Radio frequency ion thruster with additional magnetic field

Abstract

The invention provides a radio frequency ion thruster with an additional magnetic field, and relates to the technical field of electric propulsion. The thruster comprises a discharge chamber, a radio frequency antenna, a four-claw sleeve shell, 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 sleeve shell is fixed to the back plate through a fastener, and axial pressing and fixing of the electromagnetic coil are achieved through a bolt penetrating through the claw-shaped structure of the four-claw sleeve shell. Adjustable current can be applied to the upstream electromagnetic coil and the downstream electromagnetic coil respectively, and an additional magnetic field is formed in the discharge chamber; the optical system is installed at the front end of the four-claw sleeve shell and used for accelerating the plasma to generate thrust. The ceramic base is provided with a cambered surface matched with the bottom curved surface of the discharge chamber and used for supporting the discharge chamber. The plasma is confined through the additional magnetic field, the wall surface loss is reduced, and the energy efficiency of the radio frequency ion thruster is further improved.

Description

Technical Field

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

[0002] As a new generation of electric propulsion technology, RF ion thrusters have shown important application value in the application fields of orbit maintenance and orbit transfer of micro-satellites due to their advantages of system simplification, improved reliability and easy miniaturization brought by their electrode-free structure. Compared with traditional DC ion thrusters, this technology avoids the problem of hollow cathode corrosion and significantly extends the on-orbit service life of satellites.

[0003] However, with the in-depth application of RF ion thrusters in the space field, its 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 hit the wall of the discharge chamber and cause a large amount of discharge loss. Although the prior art 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 radial transport of plasma. Therefore, the present invention proposes a RF ion thruster that restrains the wall loss of plasma by adding a magnetic field 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 plasma with an additional magnetic field, reduce plasma wall losses, increase 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 currents to form an additional magnetic field in the discharge chamber, and adjust the configuration and intensity of the magnetic field 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 for supporting 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 an axial uniform magnetic field and a 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 is 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 modularly designed 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, reduce wall losses, and thus improve the efficiency of the thruster;

[0023] 2) By independently adjusting the upstream electromagnetic coil and the downstream electromagnetic coil, 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 Schematic diagram of a front view and a left side view 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 figure are as follows:

[0028] 1. Exit grille cover 2. Acceleration 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 1-3The specific embodiments of the present invention are described. Certain terms used herein are only for convenience and are not considered to be limitations of the present invention. For example, terms such as "up", "down", "left", "right", "horizontal", "vertical", "upward" and "downward" only describe the configuration shown in the accompanying drawings. In fact, the components can be oriented in any direction, and therefore, unless otherwise indicated, the terms should be understood to include all such changes. In this description, the word "including" should be understood as its "open" meaning, i.e., the meaning of "having", and therefore should not be limited to the "closed" meaning, i.e., the meaning of "only including". The corresponding meaning also applies to the corresponding words "including", "including", etc. Although the expressions such as "1st", "2nd", "first" and "second" may be used to describe the 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 component.

[0033] Figure 1 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 Schematic diagram of a front view and a left side view 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 a radio frequency 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 by an accelerating grid fixing bolt 5, and the screen grid 3 is connected and fixed to the grid cover 6 by a screen grid fixing bolt 16, and a groove is provided at the front end of the grid cover 6 to match the clearance of the screen grid 3, so that the screen grid 3 can be embedded to prevent slippage. Six through holes are provided in the exit grid cover 1, two of which correspond to the through holes of the grid cover 6, and the exit grid cover 1, the accelerating grid 2, the screen grid 3, the stepped gasket 4, and the grid cover 6 can be pressed and connected by stainless steel bolts to form a composite grid optical system with ion focusing function. The remaining four through holes correspond to the threaded holes at the front end of the four-claw housing 8, and the optical system is rigidly connected to the four-claw housing by stainless steel bolts, and the discharge chamber 11 is pressed and pressed with the ceramic base 12. The accelerating grid fixing bolt 5 and the screen grid fixing bolt 16 can use ceramic bolts 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 by the back plate fixing bolts 10 to ensure the stability of the overall structure. The four claws of the four-claw housing 8 are specially designed to reduce the surface area of ​​the housing and prevent the RF antenna 13 from generating induced current in the four-claw housing 8, thereby reducing energy loss and improving efficiency. The outer diameters 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. The 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 3 bolt holes for installing the 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 material, formed by a melting integrated process, and is provided with an air inlet for uniformly introducing the 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 be 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 on the back plate 9, and the groove depth is about 1 mm. The RF antenna 13 is manually wound on the outer surface of the discharge chamber 11 with insulated copper wire. The RF antenna can be set to a wire diameter of 1.8 mm and 6 turns. Both ends of the RF antenna are led out through the through holes of the back plate 9 and connected to an external RF power supply.

[0037] Figure 3 The figure is a beam flow data diagram of an RF ion thruster with an additional magnetic field according to an embodiment of the present invention. The figure shows the experimental data of the beam flow of the thruster with the change of the electromagnetic coil current under the additional axial field and the additional cusp field. By adjusting the current magnitude and direction of the upstream electromagnetic coil and the downstream electromagnetic coil, the beam flow of the thruster can be increased, thereby improving the energy efficiency.

[0038] Specifically, Figure 3The horizontal axis represents the current value of the electromagnetic coil (unit: A), and the vertical axis represents the beam flux of the thruster (unit: mA). The experimental results show that when the current of the upstream electromagnetic coil and the downstream electromagnetic coil are both 2A and the axial field is added, the beam flux of the thruster reaches the maximum value, which is 40.41% higher than the beam flux without the additional magnetic field. In addition, by comparing the beam flux data under different magnetic field configurations, it can be clearly seen that the effect of the additional axial field on increasing the beam flux is better than that of the additional cusp field.

[0039] In addition, the foregoing only describes some embodiments, which may be changed, modified, added and / or varied without departing from the scope and essence of the disclosed embodiments, which are illustrative rather than restrictive. In addition, the described embodiments relate to the embodiments currently considered to be the most practical and preferred, 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 included within the essence and scope of the embodiments. In addition, 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. In addition, each independent feature or component of any given component may constitute another embodiment.

[0040] The foregoing description of the embodiment is provided for the purpose of illustration and description, and it is not intended to be exhaustive or limit the present disclosure. Each element or feature of a specific embodiment is generally not limited to the specific embodiment, but in the applicable case, even if not specifically shown or described, each element or feature is also interchangeable and can be used for the selected embodiment, and can also be changed in many ways. This change is not regarded as a deviation from the present disclosure, and all such changes are included in 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-like structures, and the electromagnetic coils are axially compressed and fixed by bolts penetrating the claw-like structures; The upstream electromagnetic coil and the downstream electromagnetic coil can respectively apply adjustable currents to form an additional magnetic field in the discharge chamber, and adjust the configuration and intensity of the magnetic field 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 for supporting the discharge chamber.

2. The radio frequency ion thruster with additional magnetic field as claimed in 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 an axial uniform magnetic field and a cusped magnetic field.

3. The radio frequency ion thruster with additional magnetic field as claimed in claim 1, characterized in that: The number of turns and the spacing between 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 as claimed in 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. The bolts pass through the 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 as claimed in 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 as claimed in claim 1, characterized in that: The optical system comprises a screen grid, an accelerating 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 accelerating grid are led out through the holes and slots.

7. The radio frequency ion thruster with additional magnetic field as claimed in 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 as claimed in 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 as claimed in 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, and each component is connected by bolt fasteners for easy replacement and maintenance.

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