阅读说明：本技术 一种基于旋转磁场加速的无电极等离子体推力器 (Electrodeless plasma thruster based on rotating magnetic field acceleration ) 是由 石峰 王国东 王志军 朱红伟 张影 于 2021-01-11 设计创作，主要内容包括：本发明涉及航天技术领域,提供一种基于旋转磁场加速的无电极等离子体推力器,包括中空的壳体和工质基座,工质基座中心设有工质进入孔,工质基座密封固定设置于壳体前部的端部,壳体前部周向外壁上缠绕有射频线圈；壳体后部周向外壁沿轴线方向上设有多个等距永磁体环,多个永磁体环的磁场方向相同；壳体后部外侧周向设有围绕壳体后部的四个轴向线圈,两组轴向线圈分别输入相位差为90°的射频电流。本申请的等离子体推力器整体结构相对比较简单,具有放电气压低,等离子体密度高、均匀性好的优势。(The invention relates to the technical field of spaceflight, and provides an electrodeless plasma thruster based on rotating magnetic field acceleration, which comprises a hollow shell and a working medium base, wherein the center of the working medium base is provided with a working medium inlet hole, the working medium base is fixedly arranged at the end part of the front part of the shell in a sealing way, and a radio frequency coil is wound on the circumferential outer wall of the front part of the shell; a plurality of equidistant permanent magnet rings are arranged on the circumferential outer wall of the rear part of the shell along the axis direction, and the magnetic field directions of the permanent magnet rings are the same; four axial coils surrounding the rear part of the shell are circumferentially arranged on the outer side of the rear part of the shell, and radio frequency currents with the phase difference of 90 degrees are respectively input into the two groups of axial coils. The plasma thruster has the advantages of being relatively simple in overall structure, low in discharge voltage, high in plasma density and good in uniformity.)

1. An electrodeless plasma thruster based on rotating magnetic field acceleration, characterized in that: the working medium base is fixedly arranged at the end part of the front part of the shell in a sealing manner, and the center of the working medium base is coaxial with the shell; a radio frequency coil is wound on the outer wall of the front part of the shell; the outer wall of the rear part of the shell is fixedly provided with a plurality of permanent magnet rings which are distributed at equal intervals along the axis direction, and the magnetic field directions of the permanent magnet rings are the same; four axial coils are circumferentially distributed around the outer wall of the shell on the outer side of the rear part of the shell, and two sets of two opposite axial coils are formed in one set; two axial coils in each group are connected in parallel, and radio frequency currents with the phase difference of 90 degrees are respectively input into the two groups of axial coils.

2. The electrodeless plasma thruster as claimed in claim 1, wherein the rotating magnetic field acceleration-based electrodeless plasma thruster comprises: the shell is a quartz glass tube.

Technical Field

The invention relates to the technical field of spaceflight, in particular to an electrodeless plasma thruster based on rotating magnetic field acceleration.

Background

The chemical propulsion system has high thrust but low specific impulse, consumes a large amount of propellant when executing single track maneuver, and can not meet the requirement of long-term on-track maneuver. Electric propulsion is a reaction type engine which converts electric energy into working medium kinetic energy, enables the working medium kinetic energy to be directionally accelerated and generates thrust, has the obvious advantage of higher specific impulse compared with chemical propulsion, and is widely applied to geosynchronous orbit satellite position maintenance, main propulsion tasks of medium and small deep space detectors and the like.

However, the conventional electric propulsion system may affect the lifetime of the thruster due to erosion by the electrode and sputtering between the plasma and the wall surface. For this reason, improvement thereof is required.

Disclosure of Invention

An object of the present invention is to provide an electrodeless plasma thruster based on rotating magnetic field acceleration, so as to solve the problems presented in the background art.

In order to achieve the purpose, the invention adopts the following technical scheme: the electrodeless plasma thruster based on rotating magnetic field acceleration comprises a hollow shell and a working medium base, wherein the front part of the shell is in a hollow cylinder shape, the rear part of the shell is in a hollow circular truncated cone shape, the front part of the shell is integrally connected with the small end of the rear part of the shell, the center of the working medium base is provided with a working medium inlet hole, the working medium base is fixedly arranged at the end part of the front part of the shell in a sealing way, and the center of the working medium base is coaxial with the; a radio frequency coil is wound on the outer wall of the front part of the shell; the outer wall of the rear part of the shell is fixedly provided with a plurality of permanent magnet rings which are distributed at equal intervals along the axis direction, and the magnetic field directions of the permanent magnet rings are the same; four axial coils are circumferentially distributed around the outer wall on the outer side of the rear part of the shell, and two opposite axial coils form one group and are divided into two groups; two axial coils in each group are connected in parallel, and radio frequency currents with the phase difference of 90 degrees are respectively input into the two groups of axial coils.

Preferably, the housing is a quartz glass tube.

In the present application, the non-limiting structures are well known in the art, and include, but are not limited to, a power source, a working medium storage container, a working medium extraction device, a bracket, a vacuum environment, and the like.

The working principle and the beneficial effects of the application are as follows: a radio frequency coil is wound on the circumferential outer wall of the front part of the shell, and according to the Faraday's law of electromagnetic induction, when alternating radio frequency current is introduced into the coil, an alternating magnetic field is generated in a cylindrical cavity chamber of the front part of the shell; meanwhile, an alternating electric field is induced by the alternating magnetic field, and when the working medium gas is introduced, the alternating electric field causes the working medium gas to discharge to generate initial plasma;

a plurality of permanent magnet rings which are arranged at equal intervals are arranged on the circumferential outer wall of the rear part of the shell along the axis direction, and the permanent magnet rings generate an axial magnetic field in a cavity at the rear part of the shell; after radio frequency currents with the phase difference of 90 degrees are respectively input into the two groups of axial coils, an angular rotating magnetic field is generated in a cavity at the rear part of the shell, electrons of initial plasma are magnetized and rotate together to form angular plasma current, the angular plasma current flows along the axial direction, a magnetic field generated by the angular plasma current is opposite to an external magnetic field, so that closed magnetic lines of force are formed, positive ions and electrons in the initial plasma are further constrained, a field inversion configuration plasma cluster is formed, the angular plasma current and the radial component of the external axial magnetic field act together to generate Lorentz force, and the plasma cluster expands and is discharged outwards under the action of the Lorentz force. In the process, the inner walls of the front part and the rear part of the shell are not in direct contact with the plasma, so that the convection and conduction losses of energy are greatly reduced, theoretically, only radiation loss exists, the energy utilization rate is high, and the service life of the thruster can be prolonged; because the discharged field inversion configuration plasmoid is neutral, a neutralizer is not needed to be added, and the problem of plume pollution of the traditional plasma thruster is solved.

The radio frequency coil structure can generate high-density plasma under lower radio frequency voltage, and a high-voltage radio frequency electrode is not needed, so that the pollution of the electrode is avoided. In addition, the plasma thruster has the advantages of relatively simple overall structure, low discharge voltage, high plasma density and good uniformity.

Drawings

Fig. 1 is a schematic perspective view of an embodiment of the present invention.

Fig. 2 is a sectional view a-a of fig. 1.

Detailed Description

The present invention will be described in further detail with reference to the following description of embodiments thereof, which is provided for helping those skilled in the art to more fully, accurately and deeply understand the concept and technical scheme of the present invention and to facilitate the implementation thereof.

Example 1

Referring to fig. 1-2, an electrodeless plasma thruster based on rotating magnetic field acceleration comprises a hollow shell 1 and a working medium base 2, wherein the shell is made of quartz glass, the front part 102 of the shell is hollow cylindrical, the rear part 101 of the shell is hollow round table-shaped, the front part of the shell and the small end of the rear part of the shell are integrally connected, the center of the working medium base is provided with a working medium inlet hole 3, the working medium base is fixedly arranged at the end part of the front part of the shell in a sealing manner, and the center of the working medium base is coaxial with the; a radio frequency coil 4 is wound on the circumferential outer wall of the front part of the shell; a plurality of permanent magnet rings 5 which are arranged at equal intervals are arranged on the circumferential outer wall of the rear part of the shell along the axis direction, and the magnetic field directions of the permanent magnet rings are the same; four axial coils a, b, c and d are circumferentially arranged on the outer side of the rear part of the shell, and two opposite axial coils form a group, namely a and d form a group, and b and c form a group; two axial coils in each group are connected in parallel, and radio frequency currents with the phase difference of 90 degrees are respectively input into the two groups of axial coils.

The principle of the embodiment is as follows:

the ions in the initial plasma form a stationary, non-uniformly distributed background of positive charges, and the electrons are considered to be inertially free, pressureless, negatively charged fluid.

The azimuthal plasma current can be understood from generalized ohm's law:

where E denotes the electric field strength, η_pIs the plasma impedance. j is the current density with a component j_zAnd j_θ，n_eIs the electron number density and e is the electron charge. B is the magnetic field vector and the oscillating component is B_rAnd B_θRMF (rotating magnetic field) frequency of ω_RMF，e_BIs a unit vector of the magnetic field,is the frequency of electron cyclotron resonance,is the electron ion collision frequency, m_eIs the electron mass, η_pj is a term of a resistance which is,is the hall term.

If Hall termIs a negative flux leaving the plasma, shielding the current j_zOccurs at the outer layer of the plasma and prevents RMF from entering the plasma.

If it is notAnd j is_zB_rIs large and negative, the Hall term η_pAnd E_θIs negative. Under these conditions, flux enters the plasma and field inversion is enhanced. Electrons are magnetized and the rotating magnetic field enters the plasma, producing an angular electron current, producing a magnetized plasma, forming an inverted field structure and ejecting to produce thrust.

If the magnetic field is to penetrate the plasma, v is required_ei＞＞ω_ceAnd the frequency ω of the applied field_RMFMust satisfy omega_ci＜ω_RMF＜ω_ceTo ensure that the ions are not synchronized with the rotating magnetic field. Density of electrons n_eAnd electron ion collision frequency v_eiThe degree to which the resistance term affects the hall term is determined.

In the absence of plasma, rotating magnetic field BETA_ωThe components of γ and θ of (a) are:

B_r＝B_ωcos(ωt-θ)

(2)

B_θ＝B_ωsin(ωt-θ)

(3)

where B is_ωIs the magnitude of the rotating field and θ is the angular cylindrical coordinate.

In the presence of plasma, magnetic loss a can be introduced to determine the axial component.In thatIn ohm's law, the form:

its exact solution can be shown to be:

A_z＝-Bωrsin(ωt-θ)

(5)

where B is_axialIs the axial magnetic field strength, gamma_pIs the plasma diameter, azimuthal current density j_θIs composed of

The results show that the plasma electrons rotate in synchronism with the rotating magnetic field. The drift velocity of electrons at any radial position is defined by gamma_ωIt is given.

Electromagnetic theory indicates that the RMF penetration depth into the plasma does not exceed the skin depth delta_SWithin this skin depth, the current drops to 0.37 times the surface current. The resistive skin depth is approximately:

when the RMF acts on the plasma, electrons rotate with the RMF, in which reference frame the RMF appears to be stationary, the field can penetrate the plasma to the axis of symmetry, the RMF must exceed a threshold in order to penetrate the plasma, and the RMF magnetic flux density must exceed B_ω。

When this condition is met, the RMF penetrates the plasma, with the penetration being greatest when the electrons are rotating in synchronism with the rotating field.

The thrust generated by the RMF is similar to that generated by a magnetic jet, and the induced angular electron current generates an axial component of the thrust in the presence of a divergent magnetic field.

If radial magnetic field B_γCan be expressed asAnd assuming a spatially uniform distribution of electron density, the thrust is estimated as:

here, R_coilIs the axial coil radius, L_AIs the length of the acceleration region, gamma_pIs the plasma radius.

The invention is described above with reference to the accompanying drawings as an example, in so far as it is a insubstantial improvement in the method concept and technical solutions of the invention; the present invention is not limited to the above embodiments, and can be modified in various ways.