A gas distributor for an electric thruster with gas path insulation properties

Abstract

This invention proposes a gas distributor for an electric thruster with gas path insulation properties, consisting of a head and a body. The head includes a shielding layer, a grid, bolts, a baffle plate, a base, an insulating pad, a shielding sheet, a porous medium, and grid connecting wires, serving to insulate the gas path. The body includes a cylindrical portion of the base, the portion where the grid connecting wires connect to the external circuit, and the porous medium, serving to connect the external circuit, the gas path, and for fixation. The advantages of this invention are that the insulating device is smaller and more compact, while still functioning as a gas distributor, and can be installed inside an ionization chamber. Furthermore, compared to traditional straight-through gas distributors, it allows for more uniform airflow distribution, and compared to existing gas distributors with insulation functions, it exhibits stronger insulation performance and robustness.

Description

Technical Field

[0001] This invention belongs to the field of space electric propulsion technology, and in particular relates to a gas distributor for an electric thruster with gas path insulation properties. Background Technology

[0002] Radio frequency ion thrusters are a type of electric thruster used for space electric propulsion (or aerospace plasma propulsion). They have advantages such as high specific impulse, wide thrust variation range, simple structure, and mature technology, and are currently widely used in the attitude and orbit control of spacecraft.

[0003] Traditional radio frequency ion thrusters require a stable accelerating voltage applied to the grid to continuously extract positively charged ions, forming a positively charged beam in space. To neutralize this beam, a common solution is to install a cathode externally to emit electrons and provide the necessary negative charge for neutralization. However, using a neutralizer necessitates designing and installing matching power supplies, wiring, and gas paths on the spacecraft, increasing complexity, reducing reliability, and hindering the development of small-scale propulsion systems. Neutralizers also introduce problems such as interference with spacecraft charging and communication. As the shortest-lived component in the thruster, the neutralizer significantly limits the thruster's operational lifespan and reliability. To avoid these problems, self-neutralizing radio frequency ion thrusters that achieve beam neutralization without a neutralizer have emerged in recent years.

[0004] The self-neutralizing radio frequency ion thruster employs a dual-gate structure consisting of a screen grid and an accelerating grid. During operation, the screen grid is connected to the radio frequency voltage source via a DC blocking capacitor, while the accelerating grid is grounded. After plasma generation, due to the capacitive asymmetric coupling discharge effect, a DC voltage component, known as the radio frequency self-bias, is self-consistently generated on the screen grid. Ions are accelerated and extracted under the influence of this self-bias. The acceleration effect on the ions is mainly related to the radio frequency self-bias; the higher the radio frequency self-bias, the better the ion acceleration effect and the higher the thruster performance. Electrons are periodically pulsed out by a periodically changing electric field. Equal amounts of electrons and ions are extracted from the ionization chamber and neutralized in the beam region. This operating mode is also known as self-neutralizing extraction in radio frequency ion thrusters.

[0005] To achieve self-neutralization extraction in a thruster, radio frequency (RF) signals need to be applied simultaneously to the gate and coil. Extensive research has confirmed that increasing the gate RF power is a direct way to achieve higher RF self-bias voltage and improve ion acceleration, requiring a high gate power level. In small self-neutralizing RF ion thrusters with an ionization power of no more than 150W applied to the coil, a gate power of over 200W can achieve good acceleration. However, when the total thruster power is high, ionization is more likely to occur within the thruster's gas supply line. This unintended ionization leads to thruster power loss, causing the thruster to operate in an uncontrollable state. Furthermore, prolonged ionization can cause ablation of the thruster's gas supply line, reducing the thruster's reliability and shortening its lifespan. Meanwhile, current gas distributors used in small self-neutralizing radio frequency ion thrusters mostly adopt a configuration with uniformly distributed axially opened vent holes. Although the uniformity of the working gas entering the ionization chamber can be improved by adjusting the distribution and diameter of the holes, this discrete air intake structure inevitably leads to uneven distribution of neutral gas near the air intake position. It also results in working gas molecules escaping from the small holes having a higher velocity, leading to lower gas utilization efficiency. Therefore, the thruster air intake structure needs further optimization. Thus, it is necessary to develop a gas distributor for electric thrusters with gas path insulation for use in small self-neutralizing radio frequency ion thrusters.

[0006] Currently, no publicly disclosed gas distributors with gas path insulation properties have been found for use in self-neutralizing radio frequency ion thrusters. However, conventional electric propulsion propellant supply lines contain gas path insulation devices and gas distributors that can prevent breakdown.

[0007] 1. High-voltage insulation device for the gas path of a mercury-based ion thruster: In the 1960s and 70s, NASA proposed various gas path insulation devices for the working fluid supply pipeline of ion thrusters using mercury as the working fluid. These can be broadly classified into two categories: passive insulators (or single-stage insulators, where the grid system and the gas supply pipeline are each considered as an electrode) and multi-stage voltage-segmented insulators. Passive insulators mostly operate in the right half of the Paschen curve. With constant gas pressure, increasing the gas path distance between the pipeline (ground potential) and the grid can increase the pd value and improve the breakdown voltage. Therefore, passive insulators increase the path length of the working fluid gas in the pipeline through various methods, increasing the actual breakdown path and reducing the possibility of working fluid breakdown. Simultaneously, filling the pipeline with a porous medium with a large specific surface area enhances the surface recombination reaction of the plasma, significantly reducing the density of charged particles in the plasma, thereby achieving an insulating effect. For example... Figure 1 As shown.

[0008] Multi-stage voltage-segmented insulators typically operate in the left half of the Paschen curve, separating the potential difference between the ion thruster grid system and the gas supply line by inserting multiple stages of grids with smaller potential differences. The grids are arranged axially sequentially, with the potential decreasing from the near-plasma region to the far-plasma region. The sum of all grid potential differences is the same as the potential difference between the grid and the line, but the potential difference between adjacent grids is smaller. This reduces the pd value between the grids and increases the breakdown voltage. Figure 2 As shown.

[0009] 2. Voltage-segmented insulators for xenon: Yang Fuquan, Wan Gengmin, and others from the Lanzhou Institute of Space Technology Physics designed and optimized electrical insulators applicable to electric propulsion systems, such as... Figure 3 As shown, the insulator's gas path is divided into 10 to 25 discontinuous stages by multiple grids, with the voltage of each stage being less than the xenon gas breakdown voltage of 150V. To prevent external contamination such as surface contamination during manufacturing and deposition contamination during testing, a labyrinthine shield is designed outside the insulating tube. Test results show that, in the flow rate range of 0–10 mL / min, the minimum breakdown DC voltages of the 10-stage, 15-stage, 20-stage, and 25-stage segmented insulators are 2700, 4000, 6000, and 8000V, respectively.

[0010] 3. A gas distributor for improving the ionization efficiency of radio frequency ion thrusters: Lu Haifeng, Li Jiyuan, and others from the Xi'an Aerospace Propulsion Institute proposed a gas distributor that can integrate multiple technical solutions to improve the ionization efficiency of radio frequency ion thrusters, such as... Figure 4a and Figure 4b As shown in the diagram, this design utilizes a cavity to buffer the working gas from the ventilation pipe, and employs a multi-dimensional swirling gas supply method to ensure more uniform gas entry into the ionization chamber and increase the residence time within the ionization chamber. The cavity is filled with numerous irregularly shaped guide spheres, which further enhances gas distribution and, to some extent, facilitates the plasma recombination rate through surface reactions, providing some protection against flashback.

[0011] Literature and patents concerning air circuit insulation in electric propulsion:

[0012] [1]Nakanishi S.Experimental investigation of a high-voltage isolation device for ion-thrustor propellant feed[R].1966.

[0013] [2]Nakanishi S.Experimental investigation of mercury propellant feedisolators for Kaufman thrusters[R].1968.

[0014] [3]Hart SL, Tighe W, Pearce C, et al. Investigation and development of a high voltage propellant isolator for ion thrusters [M]. Pasadena, CA: Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2005.

[0015] Patent related to the optimized design of the gas distributor:

[0016] [1] Chinese Patent Application No.: CN202211071740.5, Application Date: August 31, 2022

[0017] Currently, no publicly available gas distributor with gas path insulation for self-neutralizing radio frequency ion thrusters has been found that can be applied to such thrusters. Experiments with self-neutralizing radio frequency ion thrusters have revealed that small self-neutralizing radio frequency ion thrusters using straight-through gas distributors are prone to gas supply line ionization when the total thruster power is high. This is due to poor gas path insulation performance. In existing insulation technologies, regardless of whether it's a passive insulator or a voltage-segmented insulator used with any working fluid, its installation location is always within the gas supply line. In domestically published "gas distributors for improving the ionization efficiency of radio frequency ion thrusters," the addition of a flow guide ball results in limited gas path insulation capability, and its insulation capability cannot be adjusted.

[0018] The shortcomings and problems of existing technologies are as follows:

[0019] 1. The gas circuit insulation performance of small self-neutralizing radio frequency ion thrusters is poor. Under the condition of high total power and large gate radio frequency self-bias voltage, ionization is easy in the gas supply line of the thruster, which will lead to a decrease in the energy utilization efficiency of the thruster and ablation of the gas supply line.

[0020] 2. The insulators installed in the air supply pipeline of the electric thruster are large in size and mass, and the assembly position needs to be considered separately in the pipeline design, which is not conducive to the miniaturization and weight reduction of the electric propulsion system.

[0021] 3. Existing gas distributors lack strong gas path insulation performance. Most widely used gas distributors are straight-through type, such as... Figure 5a , Figure 5b and Figure 5c As shown, the working gas enters the ionization chamber directly through the through-hole on the gas distributor, offering almost no insulation. Existing improved designs employ a guide sphere, which increases the surface area to some extent, thus improving insulation. However, it is difficult to significantly increase the specific surface area of ​​the gas path simply by using a large guide sphere within a limited space, resulting in poor insulation performance.

[0022] 4. At the same time, the insulation effect of the current gas distributor is achieved by passive means, and the insulation performance of the gas circuit system cannot be adjusted by changing external parameters. It has poor robustness and is not suitable for use under different operating conditions and different thrusters.

[0023] In summary, current electric propulsion systems still have many shortcomings and problems in terms of gas circuit insulation, and the development of insulators for use in small self-neutralizing radio frequency ion thruster systems is still a blank. A gas distributor for electric thrusters that is lightweight, compact, has strong insulation performance, and is adjustable should be developed. Summary of the Invention

[0024] The technical problem to be solved by this invention:

[0025] 1. Solve the problem of poor gas circuit insulation performance in small self-neutralizing radio frequency ion thrusters, which causes power loss and gas circuit ablation.

[0026] 2. To solve the problem that existing gas distributors with certain insulation properties have poor insulation performance, cannot be adjusted, and have poor robustness.

[0027] 3. To solve the problem that existing gas circuit insulation devices can only be located in the gas supply pipeline, which is bulky and inconvenient to install.

[0028] 4. Improve the problem of uneven gas supply in direct-flow gas distributors.

[0029] Technical solutions adopted to solve technical problems:

[0030] This invention proposes a gas distributor for electric thrusters with gas path insulation properties. Unlike existing gas path insulation devices and gas distributors, this invention features a smaller, more compact insulation device that functions as a gas distributor and can be installed inside the ionization chamber. Furthermore, compared to traditional straight-through gas distributors, it achieves more uniform airflow distribution, and compared to existing gas distributors with insulation functions, it exhibits stronger insulation performance and robustness.

[0031] This invention provides a gas distributor for an electric thruster with gas path insulation properties, such as... Figure 6 , Figure 7a and Figure 7b As shown. This invention can be divided into two parts according to its functional and structural characteristics: the head and the body. The head of this invention mainly includes a shielding layer 1, gates 2-7 and 17-21, bolts 8, a baffle plate 9, a base 10, an insulating pad 11, a shielding sheet 12, a porous medium 13, gate connecting wires 16 and 22-31, and is the main part that provides insulation for the gas path. The body mainly includes the cylindrical section of the base 10 (with threads), the parts where the gate connecting wires 16 and 22-31 connect to the external circuit, and the porous medium 14, which serves to connect the external circuit, the gas path, and fix this invention to the ionization chamber. Gates 2-7 and 17-21 are the core components of this invention, placed and pressed into corresponding grooves on the base 10 and the baffle plate 9. The baffle plate 9 is connected and tightened to the base 10 via a gas path connector 15. The shielding layer 1 is a thin-shell cylindrical structure made of copper alloy. The side surface of the cylindrical shell has a metal mesh structure. One end face is completely open, and the other end face has a fixing hole through which bolt 8 passes. As shown in the figure, during assembly, it is fixed to the air baffle plate 9 by bolt 8. Bolt 8 is a commercially available M6 short bolt. Figure 7a As shown. Gates 2-7 and 17-21 are all annular metal meshes made of copper alloy. Shielding plate 12 is a copper alloy disc with a central opening. After assembly, it is pressed against the bottom of the thruster ionization chamber by the base 10, and together with shielding layer 1, it provides electromagnetic shielding for the head of the invention, as described in detail below. Gate connecting wires 16 and 22-31 are made of flexible copper wire with good conductivity. During assembly, the connecting wires are first soldered to the corresponding gates. Then, the gates are respectively placed in the corresponding annular slots on the base 10. The conductive wires soldered to the gates pass through the corresponding small holes on the base and extend to the other side of the base 10, where they are bent into connectors for connection to external circuits, such as... Figure 8 As shown. The baffle plate 9 and the substrate 10 are made of silicon-doped boron nitride ceramic sintered at high temperature; the porous media 13 and 14 are made of nickel foam.

[0032] This invention is installed at the bottom of the ionization chamber by a fixing nut, such as... Figure 8As shown. During operation, a voltage with progressively decreasing potential is applied to the stainless steel gate from the outside to the inside. The voltage difference between two adjacent annular gates is equal and can be adjusted by adjusting the parameters of the external power supply, demonstrating the robustness of the invention. The shielding layer 1 and the shielding sheet 12 serve two purposes: First, the shielding layer 1 is suspended and has a grid-like opening on its side, similar to the inlet gate of a hindrance potential analyzer, which can reduce the density of plasma entering the gas distributor and prevent plasma in the ionization chamber from directly contacting the gate system, thus preventing possible insulation failure. Second, since the self-neutralizing radio frequency ion thruster applies radio frequency signals to the coil and gate respectively during operation, the total power of electromagnetic radiation is relatively large. The shielding layer 1 can achieve electromagnetic shielding of the gate region of the gas distributor, weakening the radio frequency signals transmitted between the gates and preventing ionization inside the gas distributor, which could lead to insulation failure. The insulating pad 11 ensures the insulation between the gate connecting wires and the shielding layer, and the slots on the substrate 10 ensure that there is no short circuit between the gate connecting wires. The porous media 13 and 14 are located upstream of the gas distributor gate system. Their large specific surface area increases the surface recombination rate of the plasma and prevents ions from moving upstream of the gas supply line and causing insulation failure.

[0033] The phenomenon of ionization in the gas supply line of the self-neutralizing radio frequency ion thruster during experiments was the direct cause of this invention. However, the self-neutralizing radio frequency ion thruster was proposed relatively recently, and there are few publicly available experimental research results both internationally and domestically. Previously, few people paid attention to the ionization phenomenon in the gas supply hose of the self-neutralizing radio frequency ion thruster. The main cause of insulation failure in the pipeline of traditional radio frequency ion thrusters is DC breakdown between the gate and the gas path. However, the discharge causes in the pipeline of the self-neutralizing radio frequency ion thruster include not only DC breakdown but also radio frequency discharge due to the high radio frequency power. Previously, the discharge caused by the radio frequency power feeding into the pipeline was rarely considered.

[0034] With the rise of the international microsatellite constellation, new requirements have been placed on small electric propulsion systems for satellites. Traditional insulators are generally installed on gas pipelines, resulting in a large structure and mass, which is not conducive to the miniaturization design of propulsion systems. This invention combines the insulating device with the inherent gas distributor of the thruster, enabling the essential gas distributor in the system to have the function of gas pipeline insulation. This eliminates the need for a separate insulating device in the pipeline, minimizing the system size and mass, and facilitating the miniaturization design of satellite propulsion systems.

[0035] The beneficial effects of this invention compared to the prior art are as follows:

[0036] 1. Compared to traditional straight-through gas distributors, this invention provides excellent insulation between the ionization chamber and the gas path. In straight-through gas distributors, there is no grid on the gas path to apply voltage; the radio frequency voltage applied to the grid is directly applied between the plasma inside the ionization chamber and the upstream pipeline, making it prone to discharge breakdown. This invention improves insulation performance by innovatively adding a grid to the gas distributor.

[0037] 2. Compared to the traditional insulator installed in the xenon gas line of the electric thruster, the present invention, as an improved version of the thruster gas distributor, adopts a concentric ring grid arrangement, which is convenient for installation in the relatively small space of the thruster ionization chamber. Therefore, the gas line insulation function can be combined with the gas transport and distribution function. While achieving the DC breakdown prevention effect of the traditional insulator, there is no need to add other structures in the working fluid line, reducing the complexity of the system and effectively reducing the size of the electric propulsion system.

[0038] 3. Compared to gas distributors that achieve a certain gas path insulation function solely by increasing the specific surface area of ​​the gas path, such as... Figure 4a and Figure 4b As shown, this design employs electrical insulation, and the insulation performance can be adjusted by increasing or decreasing the number of gates and changing the potential difference between adjacent gates, thus exhibiting better robustness and applicable to different working fluids and different RF voltage parameters.

[0039] 4. Compared with the traditional straight-through gas distributor with circumferential perforation, the present invention adopts a design with a baffle plate 9 and a base 10, with multiple grids sandwiched in between, which changes the original circumferential air intake to air intake in the entire circumferential direction, thus improving the uniformity of the working gas distribution in the ionization chamber.

[0040] 5. Compared with existing insulators, this invention, taking into account the large radio frequency power in the ionization chamber of the self-neutralizing radio frequency ion thruster, adopts a design that adds a shielding layer 1 and a shielding sheet 12, which better prevents ionization caused by the feed of radio frequency signals inside the insulator and improves insulation performance.

[0041] 6. This invention helps to improve the overall performance of self-neutralizing radio frequency ion thrusters. Attached Figure Description

[0042] Figure 1 It is a passive insulator.

[0043] Figure 2 It is an electrical insulator.

[0044] Figure 3 It is an electrical insulator used with xenon working fluid.

[0045] Figure 4aThis is a full sectional view (the cutting plane passes through the axis) of a gas distributor used to improve the ionization efficiency of a radio frequency ion thruster.

[0046] Figure 4b This is a full sectional view (the cutting plane is perpendicular to the axis) of a gas distributor used to improve the ionization efficiency of a radio frequency ion thruster.

[0047] Figure 5a This is the front view of a straight-through gas distributor.

[0048] Figure 5b This is a full sectional view of a straight-through gas distributor (the cutting plane is perpendicular to the axis).

[0049] Figure 5c This is a full sectional view of a straight-through gas distributor (the cutting plane passes through the axis).

[0050] Figure 6 This is a schematic diagram of a gas distributor for an electric thruster with gas path insulation properties.

[0051] Figure 7a This is a full sectional view of the gas distributor of an electric thruster with gas path insulation (the cutting plane passes through the axis).

[0052] Figure 7b This is a bottom view of the gas distributor of an electric thruster with gas path insulation.

[0053] Figure 8 This is an isometric view of the main structural components of this invention.

[0054] Figure 9 This is a schematic diagram of the base groove.

[0055] The labels in the diagram are explained as follows:

[0056] Shielding layer 1; Gate 2-7, 17-21; Bolt 8; Air baffle 9

[0057] 10 Substrate; 11 Insulating pad; 12 Shielding sheet; 13, 14 Porous dielectric

[0058] Gas connection component 15; gate wires 16, 22-31 Detailed Implementation

[0059] The diameter of the head in this invention is 38mm, determined by the 40mm diameter of the thruster ionization chamber. The spacing between each grid layer is given based on the manufacturing conditions, and in this design, the grid spacing is greater than or equal to 1mm. This determines the upper limit of the number of grids, and with the voltage between two adjacent grid layers determined, the total voltage that the grid system can apply is also determined. The specific design values ​​can be determined as follows: First, according to Paschen's law, the minimum breakdown voltage of xenon gas between iron electrodes is 150V, determining the maximum potential difference between grids to be 130V. Then, based on the head diameter of 38mm and the grid spacing of 1mm, the number of grids is determined to be 11, with 10 grid spacings, allowing a maximum potential difference of 1300V to be applied. Since the DC self-bias voltage of most self-neutralizing radio frequency ion thrusters currently does not exceed 500V, the maximum instantaneous grid voltage can reach approximately 1000V, and the maximum total voltage difference of 1300V meets the design requirements. If the maximum instantaneous voltage of the given gate system is 1000V, then the voltage difference between any two adjacent gates is 100V. The outermost gate (gate 2) is given a voltage of 1000V, the innermost gate (gate 7) is grounded (0V voltage), and the voltages of the intermediate gates decrease inward in an arithmetic sequence.

[0060] Although the design background of this invention is a miniature self-neutralizing radio frequency ion thruster, it can still be applied to general miniature radio frequency ion thrusters. When applied to a radio frequency ion thruster, the voltage of the outermost gate is equal to the voltage of the screen gate in the gate, the innermost gate is grounded, and the voltages of the middle gates decrease inward according to an arithmetic sequence. If the thruster gate voltage is too high, causing the existing 11-layer gate to fail to meet the requirement that the voltage difference between adjacent gates is less than the minimum breakdown voltage, then the head diameter of this invention can be appropriately increased according to the actual geometry of the thruster, the process can be improved to reduce the distance between gates, the number of gates can be increased, and the voltage difference between gates can be reduced.

[0061] The gas path after the gas enters the gas distributor and before it reaches the innermost gate can be improved, allowing for a larger channel area for the working gas and a longer actual path required for breakdown, thus further enhancing insulation performance. If the gate flatness is improved and the machining precision of the ceramic components is increased, the spacing can be further reduced while ensuring no arcing between gates. This allows for the addition of more gates and improved overall insulation performance.

[0062] It can improve the shape of porous media in the channel, increase the specific surface area of ​​porous materials without significantly increasing flow resistance, and enhance the surface recombination reaction of plasma.

[0063] Although the voltage design of this invention is calculated based on xenon parameters, the maximum applicable voltage difference between the gates of the corresponding working fluid can be obtained simply by replacing the minimum breakdown voltage of xenon with the minimum breakdown voltage of other working fluids during the design process. In practical applications, it is not necessary to change the configuration of the invention; only the voltage parameters output by the external power supply need to be adjusted to achieve gas path insulation for different working fluids.

[0064] The potential difference between adjacent gates in this invention has a high degree of adaptability. The maximum voltage difference between adjacent gates in this invention is 130V. In actual operation, each gate is connected to an external power supply circuit via gate wires. The potential difference between the gates can be adjusted between 0 and 150V by regulating the power output, and can be adjusted according to the specific gate voltage value.

[0065] The operation steps of this invention are as follows:

[0066] Install the present invention at the bottom of the thruster ionization chamber → Assemble the thruster screen grid, acceleration grid, grid insulator and positioning components, radio frequency coil, Faraday cage and other parts to complete the assembly of the thruster body → Screw the threaded interface of the gas path into the threaded connection of the gas path connector 15, connect the radio frequency circuit to the thruster coil, connect the grid connection wire of the present invention to the external DC power supply → Gas path is vented, the radio frequency coil is energized → Ignition of the ionization chamber → Voltage is applied to the grid of the present invention from the inside to the outside, which serves as gas path insulation → The thruster operation ends, the radio frequency coil is de-energized, and the ionization chamber is extinguished → Power supply to the grid system of the present invention is turned off → Operation ends.

[0067] Installation process of this invention:

[0068] The entire process of installing this invention inside the thruster ionization chamber is as follows: First, gates 2-7 and 17-21 are soldered together with gate connecting wires 16 and 22-31; the gates with soldered wires are then sequentially placed in the corresponding grooves of the substrate 10, with the corresponding wires passing through the corresponding openings on the substrate, and after passing through the openings, embedded in the grooves on the back of the substrate, and led out of the ionization chamber along the grooves. The morphology of the substrate grooves is as follows: Figure 9 As shown; then, the shielding layer 1 is fixed to the baffle plate 9 with bolts 8; the porous medium 13 is placed at the corresponding position on the upper part of the middle fixing rod of the baffle plate; the baffle plate assembly with the shielding layer 1 and porous medium 13 installed is matched with the grid system on the base 10, so that each grid is snapped into the corresponding groove on the baffle plate; then, the porous medium 14 is placed in the gas path connector 15; the assembly is placed at the inlet of the ionization chamber, and a shielding sheet 12 for electromagnetic shielding and an insulating pad 11 for ensuring the insulation between the grid connection wire and the shielding sheet are placed under the base of the assembly; the invention is screwed into the ionization chamber outside the ionization chamber with bolts; finally, the gas path connector with the porous medium installed is screwed into the external thread of the base and the baffle plate fixing rod, and the grid connection wire is connected to the external power circuit to complete the assembly.

Claims

1. An electric thruster gas distributor having gas path insulation properties, characterized by: The head part includes a shielding layer, a grid, a bolt, a gas baffle, a base, an insulating pad, a shielding sheet, a porous medium and a grid wire, and plays a role of gas path insulation; the body part includes a cylindrical part of the base; The grid wire and the porous medium play a role of connecting the external circuit, the gas path and fixation; The grid is arranged and compressed in the corresponding groove of the base and the gas baffle, and the gas baffle is connected and screwed with the base through the gas path connector; The shielding layer is a cylindrical shell structure made of copper alloy, the side surface of the cylindrical shell is a metal mesh structure, one end surface is completely open, and the other end surface has a fixing hole through the bolt in the center; The grid is a circular metal mesh made of copper alloy; the shielding sheet is a copper alloy metal disc with a central hole, and after assembly, the shielding sheet is pressed on the bottom of the thruster ionization chamber by the base, and is combined with the shielding layer to play a role of electromagnetic shielding for the head part of the distributor; The grid wire is welded with the corresponding grid, and then the grid is arranged in the corresponding circular groove of the base, and the conductive wire welded on the grid passes through the corresponding small hole of the base to the other side of the base, and is bent to connect the external circuit.

2. The gas distributor for an electric thruster having gas path insulation according to claim 1, characterized in that: The distributor is installed at the bottom of the ionization chamber through a fixing nut, the grid made of stainless steel is applied with voltages from outside to inside in a decreasing order, and the voltage difference between two adjacent ring-shaped grids is equal and can be adjusted by adjusting the parameters of the external power supply.

3. The gas distributor for an electric thruster having gas path insulation according to claim 1, characterized in that: When applied to the radio frequency ion thruster, the voltage of the outermost grid of the distributor is equal to the voltage of the shielding grid in the grid, the innermost grid is grounded, and the voltage of the intermediate grid decreases inwards according to an arithmetic progression.

4. The gas distributor for an electric thruster having gas path insulation according to claim 1, characterized in that: The improved gas path before the innermost grid of the gas distributor makes the working gas flow through a larger channel area and a longer actual path for breakdown, thereby enhancing the insulation performance; the shape of the porous medium in the channel is improved to increase the specific surface area of the porous material without significantly increasing the flow resistance, thereby enhancing the surface recombination of the plasma.

5. The gas distributor for an electric thruster having gas path insulation according to claim 1, characterized in that: The minimum breakdown voltage of xenon gas is replaced by the minimum breakdown voltage of other working media, so that the maximum applicable voltage difference between the grids corresponding to the working media can be obtained.

6. A method of assembling a gas distributor for an electric thruster having gas path insulation properties according to claim 1, characterized in that: First, the grid and the grid wire are welded together; the grid with the welded wire is arranged in the corresponding groove of the base, and the corresponding wire passes through the corresponding hole of the base, and is embedded in the groove on the back surface of the base after passing through the hole, and is led to the outside of the ionization chamber along the groove; Then, the shielding layer is fixed to the gas baffle through the bolt; The porous medium is arranged at the corresponding position on the upper part of the intermediate fixing rod of the gas baffle; the gas baffle assembly with the installed shielding layer and porous medium is combined with the grid system on the base, so that each grid is clamped into the corresponding groove of the gas baffle; then, the porous medium is arranged in the gas path connector; the assembly is arranged at the entrance of the ionization chamber, the shielding sheet for electromagnetic shielding and the insulating pad for insulating the grid wire from the shielding sheet are placed under the base of the assembly, the distributor and the ionization chamber are screwed outside the ionization chamber by the bolt; finally, the gas path connector with the porous medium is screwed with the external threads of the base and the gas baffle fixing rod, and the grid wire is connected with the external power circuit, and the assembly is completed.

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