided into a perforated metal cathode and a non-perforated metal cathode. The thruster is coaxial in shape; the inner electrode is a solid cylinder, the outer electrode is a hollow pipe with a circular cross section, the solid propellant is located between the inner and outer electrodes, the supply spring is arranged between the tail of the propellant and the insulating base, and the outer electrode adopts segmented magnets and metal as the cathode. The application utilizes the magnetic field to restrict the radial movement of plasma so as to improve the collision ionization level, and provides Lorentz force to better accelerate the plasma. The segmented magnetic field provided by the segmented magnets with different magnetic poles opposite to each other can provide the magnetic field while reducing the overall mass of the thruster, and is beneficial to adjusting the magnetic field distribution in the thruster pipeline.

Description

TECHNICAL FIELD

[0001] The present application relates to a coaxial pulse plasma thruster with a magnet as an outer electrode, and belongs to the technical field of microsatellite space propulsion. BACKGROUND

[0002] Since the end of last century, the development of microsatellites and the development of electric propulsion technology have kept pace with each other. In the past decade, micro-nano satellites have become a hot research topic at home and abroad due to their small size, high integration, low power consumption, and low cost. Through cooperative control between satellites, multiple micro-nano satellites can form a satellite constellation to replace traditional large spacecraft to perform space missions, and even have better performance. The propulsion system of micro-nano satellites needs to have the characteristics of small weight, low power consumption, long service life, and accurate thrust due to the limitations of the design requirements of micro-nano satellites themselves and the needs of the task. Traditional propulsion equipment is difficult to meet the above requirements. The pulse plasma thruster in the electric propulsion system has high specific impulse, low thrust, and low power, and has the characteristics of flexible control and compact size, which can meet the needs of micro-nano satellites for propulsion systems. As the first electric propulsion system applied to spacecraft control, the pulse plasma thruster has been widely used. However, with the development of electric propulsion technology, the low propulsion efficiency and low thrust level of traditional pulse plasma thrusters have become increasingly prominent. SUMMARY

[0003] The present application discloses a coaxial pulse plasma thruster with a magnet as an outer electrode, which mainly solves the technical problem of improving the thrust performance of the coaxial pulse plasma thruster. By using a magnet as an outer electrode while providing an external magnetic field, the specific impulse of the coaxial pulse plasma thruster can be greatly improved without increasing the size, and the thrust performance can be enhanced. By using a segmented magnet and a metal such as aluminum alloy to form an outer electrode, the effective magnetic field can be provided while reducing the overall mass of the thruster, which is beneficial to adjusting the magnetic field distribution in the thrust duct and optimizing the thrust performance, and the combination scheme can be flexibly selected according to actual needs.

[0004] The purpose of the present application is achieved by the following technical scheme.

[0005] The coaxial pulse plasma thruster with a magnet as an outer electrode disclosed by the present application mainly comprises an anode, a magnet cathode, a metal cathode, a propellant, an insulating outer shell, an insulating base, a supply spring, and a spark plug. The anode is the inner electrode, and the cathode is the outer electrode. The metal cathode is divided into a perforated metal cathode and a non-perforated metal cathode, wherein the perforated metal cathode is used to install the spark plug. The magnet cathode and the metal cathode jointly form the cathode. The anode and the cathode are collectively referred to as the electrode.

[0006] The thruster is coaxial as a whole; the inner electrode is a solid cylinder, and the outer electrode is a hollow pipe with a circular cross-section, and has a threaded hole on the side surface for installing the spark plug; the spark plug is the ignition starting device of the thruster; the solid propellant is located between the inner and outer electrodes, and has a hole; the inner side of the solid propellant is matched with the outer side of the cylindrical surface of the inner electrode, and the outer side is matched with the inner side of the cylindrical surface of the outer electrode; a supply spring is arranged between the tail of the propellant and the insulating base, and is used for continuously applying force to the tail of the propellant, so that the propellant can be timely supplemented to the spark plug; the bottom center of the insulating base has a through hole, through which the inner electrode is installed; the outer electrode of the magnet is directly installed on the outer shell; the outer shell plays a role of isolating the magnet, the outer electrode and the outside; the electrodes are provided with voltage by the energy storage capacitor, and the ignition circuit of the spark plug and the charging circuit of the electrodes are independent of each other.

[0007] The outer electrode adopts a magnet as the outer electrode, which can improve the specific impulse, specific impulse, efficiency and other performances of the coaxial pulse plasma thruster without consuming additional energy; the magnet field is used to constrain the radial motion of the plasma to improve the collision ionization level, and can provide additional Lorentz force to the plasma to better accelerate the plasma, which is beneficial to improve the performance of the coaxial pulse plasma thruster.

[0008] The outer electrode adopts a magnet as the outer electrode, which is different from the coaxial pulse plasma thruster with a permanent magnet outside the ordinary electrode; the magnet electrode is lighter in weight, that is, the structure is simplified under the condition that the magnetic field strength between the electrodes is constant, and the thruster is lighter in weight, which is beneficial to the optimization of the magnetic field to improve the thrust performance.

[0009] The outer electrode adopts a segmented magnet, which is different from the coaxial pulse plasma thruster with a whole magnet as the outer electrode; the segmented magnetic field provided by the segmented magnet with different magnetic poles opposite to each other can provide effective magnetic field while reducing the overall mass of the thruster, which is beneficial to adjust the magnetic field distribution in the thrust pipe and realize the optimization of the thrust performance; and it can flexibly adjust the number of magnets according to the task requirements to adapt to the requirements of different satellites on the performance and mass of the thruster.

[0010] The working method of the coaxial pulse plasma thruster with magnets as electrodes provided by the application is as follows: the energy storage capacitor providing voltage for the electrodes is charged, and the spark plug is connected with the ignition circuit; there is a potential difference between the anode and the cathode, but the potential difference cannot be conducted and the anode cannot be self-broken in the vacuum condition; the spark plug is ignited to generate a small amount of charged particles; the generated charged particles are dispersed between the electrodes to make the electrodes conductive to generate a large current and discharge; the discharge ablates the surface of the propellant to generate neutral gas, and under the action of the high voltage between the electrodes, part of the neutral gas is ionized into a plasma cloud; the generated plasma cloud leaves the surface of the propellant and is accelerated to be sprayed along the axis under the joint action of the electric field and the self-induced electric field between the electrodes until the plasma cloud is sprayed out of the rear edge of the thruster to generate a pulse thrust; in addition, the plasma cloud can obtain additional force when passing through the magnetic field formed by the segmented magnets, so that the plasma cloud is sprayed out at a greater speed; due to the constraint of the magnetic field on the radial movement of the plasma, the plume diffusion is reduced, and the thruster can realize better ionization and improve the overall thrust performance of the thruster.

[0011] Advantages:

[0012] 1. Compared with the traditional coaxial pulse plasma thruster without a magnetic field, the coaxial pulse plasma thruster with magnets as electrodes provided by the application improves the specific impulse, specific impulse, efficiency and other performances of the coaxial pulse plasma thruster without consuming additional energy; and the magnetic field can constrain the radial movement of the plasma, reduce the plume diffusion and improve the thrust performance of the thruster.

[0013] 2. Compared with the coaxial pulse plasma thruster with an external permanent magnet, the coaxial pulse plasma thruster with magnets as electrodes provided by the application is lighter; under the condition that the overall weight of the thruster is constant, the rationality of the weight distribution is improved, and the space is saved.

[0014] 3. Compared with the coaxial pulse plasma thruster with a whole magnet as an electrode, the coaxial pulse plasma thruster with magnets as electrodes provided by the application adopts segmented magnets and aluminum alloy to jointly form the electrode, which is different from the magnetic field distribution provided by the whole magnet, and the magnetic field provided by the segmented magnet is conducive to adjusting the magnetic field distribution inside the pipeline, can better constrain the radial movement of the plasma, improve the overall acceleration efficiency of the thruster, and greatly improve the efficiency of the thruster.

[0015] 4. The coaxial pulse plasma thruster with magnets as electrodes provided by the application is suitable for space application occasions of microsatellites, meets the needs of power consumption, volume, weight, thrust and efficiency level, can be used as the main propelling device and auxiliary thrust device of the microsatellite, and can be applied to attitude control, orbit transfer, position keeping and other tasks. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1Structure diagram of coaxial pulse plasma thruster with magnet electrode;

[0017] Figure 2 Structure diagram of coaxial pulse plasma thruster with magnet electrode;

[0018] Figure 3 Structure diagram of coaxial pulse plasma thruster with magnet electrode;

[0019] Wherein: 1-anode, 2-insulating base, 3-propellant, 4-magnet cathode, 5-porous metal cathode, 6-non-porous metal cathode, 7-insulating outer shell, 8-spark plug, 9-feeding spring. DETAILED DESCRIPTION

[0020] In order to better illustrate the purposes and advantages of the present application, the application is further described below in conjunction with the drawings and examples.

[0021] Example 1:

[0022] The coaxial pulse plasma thruster with magnet electrode disclosed in the present embodiment is mainly composed of metal cathode 5, 6, anode 1, magnet cathode 4, propellant 3, insulating outer shell 7, insulating base 2, feeding spring 9 and spark plug 8.

[0023] The thruster is coaxial in whole; the electrodes function to ablate the propellant and accelerate the charged particles generated thereby; the electrodes are composed of anode 1, 4-section magnet 4, 1-section porous metal cathode 5 and 2-section non-porous metal cathode 6, the anode 1 being a brass rod with a diameter of 3 mm and a length of 152 mm; the single-section cathodes 5, 6 are hollow tubes with a circular cross section, with an inner diameter of 29 mm, an outer diameter of 37 mm and a length of 8 mm, and are made of aluminum alloy, wherein the cathode 5 has a threaded hole on the outer side for mounting the spark plug 8; the spark plug 8 is a thruster ignition starting device; the single-section magnet 4 is a circular tube with the same inner and outer diameters as the cathode, with a length of 25 mm and made of sintered neodymium iron boron magnet; the insulating base 2 is made of insulating plastic, with a through hole with a diameter of 3 mm in the center of the bottom, through which the anode 1 is mounted; the propellant 3 is located between the anode and the cathode, and is a porous cylinder with an inner diameter of 3 mm, an outer diameter of 29 mm and a length of 35 mm, and is made of polytetrafluoroethylene; there is a feeding spring 9 between the tail of the propellant 3 and the insulating base 1, which functions to apply a continuous force to the tail of the propellant 3 so as to replenish it to the spark plug 8 in time; the cathodes 5 and 6, the magnet 4 and the spark plug 8 are directly mounted on the insulating outer shell 7; the outer shell 7 has a thickness of 2 mm and a total length of 146 mm, and functions to isolate the outer electrode of the thruster from the outside; the electrodes are provided with voltage by an energy storage capacitor, and the ignition circuit of the spark plug 8 is independent of the electrode charging circuit.

[0024] Since the outer electrode is composed of the segmented magnet 4 and the cathode 5, 6, it can provide greater thrust without consuming extra energy.

[0025] Since the outer electrode is composed of the segmented magnet 4 and the cathode 5, 6, unlike the traditional coaxial pulse plasma thruster which needs to increase the mass of the magnet on the basis of the traditional outer electrode, causing the weight distribution of the thruster to be tense, the neodymium iron boron magnet and the aluminum alloy ring are used to jointly compose the outer electrode, which can ensure effective discharge and provide a magnetic field to constrain the radial movement of the plasma, thereby optimizing the ionization performance of the thruster and improving the overall propulsion efficiency of the thruster.

[0026] Since the magnet 4 of the outer electrode is segmented, compared with the coaxial pulse plasma thruster composed of a whole magnet electrode, the segmented magnetic field is used to replace the whole magnetic field, which can provide an effective magnetic field while reducing the overall mass of the thruster, is conducive to adjusting the magnetic field distribution in the thrust pipeline, and realizes the optimization of the thrust performance; and the number of magnets can be flexibly adjusted according to the task requirements to adapt to the requirements of different satellites on the performance and mass of the thruster.

[0027] The working method of the pulse plasma thruster with a magnet as an electrode disclosed in the embodiment is as follows: first, the energy storage capacitor providing voltage for the electrode is charged, and the spark plug 8 is connected with the ignition circuit; there is a potential difference between the electrodes, but it cannot be conducted under vacuum conditions and cannot be self-breakdown; the spark plug is controlled to ignite, and a small amount of charged particles are generated; the generated charged particles are dispersed between the electrodes, so that the electrodes are conducted to generate a large current and discharge; the discharge ablates the surface of the propellant 3, generates neutral gas, and under the action of the high voltage between the electrodes, part of the neutral gas is ionized into a plasma cloud; the generated plasma cloud leaves the surface of the propellant 3, and under the joint action of the electric field and the self-induced electric field between the electrodes, accelerates along the axis and is sprayed out until the rear edge of the thruster, generating a pulse thrust; in addition, the plasma group can obtain additional force when passing through the magnetic field formed by the segmented magnet 4, so as to be sprayed out at a greater speed; since the magnetic field constrains the radial movement of the plasma, the thruster can realize better ionization and improve the overall thrust performance of the thruster.

[0028] Embodiment 2:

[0029] The coaxial pulse plasma thruster with a magnet as an electrode disclosed in the embodiment is mainly composed of a holed metal cathode 5, an anode 1, a magnet cathode 4, a propellant 3, an insulating outer shell 7, an insulating base 2, a supply spring 9 and a spark plug 8.

[0030] The thruster is coaxial in whole; the electrode functions to ablate the propellant and accelerate the charged particles generated by the propellant; the electrode is composed of an anode 1, two section magnets 4 and a cathode 5; the anode 1 is a metal cathode with a diameter of 3 mm and a length of 86 mm; the cathode 5 is a hollow tube with a circular ring cross section, with an inner diameter of 29 mm, an outer diameter of 37 mm, a length of 8 mm and made of aluminum alloy, and has a threaded through hole on the outer side for mounting a spark plug 8; the spark plug 8 is a thruster ignition starting device; the magnet 4 is a circular tube with the same inner and outer diameters as the cathode, with a length of 25 mm and made of sintered Nd-Fe-B magnet; the insulating base 2 is made of insulating plastic, with a through hole with a diameter of 3 mm in the center of the bottom for mounting the anode 1; the propellant 3 is located between the anode and the cathode, and is a perforated cylinder with an inner diameter of 3 mm, an outer diameter of 29 mm, a length of 35 mm and made of polytetrafluoroethylene; there is a supply spring 9 between the tail of the propellant 3 and the insulating base 1, which functions to apply a continuous force to the tail of the propellant 3 to replenish it to the spark plug 8 in time; the cathode 5, the magnet 4 and the spark plug 8 are directly mounted on the insulating outer shell 7; the outer shell 7 has a thickness of 2 mm and a total length of 80 mm, and can isolate the magnet 4 and the electrode of the thruster from the outside; the electrode is provided with voltage by an energy storage capacitor, and the ignition circuit of the spark plug 8 is independent of the charging circuit of the electrode.

[0031] The outer electrode is composed of the section magnet 4 and the cathode 5, which can provide greater thrust without consuming additional energy.

[0032] The outer electrode is composed of the section magnet 4 and the cathode 5, which is different from the traditional coaxial pulse plasma thruster that needs to increase the mass of the magnet on the traditional outer electrode, causing the weight distribution of the thruster to be tight. The Nd-Fe-B magnet and the aluminum alloy ring are used to compose the outer electrode, which can provide a magnetic field to constrain the radial movement of the plasma while ensuring effective discharge, thereby optimizing the ionization performance of the thruster and improving the overall propulsion efficiency of the thruster.

[0033] The magnet 4 of the outer electrode is segmented, which can replace the whole magnet with a segmented magnetic field to provide an effective magnetic field while reducing the overall mass of the thruster, which is conducive to adjusting the magnetic field distribution in the thrust pipe and optimizing the thrust performance. Moreover, the number of magnets can be flexibly adjusted according to the task requirements to adapt to different satellite requirements for the performance and mass of the thruster.

[0034] The working method of the pulse plasma thruster with the magnet as the electrode disclosed by the embodiment is as follows: firstly, the energy storage capacitor providing voltage for the electrode is charged, and the spark plug 8 is connected with the ignition circuit; there is a potential difference between the electrodes, but it cannot be conducted and cannot be self-breakdown under the vacuum condition; the spark plug is controlled to ignite, and a small amount of charged particles are generated; the generated charged particles are dispersed between the electrodes, so that the electrodes are conducted to generate a large current and discharge; the discharge ablates the surface of the propellant, generates neutral gas, and under the action of the high voltage between the electrodes, part of the neutral gas is ionized into a plasma cloud; the generated plasma cloud leaves the surface of the propellant 3, and under the joint action of the electric field and the self-induced electric field between the electrodes, accelerates along the axis and is sprayed out until the rear edge of the thruster, so as to generate a pulse thrust; in addition, when the plasma cloud passes through the magnetic field formed by the segmented magnet 4, it can obtain additional force and be sprayed out at a greater speed; due to the constraint of the magnetic field on the radial movement of the plasma, the plume diffusion is reduced, the thruster can realize better ionization, and the overall thrust performance of the thruster is improved.

[0035] The above specific description further details the purpose, technical scheme and beneficial effects of the application, and it should be understood that the above description is only a specific embodiment of the application and is not used to limit the protection scope of the application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A coaxial pulsed plasma thruster using magnets as external electrodes, characterized in that: It mainly consists of an anode, a cathode, propellant, an insulating outer shell, an insulating base, a supply spring, and a spark plug; the anode is the inner electrode, and the cathode is the outer electrode; the cathode is composed of a magnetic cathode and a metal cathode; the anode, magnet, and metal cathode form the electrode; the metal cathode is divided into perforated metal cathode and non-perforated metal cathode, among which the perforated metal cathode is used to install the spark plug; The thruster is coaxial in shape; the inner electrode is a solid cylinder, and the outer electrode is a hollow tube with a circular cross-section, and has a threaded through hole on its side for installing a spark plug; the spark plug is the thruster's ignition and starting device; the solid propellant is located between the inner and outer electrodes and is a perforated cylindrical tube; the inner dimensions of the solid propellant mate with the outer cylindrical surface of the inner electrode, and the outer dimensions mate with the inner cylindrical surface of the outer electrode; a supply spring is placed between the propellant tail and the insulating base, which continuously applies force to the propellant tail to ensure timely replenishment of propellant to the spark plug; the insulating base has a through hole at the center of its bottom, through which the inner electrode is installed; the magnet's outer electrode and the spark plug are directly mounted on the outer housing; the outer housing isolates the magnet, outer electrode, and external environment; the electrodes are powered by an energy storage capacitor, and the spark plug ignition circuit and electrode charging circuit are independent of each other.

2. The coaxial pulsed plasma thruster with a magnet as the external electrode as described in claim 1, characterized in that: The external electrode uses a magnet as the magnetic cathode; the external electrode uses segmented magnets, and the segmented magnetic field provided by the segmented magnets with different magnetic poles opposite each other can reduce the overall mass of the thruster while providing an effective magnetic field, which is beneficial to adjusting the magnetic field distribution in the thrust pipe and optimizing the thrust performance.

3. A coaxial pulsed plasma thruster with a magnet as the external electrode as described in claim 2, characterized in that: The number of magnets can be flexibly adjusted according to mission requirements to meet the thruster performance and quality requirements of different satellites.

4. A coaxial pulsed plasma thruster with a magnet as the external electrode as described in claim 1, 2, or 3, characterized in that: The energy storage capacitor that provides voltage to the electrodes is charged, connecting the spark plug to the ignition circuit; there is a potential difference between the anode and cathode, but they cannot conduct under vacuum conditions and cannot break down on their own; the spark plug is controlled to ignite, generating a small number of charged particles; the generated charged particles are dispersed between the electrodes, causing the electrodes to conduct and generate a large current for discharge; the discharge ablates the surface of the propellant, generating neutral gas, and under the action of high voltage between the electrodes, part of the neutral gas is ionized into a plasma cloud; The generated plasma cloud leaves the propellant surface and is accelerated along the axis by the combined action of the electric field between the electrodes and the self-induced electric field until it is ejected from the trailing edge of the thruster, generating pulse thrust. Furthermore, when the plasma plume passes through the magnetic field formed by the segmented magnets, it can gain additional force and be ejected at a greater speed. Due to the constraint of the radial motion of the plasma by the magnetic field, the plume diffusion is reduced, the thruster can achieve better ionization and improve the overall thrust performance of the thruster.

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