A self-neutralizing gate system

Abstract

The application provides a self-neutralizing grid system, and belongs to the technical field of ion propulsion. The system comprises a screen grid, a first insulating gasket, an acceleration grid, a second insulating gasket and a deceleration grid. First, plasma is formed in a discharge chamber, and because the areas of the screen grid and the acceleration grid in contact with the plasma are different, the applied RF voltage drop is mainly formed in front of the acceleration grid hole. Second, because there is a direct-current capacitor between the screen grid and the acceleration grid, the RF voltage will be rectified into a direct-current bias voltage; ions are accelerated and extracted by the self-neutralizing grid system, and when the plasma potential approaches zero, the sheath between the grids collapses, and a large amount of electrons is extracted, so that the self-neutralization of the beam current is finally realized. Finally, because of the deceleration grid, the upstream potential is reduced, and the downstream electron backflow is inhibited. The application inherits the advantages of the self-neutralizing grid system, reduces the electron backflow by the deceleration grid, avoids the local overheating of some parts, prolongs the service life of the grid, and maintains the good operation of the thruster.

Description

Technical Field

[0001] This invention belongs to the field of ion propulsion technology, specifically relating to a self-neutralizing gate system. Background Technology

[0002] Satellite internet is a crucial component of China's new infrastructure development and a key development area of ​​national strategic projects. It's a new type of network that provides broadband internet access globally via space-based means, using dozens, hundreds, or even thousands of satellites. It offers connectivity to areas difficult to reach via terrestrial networks, such as aircraft, ships, islands, and floating platforms, offering advantages in specific application scenarios. Compared to geostationary orbit (GEO) satellites, low-Earth orbit (200-2000km) satellite constellations offer lower latency, higher speeds, true global coverage, and stability. Compared to terrestrial base station construction, satellite internet is more cost-effective and economical. Furthermore, satellite internet constellations also possess military attributes, providing normal communication services to users during peacetime and ensuring communication for the military during wartime. In recent years, dozens of constellation plans, such as Starlink, OneWeb, Hongyan, Hongyun, and Xingyun, have been proposed globally, further fueling the development of satellite internet and attracting widespread global attention. Therefore, satellite internet will inevitably become another major national emerging industry in my country, following major national aerospace projects such as BeiDou and Gaofen.

[0003] Satellite internet requires a large number of satellites in a network formation, and their attitude control and position maintenance rely heavily on low-cost, high-performance advanced propulsion systems. Therefore, electric propulsion, characterized by long lifespan, high reliability, high efficiency, and high specific impulse, plays a crucial role in the development of the satellite internet industry. To reduce satellite costs, projects such as "Starlink" and "OneNet" have extensively applied electric propulsion technology. This demonstrates that the development of my country's satellite internet industry requires the development of new, low-cost, high-performance electric propulsion devices. Ion propulsion technology, as one of the world's most advanced space propulsion technologies, has been practically applied in numerous spacecraft missions. The grid system is a crucial structure in ion propulsion technology, closely related to the thrust, specific impulse, and lifespan of the thruster. Traditional grid systems use DC bias to extract ions to generate thrust. To prevent the accumulation of charge on the satellite, the plume ejected into space needs to be electrically neutral. This requires a dedicated neutralizer. Self-neutralizing grid systems, however, use radio frequency power supply. Based on the self-bias effect, ions are continuously extracted, while electrons are extracted at specific times, thus achieving self-neutralization. Ion thrusters equipped with a self-neutralizing gate system eliminate the need for a neutralizer, reducing thruster size and weight, lowering costs, and enhancing reliability.

[0004] However, due to the grounding of the accelerating gate, electron backflow cannot be effectively suppressed, which will lead to: (1) the generation of ions in the gate gap, which will bombard the gate system and reduce the gate lifetime; (2) local overheating problems; and (3) a reduction in the effective accelerating voltage, affecting the overall performance of the thruster. Therefore, the electron backflow problem not only affects the performance of the ion thruster, but also greatly limits the further development and application of the ion thruster. Summary of the Invention

[0005] In order to suppress electron backflow and improve the lifetime of the gate system, the present invention aims to provide a self-neutralizing gate system.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A self-neutralizing gate system includes a screen gate, a first insulating pad, an accelerating gate, a second insulating pad, and a decelerating gate.

[0008] The screen gate is a circular plate structure with multiple circular through holes of the same diameter distributed on it; the screen gate is placed close to the discharge chamber.

[0009] The accelerating gate is a circular plate structure, and the outer diameter of the accelerating gate is the same as that of the screen gate. Multiple circular through holes of the same diameter are distributed on the accelerating gate, and the positions of the circular through holes are the same as those of the through holes on the screen gate. The diameter of the circular through holes is smaller than that of the through holes on the screen gate. The accelerating gate and the screen gate are coaxially arranged.

[0010] The deceleration gate is a circular plate structure, and the outer diameter of the deceleration gate is the same as that of the screen gate. Multiple circular through holes of the same diameter are distributed on the deceleration gate, and the positions of the circular through holes are the same as those of the through holes on the screen gate. The diameter of the circular through holes is larger than that of the through holes on the acceleration gate. The deceleration gate and the screen gate are coaxially arranged.

[0011] The first insulating pad is an annular plate structure, and its outer diameter is the same as that of the screen gate. The first insulating pad is installed between the screen gate and the accelerating gate, and is coaxial with the screen gate.

[0012] The second insulating pad has an annular plate structure, and its inner and outer diameters are the same as those of the first insulating pad. The second insulating pad is installed between the accelerating gate and the decelerating gate, and is coaxial with the screen gate.

[0013] The circular through holes on the gate, the acceleration gate, and the deceleration gate are all arranged in a hexagonal structure.

[0014] After installation, the axes of the corresponding circular through holes on the screen gate, acceleration gate, and deceleration gate coincide.

[0015] Furthermore, an radio frequency voltage is applied between the screen gate and the acceleration gate.

[0016] Furthermore, there is a capacitive connection between the screen gate and the acceleration gate.

[0017] Furthermore, the deceleration gate is connected to a DC negative bias voltage.

[0018] Furthermore, the screen gate, acceleration gate, and deceleration gate are all made of metal or carbon materials.

[0019] Furthermore, both the first insulating pad and the second insulating pad are made of insulating material.

[0020] The working principle of the above self-neutralizing gate system is as follows:

[0021] First, plasma is formed in the discharge chamber. Since the grid directly contacts the plasma within the discharge chamber, while the accelerating grid is placed downstream of the grid, the accelerating grid can only contact the plasma through a via on the grid. Therefore, the effective contact area ratio between the grid and the accelerating grid is greater than 1. Sheaths will form between the plasma and the grid, and between the plasma and the accelerating grid. Due to the mass difference between ions and electrons, their time responses to the applied electric field differ. Electrons are controlled by the instantaneous electric field, while the motion of ions is determined by the average electric field.

[0022] Based on asymmetric capacitive coupling discharge, the effective areas of the two gates differ, resulting in different sheath thicknesses and potential drops; otherwise, the radio frequency (RF) currents flowing through these sheaths would differ. For the gate with a larger effective area, the time-averaged sheath thickness in front of it is smaller, leading to a larger RF voltage drop in the sheath. Therefore, the applied RF voltage drop is primarily concentrated in the sheath before the accelerating gate aperture. Furthermore, due to the DC blocking capacitance between the gate and the accelerating gate, the RF voltage is rectified into a DC bias voltage. Under this DC bias voltage, ions are accelerated and extracted from the self-neutralizing gate system. When the plasma potential approaches zero, the sheath between the gates collapses, and a large number of electrons are extracted. Ultimately, the extraction rates of electrons and ions are approximately equal per unit time, thus achieving beam self-neutralization.

[0023] In the original self-neutralizing gate system, when the RF voltage applied to the gate is negative, because the voltage in the upstream region is higher than that in the downstream region, some electrons in the downstream region will be accelerated through the gate and then flow back into the upstream region, i.e., electron recirculation. As the voltage increases further, the electron recirculation rate also increases. However, now, due to the presence of the decelerating gate, the upstream potential decreases, inhibiting the downstream electrons from passing through the gate, thereby reducing the electron recirculation rate.

[0024] The beneficial effects of this invention are as follows: First, it inherits the advantages of a self-neutralizing gate system, including: thrusters equipped with a self-neutralizing gate system no longer need a neutralizer, reducing the size and weight of the thruster; no additional DC power supply system is required to power the neutralizer, reducing costs; and the thruster's lifespan is no longer limited by the neutralizer, enhancing reliability. Furthermore, this invention has even more significant advantages: the presence of the decelerating gate can suppress downstream electron backflow, reduce ions generated between gates, reduce corrosion of the gate system, and improve the lifespan of the gate system, thereby improving the overall lifespan of the thruster; it avoids localized overheating of some components leading to deformation or even failure; and it stabilizes and effectively accelerates the voltage, maintaining good thruster operation and ensuring thruster performance. Attached Figure Description

[0025] Figure 1 This is a front view of the self-neutralizing gate system after installation according to the present invention;

[0026] Figure 2 This is a side view of the self-neutralizing gate system after installation according to the present invention;

[0027] Figure 3 This is a perspective view of a self-neutralizing gate system according to the present invention;

[0028] Figure 4 This is a schematic diagram illustrating the working principle of a self-neutralizing gate system according to the present invention.

[0029] In the figure: 1. Screen gate; 2. First insulating pad; 3. Accelerating gate; 4. Second insulating pad; 5. Decelerating gate. Detailed Implementation

[0030] To make the objectives, features, and advantages of this invention more apparent and understandable, the invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can implement it based on the description. The scope of protection of this invention is not limited to these specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0031] like Figures 1-3 The self-neutralizing gate system shown includes a screen gate 1, a first insulating pad 2, an accelerating gate 3, a second insulating pad 4, and a decelerating gate 5.

[0032] The screen gate 1 is placed close to the discharge chamber; the screen gate 1 is a circular plate structure with multiple circular through holes of the same diameter distributed on it.

[0033] The accelerating gate 3 is a circular plate structure, and its outer diameter is the same as that of the screen gate 1. Multiple circular through holes of the same diameter are distributed on the accelerating gate 3, and the positions of the circular through holes are the same as those of the through holes on the screen gate 1. The diameter of the circular through holes on the accelerating gate 3 is smaller than that of the through holes on the screen gate 1. The accelerating gate 3 and the screen gate 1 are coaxially arranged.

[0034] The deceleration gate 5 is a circular plate structure, and its outer diameter is the same as that of the screen gate 1. Multiple circular through holes of the same diameter are distributed on the deceleration gate 5. The positions of the circular through holes on the deceleration gate 5 are the same as those of the through holes on the screen gate 1. The diameter of the circular through holes on the deceleration gate 5 is larger than that of the through holes on the acceleration gate 3. The deceleration gate 5 and the screen gate 1 are coaxially arranged.

[0035] The first insulating pad 2 is an annular plate structure, and its outer diameter is the same as that of the screen gate 1. The first insulating pad 2 is installed between the screen gate 1 and the accelerating gate 3, and is coaxial with the screen gate 1.

[0036] The second insulating pad 4 is an annular plate structure, and its inner and outer diameters are the same as those of the first insulating pad 2. The second insulating pad 4 is installed between the accelerating gate 3 and the decelerating gate 5, and is coaxial with the screen gate 1.

[0037] The circular through holes on the screen gate 1, the circular through holes on the acceleration gate 3, and the circular through holes on the deceleration gate 5 are all arranged in a hexagonal structure.

[0038] After installation, the axes of the corresponding circular through holes on the screen gate 1, acceleration gate 3 and deceleration gate 5 coincide.

[0039] An radio frequency voltage is applied between the screen gate 1 and the acceleration gate 3, and there is a capacitor connection between the screen gate 1 and the acceleration gate 3; the deceleration gate 5 is connected to a DC negative bias voltage.

[0040] The working principle of the above self-neutralizing gate system is as follows:

[0041] First, plasma forms in the discharge chamber in front of the grid gate. Since the grid gate directly contacts the plasma within the discharge chamber, while the accelerating gate is placed downstream of the grid gate, the accelerating gate can only contact the plasma through a via on the grid gate; that is, the effective area ratio of the contacting plasma between the grid gate and the accelerating gate is greater than 1. Sheaths will form between the plasma and the grid gate, and between the plasma and the accelerating gate. Due to the mass difference between ions and electrons, their time responses to the applied electric field differ; electrons are controlled by the instantaneous electric field, while the motion of ions is determined by the average electric field.

[0042] Secondly, such as Figure 4As shown, an RF voltage is applied between the screen gate and the accelerating gate, and a capacitance exists between them. Based on asymmetric capacitive coupling discharge, the effective areas of the two gates are different, resulting in different sheath thicknesses and potential drops; otherwise, the RF current flowing through these two sheaths would differ. For the screen gate with a larger effective area, the time-averaged sheath thickness in front of it is smaller, resulting in a larger sheath RF voltage drop. Therefore, the applied RF voltage drop is mainly on the sheath in front of the accelerating gate aperture. Furthermore, due to the DC blocking capacitance between the screen gate and the accelerating gate, the RF voltage is rectified into a DC bias voltage. Under the action of the DC bias voltage, ions are accelerated and extracted by the self-neutralizing gate system. When the plasma potential approaches zero, the sheath between the gates collapses, and a large number of electrons are extracted. Ultimately, the extraction and extraction rates of electrons and ions are approximately equal per unit time, thus achieving beam self-neutralization.

[0043] Finally, a negative bias DC voltage is applied to the deceleration gate, which reduces the upstream potential and inhibits downstream electrons from passing through the gate, thereby reducing electron backflow.

[0044] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A self-neutralizing gate system, characterized by The self-neutralizing grid system comprises a screen grid, a first insulating spacer, an accelerating grid, a second insulating spacer and a retarding grid. The screen grid is placed close to the discharge chamber; the screen grid is a circular plate structure, and a plurality of circular through holes with the same diameter are distributed on the screen grid. The accelerating grid is a circular plate structure, and the outer diameter of the accelerating grid is the same as that of the screen grid; a plurality of circular through holes with the same diameter are distributed on the accelerating grid, the positions of the circular through holes on the accelerating grid are the same as those on the screen grid, the diameter of the circular through holes on the accelerating grid is smaller than that of the through holes on the screen grid, and the accelerating grid is coaxially arranged with the screen grid. The retarding grid is a circular plate structure, and the outer diameter of the retarding grid is the same as that of the screen grid; a plurality of circular through holes with the same diameter are distributed on the retarding grid, the positions of the circular through holes on the retarding grid are the same as those on the screen grid, the diameter of the circular through holes on the retarding grid is larger than that of the through holes on the accelerating grid, and the retarding grid is coaxially arranged with the screen grid. The first insulating spacer is an annular plate structure, and the outer diameter of the first insulating spacer is the same as that of the screen grid; the first insulating spacer is installed between the screen grid and the accelerating grid, and the first insulating spacer is coaxial with the screen grid. The second insulating spacer is an annular plate structure, and the inner and outer diameters of the second insulating spacer are the same as those of the first insulating spacer; the second insulating spacer is installed between the accelerating grid and the retarding grid, and the second insulating spacer is coaxial with the screen grid. The circular through holes on the screen grid, the circular through holes on the accelerating grid and the circular through holes on the retarding grid are arranged in a hexagonal structure.

2. A self-neutralizing gate system according to claim 1, characterized in that An RF voltage is applied between the screen grid and the accelerating grid, and a capacitor is connected between the screen grid and the accelerating grid.

3. A self-neutralizing gate system according to claim 1 or 2, characterized in that The retarding grid is connected to a DC negative bias voltage.

4. A self-neutralizing gate system according to claim 1 or 2, characterized in that The axes of the corresponding circular through holes on the screen grid, the accelerating grid and the retarding grid coincide.

5. A self-neutralizing gate system according to claim 3, wherein The axes of the corresponding circular through holes on the screen grid, the accelerating grid and the retarding grid coincide.

6. A self-neutralizing gate system according to claim 1, 2 or 5, characterized in that The screen grid, the accelerating grid and the retarding grid are made of metal or carbon material, and the first insulating spacer and the second insulating spacer are made of insulating material.

7. A self-neutralizing gate system according to claim 3, wherein The screen grid, the accelerating grid and the retarding grid are made of metal or carbon material, and the first insulating spacer and the second insulating spacer are made of insulating material.

8. A self-neutralizing gate system according to claim 4, wherein, The screen grid, the accelerating grid and the retarding grid are made of metal or carbon material, and the first insulating spacer and the second insulating spacer are made of insulating material.

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