A sputter-resistant shield assembly for a hall thruster

Abstract

The application discloses a sputtering-resistant protection assembly of a Hall thruster, and belongs to the technical field of space electric propulsion.The application is aimed at solving the problems of easy sputtering failure, insufficient connection reliability, poor anti-mechanical and thermal cycle environment capability and possible channel pollution caused by the protection structure based on edge fixation.The assembly is respectively composed of a graphite protection cap and a metal cap, and a graphite protection cap and a pure iron inner magnetic pole for the two Hall thruster configurations of permanent magnet and coil excitation.The core of the application is that the graphite protection cap is connected with the lower component through a mechanical locking structure arranged at the center of the assembly, and the connecting point is completely covered by the graphite protection cap, so that the ion sputtering erosion of the connecting structure is fundamentally avoided.In order to further improve the reliability, a brazing layer or a high-temperature-resistant inorganic glue layer is arranged between the contact surfaces on the basis of the mechanical connection, so that a double fixation strategy of "mechanical + chemical" is formed, and the severe vibration of the rocket launching and the high and low temperature thermal cycle in the on-orbit operation can be effectively resisted.

Description

Technical Field

[0001] This invention relates to the field of aerospace electric propulsion technology, and more specifically, to a splash-proof protection component for the magnetic poles inside a Hall thruster. Background Technology

[0002] As a core technology of modern spacecraft electric propulsion systems, Hall thrusters, with their high specific impulse and high energy conversion efficiency, have become a key propulsion method for spacecraft attitude control, orbit maintenance, and deep space exploration missions. However, during operation, the high-energy ion beam generated in the discharge channel of a Hall thruster continuously bombards the inner magnetic pole assembly located at the bottom of the channel, leading to two critical issues that urgently need to be addressed: first, sputtering corrosion of the inner magnetic pole material, which, over time, will damage the geometry and functional integrity of the precision magnetic circuit; second, the heat accumulation effect caused by the bombardment may lead to irreversible demagnetization of the magnetic material, especially in permanent magnet thrusters, due to overheating, resulting in thruster performance degradation or failure.

[0003] To address the aforementioned problems, existing technologies typically employ protective cover plates. For example, Chinese patent CN114320802B discloses a graphite protective cover plate solution for a Hall thruster. This solution uses an upward-flanged structure made of titanium alloy to wrap around and braze the edge of the graphite cover plate, forming a "titanium alloy-wrapped graphite" configuration. This solution directly exposes the core titanium alloy fixing structure to the edge region most severely bombarded by the ion beam, making it the primary target of sputtering erosion. Experiments show that the titanium alloy flange is severely eroded and fails after several hundred hours of discharge, causing the entire protective structure to lose its fixation.

[0004] Furthermore, this design, which embeds graphite within a titanium alloy top cover and connects them via edge brazing, has a fatal weakness in the extreme environments of spaceflight: During the intense vibrations of rocket launch, this brittle edge-brazed joint is prone to cracking due to its cantilevered structure; during on-orbit operation, the spacecraft's frequent entry into and exit from sunlight causes components to undergo extreme high and low temperature cycles (the Hall thruster's temperature is below -100 degrees Celsius on the shaded side and above 100 degrees Celsius on the sunlit side). The significant difference in thermal expansion coefficients between graphite and titanium alloy generates repeated alternating thermal stress at the brazing interface, easily leading to fatigue and detachment of the brazed layer. Once the brazing fails, the entire protective cover will only be maintained by physical enclosure, resulting in extremely low reliability.

[0005] Meanwhile, since the sputtering rate of titanium alloy is significantly higher than that of graphite, its sputtering products will contaminate the insulating wall surface of the discharge channel, forming a conductive deposition film. In severe cases, this can induce abnormal discharge in the channel (i.e., "arcing"), directly threatening the stable operation of the thruster.

[0006] Therefore, the existing edge-wrapping brazing solution has a mismatch between the roles of the fixing structure and the protective structure, and the connection method cannot simultaneously adapt to the two very different extreme environmental challenges of launch vibration and on-orbit thermal cycling, which fundamentally limits its reliability and lifespan. Summary of the Invention

[0007] To address the inherent problems of edge-fixed protective structures, such as susceptibility to sputtering failure, insufficient connection reliability, poor resistance to mechanical and thermal cycling environments, and potential channel contamination, this invention provides a sputtering protection component for Hall thrusters.

[0008] In one aspect, the present invention provides a splash-proof protection component for a Hall thruster, used for the protection of the inner magnetic poles of a permanent magnet Hall thruster, comprising a graphite protective cap 1 and a metal cap 2, wherein the graphite protective cap 1 is fully covered on the top of the metal cap 2; and the metal cap 2 is fully covered and fastened to the permanent magnet 4 of the Hall thruster.

[0009] The graphite protective cap 1 includes a graphite protective cap body 1-1;

[0010] The metal cap 2 includes a metal cap top plate 2-1, a metal cap side wall 2-2, and an inner permanent magnet fixing post 2-4; there is a radial gap between the metal cap side wall 2-2 and the permanent magnet 4 fastened inside;

[0011] The bottom edge of the graphite protective cap body 1-1 is chamfered to form a chamfered bottom edge 1-3, which is then fully covered and fastened to the metal cap top plate 2-1.

[0012] The graphite protective cap body 1-1 and the metal cap top plate 2-1 are mechanically connected at the center by a mechanical locking structure;

[0013] The joint surfaces of the graphite protective cap body 1-1 and the metal cap top plate 2-1 are further fixed by an auxiliary fixing layer.

[0014] Preferably, the mechanical locking structure between the graphite protective cap body 1-1 and the metal cap top plate 2-1 is a threaded connection, and the connection is completed using any of the following methods:

[0015] Method 1: A graphite external threaded connecting post 1-2 is provided at the center of the bottom surface of the graphite protective cap body 1-1, and an internal threaded hole 2-3 is provided at the center of the top of the metal cap top plate 2-1. The graphite external threaded connecting post 1-2 and the internal threaded hole 2-3 of the top plate are threaded together for connection.

[0016] Method 2: The bottom center of the graphite protective cap body 1-1 is provided with a graphite internal thread hole 1-4, and the top center of the metal cap top plate 2-1 is provided with a top plate external thread connecting post 2-5. The graphite internal thread hole 1-4 and the top plate external thread connecting post 2-5 are threaded together for connection.

[0017] Preferably, it also includes an inner permanent magnet fixing column 2-4, with the inner permanent magnet fixing column 2-4 disposed at the center of the bottom surface of the metal cap plate 2-1, and the inner permanent magnet fixing column 2-4 being used for mechanical connection with the Hall thruster permanent magnet bracket 5.

[0018] Preferably, the metal cap 2 is made of titanium or a titanium alloy.

[0019] Preferably, the graphite protective cap body 1-1 is fully covered and fastened to the metal cap top plate 2-1 in the following manner: the bottom edge of the graphite protective cap body 1-1 is chamfered, the top edge of the metal cap top plate 2-1 is chamfered, and the outer diameter of the bottom edge of the graphite protective cap body 1-1 is larger than the outer diameter of the top edge of the metal cap top plate 2-1.

[0020] Preferably, the auxiliary fixing layer is a brazing layer or an inorganic adhesive layer that can withstand temperatures above 500°C.

[0021] In another aspect, the present invention provides a splash protection component for Hall thrusters, used for the protection of the inner magnetic poles of excitation coil Hall thrusters, including a graphite protective cap 1, which is fully covered on the top of the inner magnetic poles 3 of the Hall thruster.

[0022] The graphite protective cap 1 includes a graphite protective cap body 1-1;

[0023] The bottom edge of the graphite protective cap body 1-1 is chamfered to form a chamfered bottom edge 1-3, which is then fully covered and fastened to the top of the inner magnetic pole 3.

[0024] The graphite protective cap body 1-1 and the inner magnetic pole 3 are mechanically connected at the center by a mechanical locking structure;

[0025] The graphite protective cap body 1-1 and the inner magnetic pole 3 are fixed in place by an auxiliary fixing layer.

[0026] Preferably, the mechanical locking structure between the graphite protective cap body 1-1 and the inner magnetic pole 3 is a threaded connection, and the connection is completed using any of the following methods:

[0027] Method 1: A graphite external threaded connecting post 1-2 is provided at the center of the bottom surface of the graphite protective cap body 1-1, and an internal threaded hole is provided at the center of the top of the inner magnetic pole 3. The graphite external threaded connecting post 1-2 and the internal threaded hole at the top of the inner magnetic pole 3 are threaded together for connection.

[0028] Method 2: The bottom center of the graphite protective cap body 1-1 is provided with a graphite internal thread hole 1-4, and the top center of the inner magnetic pole 3 is provided with an inner magnetic pole external thread connecting post. The graphite internal thread hole 1-4 and the inner magnetic pole external thread connecting post are threaded together for connection.

[0029] Preferably, the inner magnetic pole 3 of the Hall thruster is made of pure iron.

[0030] Preferably, the graphite protective cap body 1-1 is fully covered and fastened to the inner magnetic pole 3 in the following manner: the bottom edge of the graphite protective cap body 1-1 is chamfered, the top edge of the inner magnetic pole 3 is chamfered, and the outer diameter of the bottom edge of the graphite protective cap body 1-1 is larger than the outer diameter of the top edge of the inner magnetic pole 3.

[0031] Preferably, the auxiliary fixing layer is a brazing layer or an inorganic adhesive layer that can withstand temperatures above 500°C.

[0032] The beneficial effects of this invention are:

[0033] 1. By moving the core fixing connection point from the vulnerable edge area to the protected central area, the present invention fundamentally eliminates the risk of the fixing structure itself failing first due to sputtering erosion, so that the lifespan of the protective component is no longer limited by the fixing component.

[0034] 2. The dual-fixation strategy adopted in this invention, combining a central mechanical connection with auxiliary fixation, refers to a structure that uses welding / adhesion to fix the metal cover plate to the graphite protective cap. This greatly improves the reliability of the connection structure, and the dual-fixation structure consistently demonstrates excellent vibration resistance and thermal cycling capabilities throughout the entire mission cycle. During the launch phase, the auxiliary fixation and mechanical locking work together to provide strong rigid support to resist severe vibrations. During on-orbit operation, in the early and middle stages of the on-orbit lifespan, the dual-fixation strategy ensures a tight bond between the graphite protective cap and the metal cover plate, resisting high and low temperature cycles. At the end of the lifespan, the mechanical connection provides the main constraint against thermal fatigue. Even if the auxiliary fixation layer degrades at the end of the lifespan, the mechanical connection still provides redundancy, perfectly adapting to the environmental challenges at different stages.

[0035] 3. By avoiding the exposure of easily sputtered metal materials in critical areas, the contamination of the discharge channel by highly conductive metal sputtering products is significantly reduced, which helps to reduce the risk of abnormal discharge and improve operational stability.

[0036] 4. Through the comprehensive thermal design of air gap thermal barrier and high radiation heat dissipation of graphite cap, the transfer of heat to permanent magnet is effectively suppressed, providing excellent thermal protection. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the anti-splashing protection component of a Hall thruster according to the present invention, used for the internal magnetic pole protection of a permanent magnet Hall thruster;

[0038] Figure 2 yes Figure 1 A cross-sectional view of AA, showing a threaded connection structure;

[0039] Figure 3 yes Figure 1 AA cross-sectional view, another threaded connection structure;

[0040] Figure 4 yes Figure 1 A schematic diagram of the protective components installed on the Hall thruster;

[0041] Figure 5 This is a schematic diagram of the anti-splash protection component of a Hall thruster according to the present invention, used for the protection of the inner magnetic poles of a coil-excited Hall thruster;

[0042] Figure 6 yes Figure 5 BB cross-sectional view.

[0043] Figure label:

[0044] 1. Graphite protective cap;

[0045] 1-1. Graphite protective cap body; 1-2. Graphite external thread connecting post; 1-3. Chamfered bottom edge; 1-4. Graphite internal thread hole;

[0046] 2. Metal cap;

[0047] 2-1. Metal cap top plate; 2-2. Metal cap side wall; 2-3. Internal threaded hole in top plate; 2-4. Internal permanent magnet fixing post; 2-5. External threaded connecting post in top plate.

[0048] 3. Inner magnetic pole; 3-1. Inner magnetic pole external threaded connection post;

[0049] 4. Permanent magnet;

[0050] 5. Permanent magnet support for Hall thruster. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0053] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0054] This invention, through its core design of "centrally protected connection" and "dual fixing strategy," successfully solves the fundamental problems of easy failure of edge fixing, poor reliability, and insufficient environmental resistance in the prior art, providing a long-life and highly reliable internal magnetic pole protection solution for two mainstream Hall thruster configurations.

[0055] Specific Implementation Method 1: The following is combined with... Figures 1 to 4 This embodiment describes a splash protection component for a Hall thruster, used for the protection of the inner magnetic poles of a permanent magnet Hall thruster. The component mainly consists of a graphite protective cap 1 and a metal cap 2.

[0056] The metal cap 2 is used to cover and protect the internal permanent magnet 4. The metal cap 2 is preferably made of titanium or titanium alloy and includes a metal cap top plate 2-1, metal cap sidewalls 2-2, and an inner permanent magnet fixing post 2-4 located at the center of the bottom surface of the top plate. The inner diameter of the metal cap sidewall 2-2 is designed to be larger than the outer diameter of the permanent magnet 4, forming a radial gap between them. This gap acts as a highly efficient thermal barrier, significantly increasing thermal resistance and effectively blocking the solid-state conduction path of heat through the metal cap 2 to the permanent magnet 4. This is a key design feature to prevent the permanent magnet from demagnetizing due to overheating.

[0057] The graphite protective cap 1 is mounted on top of the metal cap 2, and its core part is the graphite protective cap body 1-1. The bottom edge of the graphite protective cap body 1-1 is chamfered to form a chamfered bottom edge 1-3. The outer diameter of its bottom edge is designed to be larger than the outer diameter of the top edge of the metal cap top plate 2-1, thereby achieving full coverage and ensuring that the ion beam can only bombard the graphite material with excellent sputtering resistance.

[0058] The graphite protective cap body 1-1 and the metal cap top plate 2-1 are primarily connected by a mechanical locking structure located at their center. Specifically, this mechanical locking structure is a threaded connection, which can be implemented using one of the following two equivalent methods:

[0059] Method 1 (see) Figure 2 A graphite external threaded connecting post 1-2 is integrally set at the center of the bottom surface of the graphite protective cap body 1-1, and an internal threaded hole 2-3 is machined at the center of the top of the metal cap top plate 2-1. The connection is completed by tightening the two.

[0060] Method 2 (see) Figure 3 ): A graphite internal threaded hole 1-4 is machined at the center of the bottom surface of the graphite protective cap body 1-1. At the same time, an external threaded connecting post 2-5 is integrally set at the center of the top of the metal cap top plate 2-1. The connection is completed by tightening the two.

[0061] Threaded connections are a mature, reliable, and tensile / compressive mechanical connection method. Placing the threaded pair in a centrally protected area ensures its lifespan is synchronized with that of the graphite cap. Providing two interchangeable implementations (studs on graphite or metal) offers design flexibility, allowing selection of the optimal solution based on machining processes (e.g., the difficulty of tapping threads in graphite) or assembly sequence.

[0062] This center-threaded connection method moves the mechanical connection point from the edge, which is susceptible to ion bombardment, to the center, which is completely shielded by the graphite cap. This places the protected connection point outside the ion bombardment range, fundamentally solving the problem of traditional edge-fixed structures being easily corroded by sputtering. It also fundamentally avoids the problem of titanium alloy flanged structures, as seen in CN114320802B, failing prematurely due to sputtering corrosion. The excellent sputtering resistance of graphite is fully utilized, so the component lifespan is no longer limited by the lifespan of metal connectors.

[0063] To further enhance connection reliability to cope with the extreme aerospace environment, an auxiliary fixing layer is installed between the mating surfaces of the graphite protective cap body 1-1 and the metal cap top plate 2-1 after the central mechanical connection is completed. This auxiliary fixing layer can be a brazed layer or an inorganic adhesive layer resistant to temperatures above 500℃. This dual strategy of "central mechanical locking + auxiliary chemical fixing" constitutes a reliability guarantee throughout the entire mission cycle: During the rocket launch phase, the auxiliary fixing layer (brazing / adhesive bonding) and the mechanical connection work together to provide strong rigid support and impact resistance, effectively preventing loosening that may occur under severe vibration of the purely mechanical connection, ensuring the integrity of the launch phase; during on-orbit operation, the two work together to resist high and low temperature thermal cycling; the central mechanical threaded connection provides the main, reliable, and thermal fatigue-resistant constraint force. Even if the auxiliary fixing layer experiences stress, performance degradation, or local detachment due to the difference in thermal expansion coefficients between graphite and metal under long-term severe high and low temperature thermal cycling, the core mechanical threaded connection can still independently and effectively maintain the structural integrity and function of the entire component, providing crucial redundancy backup capability. This ensures connection reliability throughout the entire mission cycle.

[0064] In addition, see Figure 4 The entire protective assembly can be connected to the Hall thruster permanent magnet bracket 5 via the internal permanent magnet fixing columns 2-4. The connection to the permanent magnet bracket via a centralized connecting column is simple in structure, provides a clear force transmission path, and easily ensures coaxiality and perpendicularity after assembly. This is crucial for maintaining the uniformity of the air gap in the thruster's internal magnetic circuit. A standard interface is provided to securely install the entire protective assembly onto the thruster, ensuring the overall rigidity and positioning accuracy of the assembly within the thruster.

[0065] The graphite protective cap body 1-1 is fully fastened to the metal cap top plate 2-1 in the following manner: the bottom edge of the graphite protective cap body 1-1 is chamfered, the top edge of the metal cap top plate 2-1 is chamfered, and the outer diameter of the bottom edge of the graphite protective cap body 1-1 is larger than the outer diameter of the top edge of the metal cap top plate 2-1.

[0066] The chamfered design not only ensures full coverage but also optimizes the electric field distribution at the component edges, reducing local electric field concentration. This helps suppress abnormal discharge (arson) induced by sputtered deposits and improves operational stability.

[0067] The outer diameter of the bottom surface of the graphite protective cap is greater than the outer diameter of the top surface of the metal cap. This dimensional relationship ensures that the ion beam can only bombard the graphite material, which has excellent sputter resistance, and cannot make contact with the metal cap below. This is one of the core design features that overcomes the structural defects of existing "titanium-coated graphite" technologies. Ensuring that the graphite protective cap can completely cover and protect the metal cap top plate and the central connecting structure is a key dimensional guarantee for realizing the "graphite-coated titanium" protection concept.

[0068] Specific Implementation Method Two: The following is combined with... Figures 5 to 6 This embodiment describes a splash protection component for a Hall thruster, used for the protection of the inner magnetic poles of the excitation coil Hall thruster. This component is more simplified, consisting of only a graphite protective cap 1 directly mounted on the inner magnetic pole 3 of the thruster.

[0069] The inner magnetic pole 3 is preferably made of pure iron. Pure iron (such as electrical pure iron) has soft magnetic properties such as high magnetic permeability and low coercivity, making it an ideal material for constructing magnetic circuits. Simultaneously, its excellent mechanical properties allow for the fabrication of high-quality external threaded connecting posts. The structure of the graphite protective cap 1 is similar to that of Embodiment 1, including a graphite protective cap body 1-1, the bottom edge of which is chamfered to form a chamfered bottom edge 1-3, and the outer diameter of its bottom surface is larger than the outer diameter of the top surface of the inner magnetic pole 3, achieving full coverage and fastening to protect the underlying metal magnetic pole.

[0070] The graphite protective cap body 1-1 is connected to the pure iron inner magnetic pole 3 through a mechanical locking structure located in the center, and is further fixed by an auxiliary fixing layer. The principle and beneficial effect of its double fixing are exactly the same as those of Embodiment 1.

[0071] The mechanical locking structure is a threaded connection, which can be implemented using one of the following two equivalent methods:

[0072] Method 1: A graphite external thread connecting post 1-2 is set at the center of the bottom surface of the graphite protective cap body 1-1, and an internal thread hole is machined at the center of the top of the inner magnetic pole 3. The two are then connected together.

[0073] Method 2: A graphite internal thread hole 1-4 is machined at the center of the bottom surface of the graphite protective cap body 1-1, and an internal magnetic pole external thread connecting post 3-1 is integrally set at the center of the top of the internal magnetic pole 3, and the two are connected together.

[0074] Machining external threaded posts on pure iron inner magnetic poles is technically very convenient and reliable. Placing the threaded posts on pure iron inner magnetic poles results in higher strength than machining threads on graphite, and they are better able to withstand the intense vibration loads of rocket launches. This provides a robust and reliable connection method particularly suitable for coil excitation thrusters.

[0075] Preferably, the effective engagement length of the thread is not less than 3 mm to ensure sufficient connection strength to resist emission vibration.

[0076] The graphite protective cap body 1-1 is fully covered and fastened to the inner magnetic pole 3 in the following way: the bottom edge of the graphite protective cap body 1-1 is chamfered, the top edge of the inner magnetic pole 3 is chamfered, and the outer diameter of the bottom edge of the graphite protective cap body 1-1 is larger than the outer diameter of the top edge of the inner magnetic pole 3.

[0077] The outer diameter of the bottom surface of the graphite protective cap is greater than the outer diameter of the top surface of the inner magnetic pole. This design ensures that the ion beam bombards only the graphite cap, protecting the surface of the pure iron inner magnetic pole from sputtering corrosion, thereby maintaining the long-term stability of the magnetic pole's geometry and magnetic circuit performance. Ensuring that the graphite cap completely covers and protects the surface of the underlying metal inner magnetic pole and the central connecting structure is crucial for achieving effective protection.

[0078] Since the coil excitation thruster does not need to worry about permanent magnet demagnetization, this embodiment eliminates the need for a metal cap and radial air gap structure, making the solution more compact and efficient.

[0079] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A splash protection assembly for a Hall thruster, used for internal magnetic pole protection of a permanent magnet Hall thruster, characterized in that, It includes a graphite protective cap (1) and a metal cap (2), with the graphite protective cap (1) fully covering the top of the metal cap (2); the metal cap (2) fully covers the permanent magnet (4) of the Hall thruster; The graphite protective cap (1) includes the graphite protective cap body (1-1). The metal cap (2) includes a metal cap top plate (2-1), a metal cap side wall (2-2), and an inner permanent magnet fixing post (2-4); there is a radial gap between the metal cap side wall (2-2) and the permanent magnet (4) fastened inside; The bottom edge of the graphite protective cap body (1-1) is chamfered to form a chamfered bottom edge (1-3) and is fully covered and fastened to the metal cap top plate (2-1); The graphite protective cap body (1-1) and the metal cap top plate (2-1) are mechanically connected at the center by a mechanical locking structure; The joint surfaces of the graphite protective cap body (1-1) and the metal cap top plate (2-1) are fixed in a secondary manner through an auxiliary fixing layer; the auxiliary fixing layer is a brazing layer or an inorganic adhesive layer that can withstand temperatures above 500℃; The mechanical locking structure between the graphite protective cap body (1-1) and the metal cap top plate (2-1) is a threaded connection, which can be completed using any of the following methods: Method 1: A graphite external threaded connecting post (1-2) is provided at the center of the bottom surface of the graphite protective cap body (1-1), and an internal threaded hole (2-3) is provided at the center of the top of the metal cap top plate (2-1). The graphite external threaded connecting post (1-2) and the internal threaded hole (2-3) of the top plate are connected by thread. Method 2: The bottom center of the graphite protective cap body (1-1) is provided with a graphite internal thread hole (1-4), and the top center of the metal cap top plate (2-1) is provided with a top plate external thread connecting post (2-5). The graphite internal thread hole (1-4) and the top plate external thread connecting post (2-5) are threaded together for connection.

2. The anti-splash protection assembly for a Hall thruster according to claim 1, characterized in that, It also includes an inner permanent magnet fixing column (2-4), and an inner permanent magnet fixing column (2-4) is set at the center of the bottom surface of the metal cap plate (2-1). The inner permanent magnet fixing column (2-4) is used to mechanically connect with the Hall thruster permanent magnet bracket (5).

3. The anti-splash protection assembly for a Hall thruster according to claim 1, characterized in that, The metal cap (2) is made of titanium or titanium alloy.

4. The anti-splash protection assembly for a Hall thruster according to claim 1, characterized in that, The graphite protective cap body (1-1) is fully covered and fastened to the metal cap top plate (2-1) in the following way: the bottom edge of the graphite protective cap body (1-1) is chamfered, the top edge of the metal cap top plate (2-1) is chamfered, and the outer diameter of the bottom edge of the graphite protective cap body (1-1) is larger than the outer diameter of the top edge of the metal cap top plate (2-1).

5. A splash protection assembly for a Hall thruster, used for internal magnetic pole protection of an excitation coil Hall thruster, characterized in that, Includes a graphite protective cap (1), which is fully covered on the top of the inner magnetic pole (3) of the Hall thruster; The graphite protective cap (1) includes the graphite protective cap body (1-1). The bottom edge of the graphite protective cap body (1-1) is chamfered to form a chamfered bottom edge (1-3) and is fully covered and fastened to the top of the inner magnetic pole (3); The graphite protective cap body (1-1) and the center of the inner magnetic pole (3) are mechanically connected by a mechanical locking structure; The graphite protective cap body (1-1) and the inner magnetic pole (3) are fixed in a secondary manner through an auxiliary fixing layer; the auxiliary fixing layer is a brazing layer or an inorganic adhesive layer that can withstand temperatures above 500℃. The mechanical locking structure between the graphite protective cap body (1-1) and the inner magnetic pole (3) is a threaded connection, which is completed by any of the following methods: Method 1: A graphite external threaded connecting post (1-2) is provided at the center of the bottom surface of the graphite protective cap body (1-1), and an internal threaded hole is provided at the center of the top of the inner magnetic pole (3). The graphite external threaded connecting post (1-2) and the internal threaded hole at the top of the inner magnetic pole (3) are connected by thread. Method 2: The bottom center of the graphite protective cap body (1-1) is provided with a graphite internal thread hole (1-4), and the top center of the inner magnetic pole (3) is provided with an inner magnetic pole external thread connecting post. The graphite internal thread hole (1-4) and the inner magnetic pole external thread connecting post are connected by thread.

6. The anti-splash protection assembly for a Hall thruster according to claim 5, characterized in that, The inner magnetic pole (3) of the Hall thruster is made of pure iron.

7. The anti-splash protection assembly for a Hall thruster according to claim 5, characterized in that, The graphite protective cap body (1-1) is fully covered and fastened to the inner magnetic pole (3) in the following way: the bottom edge of the graphite protective cap body (1-1) is chamfered, the top edge of the inner magnetic pole (3) is chamfered, and the outer diameter of the bottom edge of the graphite protective cap body (1-1) is larger than the outer diameter of the top edge of the inner magnetic pole (3).

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