Thruster with magnetically-coated cusped Laval nozzle

Abstract

The invention discloses a thruster with a magnetically-coated cusped Laval nozzle. The thruster comprises an injection unit, a combustion chamber, the magnetically-coated cusped Laval nozzle and a hollow cathode, the magnetic coating cusped type Laval nozzle comprises a Laval nozzle body and a magnetic coating cusped type assembly. The Laval nozzle comprises a metal shrinkage pipe and a ceramic expansion pipe which are sequentially arranged in the axial direction. The periphery of the ceramic expansion tube is coaxially sleeved with the magnetic coating cusped assembly, and the magnetic coating cusped assembly comprises N stages of permanent magnets and N-1 spacer rings; the hollow cathode is arranged on the outer side of the tail end of the ceramic expansion tube. The magnetic-coated cusped Laval nozzle is adopted, a cusped field is introduced, rapid switching between a chemical direct-current propulsion mode and a magnetic jet propulsion mode can be achieved, and when the thruster needs rapid maneuvering orbital transfer, the chemical direct-current propulsion mode is adopted, and 10N-level thrust can be provided; when the thruster operates in a low orbit and needs to maintain the orbit height, a magnetic jet propulsion mode is adopted to generate thrust in a set direction, so that the orbit height of the satellite is kept unchanged.

Description

Technical Field

[0001] This invention relates to the field of spacecraft propulsion technology, and in particular to a thruster with a magnetically coated tangential Laval nozzle. Background Technology

[0002] While traditional electric propulsion technology has proven highly effective in satellite attitude maintenance, orbital altitude compensation, and long-term acceleration missions for deep space probes due to its extremely high specific impulse and excellent fuel efficiency, its inherently low thrust levels, ranging from micronewtons (μN) to millinenewtons (mN), limit its ability to handle rapid response and large orbital changes. This negligible thrust means that the acceleration generated by the spacecraft is extremely limited (typically well below 0.001 g), resulting in extremely long timescales required to complete orbital transfers or maneuvers. For example, raising a satellite from Low Earth Orbit (LEO) to Geostationary Orbit (GEO) using chemical propulsion might take only a few days or weeks, while relying on traditional electric propulsion often takes months or even more than a year. More importantly, in response to sudden threats (such as space debris avoidance) or in deep space exploration missions with tight time windows, traditional electric propulsion is completely unable to meet the urgent needs for rapid orbital transfers and agile maneuvers.

[0003] Therefore, although high efficiency and energy saving are significant advantages of electric propulsion technology, insufficient thrust leading to slow response, long mission cycles, and lack of maneuverability are core shortcomings that traditional electric propulsion technology cannot avoid when applied to rapid orbital operations. While conventional chemical-electric combined engines are mainly designed for classic large-scale Hohmann transfer orbits such as the Earth-Moon transfer orbit, satellites in Earth orbit still have the need for rapid orbital elevation or descent and space debris avoidance. Furthermore, with the explosive growth in the number of spacecraft in orbit and the in-depth development of orbital resources, this demand will increase significantly, yet there is no corresponding thrust type to meet these needs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a thruster with a magnetically coated tangential Laval nozzle. This thruster with a magnetically coated tangential Laval nozzle introduces a tangential field and has both chemical DC propulsion mode and magnetic jet propulsion mode. When the thruster needs to rapidly maneuver and change orbit, the chemical DC propulsion mode is used, which can provide thrust in the range of 10N. When the thruster is operating in low Earth orbit and needs to maintain its orbital altitude, the magnetic jet propulsion mode is used to generate thrust in the range of microNewtons in a set direction, thereby maintaining the satellite's orbital altitude.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A thruster with a magnetically coated, cross-cutting Laval nozzle includes an injection unit, a combustion chamber, a magnetically coated, cross-cutting Laval nozzle, and a hollow cathode.

[0007] The injection unit is coaxially disposed at the upstream end of the combustion chamber and is used to inject oxidant and fuel into the combustion chamber; wherein, at least one of the oxidant and fuel can also serve as an ionization working fluid.

[0008] The magnetically coated cross-cut Laval nozzle includes the Laval nozzle and the magnetically coated cross-cut assembly.

[0009] The Laval nozzle is coaxially arranged at the downstream end of the combustion chamber, including a metal contraction tube and a ceramic expansion tube arranged axially.

[0010] The metal shrink tube is connected to the positive terminal of an external power supply.

[0011] The magnetically coated tangential assembly is coaxially sleeved on the outer periphery of the ceramic expansion tube, including an N-level permanent magnet and N-1 spacer rings.

[0012] The N-class permanent magnets are coaxially arranged along the expansion direction of the ceramic expansion tube, and the radial thickness gradually decreases.

[0013] A spacer ring is arranged between two adjacent permanent magnets.

[0014] The hollow cathode is located on the outer side of the tail end of the ceramic expansion tube and is connected to the negative terminal of the external power supply. The electron emission direction of the hollow cathode is perpendicular to the plume in the ceramic expansion tube.

[0015] The magnetically coated cutting Laval nozzle also includes a support assembly; the support assembly includes a support sleeve and a bracket.

[0016] The support sleeve is coaxially sleeved around the outer periphery of the magnetically coated cutting component, and the magnetically coated cutting component is installed on the metal shrink tube through the bracket.

[0017] N=3, and the N-level permanent magnets are respectively the first-level permanent magnet, the second-level permanent magnet, and the third-level permanent magnet along the expansion direction of the ceramic expansion tube; each level of permanent magnet is a hollow inverted frustum or ring.

[0018] Each stage of permanent magnet is a hollow inverted frustum shape. The radial thickness of the permanent magnet in the same stage gradually decreases along the expansion direction of the ceramic expansion tube. The maximum radial thickness of the second stage permanent magnet is less than the minimum radial thickness of the first stage permanent magnet. The maximum radial thickness of the third stage permanent magnet is less than the minimum radial thickness of the second stage permanent magnet. The axial length of each stage of permanent magnet also gradually decreases.

[0019] Each permanent magnet is ring-shaped, and the radial thickness of the permanent magnets in the same level is equal. The radial thickness of the first-level, second-level, and third-level permanent magnets gradually decreases. The outer diameter of each permanent magnet is equal, and the inner side of each permanent magnet is filled with cast iron that matches the outer wall of the ceramic expansion tube.

[0020] The axial lengths of the N-1 spacer rings are equal, ranging from 1.8 mm to 2.2 mm.

[0021] It has both chemical DC propulsion mode and magnetic jet propulsion mode; their working principles are as follows:

[0022] A. Chemical DC propulsion mode: When the thruster needs to quickly maneuver and change course, the metal contraction tube and the hollow cathode are de-energized. The injection unit simultaneously injects oxidizer and fuel into the combustion chamber, and ignites and burns them in the combustion chamber to form high-temperature and high-pressure gas, which is discharged out through the Laval nozzle to form a thrust of 10N.

[0023] B. Magnetic jet propulsion mode: When the thruster is operating in low Earth orbit and needs to maintain its orbital altitude, both the metal contraction tube and the hollow cathode are energized, creating a tangential field inside the Laval nozzle; the hollow cathode emits electrons perpendicular to the axis of the Laval nozzle, and the electrons are bound in the tangential magnetic field under the action of the electromagnetic field and reciprocate; at the same time, the injection unit injects ionized working fluid into the combustion chamber, and the ionized working fluid moves into the tangential field and is ionized by the moving electrons, and then is accelerated and ejected under the action of the electric field, generating a micronewton-level thrust in the set direction, thereby maintaining the satellite orbital altitude.

[0024] In magnetic jet propulsion mode, the set voltage of the hollow cathode is 290V~350V, and the remanence of each permanent magnet is 1.3T~1.1T.

[0025] The oxidant is oxygen, and the fuel is hydrogen, methane, or acetylene; under the same chamber pressure conditions, the injection area ratio of oxidant to fuel is 1:5.

[0026] The ceramic expansion tube has an expansion ratio of 50.262, an angle of 30°, and an axial length of 50 mm.

[0027] The present invention has the following beneficial effects:

[0028] 1. It adopts a magnetically coated Laval nozzle with a tangential field, which introduces a tangential field and has chemical DC propulsion mode and magnetic jet propulsion mode. When the thruster needs to quickly maneuver and change orbit, the chemical DC propulsion mode is used, which can provide 10N level thrust. When the thruster is operating in low Earth orbit and needs to maintain its orbital altitude, the magnetic jet propulsion mode is used to generate microNewton level thrust in the set direction, thereby maintaining the satellite orbital altitude unchanged.

[0029] 2. Magnetic-coated Laval nozzle. This magnetic nozzle can both accelerate high-temperature gas and provide space for the magnetic field to confine electron movement, effectively saving the mass and space of the thruster and improving the thrust-to-weight ratio of the thruster.

[0030] 3. In this invention, the ceramic expansion tube and the metal contraction tube are clamped together by two flanges and a copper gasket is arranged on the mating surface to enhance the sealing effect, ensuring effective bonding and sealing between the ceramic nozzle and the metal body.

[0031] 4. The design of the shearing magnetic field in this invention forms a special shearing magnetic field by using permanent magnets that gradually thicken from the throat to the ejection surface. This effectively confines electrons within the space of the nozzle, increasing the probability of their collision with neutral gas, thereby improving the ionization rate of the thruster.

[0032] 5. Inverted conical electric field design. This reduces the plume divergence angle to some extent, thereby improving propulsion efficiency in an electromagnetic environment. The anode extends from the throat to the metal flange surface, generating an inverted conical electric field with the cathode outside the injection surface. This electric field can suppress ion divergence to some extent, thus improving propulsion efficiency.

[0033] 6. The support assembly, consisting of an annular iron hoop and a bracket, effectively reduces the load on the throat of the ceramic expander tube while ensuring the permanent magnet remains firmly attached to its outer wall, thus improving the overall reliability of the thruster. Although gravity acts as the centripetal force in space orbit, preventing the weight of the permanent magnet from exerting excessive pressure on the ceramic expander tube, it is still possible for the permanent magnet to break the ceramic throat shortly before launch into orbit. The iron hoop and bracket effectively distribute the weight of the magnet across the metal flange, thereby reducing the load-bearing pressure on the ceramic throat. Attached Figure Description

[0034] Figure 1 The diagram shows a three-dimensional overall structure of a thruster with a magnetically coated tangential Laval nozzle according to the present invention.

[0035] Figure 2 The image shows a three-dimensional cross-sectional view of a thruster with a magnetically coated tangential Laval nozzle according to the present invention.

[0036] Figure 3 An enlarged schematic diagram of the injection unit in this invention is shown.

[0037] Figure 4 The diagram shows an electron emitted by a hollow cathode reciprocating within a tangential magnetic field under the influence of an electromagnetic field in magnetic jet propulsion mode.

[0038] Figure 5 The diagram shows a simulation of the magnetic field of the thruster of the present invention in magnetic jet propulsion mode.

[0039] Among them are:

[0040] 10. Injection unit; 11. Injection panel; 12. Oxidant inlet; 13. Fuel inlet;

[0041] 20. Combustion chamber; 21. Spark plug;

[0042] 30. Magnetic-coated cross-cutting Laval nozzle;

[0043] 31. Laval nozzle; 311. Metal contraction nozzle; 312. Ceramic expander nozzle; 313. Shoulder;

[0044] 32. Magnetic-coated cut-type component;

[0045] 321. Primary permanent magnet; 322. Secondary permanent magnet; 323. Tertiary permanent magnet; 324. Spacer ring; 325. Pig iron;

[0046] 33. Support component; 331. Support sleeve; 332. Bracket;

[0047] 40. Hollow cathode; 41. Electron emission cavity. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0049] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0050] like Figure 1 and Figure 2 As shown, a thruster with a magnetically coated, cross-cutting Laval nozzle includes an injection unit 10, a combustion chamber 20, a magnetically coated, cross-cutting Laval nozzle 30, and a hollow cathode 40.

[0051] The injection unit is coaxially disposed at the upstream end of the combustion chamber and is used to inject oxidant and fuel into the combustion chamber; wherein, at least one of the oxidant and fuel can also serve as an ionization working fluid.

[0052] like Figures 1-3 As shown, the injection unit includes an injection panel 11, an oxidizer inlet 12, and a fuel inlet 13.

[0053] The injection panel has an oxidizer inner channel and a fuel outer channel arranged coaxially from the inside to the outside. The oxidizer inner channel includes an oxidizer reservoir and an oxidizer nozzle arranged along the propellant flow direction, and the oxidizer reservoir is connected to the oxidizer inlet. The fuel outer channel includes a fuel reservoir and a fuel annular nozzle arranged along the propellant flow direction, and the fuel reservoir is connected to the fuel inlet.

[0054] The preferred oxidant is oxygen, and the preferred fuel is hydrogen, methane, or acetylene, with methane being more preferred as the ionization medium; the reaction equation for the complete combustion of propane with oxygen is:

[0055]

[0056] As can be seen from the reaction equation, under complete combustion conditions, the molar ratio of propane to oxygen is 1:5, and the volume ratio is also 1:5 under isothermal and isobaric conditions. Therefore, under the same chamber pressure conditions, the ratio of the annular injection area of ​​the two substances is set to 1:5 to achieve better combustion effect.

[0057] Spark plug 21 is preferably provided on the inlet side wall of the combustion chamber for igniting propane and oxygen. All-ceramic model aircraft spark plugs are preferred, as they are small in size and highly efficient, and can meet the ignition requirements of this thruster.

[0058] In this embodiment, the total mass flow rate of the thruster is preferably 10 g / s. At this point, the molar ratio of oxidizer to fuel is 5:1, and the mass flow rate ratio is 40:11. Therefore, the oxidizer flow rate is 7.843 g / s, and the fuel flow rate is 2.157 g / s. Mass flow rate is the rate at which the propellant enters the combustion chamber, and it directly affects the combustion chamber pressure. Under stable operating conditions, the mass flow rate and combustion chamber pressure satisfy the following relationship:

[0059]

[0060] in, This refers to the throat area of ​​the Laval nozzle. Combustion chamber pressure, The characteristic velocity is related only to propellant properties and combustion efficiency. Based on compressible flow theory, the flow rate reaches its maximum when the gas flow velocity at the throat of the Laval nozzle is the speed of sound. The expression for the flow rate at this point is:

[0061]

[0062] in, For specific heat ratio, Let be the ideal gas constant. This refers to the combustion chamber temperature.

[0063] Taking into account the mixing ratio of propane and oxygen and the combustion properties, the optimal combustion chamber parameters are determined to be: diameter of 13.914 mm, axial length of 74-76 mm, temperature of 2700 K, flow rate of 10 g / s, and chamber pressure of 1 MPa-1.4 MPa, with a further preferred value of 1.2 MPa. Thus, the thrust in chemical direct current propulsion mode is calculated to be approximately 10 N.

[0064] The magnetically coated cutting-type Laval nozzle includes a Laval nozzle 31, a magnetically coated cutting-type assembly 32, and a support assembly 33.

[0065] The Laval nozzle is coaxially arranged at the downstream end of the combustion chamber, including a metal contraction tube 311 and a ceramic expansion tube 312 arranged axially.

[0066] The metal shrink tube is connected to the positive terminal of an external power supply, and its shrinkage ratio is preferably 10, which is the anode, and it has a throat.

[0067] The preferred expansion ratio of the ceramic expander tube is 50.262, the preferred angle is 30°, and the preferred axial length is 50 mm. At this axial length, a complete tangential magnetic field and two magnetic tips can be constructed. This ensures that the high-temperature, high-pressure gas is sufficiently accelerated in chemical direct current propulsion mode, and that electrons are fully ionized by collision with propane gas in magnetic jet propulsion mode. A ceramic expander tube length of approximately 50 mm is the minimum length required to achieve the above functions.

[0068] Furthermore, the tail end of the ceramic expansion tube is provided with a protruding shoulder 313 for axial positioning of the subsequent Nth stage permanent magnet. The ceramic nozzle and the metal contraction tube are preferably connected by a flange, and copper gaskets are preferably arranged on the mating surface to enhance the sealing effect, ensuring effective connection and sealing between the ceramic nozzle and the metal contraction tube.

[0069] The magnetically coated tangential assembly is coaxially sleeved on the outer periphery of the ceramic expansion tube, including an N-level permanent magnet and N-1 spacer rings 324.

[0070] In this invention, the tangential field formed by the N-stage permanent magnets provides more space for the ionization of the working fluid and better fits the shape of the nozzle, meeting the structural requirements for accelerating high-temperature gas to supersonic speeds. In this embodiment, N=3 is preferred, with the N-stage permanent magnets being a primary permanent magnet 321, a secondary permanent magnet 322, and a tertiary permanent magnet 323 along the expansion direction of the ceramic expansion tube. If N=2, only one magnetic tip can be formed, significantly reducing the number of electrons bound in the nozzle region and resulting in a severe decline in ionization rate. While using four or more permanent magnets can slightly improve the ionization rate, considering factors such as the limitation of the ceramic expansion tube length, four or more permanent magnets would increase processing complexity and reduce the reliability of the thruster. Therefore, N=3 is preferred.

[0071] The aforementioned N-stage permanent magnets are arranged coaxially along the expansion direction of the ceramic expansion tube, with the radial thickness gradually decreasing. This design is consistent with the electron density distribution. The electron density is relatively high near the Laval nozzle outlet, which is the main region for ionizing the working gas. Reducing the thickness of the permanent magnets in this region helps to form multiple magnetic tips, increase the electron movement path, and reduce the probability of electrons colliding with the wall, thereby improving the ionization rate of the thruster.

[0072] In this embodiment, the structure of the N-stage permanent magnet has the following two preferred embodiments.

[0073] Example 1: Each stage of permanent magnet is a hollow inverted frustum shape.

[0074] Each stage of permanent magnet is a hollow, inverted frustum shape. The radial thickness of the permanent magnet in the same stage gradually decreases along the expansion direction of the ceramic expansion tube. The maximum radial thickness of the second-stage permanent magnet is less than the minimum radial thickness of the first-stage permanent magnet. The maximum radial thickness of the third-stage permanent magnet is less than the minimum radial thickness of the second-stage permanent magnet. This configuration is difficult to manufacture and has a high cost.

[0075] Furthermore, the axial length of each stage of permanent magnet gradually decreases. The axial length of the second stage permanent magnet is smaller than that of the first stage permanent magnet, and the axial length of the third stage permanent magnet is smaller than that of the second stage permanent magnet. This makes the shear magnetic field change more drastically near the nozzle exit, so as to increase the probability of collision between bound electrons and working gas (propane) and increase the ionization rate.

[0076] Example 2: Each stage of permanent magnet is ring-shaped.

[0077] Each permanent magnet is ring-shaped, with equal radial thickness within the same level. The radial thickness gradually decreases from the first to the third level. The outer diameter of each permanent magnet is equal, and the inner side of each permanent magnet is filled with cast iron 325 that matches the outer wall of the ceramic expansion tube. This reduces processing difficulty and manufacturing cost while ensuring compatibility with the outer wall of the ceramic expansion tube.

[0078] Furthermore, in the magnetic jet propulsion mode, the set voltage of the hollow cathode is preferably 290V~350V, and the remanence of each permanent magnet is preferably 1.3T~1.1T. This is to create a magnetic field with sufficient magnetic induction intensity to capture electrons, so that the electrons can move around the magnetic field lines instead of being directly attracted to the anode. If the remanence is too high, the magnetic induction intensity will be stronger, which will make the magnetic field have a stronger effect on the electrons, while the electric field has a relatively weaker effect on the electrons, causing a large accumulation of electrons at the nozzle orifice, resulting in a decrease in ionization rate.

[0079] The aforementioned spacer rings are arranged between two adjacent permanent magnets and have equal axial lengths. The axial length should not be too large, as this would prevent the formation of magnetic tips in the internal region of the ceramic expansion tube; nor should it be too small, as this would increase the difficulty of installing the permanent magnets and fail to effectively protect them. For the length of the ceramic expansion tube of this invention, the axial length of the spacer rings is preferably designed to be 1.8mm to 2.2mm.

[0080] The support assembly includes a support sleeve 331 and a bracket 332; the support sleeve is coaxially sleeved around the outer periphery of the magnetically coated cutting component, and the bracket is used to install the magnetically coated cutting component onto the metal shrink tube. In this embodiment, the support sleeve is preferably an iron hoop, which is tightly clamped around the outer periphery of the magnetically coated cutting component and tightened with bolts.

[0081] The hollow cathode is located on the outer side of the tail end of the ceramic expansion tube and is connected to the negative terminal of the external power supply. The electron emission direction of the hollow cathode is perpendicular to the plume in the ceramic expansion tube.

[0082] This invention features both chemical DC propulsion and magnetic jet propulsion modes.

[0083] A. Chemical DC propulsion mode

[0084] When the thruster needs to rapidly maneuver and change course, the metal contraction tube and the hollow cathode are de-energized. The injection unit simultaneously injects oxidizer and fuel into the combustion chamber, where they are ignited and burned to form high-temperature, high-pressure gas, which is then discharged outward through the Laval nozzle, generating a thrust of 10N.

[0085] B. Magnetic jet propulsion mode

[0086] When the thruster is operating in low orbit and needs to maintain its orbital altitude, both the metal contraction tube and the hollow cathode are energized, creating a tangential field within the Laval nozzle, such as... Figure 5 As shown.

[0087] A hollow cathode emits electrons perpendicular to the axis of the Laval nozzle. These electrons are bound by an electromagnetic field and reciprocate within a tangential magnetic field. Figure 4 As shown. Due to the small cyclotron radius of electrons, they move almost along the magnetic field lines and collide with the supplied neutral gas, resulting in ionization. The ions produced by ionization have a large mass and a cyclotron radius much larger than the channel length. They are accelerated and ejected under the influence of the axial electric field, generating thrust.

[0088] At the same time, the injection unit injects ionized working fluid into the combustion chamber. The ionized working fluid moves to the tangential field and is ionized by the moving electrons. Then, under the action of the electric field, it is accelerated and ejected, generating a micronewton-level thrust in the set direction, thereby maintaining the satellite's orbital altitude.

[0089] This invention, through innovative magnetic coating design of traditional Laval nozzles and incorporating shear field technology, enables the thruster to have multiple operating modes, greatly expanding the range of on-orbit applications. It can be used for long-term low-consumption maintenance of satellites, as well as for on-orbit emergency collision avoidance and rapid orbital transfer deployment, making it highly adaptable.

[0090] This invention innovatively proposes a magnetically coated nozzle, which optimizes the thruster structure, effectively improves the thrust-to-weight ratio of the thruster, expands the thrust range of the thruster, and can generate complex thrust combinations as needed, comprehensively improving the performance of general space thrusters and providing power support for adapting to future complex space orbit missions.

[0091] A significant advantage of this invention is the rapid switching between DC propulsion mode and magnetic jet propulsion mode.

[0092] When switching from magnetic jet propulsion mode to DC propulsion mode, the operating state is as follows: only propane is supplied. When the propane is ejected from the magnetic nozzle, it is ionized by electron impact and accelerated outward under the influence of the electric field. If it is necessary to switch from magnetic jet propulsion mode to DC propulsion mode, simply turn off the power supply to the cathode and anode, continue to supply propane while simultaneously supplying oxygen, and ignite the propane and oxygen mixture with a spark plug. This process usually takes less than 3 seconds.

[0093] When switching from DC propulsion mode to magnetic jet propulsion mode, the operating state is as follows: oxygen and propane are simultaneously introduced and fully combusted in the thrust chamber. The resulting high-temperature, high-pressure gas is accelerated and ejected through the Laval nozzle. To switch back to magnetic jet propulsion mode, oxygen supply is stopped and the power to the cathode and anode is turned on. The cathode is heated, emitting electrons that ionize the propane gas within the magnetic nozzle. The propane ions are then accelerated and ejected under the influence of the electric field. This switching process typically takes less than one minute.

[0094] The rapid switching between magnetic jet propulsion and DC propulsion modes allows this thruster to quickly switch between high and low thrust. Other thrusters typically require tens of minutes to switch between high and low thrust, while the thrust switching process of this invention can be completed within 1-2 minutes at most. This enables more complex orbital transformations. For example, the following three types of orbital missions all require the rapid thrust switching technology supported by this invention.

[0095] The first category is on-orbit refueling or on-orbit satellite maintenance missions. When approaching the satellite to be refueled or maintained, it is necessary to quickly switch from a large thrust to a small thrust to adjust the attitude or maintain the orbit, ensuring relative stationary contact with the satellite for refueling or on-orbit maintenance. After the operation is completed, it is necessary to quickly detach from the satellite, requiring a rapid switch from a small thrust to a large thrust to change the orbit. Therefore, this invention provides technical support for future on-orbit refueling or on-orbit satellite maintenance missions.

[0096] The second category is low-thrust optimal transfer orbits. These orbits involve a spacecraft transferring from one orbit to another in a gravitational field (such as from geostationary orbit (GEO) to a translational orbit or an interplanetary transfer), using continuous low-thrust propulsion (typically less than 10 N). The thruster needs to switch rapidly between large and small thrusts to follow a "bang-bang control" strategy, where the thrust jumps between a maximum value (around 10 N) and a minimum value (close to 0 N) to optimize fuel efficiency or transfer time.

[0097] For example, during the transfer from GEO to Lyapunov orbit, the thrusters need to use a relatively large thrust of around 10N during the initial acceleration phase to change the trajectory, and then switch to a small thrust during the glide phase to fly unpowered along a stable current. This rapid switching between large and small thrust is crucial to ensure a smooth transition for the spacecraft. Multiple rapid switchings between large and small thrust can save up to 36.7% of fuel compared to constant thrust.

[0098] The third category is asteroid rendezvous missions. With the successful launch of Tianwen-2, more and more asteroid rendezvous missions are being planned. Asteroids have very weak gravity, requiring spacecraft to rely on thrusters to simulate "orbital flight" or hover. This necessitates that the spacecraft's thrusters have the ability to rapidly switch between large and small thrust. Once the spacecraft has completed its orbital switch and approached the asteroid using a larger thrust, it needs to immediately switch to a smaller thrust to finely adjust its orbit or attitude. After a period of time, when the spacecraft's orbit deviates from the asteroid's orbit, it needs to immediately switch back to a larger thrust to change its orbit and bring it back closer to the asteroid.

[0099] During the transition between propulsion modes, spacecraft are essentially in an uncontrolled flight state. Conventional multi-mode thrusters have excessively long switching processes, resulting in prolonged periods of uncontrolled flight and significantly reduced control accuracy. This invention, however, can rapidly switch between two propulsion modes, greatly shortening the duration of uncontrolled flight and thus improving control accuracy. Furthermore, the thrust provided by this thruster in both modes is relatively small, and the acceleration provided to the spacecraft is also relatively low, which also contributes to improved control accuracy.

[0100] In summary, with the diversification of aerospace orbital missions, increasingly higher requirements are being placed on the ability of spacecraft thrusters to switch thrust rapidly. This invention meets this requirement to a certain extent and has certain application value.

[0101] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A thruster with a magnetically coated, tangentially slicing Laval nozzle, characterized in that: Includes injection unit, combustion chamber, magnetically coated cross-cut Laval nozzle and hollow cathode; The injection unit is coaxially arranged at the upstream end of the combustion chamber and is used to inject oxidant and fuel into the combustion chamber; wherein, at least one of the oxidant and fuel can also serve as an ionization working fluid; The magnetically coated cross-cutting Laval nozzle includes a Laval nozzle and a magnetically coated cross-cutting assembly; The Laval nozzle is coaxially arranged at the downstream end of the combustion chamber, including a metal contraction tube and a ceramic expansion tube arranged axially. The metal shrink tube is connected to the positive terminal of an external power supply; The magnetically coated tangential assembly is coaxially sleeved on the outer periphery of the ceramic expansion tube, including an N-level permanent magnet and N-1 spacer rings; The N-class permanent magnets are coaxially arranged along the expansion direction of the ceramic expansion tube, and the radial thickness gradually decreases. A spacer ring is arranged between two adjacent permanent magnets; The hollow cathode is located on the outer side of the tail end of the ceramic expansion tube and is connected to the negative terminal of the external power supply. The electron emission direction of the hollow cathode is perpendicular to the plume in the ceramic expansion tube.

2. The thruster with a magnetically coated, tangentially slicing Laval nozzle according to claim 1, characterized in that: The magnetically coated, cross-cutting Laval nozzle also includes a support assembly; the support assembly includes a support sleeve and a bracket; The support sleeve is coaxially sleeved around the outer periphery of the magnetically coated cutting component, and the magnetically coated cutting component is installed on the metal shrink tube through the bracket.

3. The thruster with a magnetically coated, tangentially slicing Laval nozzle according to claim 1 or 2, characterized in that: N=3, and the N-level permanent magnets are respectively the first-level permanent magnet, the second-level permanent magnet, and the third-level permanent magnet along the expansion direction of the ceramic expansion tube; each level of permanent magnet is a hollow inverted frustum or ring.

4. The thruster with a magnetically coated, tangentially slicing Laval nozzle according to claim 3, characterized in that: Each stage of permanent magnet is a hollow inverted frustum shape. The radial thickness of the permanent magnet in the same stage gradually decreases along the expansion direction of the ceramic expansion tube. The maximum radial thickness of the second stage permanent magnet is less than the minimum radial thickness of the first stage permanent magnet. The maximum radial thickness of the third stage permanent magnet is less than the minimum radial thickness of the second stage permanent magnet. The axial length of each stage of permanent magnet also gradually decreases.

5. The thruster with a magnetically coated, tangentially slicing Laval nozzle according to claim 3, characterized in that: Each permanent magnet is ring-shaped, and the radial thickness of the permanent magnets in the same level is equal. The radial thickness of the first-level, second-level, and third-level permanent magnets gradually decreases. The outer diameter of each permanent magnet is equal, and the inner side of each permanent magnet is filled with cast iron that matches the outer wall of the ceramic expansion tube.

6. The thruster with a magnetically coated tangential Laval nozzle according to claim 1, characterized in that: The axial lengths of the N-1 spacer rings are equal, ranging from 1.8 mm to 2.2 mm.

7. The thruster with a magnetically coated tangential Laval nozzle according to claim 1, characterized in that: It has both chemical DC propulsion mode and magnetic jet propulsion mode; their working principles are as follows: A. Chemical DC propulsion mode: When the thruster needs to quickly maneuver and change course, the metal contraction tube and the hollow cathode are de-energized. The injection unit simultaneously injects oxidizer and fuel into the combustion chamber, and ignites and burns them in the combustion chamber to form high-temperature and high-pressure gas, which is discharged out through the Laval nozzle to form a thrust of 10N. B. Magnetic jet propulsion mode: When the thruster is operating in low Earth orbit and needs to maintain its orbital altitude, both the metal contraction tube and the hollow cathode are energized, creating a tangential field inside the Laval nozzle; the hollow cathode emits electrons perpendicular to the axis of the Laval nozzle, and the electrons are bound in the tangential magnetic field under the action of the electromagnetic field and reciprocate; at the same time, the injection unit injects ionized working fluid into the combustion chamber, and the ionized working fluid moves into the tangential field and is ionized by the moving electrons, and then is accelerated and ejected under the action of the electric field, generating a micronewton-level thrust in the set direction, thereby maintaining the satellite orbital altitude.

8. The thruster with a magnetically coated tangential Laval nozzle according to claim 7, characterized in that: In magnetic jet propulsion mode, the set voltage of the hollow cathode is 290V~350V, and the remanence of each permanent magnet is 1.3T~1.1T.

9. The thruster with a magnetically coated, tangentially slicing Laval nozzle according to claim 1, characterized in that: The oxidant is oxygen, and the fuel is hydrogen, methane, or acetylene; under the same chamber pressure conditions, the injection area ratio of oxidant to fuel is 1:

5.

10. The thruster with a magnetically coated, tangentially slicing Laval nozzle according to claim 1, characterized in that: The ceramic expansion tube has an expansion ratio of 50.262, an angle of 30°, and an axial length of 50 mm.

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