An external discharge Hall thruster with planar field-shaping

Abstract

The application provides an external discharge Hall thruster with a planar shearing magnetic field design, which comprises a thruster structure body, an outer ring magnet, a thruster ceramic wall, an additional anode, an outer magnet, a magnetic screen, an anode, a ceramic structure body, an inner magnet, a short insulating pad, an M2 flat washer, an M2 elastic washer, an M2 nut, a long insulating pad, an M3 flat washer, an M3 elastic washer and an M3 nut. The application increases permanent magnets outside the additional anode to form a new magnetic mirror field to confine electrons, reduces the current of the additional anode, adjusts the magnetic field near the surface of the anode to make the positive gradient magnetic field on the surface of the anode, weakens the bombardment and heating of the electrons during the operation of the anode, improves the heating of the thruster and the demagnetization of the permanent magnet, increases the insulation between the anode and the additional anode, and improves the service life and reliability of the thruster.

Description

Technical Field

[0001] This invention belongs to the field of space electric propulsion technology, and in particular relates to an external discharge Hall thruster that employs a planar tangential magnetic field design. Background Technology

[0002] With the rise of commercial spaceflight and the reduction in satellite launch costs, a wave of microsatellite networking has swept the world. The need for precise control of microsatellites has placed new demands on the miniaturization and low-power design of commonly used electric thrusters on satellites. Hall thrusters have advantages such as simple structure, absence of space charge effect, higher specific impulse than chemical propulsion, higher thrust density than ion thrusters, and longer lifespan. They are currently widely used in the attitude and orbit control of spacecraft and have become an important research subject for the miniaturization and low-power design of electric thrusters.

[0003] Traditional Hall thrusters, including stationary plasma thrusters (SPT) and anode layer thrusters (ALT), have discharge channels made of ceramic or metal. When thrusters are miniaturized, the surface-to-volume ratio of the discharge channel increases, leading to increased plasma erosion of the channel walls and reduced thruster lifespan. This has become a key problem to be overcome in the miniaturization design of Hall thrusters.

[0004] The external discharge Hall thruster with the discharge channel eliminated is a solution to solve the wall erosion of Hall thrusters and extend the life of thrusters. However, due to the lack of discharge channel restrictions, the beam divergence angle of the thruster is larger than that of the traditional Hall thruster. This not only causes a large non-axial thrust loss, but also poses a challenge to the safe operation of other instruments and equipment on the satellite. At the same time, when the thruster selects a large working fluid flow rate, the thruster oscillation intensifies, threatening the normal operation of the satellite. To solve the above problems, Princeton University in the United States proposed a solution of adding an additional anode outside the anode of the Hall thruster, and confirmed its effect on suppressing oscillation and reducing the beam divergence angle. The additional anode applies a positive voltage to the outside of the anode, which increases the positive potential at the edge of the beam and has a certain compression effect on the ion beam, thus reducing the beam divergence angle of the thruster. At the same time, the experiment also found that adding an additional anode can reduce the oscillation of the anode. The present invention will not discuss the effect of the additional anode in detail. For details, please refer to reference [1]. However, a certain current will be generated on the additional anode, which increases the load on the satellite power supply and violates the original intention of the low-power design of the thruster. Meanwhile, metal atoms sputtered from the anode can flow back and deposit onto the walls of the thrust anode and auxiliary anode. When the deposition reaches a certain thickness, it can cause conductivity between the anode and auxiliary anode, resulting in a short circuit in the thruster, which is detrimental to thruster control and satellite safety. Therefore, comprehensive optimization of the external discharge Hall thruster should be carried out to reduce the auxiliary anode current and improve the thruster's operational reliability.

[0005] Currently, no publicly available literature describes methods for reducing the additional anode current and its power consumption. Furthermore, there is limited work on optimizing the magnetic field near the anode of external Hall thrusters, and no publicly published research results have been found on this topic. Similar solutions exist in other areas of electric propulsion to avoid reduced resistance between insulating components due to coating.

[0006] 1. A sputter-contamination-resistant, insulation-enhanced gate system: Sputtering of the gate and accelerating gate in a radio frequency ion thruster can lead to reduced inter-gate resistance and gate arcing, resulting in thruster performance loss. To address this issue, Wang Weizong, Fu Chencong, and others from Beijing University of Aeronautics and Astronautics pointed out that increasing the surface area of ​​the inter-gate separator and artificially creating areas on the surface of the separator that are difficult for metal atoms to cover can reduce the probability of arcing caused by reduced inter-gate resistance. [3] .

[0007] 2. Tangential Field Configuration Electric Thruster: Currently, thrusters using tangential magnetic fields to confine electrons for ionization exist. These thrusters have a wall, with the magnetic interface of the tangential magnetic field perpendicular to the cylindrical wall. Multiple magnetic interfaces exist within the channel, forming a multi-stage tangential magnetic field configuration. The anode is located at the bottom of the channel, and the cathode is located outside the channel entrance. After entering the channel from the cathode, electrons are subjected to electric force and confined by the magnetic mirror field (spiral oscillation) and radial magnetic field lines near the magnetic interface (EXB drift). The tangential field configuration significantly extends the path of electrons to the anode, increasing the thruster's ionization rate and improving its overall performance. However, this type of tangential field thruster uses a tangential magnetic field to increase the confinement level of electrons within the channel and improve the ionization rate. It is designed within the channel rather than on a plane and does not have an additional anode, making it structurally and objectively different from this invention. [2] .

[0008] The auxiliary anode is an anode located outside the anode region, which influences the beam current through the application of voltage. The auxiliary anode region is not the primary area of ​​ionization. Furthermore, in existing planar external discharge Hall thrusters, the magnetic field near the anode often has a negative gradient, and the magnetic induction intensity at the anode surface is relatively high, which is detrimental to reducing anode heating. The specific shortcomings of existing external discharge Hall thruster technology with auxiliary anodes are as follows:

[0009] 1. The currently disclosed additional anode current is relatively large compared to the anode current, and in some operating conditions it even exceeds the anode current [1], see Figure 2a and Figure 2b The voltage magnitude at the additional anode is close to that at the anode, meaning that although the additional anode does not directly provide energy for ionization, it consumes a significant portion of the energy. The large current generated at the additional anode is due to the weak radial magnetic field above it, resulting in insufficient magnetization of electrons. A large number of electrons are attracted directly to the additional anode. Appropriately strengthening the radial magnetic field above the additional anode can improve its magnetic shielding and reduce the anode current.

[0010] 2. The anode and auxiliary anode are prone to conduction. Experiments revealed that when the anode is made of stainless steel that is not resistant to sputtering, atoms sputtered from the anode surface easily deposit between the auxiliary and anodes, forming a conductive metal film that significantly reduces the resistance between the two anodes. However, during thruster operation, the potentials of the anode and auxiliary anode often differ, creating a conductive path between them. This poses a significant risk to thruster performance control and the safe operation of the satellite.

[0011] 3. In existing planar Hall thrusters, since the discharge region is located outside the magnetic end face, the commonly used magnetic field configuration is a negative gradient. This configuration moves the region with the strongest magnetic field to the anode surface, resulting in strong electron EXB drift near the anode, a large potential gradient, and accelerated electron bombardment of the anode surface due to the large potential difference. This leads to a strong thermal effect on the anode surface and severe demagnetization of the permanent magnets near the anode and ionization region. Currently, magnetic field post-loading techniques to address this problem are mostly applied to Hall thrusters with channels, such as stationary plasma thrusters (SPT). No publicly disclosed design enables post-loading of the magnetic field in an externally discharged Hall thruster.

[0012] In summary, existing external discharge Hall thrusters employing additional anodes are prone to problems such as high additional anode power, short circuits between the additional anode and the anode, and thruster overheating leading to magnet demagnetization. This reflects the need for further optimization of existing external discharge plasma configurations. This invention, through innovative changes to the magnetic field configuration and wall structure, can optimize the aforementioned problems.

[0013] References:

[0014] [1]Simmonds J,Raitses Y. Mitigation of breathing oscillations and focusing of the plume in a segmented electrode wall-less Hall thruster[J].Applied Physics Letters, 2021,119(21).

[0015] [2]Hu P, Liu H, Mao W, et al. The effects of magnetic field in plumeregion on the performance of multi-cusped field thruster[J]. Physics of Plasmas, 2015, 22(10).

[0016] Related patent applications:

[0017] [3] Wang Weizong, Fu Chencong, Li Yifei, et al. An insulating reinforced gate system resistant to sputter contamination [P]. China. Invention Patent Application 202210185048.9;

[0018] [4] Wang Weizong, Dong Yicheng, Kong Weiyi, et al. A radio frequency ion thruster ionization chamber wall cleaning system and method [P]. China. Invention Patent Application. 202310886668.X. Summary of the Invention

[0019] In recent years, the rise of international microsatellite constellations has placed new demands on the miniaturization of satellite electric propulsion systems. External discharge Hall thrusters have been extensively studied in recent years as a result of this trend, while external discharge Hall thrusters with additional anode configurations have emerged later and have received less research. Many problems in this field remain unresolved, and many potential technical challenges have yet to be discovered.

[0020] This invention reduces the additional anode current by adding a permanent magnet to the outside of the additional anode to form a new magnetic mirror field to constrain electrons; by adjusting the magnetic field near the anode surface to create a positive gradient magnetic field on the anode surface, the bombardment heating of electrons during anode operation is weakened, improving thruster heating and permanent magnet demagnetization; and by increasing the insulation between the anode and the additional anode, the lifespan and reliability of the thruster are improved.

[0021] The purpose of this invention is to solve the following problems:

[0022] 1. Solve the problem of high additional anode current and power consumption in external discharge Hall thrusters with additional anode design.

[0023] 2. Solve the problem that the additional anode shielding magnetic ring on the outer ring of the thruster is difficult to process and easy to be damaged during installation.

[0024] 3. Solve the problem of easy short circuits in the anode and auxiliary anode of the external discharge Hall thruster with an auxiliary anode design.

[0025] 4. Solve the problems of excessive magnetic induction intensity near the anode leading to severe electron bombardment of the anode and excessive thrust thermal effect leading to magnet demagnetization.

[0026] Therefore, this invention proposes an external discharge Hall thruster that employs a planar tangential magnetic field, features an anode-additional anode-to-anode insulation design, and applies a post-loaded magnetic field to the anode surface. Specifically, it employs an external discharge Hall thruster with a planar tangential magnetic field design, such as... Figure 3 , Figure 4a and Figure 4b As shown.

[0027] The present invention includes a thruster structure 6, an outer ring magnet 7 (32 magnets evenly distributed around the circumference), a thruster ceramic wall 8, an additional anode 9, an outer magnet 10, a magnetic screen 11, an anode 12, a ceramic structure 13, an inner magnet 14, a short insulating pad 15, an M2 flat washer 16, an M2 elastic washer 17, an M2 nut 18, a long insulating pad 19, an M3 flat washer 20, an M3 elastic washer 21, and an M3 nut 22.

[0028] Among them, the thruster structure 6 is made of cast aluminum alloy which is easy to manufacture by 3D printing; the outer ring magnet 7, outer magnet 10, and inner magnet 14 are made of samarium cobalt permanent magnets with a samarium cobalt ratio of 2:17; the auxiliary anode 9 and anode 12 are made of stainless steel; the magnetic screen 11 is made of silicon steel; the thruster ceramic wall 8 and ceramic structure 13 are made of boron nitride ceramic; the short insulating pad 15 and long insulating pad 19 are made of alumina ceramic; the M2 flat washer 16, M2 elastic washer 17, M2 nut 18, M3 flat washer 20, M3 elastic washer 21, and M3 nut 22 are all commercially available standard parts. When assembling the thruster, based on the thruster structure 6, the outer magnet 10, ceramic structure 13, inner magnet 14, magnetic screen 11, 32 outer ring magnets 7, and thruster ceramic wall 8 are assembled sequentially. Finally, short insulating pads 15, M2 flat washers, M2 spring washers, and M2 nuts are used to ensure the insulation and fixation of the additional anode 9 to the thruster structure 6, while long insulating pads 19, M3 flat washers, M3 spring washers, and M3 nuts are used to ensure the insulation and fixation of the anode 12 to the thruster structure 6 assembly. The specific assembly process is described at the end of the document.

[0029] Currently, based on experimental phenomena obtained from performance testing experiments of external discharge Hall thrusters with additional anodes and published literature, it can be determined that the additional anode has the effect of reducing the thruster divergence angle and suppressing oscillations. This is the technical background of this invention. However, when the additional anode is directly located at the edge of the thruster, the working gas number density above it is low, and the additional anode contributes little to ionization. But when it is located outside the additional anode, electrons drawn from the cathode need to cross the top of the additional anode along magnetic field lines to reach the ionization region near the anode. During this movement, they are attracted by the positive potential of the additional anode and flow away directly from the additional anode without participating in ionization, resulting in a larger current and higher additional power. Adding an outer ring magnet 7 and a magnetic mirror field outside the thruster, see... Figure 5a This confines more electrons above the auxiliary anode, reducing the auxiliary anode current. Simultaneously, to facilitate processing, assembly, and cost reduction, corresponding circular grooves are cut into the thruster structure 6 and the thruster ceramic wall 8, and 32 cylindrical outer ring magnets 7 are circumferentially fixed therein, as shown in Figures 6 and 7. Figure 10 As shown, instead of using a single magnetic ring.

[0030] By adjusting the geometric parameters and spatial arrangement of the permanent magnets and employing a magnetic screen design, a certain magnetic field post-loading phenomenon can be achieved in the near-anode region. This ensures that the magnetic flux density is at a level sufficient to effectively confine electrons during EXB drift, while simultaneously moving the location of the maximum magnetic flux density 2–4 mm away from the anode. Figure 5b This design can push areas with larger electric field gradients away from the anode, reducing electron bombardment, heat generation, and mitigating demagnetization of the permanent magnet. Due to the use of an additional anode and a flat plate configuration, the effects of anode ion sputtering, atomic deposition, and the wall surface increase the likelihood of metal atoms depositing between the two anodes, leading to anode conductivity. This invention, based on data from the atomic free path at different locations, designs two annular grooves on the ceramic wall surface, see... Figure 7c They believe that increasing the atomic deposition area and difficulty improves the conductivity between the two anodes.

[0031] The beneficial effects of this invention compared to the prior art are as follows:

[0032] 1. Compared with external discharge Hall thrusters using additional anodes, by adding permanent magnets outside the additional anode, a new magnetic mirror field is formed to constrain electrons, creating a tangential magnetic field distributed in concentric rings on the plane. This reduces the additional anode current and power, thereby increasing the proportion of anode power used for ionization and improving thruster efficiency.

[0033] 2. Compared with existing external discharge Hall thrusters, a positive gradient configuration is formed on the anode surface, which weakens the electric field gradient on the anode surface. This innovatively achieves a post-loading effect in external discharge Hall thrusters, reducing the degree of electron bombardment of the anode surface, reducing thruster heating, and improving permanent magnet demagnetization.

[0034] 3. The use of an insulating trench design increases the insulation between the anode and the auxiliary anode, preventing conduction between the two anodes and improving the thruster's service life and reliability.

[0035] 4. This invention uses a design that replaces the entire magnetic ring with small magnets arranged circumferentially, which facilitates processing and assembly and reduces costs.

[0036] 5. This invention helps to improve the overall performance of external discharge Hall thrusters and promote their engineering and practical application. Attached Figure Description

[0037] Figure 1 This is a schematic cross-sectional view of a sputter-resistant, insulating, enhanced gate system.

[0038] Figure 2a This is a structural diagram of a field-cutting thruster.

[0039] Figure 2bIt is the beam extracted from the field thruster.

[0040] Figure 3 This is a schematic diagram of an external discharge Hall thruster that cuts the magnetic field.

[0041] Figure 4a It is a cross-sectional view of the assembly diagram.

[0042] Figure 4b It is a side-view or bottom view of the assembly diagram.

[0043] Figure 5a This is a cross-sectional view of the magnetic field distribution above the anode of this invention.

[0044] Figure 5b It is the magnetic flux density mode above the anode of the magnetic field distribution above the anode in this invention.

[0045] Figure 6a This is a side-top view of the thruster structure.

[0046] Figure 6b This is a side-bottom view of the thruster structure.

[0047] Figure 7a This is a side-top view of a schematic diagram of a ceramic wall surface.

[0048] Figure 7b This is a side-bottom view of a schematic diagram of a ceramic wall surface.

[0049] Figure 7c This is a cross-sectional view of a schematic diagram of a ceramic wall surface.

[0050] Figure 8 This is an anode axial view.

[0051] Figure 9 This is an additional anode axial view.

[0052] Figure 10 This is an exploded image of the thruster.

[0053] Figure 11 It refers to the matching relationship between long and short insulating pads in the thruster.

[0054] Figure 12 This is an axonometric view of a ceramic structure.

[0055] Figure 13 This is a diagram showing the ratio of additional anode power between thrusters designed using this invention and thrusters not designed using this invention.

[0056] The labels in the diagram are explained as follows:

[0057] 1. Bowl-shaped acceleration grid; 2. Inter-grid insulation; 3. Screen grid.

[0058] 4 Accelerator vent 5 Sputter-resistant insulating trench 6 Thrust structure

[0059] Outer ring magnets 7 (32 evenly distributed around the circumference) Thrust ceramic wall 8

[0060] Additional anode 9, external magnet 10, magnetic shield 11

[0061] Anode 12, Ceramic Structure 13, Internal Magnet 14

[0062] Short insulating pad 15 M2 flat washer 16 M2 elastic washer 17

[0063] M2 nut 18, long insulating washer 19, M3 flat washer 20.

[0064] M3 elastic washer 21 M3 nut 22 Detailed Implementation

[0065] This invention allows for the adjustment of numerous electrical parameters, among which the selection of anode voltage and auxiliary anode is crucial. Based on the selection of anode voltage in already disclosed miniaturized Hall thrusters and combined with experimental measurements, it is believed that to achieve thrust in the "mN" range, the anode voltage can be varied between 150 and 400 V with a xenon flow rate of 2–10 sccm. The auxiliary anode voltage should not be too high and can be selected within the range of 100–300 V, which is lower than the anode voltage. The selection of cathode parameters is beyond the scope of this invention.

[0066] Installation process of this invention:

[0067] When assembling the thruster, based on the thruster structure 6, first assemble the outer magnet 10 and the ceramic structure 13 according to... Figure 4a The assembly shown (ignoring internal details of anode 12) is placed in the cylindrical cavity in the center of thruster structure 6 (see Figure 6), noting that the hole on ceramic structure 13 should be aligned with the hole on thruster structure 6; the inner magnet 14 is placed in the central groove of the ceramic structure (see Figure 6). Figure 12 Then, the magnetic screen 11 is placed between the inner and outer magnets, making close contact with the ceramic structure 13; the 32 outer ring magnets 7 are then placed into the slots of the thruster structure 6 in sequence, and the magnetic screen 11, outer magnets 10, and 32 outer ring magnets 2 are pressed together by the ceramic wall 8 of the thruster. Note that the holes on the ceramic wall 8 (see Figure 7) should be aligned with the corresponding holes on the thruster structure 6 and the ceramic structure 13, and the 32 outer ring magnets should be inserted into the circumferential slots on the lower side of the ceramic wall 8 (see Figure 7). Figure 7b Finally, the pins of anode 12 and auxiliary anode 4 are passed through the corresponding holes on the ceramic wall 8, ceramic structure 13, and thruster structure 6. Anode 12 has two pins (see...). Figure 8Insulation and fixation are ensured by two long insulating pads 19, M3 flat washers 20, M3 elastic washers 21, and M3 nuts 22. The two leads of the additional anode 9 (see...) Figure 9 The mating relationship between the long and short insulating pads is shown in the diagram. The components are: two short insulating pads 15, an M2 flat washer 16, an M2 elastic washer 17, and an M2 nut 18. Figure 11 The longer pin of the anode is hollow and used to connect to the gas path, while the other pin is used to connect to the circuit. The two pins of the auxiliary anode are both connected to another power source; the circuit design is beyond the scope of this invention. The assembly relationship of the entire thruster is shown in [reference needed]. Figure 10 .

[0068] The ground-based experimental operation procedure of this invention is as follows:

[0069] Assemble the thruster in the order described above → Connect the circuits of thruster anode 12 and auxiliary anode 9 → Connect the gas path on the long pin of anode 12 → Enter the vacuum chamber for the thruster → Evacuate the vacuum → Intake gas into thruster anode 12 → Apply positive voltage to main anode 12 to the given value → Turn on cathode and ignite thruster → Apply positive voltage to auxiliary anode 9 to the given value → Turn off power to auxiliary anode 9 → Turn off cathode → Turn off power to anode 12 → Turn off gas path to anode 12 → Break the vacuum in the vacuum chamber → Disassemble the thruster circuit and gas path, and store the thruster properly.

[0070] The positive voltage phases on anode 12 and auxiliary anode 9 of this invention refer to the positive voltage generated relative to the common ground of the thruster circuit. The design of the external circuit of the thruster is not within the scope of this invention.

[0071] Typical operating conditions of this invention:

[0072] With an anode voltage of 250V, a flow rate of 6 sccm, an additional anode voltage of 200V, and a cathode flow rate of 4 sccm, the main anode current is approximately 0.5A, and the additional anode current can be kept below 50mA, which is less than the current of the additional anode without the outer ring magnet 2 (in the 100mA range). This reduces the proportion of power consumed by the additional anode in the total power. The results of the proportion of additional anode power in the total power (anode power + additional anode power) under different additional anode voltages are shown below. Figure 13 .

[0073] In the design of this invention, a positive bias voltage is applied to the auxiliary anode, thus enabling it to function as an anode. However, if the auxiliary anode voltage is made adjustable, the operating range of the thruster can be increased, and the robustness of the thruster's regulation and control can be improved.

[0074] Specifically, the method described in patent application [4] can be used to innovatively clean the metal coating in an external discharge Hall thruster. If a negative voltage is applied to the additional anode, the coating area in contact with the additional anode may also be subjected to a negative voltage. Positively charged ions will be attracted and collide with the coating area. With reasonable control to limit the degree of sputtering of the wall substrate material, the effect of the wall coating on the thruster may be eliminated to a certain extent, thus extending the thruster's lifespan.

[0075] The design of the thruster's magnetic field can be further improved through experiments, and magnets with higher remanence and temperature resistance can be used in accordance with technological advancements to enhance the rationality and reliability of the thruster's magnetic field design.

Claims

1. An external discharge Hall thruster employing a planar tangential magnetic field design, characterized in that: The assembly includes a thruster structure, outer ring magnets, thruster ceramic wall, additional anode, outer magnet, magnetic shield, anode, ceramic structure, inner magnet, short insulating pad, M2 flat washer, M2 elastic washer, M2 nut, long insulating pad, M3 flat washer, M3 elastic washer, and M3 nut. Based on the thruster structure, the outer magnet, ceramic structure, inner magnet, magnetic shield, 32 outer ring magnets, and thruster ceramic wall are assembled sequentially. Finally, short insulating pads, M2 flat washers, M2 spring washers, and M2 nuts ensure insulation and fixation between the additional anode and the thruster structure, while long insulating pads, M3 flat washers, M3 spring washers, and M3 nuts ensure insulation and fixation between the anode and the thruster structure assembly. In this design, corresponding circular grooves are cut into the thruster structure and the ceramic wall of the thruster, and a cylindrical outer ring magnet is fixed circumferentially, instead of using an integral magnetic ring; Place the external magnet and ceramic structure into the cylindrical cavity in the center of the thruster structure, and align the holes on the ceramic structure with the holes on the thruster structure. The inner magnet is placed in the central groove of the ceramic structure; then the magnetic screen is placed between the inner and outer magnets, making close contact with the ceramic structure.

2. The external discharge Hall thruster with a planar tangential magnetic field design according to claim 1, characterized in that: The thruster structure is made of cast aluminum alloy, which is easy to manufacture by 3D printing; the outer ring magnet, outer magnet, and inner magnet are made of samarium cobalt permanent magnets with a samarium cobalt ratio of 2:17; the auxiliary anode and anode are made of stainless steel; the magnetic screen is made of silicon steel; the thruster ceramic wall and ceramic structure are made of boron nitride ceramic; and the short insulating pad and long insulating pad are made of alumina ceramic.

3. The external discharge Hall thruster with a planar tangential magnetic field design according to claim 1, characterized in that: Place the 32 outer ring magnets into the slots in the thruster structure in sequence, and use the ceramic wall of the thruster to press the magnetic screen, outer magnets and 32 outer ring magnets together. The holes on the ceramic wall should be aligned with the corresponding holes on the thruster structure and the ceramic structure. The 32 outer ring magnets should be inserted into the circumferential slots on the lower side of the ceramic wall.

4. An external discharge Hall thruster with a planar tangential magnetic field design according to claim 1, characterized in that: The leads of the anode and the auxiliary anode are passed through corresponding holes in the ceramic wall, ceramic structure, and thruster structure. The anode has two leads and is insulated and fixed by two long insulating pads, an M3 flat washer, an M3 elastic washer, and an M3 nut.

5. An external discharge Hall thruster employing a planar tangential magnetic field design according to claim 1 or 4, characterized in that: The two pins of the auxiliary anode are connected by two short insulating pads, an M2 flat washer, an M2 elastic washer, and an M2 nut; the longer pin of the anode is hollow and used to connect to the gas path, while the other pin of the anode is used to connect to the circuit; both pins of the auxiliary anode are connected to another power source.

6. An external discharge Hall thruster with a planar tangential magnetic field design according to claim 5, characterized in that: A positive bias voltage is applied to the auxiliary anode, which can act as an anode; the positive voltage on both the anode and the auxiliary anode refers to the positive voltage generated relative to the common ground of the thruster circuit.

7. An external discharge Hall thruster employing a planar tangential magnetic field design according to claim 1, 2, 3, or 4, characterized in that: With xenon flow rate between 2 and 10 sccm, the anode voltage varies between 150 and 400V; the additional anode voltage is selected within the range of 100 to 300V.

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