A radio frequency ion thruster with additional magnetic field

Abstract

The present invention provides a radio frequency ion thruster with an additional magnetic field, which relates to the field of electric propulsion technology. The thruster includes a discharge chamber, a radio frequency antenna, a four-claw housing, an upstream electromagnetic coil, a downstream electromagnetic coil, an optical system, a back plate, and a ceramic base. The radio frequency antenna is coaxially wound on the outer surface of the discharge chamber; the four-claw housing is fixed to the back plate by fasteners, and the electromagnetic coil is axially compressed and fixed by bolts penetrating its claw-shaped structure; the upstream electromagnetic coil and the downstream electromagnetic coil can be applied with adjustable currents respectively to form an additional magnetic field in the discharge chamber; the optical system is installed at the front end of the four-claw housing to accelerate plasma to generate thrust; the ceramic base is provided with an arc surface that matches the curved surface of the bottom of the discharge chamber to support the discharge chamber. The present invention confines plasma through an additional magnetic field, reduces wall losses, and thereby improves the energy efficiency of the radio frequency ion thruster.

Description

Technical Field

[0001] The present invention relates to the field of electric propulsion technology, and in particular to a radio frequency ion thruster with an additional magnetic field. Background Art

[0002] As a next-generation electric propulsion technology, radio frequency ion thrusters, with their electrode-less structure, offer advantages such as system simplification, improved reliability, and ease of miniaturization. They are demonstrating significant application value in orbit maintenance and orbit transfer for microsatellites. Compared to traditional DC ion thrusters, this technology avoids hollow cathode corrosion, significantly extending the satellite's on-orbit service life.

[0003] However, with the in-depth application of RF ion thrusters in the space field, their core problems have gradually emerged. According to the principle of inductively coupled plasma, the skin effect caused by the RF alternating electromagnetic field causes the RF energy deposition to be concentrated in the near-wall area of ​​the discharge chamber. At the same time, unconfined plasma will collide with the wall of the discharge chamber, causing a large amount of discharge loss. Although the existing technical methods attempt to reduce the discharge loss by optimizing the structure of the discharge chamber, they still do not effectively solve the energy loss problem caused by the radial transport of plasma. Therefore, the present invention proposes a RF ion thruster that uses an additional magnetic field to confine the wall loss of plasma to improve the ionization efficiency of the thruster. Summary of the Invention

[0004] In order to solve the above problems, the present invention proposes a radio frequency ion thruster with an additional magnetic field, which can confine the plasma with an additional magnetic field, reduce the wall loss of the plasma, increase the plasma density in the discharge chamber, and thus improve the energy efficiency of the radio frequency ion thruster.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A radio frequency ion thruster with an additional magnetic field, characterized in that it comprises: a discharge chamber, a radio frequency antenna, a four-claw housing, an upstream electromagnetic coil, a downstream electromagnetic coil, an optical system, a back plate and a ceramic base;

[0007] The radio frequency antenna is coaxially wound on the outer surface of the discharge chamber;

[0008] The four-claw housing is fixed to the axial end surface of the back plate by fasteners;

[0009] The upstream electromagnetic coil and the downstream electromagnetic coil are fixed by a four-claw housing, and the four-claw housing includes four symmetrically distributed claw-like structures, and the electromagnetic coils are axially compressed and fixed by bolts penetrating the claw-like structures;

[0010] The upstream electromagnetic coil and the downstream electromagnetic coil can respectively apply adjustable current to form an additional magnetic field in the discharge chamber, and the configuration and intensity of the magnetic field can be adjusted by changing the direction and magnitude of the current to optimize the discharge performance of the thruster.

[0011] The optical system is installed at the front end of the four-claw housing, and the input end of the optical system is connected to the output end of the discharge chamber;

[0012] The ceramic base is provided with a curved surface matching the curved surface of the bottom of the discharge chamber and is used to support the discharge chamber.

[0013] In an optional embodiment, the upstream electromagnetic coil and the downstream electromagnetic coil are relatively independent and can apply currents of different directions and magnitudes respectively to form different types of magnetic field configurations in the discharge chamber, including axial uniform magnetic field and cusped magnetic field.

[0014] In an optional embodiment, the number of turns and the spacing between the upstream electromagnetic coil and the downstream electromagnetic coil can be adjusted according to the magnetic field strength requirement, and the outside of the coil is coated with an insulating layer.

[0015] In an optional embodiment, the inner diameter of the four-claw housing forms a clearance fit with the outer diameter of the electromagnetic coil, and each claw-like structure is provided with three through bolt holes, through which bolts pass to limit the axial movement of the electromagnetic coil, thereby axially compressing and fixing the electromagnetic coil.

[0016] In an optional embodiment, the material of the four-claw housing is a high-strength non-magnetic alloy to ensure that no magnetization effect occurs in a strong magnetic field environment, while providing sufficient mechanical strength to fix the electromagnetic coil.

[0017] In an optional embodiment, the optical system includes a screen grid, an acceleration grid, a grid cover, a step gasket and an exit grid cover, wherein the step gasket and the exit grid cover are provided with holes and slots, and circuit connectors of the screen grid and the acceleration grid are led out through the holes and slots.

[0018] In an optional embodiment, the back plate is provided with two through holes for leading out the electromagnetic coil and the circuit connector of the optical system; a groove matching the outer diameter of the ceramic base is provided in the center of the back plate to prevent the ceramic base from slipping.

[0019] In an optional embodiment, the discharge chamber is integrally formed and provided with a gas path input end, and the bottom of the discharge chamber is designed to be a curved surface to reduce the plasma loss area.

[0020] In an optional embodiment, the optical system is modular in design and includes a detachable screen grid, an acceleration grid, a grid cover, a step gasket and an exit grid cover, and each component is connected by bolt fasteners to facilitate replacement and maintenance.

[0021] Advantages of the present invention:

[0022] 1) Effectively confine the plasma through an additional magnetic field, reducing wall losses and thus improving the efficiency of the thruster;

[0023] 2) By independently adjusting the upstream and downstream electromagnetic coils, different types of magnetic fields can be generated, the plasma distribution can be optimized, and the stability and controllability of the discharge can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A three-dimensional cross-sectional view of a radio frequency ion thruster with an additional magnetic field according to one embodiment of the present invention.

[0025] Figure 2 1. Front and left side views of a radio frequency ion thruster with an additional magnetic field according to one embodiment of the present invention.

[0026] Figure 3 FIG. 4 is a graph showing beam flux data of a radio frequency ion thruster with an additional magnetic field according to an embodiment of the present invention.

[0027] The components indicated by the reference numerals in the figures are as follows:

[0028] 1. Exit grille cover 2. Accelerator grille 3. Screen grille 4. Step gasket

[0029] 5. Accelerator grid fixing bolt 6. Grid cover 7. Coil fixing bolt 8. Four-claw housing

[0030] 9. Back plate 10. Back plate fixing bolts 11. Discharge chamber 12. Ceramic base

[0031] 13. RF antenna 14. Upstream electromagnetic coil 15. Downstream electromagnetic coil 16. Screen fixing bolt DETAILED DESCRIPTION

[0032] The following is combined with Figure 1-3Specific embodiments of the present invention are described. Certain terms used herein are for convenience only and are not to be considered as limiting the present invention. For example, terms such as "upper," "lower," "left," "right," "horizontal," "vertical," "upward," and "downward" merely describe the configurations shown in the accompanying drawings. In practice, components can be oriented in any direction, and therefore, unless otherwise indicated, terms should be understood to include all such variations. In this description, the word "comprising" should be understood in its "open" sense, i.e., meaning "having," and should not be limited to its "closed" sense, i.e., meaning "only comprising." Corresponding meanings also apply to corresponding words such as "comprising," "including," and "having." Although expressions such as "first," "second," "first," and "second" may be used to describe various elements of the present invention, they are not intended to limit the corresponding elements. For example, the above expressions are not intended to limit the order or importance of the corresponding elements. The above expressions are only used to distinguish one component from another.

[0033] Figure 1 FIG. 4 is a cross-sectional view of a radio frequency ion thruster with an additional magnetic field according to one embodiment of the present invention. Figure 2 1. Front and left side views of a radio frequency ion thruster with an additional magnetic field according to one embodiment of the present invention. Figure 3 FIG. 4 is a graph showing beam flux data of a radio frequency ion thruster with an additional magnetic field according to an embodiment of the present invention.

[0034] like Figure 1-2 As shown, the present invention provides an RF ion thruster with an additional magnetic field, comprising: an exit grid cover 1, an accelerating grid 2, a screen grid 3, a stepped gasket 4, and a grid cover 6. The accelerating grid 2 is connected and fixed to the stepped gasket 4 via accelerating grid fixing bolts 5, and the screen grid 3 is connected and fixed to the grid cover 6 via screen grid fixing bolts 16. The front end of the grid cover 6 is provided with a groove that is clearance-matched with the screen grid 3, allowing the screen grid 3 to be embedded and prevented from slipping. The exit grid cover 1 is provided with six through-holes, two of which correspond to the through-holes of the grid cover 6. Stainless steel bolts are used to press the exit grid cover 1, accelerating grid 2, screen grid 3, stepped gasket 4, and grid cover 6 together, forming a composite grid optical system with ion focusing function. The remaining four through-holes correspond to threaded holes at the front end of a four-claw housing 8. Stainless steel bolts are used to rigidly connect the optical system to the four-claw housing and to press the discharge chamber 11 to the ceramic base 12. Ceramic bolts can be used for the accelerating grid fixing bolts 5 and the screen grid fixing bolts 16 to improve insulation and prevent breakdown discharge between the accelerating grid and the screen grid.

[0035] like Figure 1-2As shown, the four-claw housing 8 is rigidly connected to the back plate 9 via the back plate fixing bolts 10 to ensure the stability of the overall structure. The special design of the four claws of the four-claw housing 8 is to reduce the surface area of ​​the housing and prevent the radio frequency antenna 13 from generating induced current in the four-claw housing 8, thereby reducing energy loss and improving efficiency. The outer diameter of the upstream electromagnetic coil 14 and the downstream electromagnetic coil 15 should match the inner diameter of the four-claw housing 8, which can be set to an outer diameter of 60mm and an inner diameter of 50mm. The wire diameter and number of turns of the two coils can be set according to the actual required magnetic field configuration. Typical parameters are a wire diameter of 1mm and 45 turns. The four claw-shaped structures of the four-claw housing 8 are each provided with three bolt holes for installing coil fixing bolts 7. The coil fixing bolts 7 are used to limit the axial displacement of the upstream electromagnetic coil 14 and the downstream electromagnetic coil 15. The design of their position and spacing should take into account the installation position and thickness of the upstream electromagnetic coil 14 and the downstream electromagnetic coil 15. The upstream electromagnetic coil 14 and the downstream electromagnetic coil 15 are named according to the flow direction of the propellant in the discharge chamber 11. The upstream electromagnetic coil 14 is located at the propellant gas inlet side, and the downstream electromagnetic coil 15 is located at the propellant gas outlet side.

[0036] like Figure 1-2 As shown, the discharge chamber 11 is made of quartz glass and formed through a fusion-integrated process. It is equipped with an air inlet for uniformly introducing propellant gas. The inner diameter of the discharge chamber 11 can be set to 30 mm, and the outlet of the air inlet is designed to have a conical structure to reduce the plasma loss area. The discharge chamber 11 is fixed by axial clamping of an alumina ceramic base 12 and a grid cover 6. The ceramic base 12 is placed in an annular groove provided in the back plate 9, and the groove depth is approximately 1 mm. The RF antenna 13 is hand-wound on the outer surface of the discharge chamber 11 using insulated copper wire. The RF antenna can be set to a wire diameter of 1.8 mm and the number of turns is 6. The two ends of the RF antenna are led out through the through-holes in the back plate 9 and connected to an external RF power supply.

[0037] Figure 3 This figure shows beam flux data for an RF ion thruster with an additional magnetic field, according to one embodiment of the present invention. This figure demonstrates experimental data showing how the thruster's beam flux varies with electromagnetic coil current under both additional axial and cusped fields. By adjusting the current magnitude and direction of the upstream and downstream electromagnetic coils, the thruster's beam flux can be increased, thereby improving energy efficiency.

[0038] Specifically, Figure 3The horizontal axis represents the electromagnetic coil current (unit: A), and the vertical axis represents the thruster beam flux (unit: mA). Experimental results show that when the current of both the upstream and downstream electromagnetic coils is 2A and an axial field is applied, the thruster beam flux reaches its maximum value, increasing by 40.41% compared to the beam flux without the additional magnetic field. Furthermore, by comparing the beam flux data under different magnetic field configurations, it is clear that the additional axial field is more effective in increasing the beam flux than the additional cusp field.

[0039] Furthermore, the foregoing describes only some embodiments, which may be changed, modified, added and / or varied without departing from the scope and spirit of the disclosed embodiments, which are illustrative and not restrictive. Furthermore, the embodiments described relate to what are currently considered to be the most practical and preferred embodiments, and it should be understood that the embodiments should not be limited to the disclosed embodiments, but rather are intended to cover different modifications and equivalent arrangements that are included within the spirit and scope of the embodiments. Furthermore, the various embodiments described above may be used in conjunction with other embodiments, such as aspects of one embodiment may be combined with aspects of another embodiment to achieve yet another embodiment. Additionally, each independent feature or component of any given component may constitute another embodiment.

[0040] The foregoing description of the embodiments is provided for the purpose of illustration and description, and is not intended to be exhaustive or limit the present disclosure. Each element or feature of a specific embodiment is generally not limited to that specific embodiment, but in applicable cases, even if not specifically shown or described, each element or feature is also interchangeable and can be used for the embodiment of selection, and can also be changed in many ways. This change is not considered to be a deviation from the present disclosure, and all such changes are included within the scope of the present disclosure.

[0041] Therefore, it should be understood that the drawings and description herein are provided by way of illustration to facilitate understanding of the present invention and should not be construed as limiting the scope thereof.

Claims

1. A radio frequency ion thruster with an additional magnetic field, characterized in that: include: Discharge chamber, RF antenna, four-claw housing, upstream electromagnetic coil, downstream electromagnetic coil, optical system, back plate and ceramic base; The radio frequency antenna is coaxially wound on the outer surface of the discharge chamber; The four-claw housing is fixed to the axial end surface of the back plate by fasteners; The upstream electromagnetic coil and the downstream electromagnetic coil are fixed by a four-claw housing, and the four-claw housing includes four symmetrically distributed claw-shaped structures. The electromagnetic coil is axially compressed and fixed by bolts penetrating the claw-shaped structure; The upstream electromagnetic coil and the downstream electromagnetic coil can respectively apply adjustable current to form an additional magnetic field in the discharge chamber, and the configuration and intensity of the magnetic field can be adjusted by changing the direction and magnitude of the current to optimize the discharge performance of the thruster; The optical system is installed at the front end of the four-claw housing, and the input end of the optical system is connected to the output end of the discharge chamber; The ceramic base is provided with a curved surface matching the curved surface of the bottom of the discharge chamber and is used to support the discharge chamber.

2. The radio frequency ion thruster with additional magnetic field according to claim 1, characterized in that: The upstream electromagnetic coil and the downstream electromagnetic coil are relatively independent and can apply currents of different directions and magnitudes respectively to form different types of magnetic field configurations in the discharge chamber, including axial uniform magnetic field and cusped magnetic field.

3. The radio frequency ion thruster with additional magnetic field according to claim 1, characterized in that: The number of turns and spacing of the upstream electromagnetic coil and the downstream electromagnetic coil can be adjusted according to the requirements of the magnetic field strength, and the outside of the coil is coated with an insulating layer.

4. The radio frequency ion thruster with additional magnetic field according to claim 1, characterized in that: The inner diameter of the four-claw housing forms a clearance fit with the outer diameter of the electromagnetic coil. Each claw-shaped structure is provided with three penetrating bolt holes. Bolts pass through the bolt holes to limit the axial movement of the electromagnetic coil, thereby axially compressing and fixing the electromagnetic coil.

5. The radio frequency ion thruster with additional magnetic field according to claim 1, characterized in that: The material of the four-claw housing is a high-strength non-magnetic alloy to ensure that no magnetization effect is generated in a strong magnetic field environment, while providing sufficient mechanical strength to fix the electromagnetic coil.

6. The radio frequency ion thruster with additional magnetic field according to claim 1, characterized in that: The optical system comprises a screen grid, an accelerating grid, a grid cover, a stepped gasket and an exit grid cover, wherein the stepped gasket and the exit grid cover are provided with holes and slots, and circuit connectors of the screen grid and the accelerating grid are led out through the holes and slots.

7. The radio frequency ion thruster with additional magnetic field according to claim 1, characterized in that: The back plate is provided with two through holes for leading out the electromagnetic coil and the circuit connector of the optical system; the center of the back plate is provided with a groove matching the outer diameter of the ceramic base to prevent the ceramic base from slipping.

8. The radio frequency ion thruster with additional magnetic field according to claim 1, characterized in that: The discharge chamber is integrally formed and is provided with a gas path input end. The bottom of the discharge chamber is designed to be a curved surface to reduce the loss area of ​​plasma.

9. The radio frequency ion thruster with additional magnetic field according to claim 1, characterized in that: The optical system is modular in design and includes a detachable screen grid, an acceleration grid, a grid cover, a step gasket and an exit grid cover. Each component is connected by bolt fasteners for easy replacement and maintenance.

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