Dual-mode plasma thruster
By designing a dual-mode plasma thrust, combining a spiral wave plasma source and a multi-coil plasma thruster, the diversified working mode of the thrust in aerospace missions is achieved, the problem of single function of the existing single-mode thrust is solved, and the performance and reliability of the propulsion system are improved.
Patent Information
- Application Number
- CN202510721831.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-30
- Publication Date
- 2025-07-11
AI Technical Summary
The existing single-mode plasma thrust has a single function, a small thrust and low efficiency, which cannot meet the diverse space mission needs.
A dual-mode plasma thrust is designed, with a dual-component propulsion mode and a single-component propulsion mode. Through the combination of a spiral wave plasma source, a magnetically constrained plasma thrust and a multi-coil plasma thrust, the diversification of the thrust operation is achieved, including three operating conditions: rail change, attitude control and position maintenance.
Combining the advantages of high specific impulse of the two-component thruster and high reliability and low thrust of the single-component thruster, it improves the overall performance of the propulsion system and adapts to the flexibility requirements of aerospace missions.
Smart Images
Figure CN120292038A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of electric propulsion, and particularly relates to a dual-mode plasma thruster. Background Art
[0002] Specific impulse is an important indicator for measuring the efficiency of a propulsion system. The higher the specific impulse, the greater the velocity increment that can be generated with the same propellant mass. Although traditional chemical thrusters have played an important role in previous space missions, due to their limitations such as low specific impulse, they are gradually being phased out. Plasma thrusters utilize electrical energy to increase the jet velocity to a higher level, which can save a large amount of propellant, thereby effectively increasing the payload of a satellite and reducing the launch mass. Moreover, the electric propulsion system also has characteristics such as high control precision and high safety.
[0003] Electric propulsion has the advantages of high specific impulse, high efficiency, high reliability, and long life, and has extensive applications in deep space exploration and interstellar navigation. However, with the increasing diversification of space missions, more requirements are put forward for the diversity of propulsion systems. Existing single-mode thrusters have disadvantages such as single function, small thrust, and low efficiency, and can no longer meet the needs of space missions. Summary of the Invention
[0004] In view of the above situation, the present invention provides a dual-mode plasma thruster, which has two working modes: a bi-propellant propulsion mode and a mono-propellant propulsion mode, and can switch different working modes according to the needs of working conditions to achieve the diversification of the thruster's operation.
[0005] In order to achieve the above objectives, the present invention adopts the following technical solutions:
[0006] A dual-mode plasma thruster includes a plasma generation system and a plasma acceleration system. The plasma acceleration system further includes a magnetically confined plasma thruster with an applied voltage and a multi-coil plasma thruster.
[0007] After the dual-mode plasma thruster is installed on a space propulsion system, in the orbit transfer working condition of the bi-propellant propulsion mode, a bi-propellant thruster is used; in the mono-propellant propulsion mode, the propulsion system can be divided into two working conditions: attitude control and position keeping. When performing attitude control, a multi-coil plasma thruster is used; when performing position keeping, a magnetically confined plasma thruster with an applied voltage is used.
[0008] The plasma generation system is a helicon wave plasma source; an ionization chamber is arranged in the middle of the helicon wave plasma source, an acceleration chamber I is arranged in the middle of the magnetically confined plasma thruster, and an acceleration chamber II is arranged in the middle of the multi-coil plasma thruster.
[0009] The tail end of the ionization chamber is connected through a connecting pipe to the head ends of the two acceleration chambers. The head end of the ionization chamber is provided with a working gas inlet, and the tail ends of the first acceleration chamber and the second acceleration chamber are respectively provided with a plasma outlet one and a plasma outlet two.
[0010] A helical antenna is arranged outside the ionization chamber and is used to generate helical wave discharge in the ionization chamber to ionize the working gas to generate plasma.
[0011] An electromagnetic coil one is arranged outside the head of the first acceleration chamber and is used to pass a direct current to generate a constant magnetic field inside the first acceleration chamber. In addition, a bias electrode is arranged inside the tail of the first acceleration chamber and is used to connect a direct current voltage to generate an applied positive voltage.
[0012] A plurality of stator coils one are arranged outside the head of the second acceleration chamber, and a plurality of stator coils two are arranged outside the tail of the second acceleration chamber. The current directions passed through the two groups of stator coils are opposite.
[0013] Preferably, two annular permanent magnets are coaxially sleeved outside the middle of the ionization chamber, and the polarities of the two annular permanent magnets are opposite, one is an N pole and the other is an S pole, which can form a closed magnetic line inside and outside the ionization chamber.
[0014] Preferably, both the stator coil one and the stator coil two are annular coils with a rectangular cross-section, which can pass a larger current, generate a more uniform magnetic field, and can generate a higher density of plasma.
[0015] Preferably, the ionization chamber, the first acceleration chamber, and the second acceleration chamber are all made of high-temperature resistant glass material. The first acceleration chamber is in a horn shape, and the ionization chamber and the second acceleration chamber are both in a cylindrical shape.
[0016] Preferably, the central axes of the ionization chamber, the first acceleration chamber, and the second acceleration chamber are parallel to each other, and the tail end of the ionization chamber is integrally connected to the head ends of the two acceleration chambers through a connecting pipe to form a Y-shaped communicating cavity.
[0017] Preferably, a three-way switching ball valve is arranged in the middle of the connecting pipe and is used to realize the working mode switching of the thruster under three different working conditions: orbit change condition, attitude control, and position holding.
[0018] Preferably, the working gas is argon, an alternating radio frequency current is passed through the helical antenna, and the helical wave plasma source is a plasma generated by helical wave excited discharge.
[0019] The present invention also includes other components that can enable it to be used normally, which are all conventional means in the art. In addition, for the devices or components not defined in the present invention, the existing technologies in the art are adopted.
[0020] The beneficial effects of the present invention are as follows:
[0021] The emergence of this dual-mode plasma thruster has brought about a huge leap in the space propulsion system, combining the advantages of high reliability and low thrust of a single-component thruster with the advantages of high specific impulse and high thrust of a bi-component thruster, and further improving the performance of the propulsion system.
[0022] The dual-mode propulsion system combines the high specific impulse of the bi-component thruster and the dual advantages of high reliability and low thrust of the single-component thruster, enabling the propulsion system to have better overall performance and better adapt to the flexibility requirements of space missions. Brief Description of the Drawings
[0023] Figure 1 It is a schematic structural diagram of the dual-mode plasma thruster in the embodiment.
[0024] Figure 2 For Figure 1 It is a three-dimensional structural diagram of the helical antenna outside the ionization chamber in
[0025] Figure 3 For Figure 1 It is a three-dimensional structural diagram of the second acceleration chamber and two sets of stator coils outside it in
[0026] Figure 4 For Figure 1 It is a three-dimensional structural diagram of the spherical valve core of the three-way switching ball valve in
[0027] Figure 5 For Figure 1 It is a schematic diagram of the single-component working mode when the three-way switching ball valve switches to the position-holding working condition in
[0028] Figure 6 For Figure 1 It is a schematic diagram of the single-component working mode when the three-way switching ball valve switches to the attitude control working condition in Detailed Embodiment
[0029] Next, the technical solution of the present invention will be clearly and completely described in combination with specific embodiments. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments.
[0030] It should be noted that the terms "upper", "lower", "front", "rear", "head", "tail", "inner", "outer", etc. indicating the orientation or position relationship are all based on the drawings shown, only for the convenience of description.
[0031] Embodiment
[0032] Such as Figure 1-3As shown in the figure, a dual-mode plasma thruster includes a plasma generation system and a plasma acceleration system. The plasma acceleration system further includes a magnetically confined plasma thruster with an applied voltage and a multi-coil plasma thruster.
[0033] When the bi-propellant thruster works simultaneously, the generated thrust is relatively large, which is mainly applicable to the orbit transfer working state; the multi-coil plasma thruster is mainly applicable to the attitude control working state; the magnetically confined plasma thruster with an applied voltage is mainly applicable to the position holding working state.
[0034] The plasma generation system is a helicon wave plasma source, that is, a plasma excited by helicon waves. A cylindrical ionization chamber 1 with an outer diameter of 100 mm and an inner diameter of 60 mm is arranged in the middle of the helicon wave plasma source. A horn-shaped acceleration chamber 1 2 is arranged in the middle of the magnetically confined plasma thruster. A cylindrical acceleration chamber 2 3 is arranged in the middle of the multi-coil plasma thruster. The ionization chamber, the acceleration chamber 1 and the acceleration chamber 2 are all made of high-temperature resistant glass material, such as quartz glass tubes.
[0035] The central axes of the ionization chamber, the acceleration chamber 1 and the acceleration chamber 2 are parallel to each other. The tail end of the ionization chamber and the head ends of the two acceleration chambers are integrally and through-connected by a connecting pipe 4 to form a Y-shaped communicating cavity. A working gas inlet 5 is arranged at the head end of the ionization chamber, and the working gas is argon. Plasma outlets 1 6 and plasma outlets 2 7 are correspondingly arranged at the tail ends of the acceleration chamber 1 and the acceleration chamber 2.
[0036] A three-way switching ball valve 14 is arranged at the middle part of the connecting pipe and at the Y-shaped three-way connection part of the ionization chamber, the acceleration chamber 1 and the acceleration chamber 2, for realizing the working mode switching of the thruster under three different working conditions of orbit transfer, attitude control and position holding.
[0037] As Figure 4 shown, a T-shaped three-way connection port is arranged inside the spherical valve core of the three-way switching ball valve. When the first interface 15 of the three-way connection port is connected to both the second interface 16 and the third interface 17, it is a bi-propellant propulsion mode. At this time, both the magnetically confined plasma thruster and the multi-coil plasma thruster work, which is mainly applicable to the orbit transfer working condition; when the first interface of the three-way connection port is connected to the third interface and the second interface is closed, it is a single-component working mode of the multi-coil plasma thruster, which is mainly applicable to the attitude control working condition, as Figure 6 shown; when the first interface of the three-way connection port is connected to the second interface and the third interface is closed, it is a single-component working mode of the magnetically confined plasma thruster, which is mainly applicable to the position holding working condition, as Figure 5 shown. The switching control system of the three-way switching ball valve adopts the existing technology and will not be elaborated here.
[0038] A spiral antenna 8 is arranged outside the ionization chamber, which is used to generate spiral wave discharge in the ionization chamber to ionize the working medium gas to generate plasma. An alternating radio frequency current is introduced into the spiral antenna, and the neutral gas is ionized by static electricity and electromagnetic fields in the ionization chamber. Two annular permanent magnets 9 are also coaxially sleeved outside the middle of the ionization chamber, and the polarities of the two annular permanent magnets are opposite, one is the N pole and the other is the S pole, which can form a closed magnetic field line inside and outside the ionization chamber.
[0039] An electromagnetic coil 10 is arranged outside the head of the first acceleration chamber, which is used to introduce a direct current to generate a constant magnetic field inside the first acceleration chamber. A bias electrode 11 is also arranged inside the tail of the first acceleration chamber, which is used to connect a direct current voltage to generate an external positive voltage. On the basis of magnetic confinement, an external voltage is applied, and by adjusting the voltage bias, the confinement and acceleration effects of the plasma can be controlled.
[0040] Five stator coils 12 are arranged outside the head of the second acceleration chamber, and five stator coils 13 are arranged outside the tail of the second acceleration chamber. The stator coils 12 and 13 are both annular coils with a rectangular cross-section, and are divided into two groups. The current directions introduced into the two groups of stator coils are opposite.
[0041] The working principle of the present invention is as follows:
[0042] The plasma will propagate along the divergent axis. The electrons experience the confinement effect of the magnetic field provided by the convergent side of the magnetic field. Due to the light mass of the electrons, a low magnetic field intensity is sufficient to confine the electrons in the radial direction. The injected electron velocity slowly decreases in the exit direction and begins to drift towards the exit direction, thereby enhancing the current flux. The confinement of the magnetic field on the high-energy electron cloud not only increases the ionization rate but also increases the electron kinetic energy. From the perspective of energy conversion, the kinetic energy of the electrons is converted into the kinetic energy of the ions by the presence of a positive bias voltage.
[0043] In order to discuss the momentum gain of the plasma flow, it can be carried out from the magnetohydrodynamics theory, which regards the plasma as a conductive, single-species fluid..
[0044] This electropositive magnetic confinement can be calculated by the magnetohydrodynamics theory:
[0045]
[0046] where, ρ m is the mass density, ρ q is the charge density, v is the flow velocity, is the pressure gradient.
[0047] When the static equilibrium condition is satisfied, Equation 1 represents and ρ qThe balance between E + j×B. By taking the cross product of B on both sides of Equation 1, we can derive the current flux, and thus obtain the current density:
[0048]
[0049] The voltage applied to the anode serves as an energy converter, absorbing the kinetic energy of electrons and transferring it to the plasma. The biased anode is mainly used to regulate the potential gradient at the plume. The high-energy electrons extracted from the plasma source are trapped by the magnetic field, providing a confinement effect for the electron beam. By driving the electrons into azimuthal motion around the thruster axis, most of the kinetic energy of the electrons is maintained, thereby prolonging the residence time of the high-energy electrons and depleting their kinetic energy in the thruster.
[0050] The acceleration chamber - type plasma thruster has the following advantages:
[0051] 1. The plasma is highly non-thermalized because a high-energy electron beam is used to generate the plasma, and only a relatively weak magnetic field strength is sufficient to completely confine the plasma.
[0052] 2. Injecting the electron beam into a converging - diverging nozzle provides a plasma discharge similar to a normal discharge, capable of generating a high plasma production rate, facilitating the formation of a radial pressure gradient in the nozzle, and enhancing the diamagnetic current of the plasma in the azimuthal direction of the nozzle.
[0053] 3. The presence of the anode significantly alleviates the problems of plasma bombardment and ohmic heating. In addition, due to the confinement of the radial electric field, the plasma is kept around the nozzle, significantly reducing the frictional energy loss between the plasma and the nozzle wall.
[0054] The acceleration chamber two is surrounded by multiple coaxial coils. Two stator coils are excited with a delay to generate an axially propagating magnetic field. The thruster is electrically neutral, and the thrust is caused by the interaction of the Lorentz force of the phase-controlled primary stator current and the induced secondary circumferential plasma current. Changing the excitation frequency or coil details (phase or spacing) will change the magnetic wave speed, and the difference between the plasma speed and the wave speed acts to accelerate the plasma to the wave speed.
[0055] The inductance of the stator coil requires a phase voltage to be applied to the coil to change its current. Due to the inductance and resistance, there is a voltage between each coil, and due to the phase difference, there is also a voltage between the coils. Since the induced current lags behind the voltage, the voltage appears on the coil before the current flows through the coil. Essentially, the electrostatic field between the coils is larger and appears faster than the induced electric field generated after the current is induced.
[0056] Therefore, the plasma current is driven by electromagnetic induction, and the Lorentz force is applied to the plasma current by the moving magnetic field wave. Electrons carry the circumferential current, while the plasma delays and circulates in the opposite direction, forming a neutral background. The magnetic force on the axial current is applied to the electrons, and the electrons are electrostatically neutralized; the plasma provides the reaction mass for the flow, thereby generating thrust.
[0057] Analysis based on electromagnetic theory:
[0058]
[0059] J free = σE
[0060]
[0061] In the cylindrical coordinate system, we get:
[0062]
[0063] Solving the plasma equations gives the axial magnetic field as in equation (6) below, the maximum magnetic field as in equation (7) below, the solution of the electric field as in equation (8) below, the complex wave number as in equation (9) below, and the free space wave number as in equation (10) below.
[0064]
[0065] Note: The plasma dielectric constant is complex.
[0066] The plasma current density is:
[0067] J θ = iωε0ε p E θ (11)
[0068] The plasma exhibits the skin depth phenomenon, and the plasma current is concentrated at a larger radius. The skin depth is defined as:
[0069]
[0070] Here, the plasma conductivity is simplified to:
[0071]
[0072] The total plasma current is:
[0073]
[0074] The time-averaged power absorbed by the plasma is:
[0075]
[0076] This thruster can provide high thrust at high specific impulse without the need for electrodes, potentially greatly extending the life of the thruster and enabling the use of low-cost and in-situ propellants. The thruster can avoid electrode and neutralizer ablation, thus having a long life, and the flexibility of the propellant makes the thruster attractive for long-term, high-velocity missions. The system does not require transformers and superconducting magnets, keeping the overall weight low and operating effectively because the plasma is self-confined, minimizing wall interactions.
[0077] The technical solution of the present invention is not limited to the limitations of the above specific embodiments. Many modifications and changes are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. Any technical deformation made within the spirit and principle of the present invention falls within the protection scope of the present invention.
Claims
1. A dual-mode plasma thruster, comprising a plasma generation system and a plasma acceleration system, characterized in that: The plasma acceleration system further includes a magnetic confinement plasma thruster with an externally applied positive voltage and a multi-coil plasma thruster; The plasma generation system is a helicon wave plasma source; an ionization chamber is arranged in the middle of the helicon wave plasma source, an acceleration chamber I is arranged in the middle of the magnetic confinement plasma thruster, and an acceleration chamber II is arranged in the middle of the multi-coil plasma thruster; The tail end of the ionization chamber and the head ends of the two acceleration chambers are all connected through a connecting pipe in a penetrating manner. A working gas inlet is arranged at the head end of the ionization chamber, and plasma outlets I and II are correspondingly arranged at the tail ends of the acceleration chamber I and the acceleration chamber II; A helical antenna is arranged outside the ionization chamber and is used to generate helical wave discharge in the ionization chamber to ionize the working gas to generate plasma; An electromagnetic coil I is arranged outside the head of the acceleration chamber I and is used to pass a direct current to generate a constant magnetic field inside the acceleration chamber I. A bias electrode is further arranged inside the tail of the acceleration chamber I and is used to connect a direct current voltage to generate an externally applied positive voltage; A plurality of stator coils I are arranged outside the head of the acceleration chamber II, and a plurality of stator coils II are arranged outside the tail of the acceleration chamber II, and the current directions passed through the two groups of stator coils are opposite.
2. The dual-mode plasma thruster according to claim 1, characterized in that: Two annular permanent magnets are coaxially sleeved outside the middle of the ionization chamber, and the polarities of the two annular permanent magnets are opposite.
3. A dual-mode plasma thruster according to claim 1, characterized in that: Both the stator coil I and the stator coil II are annular coils with a rectangular cross-section.
4. A dual-mode plasma thruster according to claim 1, characterized in that: The ionization chamber, the acceleration chamber I, and the acceleration chamber II are all made of high-temperature resistant glass. The acceleration chamber I is in a horn shape, and the ionization chamber and the acceleration chamber II are both in a cylindrical shape.
5. A dual-mode plasma thruster according to claim 1, characterized in that: The central axes of the ionization chamber, the acceleration chamber I, and the acceleration chamber II are parallel to each other, and the tail end of the ionization chamber is integrally connected to the head ends of the two acceleration chambers through a connecting pipe to form a Y-shaped communicating cavity.
6. A dual-mode plasma thruster according to any one of claims 1-5, characterized in that: The working gas is argon, and an alternating radio frequency current is passed through the helical antenna.