Air-breathing radio frequency ion electric propulsion system powered by hybrid working media and multi-mode working method thereof
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- XIAN AEROSPACE PROPULSION INST
- Filing Date
- 2025-12-19
- Publication Date
- 2026-06-25
Smart Images
Figure CN2025143855_25062026_PF_FP_ABST
Abstract
Description
Air-breathing radio frequency ion electric propulsion system powered by mixed working fluid and its multi-mode operation method Technical Field
[0001] This invention relates to a propulsion system, specifically to a hybrid working fluid-powered air-breathing radio frequency ion electric propulsion system and its multi-mode operating method. Background Technology
[0002] Spacecraft flying in very low Earth orbit (100-300 km) can obtain clearer remote sensing information compared to conventional low Earth orbit satellites, which can shorten communication delays and are widely used in remote sensing, communication, navigation and other fields, significantly improving the service capabilities and application benefits of satellites.
[0003] However, the high atmospheric density in ultra-low Earth orbit (ULE) results in significant drag for satellites, leading to substantial resource consumption during long-term operation. Air-breathing electric propulsion systems can capture atmospheric propellant from the surrounding environment, theoretically enabling satellites to remain and maneuver in ULE without carrying a propellant. This solves the problem of current technologies being unable to enable long-term spacecraft presence and maneuverability in ULE, representing a highly promising cutting-edge space propulsion technology.
[0004] Referring to Figure 1, the existing air-breathing electric propulsion system, as an important component of the spacecraft, mainly consists of atmospheric trapping inlets 012 and thrusters 011 located on both sides of the satellite core 6, as well as several solar panels 8 connected to the satellite core 6. Its working principle is as follows: When the air-breathing electric propulsion system operates in low Earth orbit, it generates a relative velocity with the surrounding atmosphere, forming an incoming atmospheric flow 71. The atmospheric trapping inlets 012 of the air-breathing electric propulsion system are used to trap this relatively moving incoming atmospheric flow 71. The incoming atmospheric flow 71 is transported to the thrusters 011, where it is ionized and accelerated to generate thrust. The incoming atmospheric flow 71 is ultimately transformed into a plume 72.
[0005] Air-breathing electric propulsion systems can theoretically obtain atmospheric air as a working fluid to perform ultra-long-term ultra-low orbit operations. However, the complex atmospheric environment in ultra-low orbit poses significant challenges to the on-orbit application of air-breathing electric propulsion systems.
[0006] (1) Poor performance of atmospheric working fluid. The atmosphere is mainly composed of N2 and O2, and its performance is far lower than that of rare gases such as Xe and Kr commonly used in electric propulsion systems. Nitrogen and oxygen have small atomic masses and high ionization energies, and oxygen is reactive and corrosive. The working capacity of electric propulsion systems using nitrogen and oxygen as propellants is insufficient to meet many complex and extreme conditions in ultra-low orbits;
[0007] (2) The atmospheric working fluid density distribution gradient in ultra-low orbit is large. At an orbital altitude of 150km to 250km, the atmospheric density decreases by tens of times. Even at the same orbital altitude, the atmospheric density can fluctuate by more than an order of magnitude due to factors such as solar activity. Both excessively high and excessively low atmospheric density are not conducive to the normal operation of the air-breathing electric propulsion system. When the atmospheric density is too high, the satellite is subject to increased atmospheric drag. When the atmospheric density is too low, the atmospheric capture inlet 012 cannot capture a sufficient amount of working fluid.
[0008] The above factors impose a core requirement on the air-breathing electric propulsion system: to always supply a sufficient amount of working fluid to the thruster 011. It is almost impossible to achieve this by relying solely on the atmospheric capture inlet 012 to passively capture the atmosphere from the environment. This is because, firstly, the efficiency of the inlet in capturing the incoming airflow is limited, and secondly, the gas captured by the inlet cannot be further pressurized and stored. Furthermore, the flow rate of the working fluid supplied to the thruster 011 cannot be throttled, regulated, or controlled.
[0009] One proposed solution is to add a turbomolecular pump to an air-breathing electric propulsion system. This would improve the efficiency of capturing incoming air in the intake and pressurize and store the captured air in cylinders. The stored high-pressure gas could then be throttled, regulated, and controlled to be delivered to the thruster via a valve system. However, the turbomolecular pump is expensive due to its weight and power consumption, and it also makes the system more complex. Therefore, this solution has not yet been implemented in engineering. Summary of the Invention
[0010] The purpose of this invention is to solve the problem that existing air-breathing electric propulsion systems use only the atmosphere as a single working medium, resulting in low atmospheric capture efficiency and thus affecting spacecraft performance. The invention provides an air-breathing radio frequency ion electric propulsion system with a mixed working medium and its multi-mode operation method. The mixed working medium is a mixture of atmosphere and xenon gas.
[0011] To achieve the above objectives, the technical solution provided by this invention is:
[0012] A hybrid propellant-powered air-breathing radio frequency ion electric propulsion system, characterized by:
[0013] Includes a propulsion and gas trapping unit, a radio frequency neutralizer, a power and control unit, and a xenon gas storage and supply unit;
[0014] The propulsion and gas capture unit includes a radio frequency ion thruster and an atmospheric capture inlet connected to the input end of the radio frequency ion thruster.
[0015] The power and control unit includes a DC module, a control module, and a radio frequency module that are electrically connected to an external spacecraft control system via a communication and power supply bus.
[0016] The xenon gas storage and supply unit includes xenon cylinders for storing high-pressure xenon gas and valve and sensor assemblies for supplying xenon gas, which are interconnected by gas lines.
[0017] The control module and valves are electrically connected to the sensor assembly; the radio frequency ion thruster is electrically connected to the radio frequency neutralizer via the radio frequency module; the first output terminal of the xenon gas supply unit is connected to the gas input terminal of the radio frequency neutralizer; the second output terminal of the xenon gas supply unit is connected to the gas input terminal of the radio frequency ion thruster; the DC module is electrically connected to the radio frequency neutralizer and the radio frequency ion thruster.
[0018] The control module is used to control the flow rate of xenon in the xenon storage and supply unit, the radio frequency neutralizer is used to neutralize the positive valence ion plume ejected by the radio frequency ion thruster, and the DC module is used to provide power to the radio frequency neutralizer and the radio frequency ion thruster.
[0019] Furthermore, the radio frequency ion thruster includes a cylindrical thruster housing, a first air inlet and a radio frequency connector disposed on the side wall of the thruster housing, multiple annular first radio frequency antennas embedded in the thruster housing, a second collimating grid disposed near one end of the atmospheric capture air inlet, and a gate disposed opposite to the other end, wherein the space enclosed by the gate, the second collimating grid and the inner wall of the thruster housing constitutes the discharge chamber of the radio frequency ion thruster;
[0020] The gate is electrically connected to the DC module, and the multiple ring-shaped first radio frequency antennas are all electrically connected to the radio frequency module.
[0021] Furthermore, the atmospheric capture inlet includes a cylindrical inlet housing and a first collimating grid disposed at the end of the inlet housing away from the radio frequency ion thruster, and the inlet housing is connected to the thruster housing.
[0022] The inner walls of the air intake housing and the thruster housing are provided with an integral liner.
[0023] Furthermore, the radio frequency neutralizer includes a neutralizer housing, a discharge chamber disposed within the neutralizer housing and a second radio frequency antenna, a second air inlet communicating with the neutralizer housing and the discharge chamber, an ion collector disposed within the discharge chamber, an ignition probe communicating with the interior of the discharge chamber, a radio frequency power supply connected to the second radio frequency antenna, and a DC power supply with its negative terminal connected to the ion collector.
[0024] The second radio frequency antenna is electrically connected to the radio frequency module, and the positive terminal of the DC power supply is electrically connected to the DC module.
[0025] Furthermore, the valve and sensor assembly includes a first pressure sensor, a first self-locking valve, a first proportional valve, and a second pressure sensor, which are sequentially connected to the output end of the xenon cylinder via a gas path. The output gas path of the second pressure sensor is divided into two paths: one path includes a second self-locking valve, a second proportional valve, and a first flow sensor connected in sequence; the other path includes a third self-locking valve, a third proportional valve, and a second flow sensor connected in sequence. The output end of the first flow sensor is connected to the first air inlet in the propulsion and gas capture unit, and the output end of the second flow sensor is connected to the second air inlet in the radio frequency neutralizer. The input end of the xenon cylinder is equipped with an add / exhaust valve.
[0026] The addition / extraction valve is used to add or remove xenon gas from the xenon cylinder. The first self-locking valve, the second self-locking valve, and the third self-locking valve are all used to control the opening and closing of the gas path. The first proportional valve, the second proportional valve, and the third proportional valve are all used to adjust the gas flow rate.
[0027] The first pressure sensor, the first self-locking valve, the first proportional valve, the second pressure sensor, the second self-locking valve, the second proportional valve, the first flow sensor, the third self-locking valve, the third proportional valve, and the second flow sensor are all electrically connected to the control module.
[0028] Furthermore, the cross-sectional shape of the first collimated grid and the second collimated grid is strip-shaped, fan-shaped, square-shaped, long grid-shaped, or hexagonal grid-shaped.
[0029] Furthermore, the liner is made of ceramic, and the inner wall of the liner inside the air intake housing near the radio frequency ion thruster is shaped as an elliptical paraboloid to achieve mirror reflection after the airflow collides with the wall.
[0030] Meanwhile, the present invention also provides a multi-mode operating method for the above-mentioned air-breathing radio frequency ion electric propulsion system powered by a mixed working fluid, which is characterized by including the following steps:
[0031] Step 1: The spacecraft uses sensors to determine the current operating conditions and transmits the operating condition data to the power and control unit via the communication and power supply bus. The DC module in the power and control unit adjusts the gate voltage U, the RF module adjusts the RF power P, and the control module adjusts the xenon working fluid flow rate M of the xenon storage and supply unit to adapt to different operating conditions.
[0032] Step 2: If the current operating condition is the standard operating condition, then proceed to step 3a;
[0033] If the current operating condition is a high-resistance condition, then proceed to step 3b;
[0034] If the current operating condition is a low-resistance condition, then proceed to step 3c;
[0035] If the current operating condition is an extremely high resistance condition, then proceed to step 3d;
[0036] If the current operating condition is a particularly thin atmosphere, then proceed to step 3e;
[0037] Define standard voltage U0, standard flow rate M0, standard power P0, and maximum flow rate M. max ;
[0038] Step 3a: The DC module adjusts the gate voltage U to U0±5%U0, the RF module adjusts the RF power P to P0±5%P0, and the control module adjusts the xenon working fluid flow rate M to M0±5%M0. The working mode at this time is defined as the standard working mode.
[0039] Step 3b: The DC module adjusts the gate voltage U to 0.9U0±5%U0, the RF module adjusts the RF power P to P0±5%P0, and the control module adjusts the xenon working fluid flow rate M to M0~1.4M0. The working mode at this time is defined as the high thrust working mode.
[0040] Step 3c: The DC module adjusts the gate voltage U to 1.2U0±5%U0, the RF module adjusts the RF power P to P0±5%P0, and the control module adjusts the xenon working fluid flow rate M to 0~1.2M0. The working mode at this time is defined as the high specific impulse working mode.
[0041] Step 3d: The DC module adjusts the gate voltage U to 0.9U0±5%U0, the RF module adjusts the RF power P to 1.2P0±5%P0, and the control module adjusts the xenon working fluid flow rate M to 1.4M0~M max The operating mode at this time is defined as the high flow rate and high thrust operating mode;
[0042] Step 3e: The DC module adjusts the gate voltage U to 1.2U0 ± 5%U0; the RF module adjusts the RF power P to P0 ± 5%P0; and the control module adjusts the xenon working fluid flow rate M to 1.2M0 ~ M0. max The operating mode at this time is defined as the high flow rate and high specific impulse operating mode.
[0043] Furthermore, step 2 also includes: if the current operating condition is another operating condition, then proceed to step 3f;
[0044] Step 3f: The DC module adjusts the gate voltage U to U1, the RF module adjusts the RF power P to P1, and the control module adjusts the xenon working fluid flow rate M to M1. The working mode at this time is defined as a custom working mode, where U1, P1 and M1 are all custom values.
[0045] Compared with the prior art, the beneficial effects of the present invention are:
[0046] 1. The hybrid propellant-powered air-breathing radio frequency ion electric propulsion system provided by this invention not only utilizes the atmosphere in the ultra-low orbit environment, but also carries its own xenon propellant. The xenon gas storage and supply unit can provide the thruster with controllable and reliable xenon propellant to compensate for the insufficiency of atmospheric propellant. The xenon gas storage and supply unit can adapt to more types of operating conditions and has higher reliability in dealing with complex and extreme operating conditions in ultra-low orbit. Compared with electric propulsion systems with a single rare gas propellant, the hybrid propellant-powered air-breathing electric propulsion system not only utilizes its own carried xenon, but also utilizes the atmosphere captured from the space environment, greatly increasing the total impulse and total range, and can meet the power requirements of satellites operating in ultra-low orbit for extended periods.
[0047] 2. The mixed working fluid powered air-breathing radio frequency ion electric propulsion system provided by the present invention adopts an integrated design of radio frequency ion thruster and atmospheric capture air intake, forming a propulsion and gas capture unit, which is beneficial to saving space and improving gas capture efficiency.
[0048] 3. The air-breathing radio frequency ion electric propulsion system powered by a hybrid working fluid provided by this invention features a relatively independent and adjustable ionization and acceleration mechanism in the radio frequency ion thruster. This allows for real-time adjustment of ionization and acceleration parameters to adapt to the complex and variable ultra-low orbit environment, enabling the execution of multiple operating modes. In contrast, the ionization and acceleration mechanisms of the Hall thruster are highly coupled, while the ionization parameters of the DC ion thruster are essentially unadjustable. The radio frequency ion thruster boasts high specific impulse and long service life, meeting the requirements for long-term operation in ultra-low orbit. Furthermore, the radio frequency ion thruster offers advantages such as simple structure, reliable operation, and high technological maturity.
[0049] 4. The air-breathing radio frequency ion electric propulsion system with mixed working fluid provided by the present invention can deliver xenon gas to the radio frequency ion thruster and the radio frequency neutralizer in two separate streams at different flow rates under the control of the control module. The xenon gas flow rate is dynamically adjusted according to the operating conditions of the spacecraft. One stream of xenon gas delivered to the radio frequency ion thruster is mixed with the atmosphere to provide a mixed working fluid for the electric propulsion system. The other stream of xenon gas delivered to the radio frequency neutralizer is to neutralize the positive valence ion plume ejected by the radio frequency ion thruster and prevent charge accumulation. This configuration allows the spacecraft equipped with the air-breathing radio frequency ion electric propulsion system with mixed working fluid to adapt to various operating conditions and achieve the optimal thrust of the spacecraft.
[0050] 5. The mixed-working-propellant air-breathing radio frequency ion electric propulsion system provided by this invention has a ceramic liner that makes the inner walls of the thruster shell and the air intake shell resistant to physical wear and chemical corrosion, and the surface can remain smooth. When the airflow collides with the smooth wall surface, it undergoes specular reflection, which helps to improve the efficiency of the air intake in capturing air and also extends the service life of the air intake. The liner adopts an elliptical parabolic surface design. After the airflow collides with the wall surface, it is reflected by the specular surface to its focal position, which helps to further improve the efficiency of the air intake in capturing the incoming airflow. The parabolic surface can play an effective role only if the airflow collides with the wall surface and undergoes specular reflection.
[0051] 6. The multi-mode operation method of the air-breathing radio frequency ion electric propulsion system with mixed working fluid provided by the present invention includes five preset operating modes (standard operating mode, high thrust operating mode, high specific impulse operating mode, high flow rate and high thrust operating mode, and high flow rate and high specific impulse operating mode) and several custom modes. The selection and switching of different modes are automatically controlled by the DC module, control module and radio frequency module in the power and control unit, which increases the stability and lifespan of the spacecraft. Attached Figure Description
[0052] Figure 1 is a schematic diagram of the principle of an existing air-breathing electric propulsion system;
[0053] Explanation of the markings in Figure 1:
[0054] 012-Atmospheric trapping inlet, 011-Thruster, 6-Satellite core, 71-Atmospheric inflow, 72-Plume; 8-Solar panel;
[0055] Figure 2 is a schematic diagram of an embodiment of the air-breathing radio frequency ion electric propulsion system powered by a hybrid working fluid according to the present invention.
[0056] Figure 3 is a schematic diagram of the xenon gas storage and supply unit in an embodiment of the air-breathing radio frequency ion electric propulsion system of the present invention with hybrid working fluid power.
[0057] Figure 4 is a schematic diagram of the structure of the radio frequency neutralizer in an embodiment of the air-breathing radio frequency ion electric propulsion system of the present invention.
[0058] Figure 5 is a schematic diagram of the propulsion and gas capture unit in an embodiment of the air-breathing radio frequency ion electric propulsion system powered by the hybrid working fluid of the present invention.
[0059] Figure 6 is a schematic diagram of the radio frequency ion thruster in an embodiment of the air-breathing radio frequency ion electric propulsion system powered by the hybrid working fluid of the present invention.
[0060] Figure 7 is a schematic diagram of the cross-sectional shape of the first collimated grid and the second collimated grid in an embodiment of the air-breathing radio frequency ion electric propulsion system of the present invention, where (a) to (e) represent different cross-sectional shapes;
[0061] Explanation of the markings in Figures 2-7: 1-Propulsion and gas trapping unit; 11-Radio frequency ion thruster; 1101-Discharge chamber; 111-Second collimating grid; 112-Grid; 113-First air inlet; 114-Radio frequency connector; 115-Thruster housing; 116-First radio frequency antenna; 12-Atmospheric trapping air inlet; 121-Air inlet housing; 122-Liner; 123-First collimating grid; 2-Radio frequency neutralizer; 21-Neutralizer housing; 22-Second air inlet; 23-Ignition probe; 24-Discharge chamber; 25-Ion collector; 26-Second radio frequency antenna; 27-Radio frequency power supply; 28-DC power supply; 3-Power and control unit; 31-DC module; 32-Control module; 33-Radio frequency module; 4-Communication and power supply bus; 5-Xenon gas storage and supply unit; 51-Xenon gas cylinder; 52-Valve and sensor assembly; 71-Atmospheric inflow; P1 - First pressure sensor, LV1 - First self-locking valve, PV1 - First proportional valve, P2 - Second pressure sensor, LV2 - Second self-locking valve, PV2 - Second proportional valve, LV3 - Third self-locking valve, PV3 - Third proportional valve, FL1 - First flow sensor, FL2 - Second flow sensor, JP - Add / extract valve. Detailed Implementation
[0062] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0063] A hybrid working fluid-powered air-breathing radio frequency ion electric propulsion system is shown in Figure 2. The hybrid working fluid includes atmosphere and xenon. Xenon is chosen because it has a large atomic mass, low ionization energy, and better performance than atmosphere, making it the most commonly used electric propulsion working fluid.
[0064] The system includes a propulsion and gas capture unit 1, a radio frequency neutralizer 2, a power and control unit 3, and a xenon gas storage and supply unit 5. The propulsion and gas capture unit 1 includes a radio frequency ion thruster 11 and an atmospheric capture inlet 12 connected to the input of the radio frequency ion thruster 11. The power and control unit 3 includes a DC module 31, a control module 32, and a radio frequency module 33 electrically connected to an external spacecraft control system via a communication and power supply bus 4. The xenon gas storage and supply unit 5 includes a xenon cylinder 51 for storing high-pressure xenon gas and a valve and sensor assembly 52 for supplying xenon gas, all interconnected via gas lines. The control module 32 and the valve and sensor assembly... Component 52 is electrically connected, and the radio frequency ion thruster 11 is electrically connected to the radio frequency neutralizer 2 through the radio frequency module 33; the first output terminal of the xenon gas storage and supply unit 5 is connected to the gas path input terminal of the radio frequency neutralizer 2, and the second output terminal of the xenon gas storage and supply unit 5 is connected to the gas path input terminal of the radio frequency ion thruster 11; the DC module 31 is electrically connected to the radio frequency neutralizer 2 and the radio frequency ion thruster 11; the control module 32 is used to control the flow rate of xenon gas in the xenon gas storage and supply unit 5, the radio frequency neutralizer 2 is used to neutralize the positive valence ion plume ejected by the radio frequency ion thruster 11, and the DC module 31 is used to provide power to the radio frequency neutralizer 2 and the radio frequency ion thruster 11.
[0065] The following is a detailed description of each component or unit:
[0066] Referring to Figures 5 and 6, the radio frequency ion thruster 11 includes a cylindrical thruster housing 115, a first air inlet 113 and a radio frequency connector 114 disposed on the side wall of the thruster housing 115, multiple annular first radio frequency antennas 116 embedded in the thruster housing 115, a second collimating grid 111 disposed near one end of the atmospheric trapping air inlet 12, and a gate 112 disposed opposite at the other end. The space enclosed by the gate 112, the second collimating grid 111, and the inner wall of the thruster housing 115 constitutes the discharge chamber 1101 of the radio frequency ion thruster 11. The gate 112 is electrically connected to the DC module 31, and the multiple annular first radio frequency antennas 116 are all electrically connected to the radio frequency module 33. The radio frequency ion thruster 11 uses electrical energy to ionize the mixed working gas and then accelerate it, thereby generating thrust. In real-world scenarios, air-breathing electric propulsion systems operate in complex environments, particularly with large concentration gradients and unstable composition of the atmospheric working fluid. Hall thrusters and DC ion thrusters rely on external electromagnetic coils to generate an electromagnetic field that confines electrons during ionization, requiring precise concentration and composition of the gaseous working fluid and exhibiting poor performance in ionizing atmospheric working fluids. In contrast, the radio frequency ion thruster 11 utilizes radio frequency energy to directly ionize the working fluid. Radio frequency ionization is one of the most effective ionization technologies, with lower requirements for gaseous working fluid concentration and composition, and can effectively ionize atmospheric working fluids.
[0067] The ionization and acceleration mechanisms of the radio frequency (RF) ion thruster 11 are relatively independent and adjustable, allowing for real-time adjustment of ionization and acceleration parameters to adapt to the complex and variable ultra-low Earth orbit (ULE) environment, and enabling the execution of multiple operating modes. In contrast, the ionization and acceleration mechanisms of the Hall effect thruster are highly coupled, while the ionization parameters of the DC ion thruster are essentially unadjustable. The RF ion thruster 11 features high specific impulse and long service life, meeting the requirements for long-term operation in ULE. Furthermore, the RF ion thruster 11 boasts advantages such as simple structure, reliable operation, and high technological maturity.
[0068] The atmospheric capture inlet 12 includes a cylindrical inlet housing 121 and a first collimation grid 123 disposed at the end of the inlet housing 121 away from the radio frequency ion thruster 11. The inlet housing 121 is connected to the thruster housing 115.
[0069] The inner walls of the air intake housing 121 and the thruster housing 115 are provided with an integral liner 122. The liner 122 is made of ceramic, and the inner wall of the liner 122 inside the air intake housing 121 near the radio frequency ion thruster 11 has an elliptical parabolic shape.
[0070] Referring to Figure 4, the radio frequency neutralizer 2 includes a neutralizer housing 21, a discharge chamber 24 disposed within the neutralizer housing 21, a second radio frequency antenna 26, a second air inlet 22 communicating with the neutralizer housing 21 and the discharge chamber 24, an ion collector 25 disposed within the discharge chamber 24, an ignition probe 23 communicating with the interior of the discharge chamber 24, a radio frequency power supply 27 connected to the second radio frequency antenna 26, and a DC power supply 28 whose negative terminal is connected to the ion collector 25; the second radio frequency antenna 26 is electrically connected to the radio frequency module 33, and the positive terminal of the DC power supply 28 is electrically connected to the DC module 31.
[0071] The working principle of the radio frequency neutralizer 2 is as follows: Xenon gas enters the discharge chamber 24 through the second inlet 22 and is ionized into plasma after being subjected to radio frequency energy. Electrons in the plasma are accelerated and extracted under the action of the electric field between the anode and the ion collector to neutralize the positive valence ion plume ejected by the radio frequency ion thruster 11 and prevent charge accumulation. The ignition probe 23 is used to apply an instantaneous ignition voltage during ignition and discharges violently at the tip to activate the ionization sequence of the gas working fluid.
[0072] Referring to Figure 3, the valve and sensor assembly 52 includes a first pressure sensor P1, a first self-locking valve LV1, a first proportional valve PV1, and a second pressure sensor P2, which are sequentially connected to the output end of the xenon cylinder 51 via a gas path. The gas path at the output end of the second pressure sensor P2 is divided into two paths: one path includes the second self-locking valve LV2, the second proportional valve PV2, and the first flow sensor FL1, which are sequentially connected; the other path includes the third self-locking valve LV3, the third proportional valve PV3, and the second flow sensor FL2, which are sequentially connected. The output end of the first flow sensor FL1 is connected to the first air inlet 113 in the propulsion and gas capture unit 1, and the output end of the second flow sensor FL2 is connected to the second air inlet 22 in the radio frequency neutralizer 2. An add / exhaust valve JP is provided at the input end of the xenon cylinder 51.
[0073] The add / exhaust valve JP is used to add or expel xenon gas from xenon cylinder 51. The first self-locking valve LV1, the second self-locking valve LV2, and the third self-locking valve LV3 are all used to control the opening and closing of the gas path. The first proportional valve PV1, the second proportional valve PV2, and the third proportional valve PV3 are all used to adjust the gas flow rate.
[0074] The first pressure sensor P1, the first self-locking valve LV1, the first proportional valve PV1, the second pressure sensor P2, the second self-locking valve LV2, the second proportional valve PV2, the first flow sensor FL1, the third self-locking valve LV3, the third proportional valve PV3, and the second flow sensor FL2 are all electrically connected to the control module 32.
[0075] Referring to Figure 7, the cross-sectional shapes of the first collimating grid 123 and the second collimating grid 111 are spoke-shaped (a), fan-shaped (b), square-shaped (c), elongated grid-shaped (d), or hexagonal grid-shaped (e). The second collimating grid 111 is designed to prevent gas backflow. Different shapes can adapt to different operating conditions. The first collimating grid 123 is beneficial for improving gas capture efficiency, facilitating airflow into the atmospheric capture inlet 12 along the axial direction, and also has the effect of slowing down the airflow, thus retaining more gaseous working fluid in the atmospheric capture inlet 12.
[0076] To cope with the complex and extreme ultra-low orbit environment, this embodiment also provides a multi-mode operation method for the above-mentioned air-breathing radio frequency ion electric propulsion system powered by a hybrid working fluid. The multi-mode operation method is achieved by controlling three parameters: gate voltage U, xenon working fluid flow rate M, and radio frequency power P, and includes the following steps:
[0077] Step 1: The spacecraft uses sensors to determine the current operating conditions and transmits the operating condition data to the power and control unit 3 via the communication bus 4. The DC module 31 in the power and control unit 3 adjusts the gate voltage U, the RF module 33 adjusts the RF power P, and the control module 32 adjusts the xenon working fluid flow rate M of the xenon storage and supply unit 5 to adapt to different operating conditions.
[0078] Step 2: If the current operating condition is the standard operating condition, then proceed to step 3a;
[0079] If the current operating condition is a high-resistance condition, then proceed to step 3b;
[0080] If the current operating condition is a low-resistance condition, then proceed to step 3c;
[0081] If the current operating condition is an extremely high resistance condition, then proceed to step 3d;
[0082] If the current operating condition is a particularly thin atmosphere, then proceed to step 3e;
[0083] If the current operating condition is another operating condition, proceed to step 3f;
[0084] Define standard voltage U0, standard flow rate M0, standard power P0, and maximum flow rate M. max ;
[0085] Step 3a: Under standard operating conditions, DC module 31 adjusts the gate voltage U to U0±5%U0, RF module 33 adjusts the RF power P to P0±5%P0, and control module 32 adjusts the xenon working fluid flow rate M to M0±5%M0. The operating mode at this time is defined as the standard operating mode.
[0086] Step 3b: Under high drag conditions, the DC module 31 adjusts the gate voltage U to 0.9U0±5%U0, the RF module 33 adjusts the RF power P to P0±5%P0, and the control module 32 adjusts the xenon working fluid flow rate M to M0~1.4M0. The working mode at this time is defined as the high thrust working mode.
[0087] Step 3c: Under low resistance conditions, the DC module 31 adjusts the gate voltage U to 1.2U0±5%U0, the RF module 33 adjusts the RF power P to P0±5%P0, and the control module 32 adjusts the xenon working fluid flow rate M to 0~1.2M0. The working mode at this time is defined as the high specific impulse working mode.
[0088] Step 3d: Under ultra-high resistance conditions, the DC module 31 adjusts the gate voltage U to 0.9U0±5%U0, the RF module 33 adjusts the RF power P to 1.2P0±5%P0, and the control module 32 adjusts the xenon working fluid flow rate M to 1.4M0~M max The operating mode at this time is defined as the high flow rate and high thrust operating mode;
[0089] Step 3e: Under extremely rarefied atmospheric conditions, the DC module 31 adjusts the gate voltage U to 1.2U0 ± 5%U0, the RF module 33 adjusts the RF power P to P0 ± 5%P0, and the control module 32 adjusts the xenon working fluid flow rate M to 1.2M0 ~ Mmax The operating mode at this time is defined as the high flow rate and high specific impulse operating mode;
[0090] Step 3f: Under other operating conditions, the DC module 31 adjusts the gate voltage U to U1, the RF module 33 adjusts the RF power P to P1, and the control module 32 adjusts the xenon working fluid flow rate M to M1. The operating mode at this time is defined as a custom operating mode, where U1, P1, and M1 are all custom values.
[0091] Table 1 summarizes the different working modes:
[0092] Table 1. Multi-mode operating parameters of a mixed-propellant air-breathing radio frequency ion electric propulsion system.
[0093] Detailed explanation:
[0094] The standard operating mode applies to standard operating conditions. Standard operating conditions are those specifically specified in the flight mission statement. Generally, standard operating conditions refer to the conditions where the satellite operates at its most frequently used orbital altitude (or orbital altitude range) and solar activity is stable. In standard operating mode, the grid voltage is set to the standard voltage U0, which can be adjusted by ±5% of U0 according to actual operating conditions; the xenon propellant flow rate is set to the standard flow rate M0, which can be adjusted by ±5% of M0 according to actual operating conditions; and the radio frequency power is set to the standard power P0, which can be adjusted by ±5% of P0 according to actual operating conditions.
[0095] The high-thrust operating mode is suitable for high-drag conditions. High-drag conditions refer to situations where the satellite's orbit decreases or solar activity fluctuates, resulting in increased atmospheric density and greater drag. Under high-drag conditions, the electric propulsion system reduces the grid voltage and increases the xenon propellant flow rate to increase thrust and counteract drag.
[0096] The high specific impulse mode is suitable for low drag conditions. Low drag conditions refer to situations where the satellite's orbit increases or solar activity fluctuates, resulting in decreased atmospheric density and reduced satellite drag. In high specific impulse mode, the electric propulsion system increases the grid voltage and adjusts the xenon propellant flow rate in real time based on atmospheric environment data transmitted back by the satellite, thereby increasing specific impulse while maintaining normal system operation. In high specific impulse mode, the xenon propellant flow rate M can be reduced to as low as 0.
[0097] The high-flow-rate, high-thrust operating mode is suitable for ultra-high drag conditions. Ultra-high drag conditions refer to situations where the satellite's orbit descends below a certain altitude or solar activity fluctuates dramatically, resulting in a significant increase in atmospheric density and extremely high drag. Due to this exceptionally high drag, the air-breathing electric propulsion system demands a higher propellant flow rate. Since the thrust provided by atmospheric propellant is limited, the xenon propellant flow rate must be increased, potentially up to the upper limit of the thruster's performance constraints. This necessitates a corresponding increase in radio frequency power and a decrease in grid voltage, significantly increasing thrust to offset the drag.
[0098] The high-flow-rate, high-specific-impulse operating mode is suitable for conditions with extremely thin atmospheres. Extremely thin atmospheres refer to situations where the satellite's orbit rises above a certain altitude or solar activity fluctuates dramatically, resulting in a significant decrease in atmospheric density and extremely low satellite drag. Due to the extremely thin atmosphere, the amount of atmospheric propellant that an air-breathing electric propulsion system can effectively capture is greatly reduced. Therefore, the xenon propellant flow rate must be increased accordingly, potentially up to the upper limit of the thruster's performance constraints. This necessitates a corresponding increase in the grid voltage to maintain normal system operation under extremely thin atmospheric conditions.
[0099] The system can operate in a custom working mode, and the system's gate voltage U, xenon working fluid flow rate M, and RF power P can be customized according to actual operating conditions.
[0100] It should be noted that the parameters in Table 1 are only for illustrating the basic idea of the multi-mode working method. The specific values of each parameter can be optimized and adjusted according to the actual situation. These optimizations and adjustments should be covered within the protection scope of this invention.
Claims
1. A hybrid working fluid powered air-breathing radio frequency ion electric propulsion system, characterized in that: It includes a propulsion and gas capture unit (1), a radio frequency neutralizer (2), a power and control unit (3), and a xenon gas storage and supply unit (5); The propulsion and gas capture unit (1) includes a radio frequency ion thruster (11) and an atmospheric capture inlet (12) connected to the input end of the radio frequency ion thruster (11); The power and control unit (3) includes a DC module (31), a control module (32), and a radio frequency module (33) that are electrically connected to an external spacecraft control system via a communication and power supply bus (4); The xenon gas storage and supply unit (5) includes a xenon cylinder (51) for storing high-pressure xenon gas and a valve and sensor assembly (52) for supplying xenon gas, which are interconnected by gas lines. The control module (32) and the valve and sensor assembly (52) are electrically connected; the radio frequency ion thruster (11) is electrically connected to the radio frequency neutralizer (2) through the radio frequency module (33); the first output terminal of the xenon gas storage and supply unit (5) is connected to the gas input terminal of the radio frequency neutralizer (2); the second output terminal of the xenon gas storage and supply unit (5) is connected to the gas input terminal of the radio frequency ion thruster (11); the DC module (31) is electrically connected to the radio frequency neutralizer (2) and the radio frequency ion thruster (11). The control module (32) is used to control the flow rate of xenon in the xenon gas storage and supply unit (5), the radio frequency neutralizer (2) is used to neutralize the positive valence ion plume ejected by the radio frequency ion thruster (11), and the DC module (31) is used to provide power to the radio frequency neutralizer (2) and the radio frequency ion thruster (11).
2. The air-breathing radio frequency ion electric propulsion system powered by a hybrid working fluid according to claim 1, characterized in that: The radio frequency ion thruster (11) includes a cylindrical thruster housing (115), a first air inlet (113) and a radio frequency connector (114) disposed on the side wall of the thruster housing (115), multiple annular first radio frequency antennas (116) embedded in the thruster housing (115), a second collimated grid (111) disposed at one end near the atmospheric trapping air inlet (12), and a gate (112) disposed opposite at the other end, wherein the space enclosed by the gate (112), the second collimated grid (111) and the inner wall of the thruster housing (115) constitutes the discharge chamber (1101) of the radio frequency ion thruster (11); The gate (112) is electrically connected to the DC module (31), and the multiple ring-shaped first radio frequency antennas (116) are all electrically connected to the radio frequency module (33).
3. The air-breathing radio frequency ion electric propulsion system powered by a hybrid working fluid according to claim 2, characterized in that: The atmospheric capture inlet (12) includes a cylindrical inlet housing (121) and a first collimating grid (123) disposed at the end of the inlet housing (121) away from the radio frequency ion thruster (11), and the inlet housing (121) is connected to the thruster housing (115). The inner walls of the air intake housing (121) and the thruster housing (115) are provided with an integral liner (122).
4. The air-breathing radio frequency ion electric propulsion system powered by a hybrid working fluid according to claim 3, characterized in that: The radio frequency neutralizer (2) includes a neutralizer housing (21), a discharge chamber (24) disposed in the neutralizer housing (21), a second radio frequency antenna (26), a second air inlet (22) communicating with the neutralizer housing (21) and the discharge chamber (24), an ion collector (25) disposed in the discharge chamber (24), an ignition probe (23) communicating with the interior of the discharge chamber (24), a radio frequency power supply (27) connected to the second radio frequency antenna (26), and a DC power supply (28) with its negative terminal connected to the ion collector (25); The second radio frequency antenna (26) is electrically connected to the radio frequency module (33), and the positive terminal of the DC power supply (28) is electrically connected to the DC module (31).
5. The air-breathing radio frequency ion electric propulsion system with hybrid working fluid power according to claim 4, characterized in that: The valve and sensor assembly (52) includes a first pressure sensor (P1), a first self-locking valve (LV1), a first proportional valve (PV1), and a second pressure sensor (P2) connected in sequence to the output end of the xenon cylinder (51) via a gas path. The gas path at the output end of the second pressure sensor (P2) is divided into two paths. One path includes the second self-locking valve (LV2), the second proportional valve (PV2), and the first flow sensor (FL1) connected in sequence. The other path includes the third self-locking valve (LV3), the third proportional valve (PV3), and the second flow sensor (FL2) connected in sequence. The output end of the first flow sensor (FL1) is connected to the first air inlet (113) in the propulsion and gas capture unit (1), and the output end of the second flow sensor (FL2) is connected to the second air inlet (22) in the radio frequency neutralizer (2). The input end of the xenon cylinder (51) is provided with a filler / exhaust valve (JP). The add / exhaust valve (JP) is used to add or expel xenon gas from the xenon cylinder (51). The first self-locking valve (LV1), the second self-locking valve (LV2), and the third self-locking valve (LV3) are all used to control the opening and closing of the gas path. The first proportional valve (PV1), the second proportional valve (PV2), and the third proportional valve (PV3) are all used to adjust the gas flow rate. The first pressure sensor (P1), the first self-locking valve (LV1), the first proportional valve (PV1), the second pressure sensor (P2), the second self-locking valve (LV2), the second proportional valve (PV2), the first flow sensor (FL1), the third self-locking valve (LV3), the third proportional valve (PV3), and the second flow sensor (FL2) are all electrically connected to the control module (32).
6. The air-breathing radio frequency ion electric propulsion system powered by a hybrid working fluid according to claim 5, characterized in that: The cross-sectional shape of the first collimated grid (123) and the second collimated grid (111) is strip-shaped, fan-shaped, square-shaped, long grid-shaped or hexagonal grid-shaped.
7. The air-breathing radio frequency ion electric propulsion system powered by a hybrid working fluid according to claim 6, characterized in that: The inner liner (122) is made of ceramic. The inner wall of the inner liner (122) near the radio frequency ion thruster (11) inside the air intake housing (121) is elliptical parabolic in shape, which is used to achieve mirror reflection after the airflow collides with the wall.
8. A multi-mode operating method for an air-breathing radio frequency ion electric propulsion system powered by a hybrid working fluid as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: The spacecraft determines the current operating condition through sensors and transmits the operating condition data information to the power and control unit (3) through the communication and power supply bus (4). The DC module (31) in the power and control unit (3) adjusts the gate voltage U, the RF module (33) adjusts the RF power P, and the control module (32) adjusts the xenon working fluid flow rate M of the xenon storage and supply unit (5) to adapt to different operating conditions. Step 2: If the current operating condition is the standard operating condition, then proceed to step 3a; If the current operating condition is a high-resistance condition, then proceed to step 3b; If the current operating condition is a low-resistance condition, then proceed to step 3c; If the current operating condition is an extremely high resistance condition, then proceed to step 3d; If the current operating condition is a particularly thin atmosphere, then proceed to step 3e; Define standard voltage U0, standard flow rate M0, standard power P0, and maximum flow rate M. max ; Step 3a: The DC module (31) adjusts the gate voltage U to U0±5%U0, the RF module (33) adjusts the RF power P to P0±5%P0, and the control module (32) adjusts the xenon working fluid flow rate M to M0±5%M0. The working mode at this time is defined as the standard working mode. Step 3b: The DC module (31) adjusts the gate voltage U to 0.9U0±5%U0, the RF module (33) adjusts the RF power P to P0±5%P0, and the control module (32) adjusts the xenon working fluid flow rate M to M0~1.4M0. The working mode at this time is defined as the high thrust working mode. Step 3c: The DC module (31) adjusts the gate voltage U to 1.2U0±5%U0, the RF module (33) adjusts the RF power P to P0±5%P0, and the control module (32) adjusts the xenon working fluid flow rate M to 0~1.2M0. The working mode at this time is defined as the high specific impulse working mode. Step 3d: The DC module (31) adjusts the gate voltage U to 0.9U0±5%U0, the RF module (33) adjusts the RF power P to 1.2P0±5%P0, and the control module (32) adjusts the xenon working fluid flow rate M to 1.4M0~M max The operating mode at this time is defined as the high flow rate and high thrust operating mode; Step 3e: The DC module (31) adjusts the gate voltage U to 1.2U0±5%U0; the RF module (33) adjusts the RF power P to P0±5%P0; and the control module (32) adjusts the xenon working fluid flow rate M to 1.2M0~M max The operating mode at this time is defined as the high flow rate and high specific impulse operating mode.
9. The multi-mode operating method of the air-breathing radio frequency ion electric propulsion system with hybrid working fluid power according to claim 8, characterized in that: Step 2 also includes: if the current operating condition is another operating condition, then proceed to step 3f; Step 3f: The DC module (31) adjusts the gate voltage U to U1, the RF module (33) adjusts the RF power P to P1, and the control module (32) adjusts the xenon working fluid flow rate M to M1. The working mode at this time is defined as a custom working mode, where U1, P1 and M1 are all custom values.