Coil-energized hollow cathode thruster

Abstract

The application discloses a coil excitation type hollow cathode thruster, which comprises a bottom plate and a shell arranged at the edge of the bottom plate, and the bottom plate and the shell form a containing space. The coil excitation type hollow cathode thruster further comprises a hollow cathode structure, an anode structure and an excitation structure. The hollow cathode structure comprises a hollow cathode tube, an emitter, a heating wire and a holding electrode, the hollow cathode tube is arranged in the containing space, the emitter is arranged in the hollow cathode tube, and the heating wire is arranged on the outer wall of the hollow cathode tube and surrounds the emitter. The anode structure comprises an insulating channel and an anode, the insulating channel is arranged outside the holding electrode, and the anode is arranged in the insulating channel. The excitation structure comprises an excitation coil, a magnetic conducting column and a permanent magnet. The excitation coil excitation type electric propulsion hollow cathode thruster structure of the application is relatively simple and has low power consumption, and meets the requirements of microsatellites on microthrusters.

Description

Technical Field

[0001] This invention belongs to the field of aerospace propulsion systems, and is mainly about a cathode thruster, particularly a coil-excited hollow cathode thruster. Background Technology

[0002] With the continuous advancement of space technology and the increasing demands of space applications, satellite miniaturization has become a new trend in satellite development. Microsatellites require a small, low-power, high-performance, stable, and reliable micro-propulsion system to perform tasks such as attitude and position control and orbital maneuvers. Cold gas propulsion and chemical propulsion, due to their relatively low specific impulse, reduce the payload of microsatellites, while electric propulsion systems offer higher efficiency and specific impulse, making them more promising. Currently, the two most mature electric propulsion products are Hall thrusters and ion thrusters. However, miniaturization of Hall thrusters and ion thrusters leads to a certain degree of reduction in propulsion efficiency. Furthermore, miniaturizing hollow cathodes is a significant technical challenge. Therefore, it is necessary to research micro-thrusters to promote the development of microsatellites.

[0003] Hollow cathodes for electric propulsion are key components in Hall thruster and ion thruster systems. They can ionize atoms or molecules at relatively low power to generate large amounts of high-density plasma, providing electrons for the electric thruster to maintain plasma discharge and neutralize the plume. However, existing hollow cathode thrusters have complex structures and high power consumption, which cannot adequately meet market demands.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide an excitation coil-excited type electric propulsion hollow cathode thruster, which has a relatively simple structure, low power consumption, reliable operation, small size, and light weight, meeting the requirements of microsatellites for micro-thrusters.

[0006] To achieve the above objectives, embodiments of the present invention provide a coil-excited hollow cathode thruster, including a base plate and a housing disposed at the edge of the base plate, wherein the base plate and the housing constitute a semi-enclosed accommodating space. The coil-excited hollow cathode thruster further includes a hollow cathode structure, an anode structure, and an excitation structure.

[0007] The hollow cathode structure includes a hollow cathode tube, an emitter, a heating wire, and a contact electrode. The hollow cathode tube is disposed within the accommodating space, the emitter is disposed inside the hollow cathode tube, the heating wire is disposed on the outer wall of the hollow cathode tube and surrounds the emitter, and the contact electrode surrounds at least a portion of the hollow cathode tube and is spaced a certain distance from the hollow cathode tube.

[0008] The anode structure includes an insulating channel and an anode, the insulating channel being disposed outside the contact electrode and the anode being disposed inside the insulating channel.

[0009] The excitation structure includes an excitation coil, a magnetic column, and a permanent magnet. The magnetic column is arranged on the outer periphery of the hollow cathode tube and the excitation coil is wound around the outer periphery of the magnetic column. The permanent magnet is arranged on the outside of the insulating channel and is fixed to the outer shell.

[0010] In one or more embodiments of the present invention, an insulating base is mounted on the base plate, and the open end of the hollow cathode tube is mounted on the insulating base.

[0011] In one or more embodiments of the present invention, the hollow cathode tube includes a top plate and a cylindrical sidewall, and the emitter is disposed inside the hollow cathode tube in close contact with the top plate and the sidewall.

[0012] In one or more embodiments of the present invention, the excitation structure further includes a magnetic screen connected to the permanent magnet and the excitation coil to construct a zero magnetic field region.

[0013] In one or more embodiments of the present invention, the coil-excited hollow cathode thruster further includes an insulating layer, which is fixedly sleeved between the hollow cathode tube and the magnetic column.

[0014] In one or more embodiments of the present invention, the selected insulating layer is made of alumina composite material, which is used to isolate the hollow cathode tube from the magnetic column and prevent discharge breakdown.

[0015] In one or more embodiments of the present invention, the insulating channel is made of ceramic to confine working fluid atoms and increase the density of gas within the channel.

[0016] In one or more embodiments of the present invention, the permanent magnet is annular and surrounds the top of the insulating channel. Preferably, the anode is annular and the applied voltage is 200V. The contact electrode is the ignition electrode and the applied voltage is 300V.

[0017] In one or more embodiments of the present invention, the anode is annular and disposed close to the magnetic screen. The permanent magnet is made of high-temperature resistant samarium cobalt.

[0018] Compared with the prior art, the coil-excited hollow cathode thruster according to embodiments of the present invention has the following advantages:

[0019] (1) The excitation coil excitation type electric propulsion hollow cathode thruster of the present invention has a relatively simple structure, low power consumption, reliable operation, small size and light weight, which meets the requirements of micro satellites for micro thrusters.

[0020] (2) The excitation coil excitation type electric propulsion hollow cathode thruster of the present invention integrates the hollow cathode and the thruster into one unit, avoiding the problem of miniaturizing the hollow cathode in the micro thruster.

[0021] (3) The excitation coil excitation type electric propulsion hollow cathode thruster described in this invention can adjust the magnetic field strength by adjusting the excitation current. Compared with the permanent magnet type hollow cathode thruster, it can have higher efficiency and specific impulse in a wider working range. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of an excitation coil-excited type electric propulsion hollow cathode thruster according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the magnetic field configuration generated by the excitation coil and permanent magnet according to an embodiment of the present invention.

[0024] Figure 3 This is an exploded perspective view of an excitation coil-excited type electric propulsion hollow cathode thruster according to an embodiment of the present invention.

[0025] Explanation of key figure labels:

[0026] 1-Base plate; 2-Insulating base; 3-Insulating layer; 4-Magnetic column; 5-Excitation coil; 6-Outer shell; 7-Magnetic screen; 8-Permanent magnet; 9-Insulating channel; 10-Anode; 11-Heating wire; 12-Emitter; 13-Contact electrode; 14-Hollow cathode tube. Detailed Implementation

[0027] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0028] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0029] like Figure 1As shown, the coil-excited hollow cathode thruster according to a preferred embodiment of the present invention includes a base plate 1 and a housing 6 covering the edge of the base plate, wherein the base plate 1 and the housing 6 constitute an accommodating space. The coil-excited hollow cathode thruster also includes a hollow cathode structure, an anode structure, and an excitation structure disposed within the accommodating space.

[0030] The hollow cathode structure includes a hollow cathode tube 14, an emitter 12, a heating wire 11, and a contact electrode 13. The hollow cathode tube 14 is disposed within the accommodating space, the emitter 12 is arranged within the hollow cathode tube 13, and the heating wire 11 is arranged on the outer wall of the hollow cathode tube and surrounds the emitter 12. The heating wire's function is to heat the emitter 12 to a rated ignition temperature, ensuring the formation of a low work function surface on the emitter 12 and generating the required electron emission density, enabling reliable ignition of the cathode at a lower voltage. The contact electrode 13 surrounds at least a portion of the hollow cathode tube 14 and is spaced a certain distance from the hollow cathode tube 14. The function of the contact electrode 13 is to achieve arc discharge ignition between the hollow cathode tube 13 and the contact electrode 13 after the ignition voltage is applied, and to maintain a stable operating current emission at an appropriate operating voltage. The distance between the contact electrode 13 and the hollow cathode tube 13 is generally 1–2 mm.

[0031] The anode structure includes an insulating channel 9 and an anode 10. The insulating channel 9 is disposed on the outside of the contact electrode 13, and the anode 10 is disposed within the insulating channel 9.

[0032] The excitation structure includes an excitation coil 5, a magnetic guide post 4, and a permanent magnet 8. The magnetic guide post 4 is arranged on the outer periphery of the hollow cathode tube 14, and the excitation coil 5 is wound around the outer periphery of the magnetic guide post 4 to enhance the magnetic field generated by the excitation coil 5. The permanent magnet 8 is arranged on the outside of the insulating channel 9 and is fixed to the outer shell 6.

[0033] The working principle of the coil-excited hollow cathode thruster according to an embodiment of the present invention will be described below, based on the above structure. First, the hollow cathode tube 14 is ignited, and working gas is injected through the emitter 12. The emitter 12 is heated to the point where it can emit electrons using the heating wire 11. A high voltage (e.g., 300V) is applied to the contact electrode 13, breaking down the working gas between the emitter 12 and the contact electrode 13, generating high-density plasma and emitting electrons. Next, the excitation coil 5 is energized, generating a magnetic field within the insulating channel 9. The magnetic field generated by the permanent magnet 8, the magnetic column 4, and the coil 5 confines the electrons within the insulating channel 9. The working gas is ionized. The anode 10 is loaded with a voltage of 200V. Electrons collide with gas molecules entering through the anode 10 and ionize, forming ions. These ions are accelerated axially under the influence of the electromagnetic field and ejected at high speed, thereby generating thrust.

[0034] The excitation coil-excited type hollow cathode electric propulsion thruster according to the above embodiments of the present invention has a relatively simple structure, low power consumption, reliable operation, small size, and light weight, which meets the requirements of microsatellites for micro-thrusters.

[0035] like Figure 1 and Figure 2 As shown, in one embodiment, an insulating base 2 is mounted on the base plate 1, and the open end of the hollow cathode tube 14 on one axial side is mounted on the insulating base 2. Preferably, both the base plate 1 and the insulating base 2 are provided with through holes, through which the open end of the hollow cathode tube 14 passes and is fixed to the insulating base 2. The insulating base 2 can be an alumina composite material, used to insulate the hollow cathode tube 14 from the outer casing 6. The hollow cathode tube 14 includes a top plate 141 and a cylindrical sidewall 142, with the top plate 141 disposed on one axial side of the hollow cathode tube 14. The emitter 12 is arranged inside the hollow cathode tube 14, closely attached to the top plate 141 and the sidewall 142.

[0036] In one embodiment, the magnetic post 4 can be made of pure iron and forms an internal magnetic circuit with the coil 5. The function of the magnetic post 4 is to enhance the magnetic field generated by the coil 5. The strength of the internal magnetic field can be changed by adjusting the excitation current, thereby changing the strength of the entire magnetic field. The permanent magnet 8 can be ring-shaped and surrounds the top of the insulating channel 9. The permanent magnet 8 can be ring-shaped and made of high-temperature resistant samarium cobalt permanent magnet, which can withstand a high temperature of 350°C without demagnetizing, thus preventing demagnetization of the permanent magnet 8 due to the high temperature inside the insulating channel 9.

[0037] In one embodiment, the coil-excited hollow cathode thruster further includes an insulating layer 3, which is fixedly sleeved between the hollow cathode tube 14 and the magnetic post 4 to isolate the hollow cathode tube 14 from the magnetic post 4 and prevent discharge breakdown. Preferably, the insulating layer 3 is made of alumina composite material.

[0038] like Figure 2 As shown, the excitation structure also includes a magnetic shield 7, which is connected to the permanent magnet 8 and the excitation coil 5. By using the magnetic shield 7 to shield the magnetic field, a magnetic field can be generated near the anode 10. Figure 2 The zero magnetic field region is shown. For example, the anode 10 can be fixed in a ring within the insulating channel 9 and positioned close to the magnetic screen 7. Because a zero magnetic field region exists near the anode 10, electrons can more easily reach it, making thruster ignition relatively easy. Under the influence of the magnetic field, electrons are magnetized, increasing their temperature and improving ionization, thus increasing the probability of collisions between electrons and neutral gas atoms. Furthermore, the magnetic field strength can be altered by changing the excitation current, allowing the thruster to operate over a wider range with higher efficiency.

[0039] The insulating channel 9 can be made of ceramic, such as boron nitride ceramic, to confine the working fluid atoms, increase the density of the gas in the channel, and insulate it from the anode 10.

[0040] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A coil-geared type hollow cathode thruster comprising a base plate and a cover provided at the edge of the base plate, the base plate and the cover constituting a housing space, characterized in that, The coil-excited hollow cathode thruster further comprises: a hollow cathode structure comprising a hollow cathode tube, an emitter, a heating wire and a holding electrode, the hollow cathode tube is arranged in the accommodating space, the emitter is arranged in the hollow cathode tube, the heating wire is arranged on the outer wall of the hollow cathode tube and surrounds the emitter, and the holding electrode surrounds at least a part of the hollow cathode tube and is spaced apart from the hollow cathode tube by a distance; an anode structure comprising an insulating channel and an anode, the insulating channel is arranged outside the holding electrode, and the anode is arranged in the insulating channel; and an excitation structure comprising an excitation coil, a magnetic conducting column and a permanent magnet and a magnetic screen, the magnetic conducting column is arranged on the outer periphery of the hollow cathode tube, the outer periphery of the magnetic conducting column is wound with the excitation coil, the permanent magnet is arranged outside the insulating channel and is fixed to the shell, and the magnetic screen is connected to the permanent magnet and the excitation coil to form a zero magnetic field area.

2. The coil-geared type hollow cathode thruster as claimed in claim 1, wherein An insulating base is arranged on the bottom plate, and the open end of the hollow cathode tube is arranged on the insulating base.

3. The coil-geared type hollow cathode thruster as claimed in claim 1, wherein The hollow cathode tube comprises a top plate and a cylindrical side wall, and the emitter is arranged in the hollow cathode tube closely to the top plate and the side wall.

4. The coil-geared type hollow cathode thruster as claimed in claim 1, wherein An insulating layer is further arranged, which is fixedly sleeved between the hollow cathode tube and the magnetic conducting column.

5. The coil-geared type hollow cathode thruster as claimed in claim 4, wherein The material of the selected insulating layer is an alumina composite material.

6. The coil-geared type hollow cathode thruster as claimed in claim 1, wherein The material of the insulating channel is ceramic.

7. The coil-geared type hollow cathode thruster as claimed in claim 1, wherein The permanent magnet is annular and surrounds the top of the insulating channel.

8. The coil-geared type hollow cathode thruster as claimed in claim 1, wherein The anode is annular and arranged close to the magnetic screen.

9. The coil-geared type hollow cathode thruster as claimed in claim 1, wherein The material of the permanent magnet is high-temperature-resistant samarium-cobalt.

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