A radio frequency ion thruster based on ICP internal coupling discharge

Abstract

The present invention relates to a radio frequency ion thruster based on ICP internal coupling discharge, and belongs to the field of plasma propulsion technology. A spiral coil coated with a protective film is placed in an ionization chamber, and the center line of the spiral coil is coaxial with the center line of the ionization chamber, and the distance from the center line of the spiral coil to the inner wall of the ionization chamber is the same as the diameter of the spiral coil, which can reduce the distance between the propulsion medium and the radio frequency antenna, improve the induced electric field distribution in the ionization chamber, effectively increase the ionization density, and improve the problem of uneven plasma distribution, thereby improving the ionization degree of the existing radio frequency ion thruster and improving the thruster performance.

Description

Technical Field

[0001] The present invention relates to the field of plasma propulsion technology, and in particular to a radio frequency ion thruster based on ICP internal coupling discharge. Background Art

[0002] As the "heart" of the spacecraft, the power system will need to meet the diverse and complex needs of space missions in the future. Compared with traditional cold gas propulsion and chemical propulsion, space electric propulsion can increase the payload of the spacecraft and effectively reduce the launch cost. As a type of electric propulsion thruster, radio frequency ion thrusters have become one of the research focuses due to their advantages such as high specific impulse and high efficiency, and have huge development and application potential.

[0003] The RF ion thruster uses an inductively coupled plasma (ICP) discharge method to feed energy into the propulsion medium in the ionization chamber through the RF antenna, causing it to ionize and generate plasma. Under the action of the optical system, the ions in the plasma are accelerated and ejected to form a beam, thereby generating thrust. The existing RF antenna is generally placed outside the ionization chamber wall, isolating the RF antenna from the plasma. In the ICP discharge mode, due to the electromagnetic induction excitation effect, the RF current generates an induced electric field when passing through the external RF antenna, thereby driving the propulsion medium to generate an induced current to maintain ionization. However, the intensity of the induced electric field will decay as the distance from the RF antenna increases, resulting in uneven distribution of the induced electric field in the ionization chamber. As a result, the ionization in the ionization chamber is strong near the RF antenna and weak near the center of the ionization chamber, resulting in uneven plasma distribution and low ionization density, which affects the performance and discharge stability of the RF ion thruster.

[0004] Based on this, there is an urgent need for a radio frequency ion thruster that can improve the distribution of the induced electric field in the ionization chamber and increase the ionization density. Summary of the invention

[0005] The purpose of the present invention is to provide a radio frequency ion thruster based on ICP internal coupled discharge, which can improve the induced electric field distribution in the ionization chamber and increase the ionization density, so as to solve the problems of weak ionization degree and uneven distribution of the induced electric field in the ionization chamber of the existing radio frequency ion thruster.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A radio frequency ion thruster based on ICP internal coupled discharge, the radio frequency ion thruster comprising an ionization chamber, a radio frequency current supply system, a radio frequency antenna and a propulsion medium located in the ionization chamber;

[0008] The radio frequency antenna comprises a spiral coil; the spiral coil is located in the ionization chamber and is electrically connected to the radio frequency current supply system; the center line of the spiral coil is coaxial with the center line of the ionization chamber, and the distance from the center line of the spiral coil to the inner wall of the ionization chamber is the same as the diameter of the spiral coil; the spiral coil is coated with a protective film; the protective film is used to prevent plasma from damaging the spiral coil;

[0009] The radio frequency current supply system is used to provide radio frequency current to the spiral coil; the spiral coil is used to generate an induced electric field under the action of the radio frequency current; the propulsion medium is used to generate an induced current driven by the induced electric field, ionize, and generate the plasma.

[0010] Optionally, the radio frequency current supply system includes a radio frequency source unit and a corresponding impedance matching network.

[0011] Optionally, the RF antenna also includes a first straight segment and a second straight segment; one end of the first straight segment is electrically connected to the RF current supply system, and the other end extends into the ionization chamber and is electrically connected to one end of the spiral coil; one end of the second straight segment is electrically connected to the RF current supply system, and the other end extends into the ionization chamber and is electrically connected to the other end of the spiral coil; the protective film is plated on part of the first straight segment and part of the second straight segment located in the ionization chamber.

[0012] Optionally, the RF ion thruster further includes a first seal and a second seal; the first seal is used to seal the connection between the first straight line segment and the ionization chamber; the second seal is used to seal the connection between the second straight line segment and the ionization chamber.

[0013] Optionally, the protective film is an alumina ceramic protective film or a zirconia ceramic protective film.

[0014] Optionally, the RF ion thruster also includes a propulsion fluid storage and supply system and an air intake pipeline; the propulsion fluid is stored in the propulsion fluid storage and supply system; the output end of the propulsion fluid storage and supply system is connected to one end of the air intake pipeline, and the other end of the air intake pipeline extends into the ionization chamber; the propulsion fluid storage and supply system is used to provide the propulsion fluid into the ionization chamber through the air intake pipeline.

[0015] Optionally, the radio frequency ion thruster further includes a diffusion nozzle; the diffusion nozzle is installed on one end of the air inlet pipeline located in the ionization chamber; the diffusion nozzle is used to uniformly spray the propulsion medium into the ionization chamber.

[0016] Optionally, the RF ion thruster further comprises an optical system and a DC source unit; the optical system is electrically connected to the DC source unit; the DC source unit is used to form an accelerating electric field in the optical system;

[0017] The optical system is installed at the outlet end of the side wall of the ionization chamber; the optical system is used to accelerate the ions in the plasma to be ejected under the action of the accelerating electric field to form a beam.

[0018] Optionally, the optical system includes a screen grid and an acceleration grid; the acceleration grid is arranged between the screen grid and the exit end.

[0019] Optionally, the RF ion thruster further includes a neutralizer; the neutralizer is used to emit electrons into the beam to make the beam electrically neutral.

[0020] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0021] The present invention is used to provide a radio frequency ion thruster based on ICP internal coupling discharge. A spiral coil coated with a protective film is placed in an ionization chamber, and the center line of the spiral coil is coaxial with the center line of the ionization chamber. The distance from the center line of the spiral coil to the inner wall of the ionization chamber is the same as the diameter of the spiral coil. A radio frequency current supply system is used to supply radio frequency current to the spiral coil. The spiral coil generates an induced electric field under the action of the radio frequency current. The propulsion medium generates an induced current under the drive of the induced electric field, and ionization occurs to generate plasma in the ionization chamber. The present invention reduces the distance between the propulsion medium and the radio frequency antenna by coating a protective film on the radio frequency antenna and installing the radio frequency antenna in the ionization chamber, improves the distribution of the induced electric field in the ionization chamber, effectively increases the ionization density, and improves the problem of uneven plasma distribution, thereby improving the ionization degree of the existing radio frequency ion thruster and improving the thruster performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is a schematic diagram of the structure of the radio frequency ion thruster provided in Example 1 of the present invention;

[0024] Figure 2 This is a schematic diagram of the connection between the radio frequency antenna and the protective film provided in Example 1 of the present invention.

[0025] Explanation of symbols:

[0026] 1-ionization chamber; 2-RF current supply system; 3-RF antenna; 4-helical coil; 5-protective film; 6-first straight line segment; 7-second straight line segment; 8-propulsion medium storage and supply system; 9-intake pipe; 10-diffusion nozzle; 11-optical system; 12-DC source unit; 13-neutralizer. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The purpose of the present invention is to provide a radio frequency ion thruster based on ICP internal coupled discharge, which can improve the induced electric field distribution in the ionization chamber and increase the ionization density, so as to solve the problems of weak ionization degree, uneven distribution of induced electric field in the ionization chamber and low plasma density in the existing radio frequency ion thruster.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Embodiment 1:

[0031] This embodiment is used to provide a radio frequency ion thruster based on ICP internal coupling discharge, such as Figure 1 and Figure 2 As shown, the radio frequency ion thruster includes an ionization chamber 1, a radio frequency current supply system 2, a radio frequency antenna 3, and a propulsion medium located in the ionization chamber 1.

[0032] The radio frequency antenna 3 can be a metal wire, and a material with low resistivity can be selected. The radio frequency antenna 3 includes a spiral coil 4, which is located in the ionization chamber 1 and is electrically connected to the radio frequency current supply system 2. The center line of the spiral coil 4 is coaxial with the center line of the ionization chamber 1, that is, the spiral coil 4 is installed inside the ionization chamber 1 and is coaxial with the ionization chamber 1, and the distance from the center line of the spiral coil 4 to the inner wall of the ionization chamber 1 is the same as the diameter of the spiral coil 4, that is, the distance from the outer wall of the spiral coil 4 to the center line of the ionization chamber 1 is the same as the distance from the inner wall of the ionization chamber 1, or the radius of the spiral coil 4 is the same as the distance from the outer wall of the spiral coil 4 to the inner wall of the ionization chamber 1. A protective film 5 is plated on the spiral coil 4, and the protective film 5 is used to prevent the plasma from damaging the spiral coil 4.

[0033] The protective film 5 of this embodiment can be a layer film that is resistant to ion sputtering, high temperature resistance and high strength, that is, the material of the protective film 5 can be a material that is resistant to ion sputtering, high temperature resistance and high strength, such as an alumina ceramic material or a zirconia ceramic material, and the protective film 5 can be an alumina ceramic protective film or a zirconia ceramic protective film. A layer of alumina ceramic protective film or a zirconia ceramic protective film that is resistant to ion sputtering, high temperature resistance and high strength is plated on the copper RF antenna 3, and the protective film 5 is used as an ionized dielectric window to prevent direct contact with plasma from causing damage to the RF antenna 3.

[0034] The RF current supply system 2 includes a RF source unit and a corresponding impedance matching network, and the RF current supply system 2 is used to provide RF current to the spiral coil 4. The spiral coil 4 is used to generate an induced electric field under the action of the RF current. The propulsion medium in the ionization chamber 1 is used to generate an induced current under the drive of the induced electric field, ionize, and generate plasma.

[0035] The RF antenna of a traditional RF ion thruster is installed on the outer wall of the ionization chamber, resulting in weak ionization intensity in the center of the ionization chamber. If the RF antenna can be placed inside the ionization chamber and the distance between the center of the ionization chamber and the RF antenna is shortened, the ionization intensity in the center of the ionization chamber can be enhanced. At the same time, the ionization intensity close to the inner wall of the ionization chamber is very large, which can ensure that the ionization intensity in the ionization chamber is roughly the same and the plasma density is evenly distributed. In order to achieve this goal, the present embodiment provides a radio frequency ion thruster based on ICP internal coupled discharge, a layer of material that is resistant to ion sputtering, high temperature and high strength is plated on the radio frequency antenna 3 to form a protective film 5, and the radio frequency antenna 3 is installed in the ionization chamber 1 of the radio frequency ion thruster, and the radio frequency current supply system 2 passes the radio frequency current into the radio frequency antenna 3. Under the action of the electromagnetic induction excitation effect, the radio frequency antenna 3 generates an induced electric field to drive the propulsion medium to generate an induced current to maintain ionization, thereby generating plasma in the ionization chamber 1, and at the same time, it can reduce the distance between the propulsion medium and the radio frequency antenna 3, enhance the central induced electric field strength in the ionization chamber 1, improve the induced electric field distribution in the ionization chamber 1, achieve more sufficient ionization, increase the ionization density, and improve the problem of uneven plasma distribution.

[0036] As an optional implementation, in order to realize the electrical connection between the RF current supply system 2 and the spiral coil 4, the RF antenna 3 of this embodiment further includes a first straight segment 6 and a second straight segment 7, one end of the first straight segment 6 is electrically connected to the RF current supply system 2, and the other end extends into the ionization chamber 1 and is electrically connected to one end of the spiral coil 4; one end of the second straight segment 7 is electrically connected to the RF current supply system 2, and the other end extends into the ionization chamber 1 and is electrically connected to the other end of the spiral coil 4, so that the RF current can be passed into the spiral coil 4 by using the first straight segment 6 and the second straight segment 7. At the same time, in order to prevent the plasma from damaging the first straight segment 6 and the second straight segment 7, a protective film 5 is plated on part of the first straight segment 6 and part of the second straight segment 7 located in the ionization chamber 1. Of course, in this embodiment, the protective film 5 can also be plated on both the first straight segment 6 and the second straight segment 7.

[0037] Since the first straight line segment 6 and the second straight line segment 7 need to extend into the ionization chamber 1, the present embodiment performs sealing treatment on the connection between the first straight line segment 6 and the wall of the ionization chamber 1 and the connection between the second straight line segment 7 and the wall of the ionization chamber 1 to prevent air leakage, thereby avoiding the influence of air leakage on the stability of ionization. Specifically, the radio frequency ion thruster further includes a first seal and a second seal, the first seal is used to seal the connection between the first straight line segment 6 and the ionization chamber 1, and the second seal is used to seal the connection between the second straight line segment 7 and the ionization chamber 1. The first seal and the second seal can be sealing rings, etc.

[0038] In order to provide the propulsion medium to the ionization chamber 1, the radio frequency ion thruster of this embodiment further includes a propulsion medium storage and supply system 8 and an air intake pipeline 9. The propulsion medium storage and supply system 8 stores the propulsion medium. The output end of the propulsion medium storage and supply system 8 is connected to one end of the air intake pipeline 9. The other end of the air intake pipeline 9 extends into the ionization chamber 1. The propulsion medium storage and supply system 8 is used to provide the propulsion medium to the ionization chamber 1 through the air intake pipeline 9. At the same time, in order to avoid air leakage, the connection between the air intake pipeline 9 and the ionization chamber 1 is sealed. Specifically, a third sealing member can be used to seal the connection between the air intake pipeline 9 and the ionization chamber 1 through the third sealing member.

[0039] In order to provide the propulsion medium to the ionization chamber 1 more evenly, the RF ion thruster of this embodiment further includes a diffusion nozzle 10, which is installed on one end of the air intake pipe 9 located in the ionization chamber 1, and is used to evenly spray the propulsion medium in the air intake pipe 9 into the ionization chamber 1.

[0040] As an optional implementation, the RF ion thruster of this embodiment further includes an optical system 11 and a DC source unit 12. The optical system 11 is electrically connected to the DC source unit 12. The DC source unit 12 is used to form an accelerating electric field in the optical system 11. The optical system 11 is installed at the outlet end of the side wall of the ionization chamber 1 and is sealed and insulated with the ionization chamber 1. The optical system 11 is used to accelerate the ions in the plasma to be ejected under the action of the accelerating electric field to form a beam.

[0041] Specifically, the optical system 11 of this embodiment includes a screen grid and an accelerating grid, and the accelerating grid is arranged between the screen grid and the exit end. The DC source unit 12 is electrically connected to the screen grid and the accelerating grid respectively to form an accelerating electric field between the screen grid and the accelerating grid. The plasma in the ionization chamber 1 diffuses to the screen grid. When passing through the screen grid, the screen grid will filter the electrons in the plasma, allowing the ions to pass through the screen grid. Under the action of the accelerating electric field, the ions are accelerated and ejected from the exit end of the ionization chamber 1 to form a beam and generate thrust.

[0042] The radio frequency ion thruster of this embodiment further includes a neutralizer 13, which is used to emit electrons into the beam to neutralize the ions and make the beam electrically neutral.

[0043] Based on the above structure, the working principle of the RF ion thruster of this embodiment is as follows: the RF antenna 3 coated with a protective film 5 is installed in the ionization chamber 1, and the RF antenna 3 is connected to the RF current supply system 2, the RF current supply system 2 supplies a RF current with a frequency of 13.56 MHz to the RF antenna 3, and at the same time, the propulsion medium storage and supply system 8 passes the propulsion medium into the air intake pipe 9 at a micro flow rate, and then the propulsion medium is uniformly passed into the ionization chamber 1 through the diffusion nozzle 10. Under the action of the electromagnetic induction excitation effect, the RF antenna 3 will generate an induced electric field. After the propulsion medium enters the induced electric field, the induced electric field will drive the propulsion medium to generate an induced current to generate ionization, so that the propulsion medium forms plasma, thereby generating plasma inside the ionization chamber 1. The optical system 11 is connected to the DC source unit 12 to form an accelerating electric field between the accelerating grid and the screen grid. The plasma diffuses to the vicinity of the first grid (i.e., the screen grid) of the optical system 11. The screen grid can filter the electrons in the plasma and allow the ions to pass through. The ions passing through are accelerated and ejected under the action of the accelerating electric field to form a beam and generate thrust. The neutralizer 13 emits electrons into the beam and neutralizes the ions in the beam, making the beam of the RF ion thruster electrically neutral. The range of micro flow rate is 1-5sccm, and sccm (Standard Cubic Centimeter per Minute) means standard milliliters per minute.

[0044] This embodiment provides a radio frequency ion thruster based on ICP internal coupling discharge to solve the problem that the ionization intensity in the existing radio frequency ion thruster becomes weaker as the distance between the radio frequency antenna 3 and the propulsion medium increases, resulting in low ionization density, and the plasma density is high near the wall of the ionization chamber 1, while the plasma density in the center of the ionization chamber 1 is low. A layer of material resistant to ion sputtering, high temperature and high strength is plated on the radio frequency antenna 3, and the radio frequency antenna 3 is installed in the ionization chamber 1. Without changing the radio frequency discharge condition, the distance between the propulsion medium and the radio frequency antenna 3 is reduced, the ionization degree of the existing radio frequency ion thruster is effectively enhanced, and the uneven distribution of plasma is improved, thereby improving the performance of the thruster. Compared with the prior art, this embodiment can effectively enhance the ionization degree of the existing radio frequency ion thruster. Without changing the radio frequency discharge condition, only the position of the radio frequency antenna 3 needs to be adjusted to achieve an increase in the plasma density in the ionization chamber 1 and a uniform distribution of plasma, while avoiding the problem of increasing the power of the radio frequency power supply and redesigning the radio frequency excitation circuit to achieve enhanced ionization.

[0045] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A radio frequency ion thruster based on ICP internal coupling discharge, characterized in that: The radio frequency ion thruster comprises an ionization chamber, a radio frequency current supply system, a radio frequency antenna, and a propulsion medium located in the ionization chamber; The radio frequency antenna comprises a spiral coil; the spiral coil is located in the ionization chamber and is electrically connected to the radio frequency current supply system; the center line of the spiral coil is coaxial with the center line of the ionization chamber, and the distance from the center line of the spiral coil to the inner wall of the ionization chamber is the same as the diameter of the spiral coil; the spiral coil is coated with a protective film; the protective film is used to prevent plasma from damaging the spiral coil; The radio frequency current supply system is used to provide radio frequency current to the spiral coil; the spiral coil is used to generate an induced electric field under the action of the radio frequency current; The radio frequency ion thruster further comprises a diffusion nozzle; the diffusion nozzle is used to uniformly spray the propulsion medium into the ionization chamber; The propulsion medium is used to generate an induced current under the drive of the induced electric field, to be ionized, and to generate the plasma.

2. The radio frequency ion thruster according to claim 1, characterized in that: The radio frequency current supply system includes a radio frequency source unit and a corresponding impedance matching network.

3. The radio frequency ion thruster according to claim 1, characterized in that: The RF antenna also includes a first straight segment and a second straight segment; one end of the first straight segment is electrically connected to the RF current supply system, and the other end extends into the ionization chamber and is electrically connected to one end of the spiral coil; one end of the second straight segment is electrically connected to the RF current supply system, and the other end extends into the ionization chamber and is electrically connected to the other end of the spiral coil; the protective film is plated on part of the first straight segment and part of the second straight segment located in the ionization chamber.

4. The radio frequency ion thruster according to claim 3, characterized in that: The radio frequency ion thruster further includes a first seal and a second seal; the first seal is used to seal the connection between the first straight line segment and the ionization chamber; the second seal is used to seal the connection between the second straight line segment and the ionization chamber.

5. The radio frequency ion thruster according to claim 1, characterized in that: The protective film is an aluminum oxide ceramic protective film or a zirconium oxide ceramic protective film.

6. The radio frequency ion thruster according to claim 1, characterized in that: The radio frequency ion thruster also includes a propulsion medium storage and supply system and an air intake pipeline; the propulsion medium storage and supply system stores the propulsion medium; the output end of the propulsion medium storage and supply system is connected to one end of the air intake pipeline, and the other end of the air intake pipeline extends into the ionization chamber; the propulsion medium storage and supply system is used to provide the propulsion medium into the ionization chamber through the air intake pipeline.

7. The radio frequency ion thruster according to claim 6, characterized in that: The diffusion nozzle is mounted on one end of the air inlet pipeline located in the ionization chamber.

8. The radio frequency ion thruster according to claim 1, characterized in that: The radio frequency ion thruster further comprises an optical system and a DC source unit; the optical system is electrically connected to the DC source unit; the DC source unit is used to form an accelerating electric field in the optical system; The optical system is installed at the outlet end of the side wall of the ionization chamber; the optical system is used to accelerate the ions in the plasma to be ejected under the action of the accelerating electric field to form a beam.

9. The radio frequency ion thruster according to claim 8, characterized in that: The optical system comprises a screen grid and an acceleration grid; the acceleration grid is arranged between the screen grid and the exit end.

10. The radio frequency ion thruster according to claim 8, characterized in that: The radio frequency ion thruster also includes a neutralizer; the neutralizer is used to emit electrons into the beam to make the beam electrically neutral.

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