A hundred-watt class hall electric thruster based on permanent magnets

Abstract

This invention provides a 100-watt Hall thruster based on permanent magnets. The thruster includes an anode and gas distributor, a plasma discharge channel, and a magnetic circuit structure. The magnetic circuit structure includes inner and outer magnetic poles, an inner permanent magnet, and an outer permanent magnet. The inner and outer permanent magnets form a ring-shaped magnetic field within the discharge channel and a zero-magnetic-field region near the central axis, used to confine electrons and increase the collision probability with krypton atoms, thereby improving ionization efficiency. This invention utilizes permanent magnet excitation, eliminating the need for an external excitation power supply, reducing system power consumption, and simultaneously improving the ionization efficiency of krypton by confining electrons in the zero-magnetic-field region, making it suitable for 100-watt-level micro / nano satellite propulsion missions.

Description

Technical Field

[0001] This invention belongs to the field of space electric propulsion technology, specifically relating to a 100-watt Hall electric thruster based on a permanent magnet. Background Technology

[0002] Hall thrusters, with their advantages of high specific impulse, long lifespan, and controllable thrust, have become key propulsion devices for space missions such as satellite attitude control, orbit maintenance, and deep space exploration. Their core working principle involves using a radial magnetic field to apply a Lorentz force to electrons within an insulated channel, causing Hall electron drift. This drift then leads to avalanche ionization with the working gas, generating plasma. Cations in this plasma are ejected at high speed under the influence of an axial electric field, producing reverse thrust.

[0003] Traditional Hall thrusters mostly use electromagnetic coil excitation, which suffers from high power consumption, large size, and complex thermal management, hindering the high integration and miniaturization of propulsion systems. With the rapid development of micro and nano satellites (such as CubeSats), the demand for low-power Hall thrusters in the hundreds of watts range is becoming increasingly urgent. However, in the miniaturization process of Hall thrusters, there are technical challenges such as increased plasma-wall interaction due to the increased surface-to-volume ratio, shortened lifespan, and insufficient magnetic field strength.

[0004] Permanent magnet excitation has become an effective way to solve the above problems due to its advantages such as simple structure, no need for external excitation power supply, and stable magnetic field. Permanent magnets have high magnetic energy, which can generate a sufficiently strong magnetic field in a miniaturized and limited space, and are easy to design with a large height-to-diameter ratio, thereby reducing the interaction between plasma and the wall and improving the thruster life. However, existing permanent magnet Hall thrusters still have shortcomings in magnetic field configuration optimization, especially in improving the ionization efficiency of inert working fluids such as krypton, which restricts their performance in practical applications. Summary of the Invention

[0005] To address the problems of existing technologies, the present invention aims to provide a 100-watt Hall thruster based on permanent magnets, which improves the ionization efficiency of krypton working fluid by optimizing the magnetic circuit structure and magnetic field distribution, while reducing system power consumption and size.

[0006] The present invention achieves the aforementioned technical effect through the following technical solution: This invention provides a 100-watt Hall thruster based on a permanent magnet, comprising an anode and gas distributor, a plasma discharge channel, and a magnetic circuit structure; The plasma discharge channel has an annular U-shaped cross-section, with the lower end being the working fluid inlet and the upper end being the working fluid outlet. The magnetic circuit structure includes an inner magnetic pole, an outer magnetic pole, an inner permanent magnet, and an outer permanent magnet. The inner permanent magnet is fixed between the inner magnetic pole and the base plate, and the outer permanent magnet is fixed between the outer magnetic pole and the base plate. The inner and outer permanent magnets form a ring-shaped magnetic field configuration within the plasma discharge channel, and a zero magnetic field region is formed near the central axis of the channel to confine electrons and increase the probability of collisions between electrons and krypton working atoms.

[0007] Preferably, the plasma discharge channel is formed by a boron nitride ceramic sleeve.

[0008] Preferably, the inner magnetic pole, the outer magnetic pole, and the base plate are all made of magnetically conductive material.

[0009] Preferably, the magnetic material is non-magnetic stainless steel, specifically non-magnetic stainless steel 06Cr19Ni10.

[0010] Preferably, the inner permanent magnet and the outer permanent magnet are samarium cobalt permanent magnets, specifically samarium cobalt permanent magnets Sm2Co17.

[0011] Preferably, a polyimide insulating layer is provided between the inner magnetic pole and the inner permanent magnet.

[0012] Preferably, a polyimide insulating layer is provided between the outer magnetic pole and the outer permanent magnet.

[0013] A polyimide insulating layer is provided between the inner magnetic pole and the inner permanent magnet, and between the outer magnetic pole and the outer permanent magnet, to prevent electrical contact.

[0014] Preferably, the anode and gas distributor are located at the bottom of the plasma discharge channel.

[0015] Preferably, the radial magnetic field strength distribution of the plasma discharge channel is saddle-shaped; the magnetic field strength is lowest near the central axis of the channel. It is understood that the central axis of the channel here refers to the central axis of the plasma discharge channel.

[0016] Preferably, under the conditions of a discharge voltage of 300V, a discharge current of 2.4A, and an anode gas flow rate of 25.0 sccm, the peak ion number density in the plasma channel reaches 2.0 × 10¹. 4 m⁻³.

[0017] The present invention provides a 100-watt Hall thruster based on permanent magnets, which has the following significant advantages compared with the prior art: The thruster provided by this invention utilizes an internal and external permanent magnet to form a ring-shaped magnetic field within the discharge channel, creating a zero-magnetic-field region near the channel's central axis. This effectively restricts the radial Hall drift of electrons, increasing the collision frequency between electrons and krypton working atoms, thereby significantly improving the ionization efficiency of the working fluid. This invention utilizes permanent magnet excitation, eliminating the need for an external excitation power supply and reducing system power consumption. Simultaneously, by confining electrons in the zero-magnetic-field region, it improves the ionization efficiency of the krypton working fluid, making it suitable for propulsion missions of micro- and nano-satellites with power levels in the hundreds of watts. Furthermore, the optimized saddle-shaped magnetic field distribution concentrates plasma near the channel's central axis, reducing sputtering erosion of the discharge channel walls by high-energy ions, thus extending the thruster's operational lifespan. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the Hall thruster of the present invention; Figure 2 This is a diagram showing the magnetic field profile of the plasma discharge channel. Figure 3 This is a diagram showing the radial magnetic field intensity distribution in the discharge channel. Figure 4 This is a diagram showing the ion number density distribution within the plasma channel.

[0019] In the diagram: 1-Inner magnetic pole, 2-Outer magnetic pole, 3-Base plate, 4-Inner permanent magnet, 5-Outer permanent magnet, 6-Ceramic sleeve, 7-Anode and gas distributor. Detailed Implementation

[0020] To make the technical problems solved, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the embodiments described herein are only some, not all, of the embodiments of this invention, and are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the protection scope of this invention.

[0021] This invention provides a 100-watt Hall thruster based on a permanent magnet. The thruster includes an anode and gas distributor 7, a plasma discharge channel, and a magnetic circuit structure. The plasma discharge channel is formed by a boron nitride ceramic sleeve 6, has an annular U-shaped cross-section, with the lower end being the working fluid (krypton) inlet and the upper end being the working fluid outlet.

[0022] The magnetic circuit structure includes an inner magnetic pole 1, an outer magnetic pole 2, an inner permanent magnet 4, and an outer permanent magnet 5. The inner permanent magnet 4 and the outer permanent magnet 5 together form a ring-shaped magnetic field configuration within the plasma discharge channel enclosed by the boron nitride ceramic sleeve 6, and form a zero magnetic field region near the central axis of the channel (here referring to the central axis of the discharge channel). This invention utilizes permanent magnet excitation, eliminating the need for an external excitation power supply, thus reducing system power consumption. Simultaneously, by confining electrons in the zero magnetic field region, it improves the ionization efficiency of the krypton working fluid, making it suitable for micro- and nano-satellite propulsion missions with power levels in the hundreds of watts.

[0023] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be described in further detail below.

[0024] like Figure 1 As shown, the magnetic circuit structure consists of an inner magnetic pole 1, an outer magnetic pole 2, an inner permanent magnet 4, an outer permanent magnet 5, and a base plate 3.

[0025] The inner magnetic pole 1 is mounted on the inner permanent magnet 4, and the outer magnetic pole 2 is mounted on the outer permanent magnet 5. The inner permanent magnet 4 is fixed between the inner magnetic pole 1 and the base plate 3, and the outer permanent magnet 5 is fixed between the outer magnetic pole 2 and the base plate 3. The inner permanent magnet 5 and the outer permanent magnet 6 respectively surround the ceramic sleeve 6, maintaining a certain gap. The anode and gas distributor 7 are located at the bottom of the discharge channel, used to inject the working gas and apply the anode voltage.

[0026] A polyimide insulating layer is wrapped between the inner magnetic pole and the inner permanent magnet, and between the outer magnetic pole and the outer permanent magnet, to ensure electrical insulation between the magnetic circuit components.

[0027] like Figure 2 As shown, the magnetic field lines within the plasma channel form a zero-magnetic-field region near the channel's central axis, with a magnetic field strength of approximately 14 Gs, far lower than the surrounding region's magnetic field strength. This zero-magnetic-field region effectively restricts the Hall drift path of electrons, forcing them to gyrate in this region, thereby significantly increasing their collision probability and energy with krypton atoms, and substantially improving ionization efficiency.

[0028] like Figure 3 As shown, the radial magnetic field strength exhibits a saddle-shaped distribution, meaning the magnetic field strength is lowest at the central axis of the channel and increases rapidly outwards radially. This magnetic field configuration helps confine electrons to the central region of the channel, forming an electron accumulation zone. This not only improves ionization efficiency but also effectively reduces ion erosion of the channel walls, thus extending the thruster's lifespan.

[0029] like Figure 4 As shown, under the conditions of discharge voltage 300V, current 2.4A, and krypton flow rate 25.0 sccm, the peak ion number density in the plasma channel can reach 2.0 × 10¹. 4m⁻³ indicates that the present invention has a high ionization capacity.

[0030] In some specific preferred embodiments, the inner permanent magnet 5 and the outer permanent magnet 6 are samarium cobalt magnets (Sm2Co17) to generate a sufficiently strong magnetic field in a small volume; the inner magnetic pole 1, the outer magnetic pole 2, the anode and the gas distributor 7 are made of non-magnetic stainless steel 06Cr19Ni10.

[0031] In summary, this invention, through innovative magnetic circuit design, utilizes permanent magnets to construct an optimized magnetic field configuration with zero magnetic field region characteristics, achieving efficient ionization, low power consumption, and long lifespan operation at 100 watt-level power. It is particularly suitable for next-generation micro-nano satellite platforms with strict requirements on size, power consumption, and lifespan.

[0032] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the nature and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention.

Claims

1. A 100-watt Hall thruster based on permanent magnets, characterized in that, Including an anode and gas distributor (7), a plasma discharge channel, and a magnetic circuit structure, characterized in that: The plasma discharge channel has an annular U-shaped cross-section, with the lower end being the working fluid inlet and the upper end being the working fluid outlet. The magnetic circuit structure includes an inner magnetic pole (1), an outer magnetic pole (2), an inner permanent magnet (4), and an outer permanent magnet (5); the inner permanent magnet (4) is fixed between the inner magnetic pole (1) and the base plate (3), and the outer permanent magnet (5) is fixed between the outer magnetic pole (2) and the base plate (3); The inner permanent magnet (4) and the outer permanent magnet (5) form a ring magnetic field configuration in the plasma discharge channel and form a zero magnetic field region at the central axis of the channel.

2. The 100-watt Hall thruster based on a permanent magnet according to claim 1, characterized in that, The plasma discharge channel is enclosed by a boron nitride ceramic sleeve (6).

3. A 100-watt Hall thruster based on a permanent magnet according to claim 1, characterized in that, The inner magnetic pole (1), outer magnetic pole (2) and base plate (3) are all made of magnetically conductive material.

4. A 100-watt Hall thruster based on a permanent magnet according to claim 1, characterized in that, The magnetic material is non-magnetic stainless steel 06Cr19Ni10.

5. A 100-watt Hall thruster based on a permanent magnet according to claim 1, characterized in that, The inner permanent magnet (4) and the outer permanent magnet (5) are samarium cobalt permanent magnets.

6. A 100-watt Hall thruster based on a permanent magnet according to claim 1, characterized in that, A polyimide insulating layer is provided between the inner magnetic pole (1) and the inner permanent magnet (4).

7. A 100-watt Hall thruster based on a permanent magnet according to claim 1, characterized in that, A polyimide insulating layer is provided between the outer magnetic pole (2) and the outer permanent magnet (5).

8. A 100-watt Hall thruster based on a permanent magnet according to claim 1, characterized in that, The anode and gas distributor (7) is located at the bottom of the plasma discharge channel.

9. A 100-watt Hall thruster based on a permanent magnet according to claim 1, characterized in that, The radial magnetic field strength distribution of the plasma discharge channel is saddle-shaped; the magnetic field strength is lowest near the central axis of the channel.

10. A 100-watt Hall thruster based on a permanent magnet according to claim 1, characterized in that, Under operating conditions of 300V discharge voltage, 2.4A discharge current, and 25.0mg / s anode gas flow rate, the thruster achieved a peak ion number density of 2.0×10¹ in the plasma channel. 4 m⁻³.

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