A working fluidless cathode neutralization circuit for a microwave ion thruster

Abstract

The application belongs to the field of space electric propulsion, and particularly relates to a working medium-free cathode neutralization circuit for a microwave ion thruster; the circuit comprises an ion thruster, a bias power supply and a cathode power supply circuit; the ion thruster is used for coupling discharge to generate an ion plume, the cathode power supply circuit is used for releasing electrons to neutralize the ion plume generated by the ion thruster; the bias power supply is used for adjusting the potential difference between the cathode neutralization ion thruster; the positive electrode of the bias power supply is connected with the ion thruster, and the negative electrode of the bias power supply is connected with the cathode power supply circuit, so that high-precision neutralization of the ion plume of the thruster is realized, the problem of thrust eccentricity caused by insufficient neutralization precision of the ion plume of the thruster is solved, and the cathode life is improved.

Description

Technical Field

[0001] The present application belongs to the field of space electric propulsion, and specifically relates to a fluid-free cathode neutralization circuit for a microwave ion thruster. Background Art

[0002] In space gravitational wave detection missions, propulsion systems using traditional hollow cathodes can suffer from eccentric thrust. Even if the hollow cathode is miniaturized, the plasma ejected from its working fluid plume will cause the thruster plume to shift in one direction on the cathode side, thereby changing the thrust direction. Therefore, a cathode that does not use working fluid must be used. Instead, it relies on the surface electric field and thermionic emission of the material to release electrons directly into the thruster's ion plume for neutralization. In miniaturized propulsion systems, a working fluid-free thermal emission cathode must meet the requirements for neutralizing the thruster's ion plume, and the project's specifications must achieve a high-precision neutralization effect. Summary of the Invention

[0003] In order to solve the problem of insufficient thrust plume neutralization accuracy of thrusters in the prior art, which leads to thrust eccentricity of the inference system, a fluidless cathode neutralization circuit for microwave ion thrusters is proposed.

[0004] A fluid-free cathode neutralization circuit for a microwave ion thruster, comprising an ion thruster, a bias power supply, and a cathode power supply circuit;

[0005] The ion thruster is used to generate an ion plume through coupled discharge, and the cathode power supply circuit is used to release electrons to neutralize the ion plume generated by the ion thruster; the bias power supply is used to adjust the potential difference between the cathode and the ion thruster; the positive pole of the bias power supply is connected to the ion thruster, and the negative pole of the bias power supply is connected to the cathode power supply circuit.

[0006] Preferably, the cathode power supply circuit includes a contact electrode power supply, a first resistor, a second resistor, a cathode and a heating power supply;

[0007] The holding electrode power supply is used to apply high voltage to the cathode holding electrode, the heating power supply is used to heat the cathode, and the cathode is used to emit an electron beam under the high voltage and heating applied by the holding electrode;

[0008] The heating power supply is connected in parallel with the cathode; the positive pole of the touch-holding electrode power supply is connected to one end of the first resistor, the other end of the first resistor is connected to the cathode touch-holding electrode, and the negative pole of the touch-holding electrode power supply is connected to the negative pole of the heating power supply; the cathode touch-holding electrode is also connected to one end of the second resistor, and the other end of the second resistor is connected to the negative pole of the bias power supply.

[0009] Preferably, the cathode includes a hot wire, a filling ceramic and a cathode tube shell; the filling ceramic is filled inside the cathode tube shell, and the hot wire is arranged inside the filling ceramic; one end of the hot wire is connected to the negative pole of the heating power supply, and the other end of the hot wire is welded to the cathode tube shell, and the other end of the hot wire is also connected to the positive pole of the heating power supply.

[0010] Preferably, the ion thruster includes a thruster ionization chamber, a gas input unit, a microwave source input unit, a screen grid power supply, a third resistor, an acceleration grid power supply and a fourth resistor;

[0011] The gas input unit is used to input the set gas into the thruster ionization chamber; the microwave source input unit is used to generate a microwave signal and input the microwave signal into the thruster ionization chamber; the microwave signal is used to ionize the input set gas in the thruster ionization chamber to generate set gas ions;

[0012] The ion thruster screen grid is connected to one end of a third resistor, the other end of the third resistor is connected to the positive electrode of the screen grid power supply, and the negative electrode of the screen grid power supply is connected to the positive electrode of the bias power supply; the ion thruster acceleration grid is connected to one end of a fourth resistor, the other end of the fourth resistor is connected to the negative electrode of the acceleration grid power supply, and the acceleration grid power supply is connected to the positive electrode of the bias power supply;

[0013] The screen grid power supply is used to apply voltage to the ion thruster screen grid, and the acceleration grid is used to apply voltage to the ion thruster acceleration grid. The thruster ionization chamber is provided with a small hole. The voltage difference between the ion thruster screen grid and the ion thruster acceleration grid accelerates the set gas ions passing through the small hole to generate an ion plume.

[0014] Beneficial effects

[0015] The present application discloses a fluidless cathode neutralization circuit for a microwave ion thruster. The circuit connects the ion thruster and the cathode neutralization circuit via a bias power supply to achieve high-precision neutralization of the thruster ion plume. The circuit has the following advantages:

[0016] (1) Improve the neutralization accuracy of the thruster ion plume; the bias power supply is connected to the cathode contact electrode to ensure the stability of the cathode contact electrode shell with respect to the plume potential;

[0017] (2) Extend the life of the cathode; the hot wire of the integrated emitter component is set to negative at one end and the shell end is set to positive, and the "thermophoresis" effect is used to suppress the ceramic insulation failure caused by evaporation of the hot wire during use, thereby extending the life of the cathode. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural diagram of a fluid-free cathode neutralization circuit for a microwave ion thruster according to a specific embodiment of the present application;

[0019] Figure 2 This is a cathode structure diagram of a specific embodiment of the present application;

[0020] In the figure, 1 is the hot wire, 2 is the cathode tube shell, 3 is the filling ceramic, 4 is the cathode, 5 is the heating power supply, 6 is the first resistor, 7 is the touch electrode power supply, 8 is the second resistor, 9 is the bias power supply, 10 is the screen grid power supply, 11 is the third resistor, 12 is the fourth resistor, 13 is the acceleration grid power supply, 14 is the thruster ionization chamber, 15 is the setting gas bottle, 16 is the pressure reducing valve, 17 is the flow meter, 18 is the gas path insulator, 19 is the microwave source, and 20 is the DC isolator. DETAILED DESCRIPTION

[0021] Specific implementation method 1: The following is combined with the attached embodiment of the present invention Figure 1 To the attached Figure 2 , illustrate this embodiment, and clearly and completely describe the technical solutions in the embodiments of the present invention:

[0022] A fluid-free cathode neutralization circuit for a microwave ion thruster, comprising an ion thruster, a bias power supply, and a cathode power supply circuit;

[0023] The ion thruster is used to generate an ion plume through coupled discharge, and the cathode power supply circuit is used to release electrons to neutralize the ion plume generated by the ion thruster; the bias power supply is used to adjust the potential difference between the cathode and the ion thruster; the positive pole of the bias power supply is connected to the ion thruster, and the negative pole of the bias power supply is connected to the cathode power supply circuit.

[0024] Specifically, as attached Figure 2 As shown in the figure, for the cathode, the key component for emitting electrons is the emitter. The emitter is a material with a low surface electron work function (work function), which allows electrons to escape from the material surface more easily. However, the emitter material must reach a certain operating temperature before it can emit electrons. By utilizing the Schottky effect, an electric field can be applied to the surface of the emitter to increase the electron emission capability. This is different from the traditional hollow cathode emitter, where the contact electrode only serves as an ignition starter during operation. The contact electrode of the working fluid-free cathode requires a constant voltage during operation, thus requiring an adjustable voltage power supply to ensure continuous operation. As the main component exposed to the external plasma, the contact electrode's potential relative to the plasma plume significantly affects the charge neutralization effect due to the plasma's high sensitivity to electric and magnetic fields. Therefore, for the neutralization circuit, the relative potential adjustment power supply for the cathode and thruster is connected to the contact electrode (gate). This minimizes the cathode's influence on the external electric field during the cathode's adjustment of the internal contact electrode grid and emitter potential.

[0025] In traditional electric propulsion systems, when the thruster and cathode work in combination, the adjustment and active control of the relative potential between the cathode and the thruster are optional, that is, it is not necessary to actively apply the potential control of the cathode relative to the thruster. However, for the entire electric propulsion system for gravitational wave detection, when using ion thrusters for coupled discharge, in order to achieve the high-precision neutralization, low thrust noise, and precise control requirements of multiple control means in the project indicators, active control is applied to the bias power supply of the cathode relative to the thruster. This means that when you want to adjust the potential of the cathode relative to the thruster, you need to connect one end of a bias power supply to the thruster and the other end to the cathode. When the voltage at both ends of the power supply is adjusted, the part where the cathode is connected to the bias power supply will be stable and controllable relative to the thruster, which is beneficial to the electron emission of the cathode and the external plasma The environment can be further controlled by an additional means, which is beneficial for high-precision neutralization and thrust noise reduction. The role of the bias power supply is to adjust the potential difference between the cathode and the plume. This is because when the cathode impedance increases, the cathode becomes insensitive to the potential change of the plume relative to the ground, and it is easy to under-neutralize. It can be understood that the impedance between the cathode and the plume is similar to the role of a resistor in a circuit. When the impedance becomes higher, the resistance value becomes larger. Even if the voltage at the plume end has the same fluctuation, the increase or decrease in the lead-out current between the cathode and the plume through this resistor will not be as sensitive as when the impedance is small, and the lead-out current value will also be very small. This is the so-called under-neutralization. Therefore, an external power supply is required to apply an additional voltage to adjust the voltage difference between the cathode and the plume to be sufficient so that the neutralization current is sufficient.

[0026] To solve the problem that when the cathode without working fluid is working, the touch-holding electrode needs to be constantly applied with potential, causing the outer shell of the touch-holding electrode exposed to the plasma environment to become an electrode plate, the cathode bias power supply is connected to the end of the touch-holding electrode, so that the touch-holding electrode and the end of the bias power supply connected to the cathode have the same potential, ensuring the stability of the cathode touch-holding electrode shell with respect to the plume potential.

[0027] Furthermore, the cathode power supply circuit includes a contact electrode power supply 7, a first resistor 6, a second resistor 8, a cathode 4 and a heating power supply 5;

[0028] The holding electrode power supply 7 is used to apply high voltage to the cathode holding electrode, the heating power supply 5 is used to heat the cathode, and the cathode is used to emit an electron beam under the high voltage and heating applied by the holding electrode;

[0029] The heating power supply 5 is connected in parallel with the cathode 4; the positive pole of the touch-holding electrode power supply 7 is connected to one end of the first resistor 6, the other end of the first resistor 6 is connected to the cathode touch-holding electrode, and the negative pole of the touch-holding electrode power supply 7 is connected to the negative pole of the heating power supply 5; the cathode touch-holding electrode is also connected to one end of the second resistor 8, and the other end of the second resistor 8 is connected to the negative pole of the bias power supply 9.

[0030] Specifically, for a traditional hollow cathode, the touch-holding electrode only needs to apply a high voltage at the beginning of the ignition process, so that a gas breakdown discharge is formed between the touch-holding electrode and the cathode top plate connected to the armored hot wire, forming a plasma. The plasma spreads to the emitter area heated by the heater, causing the gas inside the emitter to be ionized, and the hollow cathode can be ignited. After the ignition is successful, the touch-holding electrode does not need to continue to apply a high voltage. The formation of plasma can be maintained by relying on the collision heating effect of the plasma ions and the emitter and the resistance effect of the plasma and the external electric field discharge. Therefore, the voltage applied by the touch-holding electrode mainly plays an ignition role in the hollow cathode. After the cathode is successfully ignited, the touch-holding electrode is generally disconnected from the power supply, and its potential is suspended relative to other components. It is in a state of passive exposure to the plasma environment, so it will not actively affect the plasma environment.

[0031] However, in the fluidless cathode, the structure of the touch-holding electrode includes an extraction grid that maintains the electric field on the surface of the emitter, which requires the touch-holding electrode to actively apply potential all the time during the operation and regulation of the cathode. For the overall circuit of the entire thruster and cathode, if the touch-holding electrode of the cathode shell exposed to the external plasma environment is not directly connected to the cathode bias power supply that regulates the cathode relative to the thruster circuit, then when the fluidless cathode works directly, the touch-holding electrode power supply will cause most of the externally exposed cathode shell (touch-holding electrode shell) to form a large electrode relative to the plasma environment. As the potential increases and decreases, it will absorb and repel the ions and electrons in the plasma, which will seriously affect the neutralization effect of the electron beam emitted by the cathode and the ion beam emitted by the thruster. In miniaturized thrusters that require high-precision neutralization, this effect cannot be ignored and needs to be suppressed.

[0032] Furthermore, the cathode includes a hot wire 1, a filling ceramic 3 and a cathode tube shell 2; the filling ceramic 3 is filled inside the cathode tube shell 2, and the hot wire 1 is arranged inside the filling ceramic 3; one end of the hot wire 1 is connected to the negative pole of the heating power supply 5, and the other end of the hot wire 1 is welded to the cathode tube shell 2, and the other end of the hot wire 1 is also connected to the positive pole of the heating power supply 5.

[0033] Specifically, as attached Figure 1 As shown, for the cathode hot wire heating circuit, the potential of the hot wire heater of the integrated emitter component and the cathode cylindrical shell on its surface are swapped, so that one end of the hot wire is negative and one end of the shell is positive. The "thermophoresis" effect is used to suppress two special ceramic insulation failure problems caused by evaporation of the hot wire during use, reduce the evaporation and penetration of the hot wire in the ceramic sintered package, alleviate insulation failure and hot wire necking, and increase the working life of the hot wire of the working fluid-free cathode.

[0034] The cathode base is a so-called barium tungsten emitter material, and the hot sub is a hot wire wound in multiple turns, one end of which extends from the middle at the lower part, and the other end is welded to the cathode cylinder shell of the outer wall. In the past, the hot wire used in the hollow cathode is an armored heater, also known as a mineral insulated heating cable.

[0035] The hot wire inside the armored heater is insulated by the filled magnesium oxide ceramic powder, and is wrapped in a metal protective tube outside. The outer protective tube is not connected to the power or is at the same potential as the hot wire. During the process of heating the internal hot wire, the life attenuation of the hot wire is mainly due to the evaporation of the hot wire metal, which gradually penetrates into the mineral insulation layer, causing local hot wire necking. The resistance of the necked part per unit length is larger, and more heating power will be distributed here, further accelerating the evaporation of the metal and causing the hot wire to burn out. For the traditional hollow cathode, its working time life requirement is several thousand hours, while for the propellantless cathode used in gravitational wave detection, the cathode life is required to be twenty thousand hours. As a single-point failure component, the hot wire will cause the cathode to fail and the propulsion system to fail to work as soon as it is damaged. Therefore, the "thermophoresis" effect between the traditional hollow cathode hot wire and the protective tube may not constitute a major problem, and the effect of the cathode hot wire life is not prominent. However, for the propellantless hot cathode used, the diameter of the hot wire becomes very thin in the process of miniaturization and integration, only 0.15mm, which makes the thermophoresis effect on the hot wire life not negligible, and direct means such as thickening the hot wire must be taken to increase the life of the hot wire.

[0036] Thermophoresis is essentially the phenomenon that uncharged particles will drift towards the electrode under the action of an electric field. Thermophoresis effect is that at high temperature, the charges between the molecules of a material that does not have fluidity (which can be solid) will exhibit characteristics similar to those of a semiconductor, i.e. under the action of an electric field, electrons or holes can move charges. Similarly, metal vapor particles that gradually penetrate into the insulating ceramic due to evaporation will also be affected by the electric field and will move towards the electrode due to the different directions of the applied electrode. The penetration of metal vapor in the sponge-like pores will result in a consequence, i.e. the short circuit between metals, i.e. the metal vapor that penetrates into the sponge-like ceramic will deposit with repeated heating and cooling, eventually leading to the failure of the insulation of the ceramic.

[0037] For the propellantless cathode, due to the difference in structure compared to the traditional hollow cathode armored hot wire, this feature causes two main problems for the long-term life stability of the hot wire:

[0038] Firstly, unlike the hollow cathode heater, the armored heater usually only has one hot wire between the ceramic wrapping, which makes the armored heater not have the problem of short circuit between the hot wires due to the metal penetrating the ceramic.

[0039] Secondly, unlike the insulation problem between the hot wires, in the working fluid-free cathode structure, the cathode cylinder is part of the heating positive and negative electrodes, and the cathode cylinder and the hot wire wrapped inside can also be regarded as two main electrodes. There is also an insulation problem between the cathode hot wire and the ceramic cylinder.

[0040] Both of these problems will cause partial short circuit of the hot wire, causing resistance changes, and thus causing unstable heating or even hot wire burnout.

[0041] Further, the ion thruster includes a thruster ionization chamber 14, a gas input unit, a microwave source input unit, a screen grid power supply 10, a third resistor 11, an acceleration grid power supply 13, and a fourth resistor 12;

[0042] The gas input unit is used to input a set gas into the thruster ionization chamber 14; the microwave source input unit is used to generate a microwave signal and input the microwave signal into the thruster ionization chamber 14; the microwave signal is used to ionize the input set gas to generate set gas ions in the thruster ionization chamber 14;

[0043] The ion thruster screen grid is connected to one end of the third resistor 11, the other end of the third resistor 11 is connected to the positive electrode of the screen grid power supply 10, the negative electrode of the screen grid power supply 10 is connected to the positive electrode of the bias power supply 9; the ion thruster acceleration grid is connected to one end of the fourth resistor 12, the other end of the fourth resistor 12 is connected to the negative electrode of the acceleration grid power supply 13, and the acceleration grid power supply 13 is connected to the positive electrode of the bias power supply 9;

[0044] The screen grid power supply 10 is used to apply a voltage to the ion thruster screen grid, and the acceleration grid is used to apply a voltage to the ion thruster acceleration grid. The thruster ionization chamber is provided with a small hole, and the voltage difference between the ion thruster screen grid and the ion thruster acceleration grid accelerates the set gas ions passing through the small hole to generate an ion plume.

[0045] Further, the gas input unit includes a set gas bottle 15, a pressure reducing valve 16, a flow meter 17, and a gas path insulator 18;

[0046] The gas outlet of the set gas bottle 15 is connected to the gas inlet of the pressure reducing valve 16, the gas outlet of the pressure reducing valve 16 is connected to the gas inlet of the flow meter 17, the gas outlet of the flow meter 17 is connected to the gas inlet of the gas path insulator 18, and the gas outlet of the gas path insulator 18 is connected to the gas inlet of the thruster ionization chamber 14;

[0047] A set gas bottle is arranged to supply set gas to a pressure reducing valve 16; the pressure reducing valve is arranged to reduce the pressure of the input set gas and supply the reduced pressure set gas to a flow meter 17, which is arranged to obtain a flow signal of the reduced pressure set gas, and supply the reduced pressure set gas to a gas path insulator 18, which is arranged to supply the reduced pressure set gas to the ion thruster ionization chamber 14; the gas path insulator 18 is arranged to insulate the set gas bottle 15, the pressure reducing valve 16 and the flow meter 17 from the ion thruster.

[0048] Specifically, the isolated gas path prevents the gas supply line from being electrified, so that the control circuit in the upstream gas path is insulated from the thruster.

[0049] Further, the microwave source input unit comprises a microwave source 19 and a DC isolator 20.

[0050] The microwave source 19 is arranged to generate a microwave signal and supply the microwave signal to the DC isolator 20; the DC isolator 20 is arranged to isolate the DC component in the microwave signal and supply the microwave signal with the isolated DC component to the thruster ionization chamber 14.

[0051] Further, the filling ceramic is an alumina filling ceramic.

[0052] Further, the set gas is xenon gas.

[0053] Further, the bias power supply is an adjustable bias power supply.

[0054] Further, the hold-off electrode power supply is an adjustable power supply; the heating power supply is an adjustable power supply.

[0055] Specifically, the hold-off electrode power supply and the bias power supply can be controlled by a program, and are required to be always turned on and work during the whole working process, so that the electronic energy and the amount of extracted current are adjustable.

[0056] For the circuit connected with the cathode and the thruster, when the thruster needs to adjust the potential of the cathode relative to the thruster or the plume, the voltage of the bias power supply is mainly relied on, and the end of the bias power supply connected with the cathode is directly connected with the hold-off electrode, so that the potential of the main part of the cathode exposed in the plume, i.e. the hold-off electrode shell, is relatively stable from the perspective of the external plasma, and further has a small influence on the neutralization process of the plume charge.

[0057] For the connection part of the cathode and the thruster, since it is required to be controlled and adjusted, the potential of the cathode relative to the thruster needs to be controlled and adjusted, so that an adjustable bias power supply is required to be applied for control feedback.

[0058] By reversing the cathode heating power supply, the center hot wire of the micro-integrated thermal sub-section is changed from the traditional positive electrode to the negative electrode, the thermal electrophoresis phenomenon is used, the original cathode cylinder is changed from the negative electrode to the positive electrode, that is, the positive and negative electrodes of the hot wire are reversed, the two surrounding electrodes formed between the cathode cylinder outside the hot wire ceramic and the hot wire change the electric field of the metal vapor particles, the electrophoresis direction of the metal particles in the ceramic is changed, the metal vapor particles heated and evaporated by the original electric field change from accelerated evaporation to inhibition of evaporation, the insulation performance between the hot wire and the cathode cylinder is enhanced, in addition, another effect is achieved, that is, the insulation failure between the hot wire and the hot wire caused by metal vapor is inhibited, and the special problem caused by the structure of the working fluid-free cathode different from the armored hot wire heater is solved.

[0059] In order to solve the problem that the continuous application of electric field to the touch electrode will affect the external plasma environment, the position where the bias power supply for adjusting the potential of the cathode is connected to the cathode circuit is set to the position where the positive electrode of the touch electrode power supply is located, so that when the bias power supply adjusts the voltage of the cathode, the potential of the entire cathode shell as the main contact part in the perspective of the plume area relative to the external plasma environment is unchanged, and then the main exposed contact part potential of the working fluid-free cathode in the process of emitting electrons and the external excess plasma positive charge ions is relatively stable, instead of being a large-area electrode plate that absorbs or repels positive and negative charges to affect the neutralization process of cathode electrons and thruster ions.

[0060] Although the present application is described herein with reference to particular embodiments, it is to be understood that these examples are merely illustrative of principles and applications of the present application. It should therefore be understood that numerous modifications can be made to the illustrative embodiments and that other arrangements can be devised without departing from the spirit and scope of the present application as defined by the appended claims. It should be understood that the features described in connection with one embodiment can be used in conjunction with other embodiments described herein. It should be understood that the features described in connection with one embodiment can be used in conjunction with other embodiments described herein.

Claims

1. A fluidless cathode neutralization circuit for a microwave ion thruster, characterized by: Includes ion thruster, bias power supply and cathode power supply circuit; The ion thruster is used for generating ion plumes through coupled discharge, and the cathode power supply circuit is used for releasing electrons to neutralize the ion plumes generated by the ion thruster; The bias power supply is used to adjust the potential difference between the cathode and the ion thruster; the positive electrode of the bias power supply is connected to the ion thruster, and the negative electrode of the bias power supply is connected to the cathode power supply circuit; The cathode power supply circuit includes a contact electrode power supply, a first resistor, a second resistor, a cathode and a heating power supply; The holding electrode power supply is used to apply high voltage to the cathode holding electrode, the heating power supply is used to heat the cathode, and the cathode is used to emit an electron beam under the high voltage and heating applied by the holding electrode; The heating power supply is connected in parallel with the cathode; the positive electrode of the touch-holding electrode power supply is connected to one end of the first resistor, the other end of the first resistor is connected to the cathode touch-holding electrode, and the negative electrode of the touch-holding electrode power supply is connected to the negative electrode of the heating power supply; the cathode touch-holding electrode is also connected to one end of the second resistor, and the other end of the second resistor is connected to the negative electrode of the bias power supply; The cathode includes a hot wire, a filling ceramic and a cathode tube shell; the filling ceramic is filled inside the cathode tube shell, and the hot wire is arranged inside the filling ceramic; one end of the hot wire is connected to the negative pole of the heating power supply, and the other end of the hot wire is welded to the cathode tube shell, and the other end of the hot wire is also connected to the positive pole of the heating power supply.

2. The fluidless cathode neutralization circuit for a microwave ion thruster according to claim 1, characterized in that: The ion thruster includes a thruster ionization chamber, a gas input unit, a microwave source input unit, a screen grid power supply, a third resistor, an acceleration grid power supply and a fourth resistor; The gas input unit is used to input the set gas into the thruster ionization chamber; the microwave source input unit is used to generate a microwave signal and input the microwave signal into the thruster ionization chamber; the microwave signal is used to ionize the input set gas in the thruster ionization chamber to generate set gas ions; The ion thruster screen grid is connected to one end of a third resistor, the other end of the third resistor is connected to the positive electrode of the screen grid power supply, and the negative electrode of the screen grid power supply is connected to the positive electrode of the bias power supply; the ion thruster acceleration grid is connected to one end of a fourth resistor, the other end of the fourth resistor is connected to the negative electrode of the acceleration grid power supply, and the acceleration grid power supply is connected to the positive electrode of the bias power supply; The screen grid power supply is used to apply voltage to the ion thruster screen grid, and the acceleration grid is used to apply voltage to the ion thruster acceleration grid. The thruster ionization chamber is provided with a small hole. The voltage difference between the ion thruster screen grid and the ion thruster acceleration grid accelerates the set gas ions passing through the small hole to generate an ion plume.

3. The fluidless cathode neutralization circuit for a microwave ion thruster according to claim 2, characterized in that: The gas input unit includes a set gas bottle, a pressure reducing valve, a flow meter and a gas circuit insulator; The gas outlet of the gas bottle is connected to the gas inlet of the pressure reducing valve, the gas outlet of the pressure reducing valve is connected to the gas inlet of the flow meter, the gas outlet of the flow meter is connected to the gas inlet of the gas path insulator, and the gas outlet of the gas path insulator is connected to the gas inlet of the thruster ionization chamber; The setting gas bottle is used to transmit the setting gas to the pressure reducing valve; the pressure reducing valve is used to reduce the pressure of the input setting gas and input the reduced-pressure setting gas into the flow meter; the flow meter is used to obtain the flow signal of the reduced-pressure setting gas; the flow meter inputs the reduced-pressure setting gas into the gas path insulator; the gas path insulator inputs the reduced-pressure setting gas into the thruster ionization chamber; the gas path insulator is used to insulate the setting gas bottle, the pressure reducing valve and the flow meter from the ion thruster.

4. The fluidless cathode neutralization circuit for a microwave ion thruster according to claim 2, characterized in that: The microwave source input unit includes a microwave source and a DC block; The microwave source is used to generate microwave signals and transmit the microwave signals to the DC isolator; the DC isolator is used to isolate the DC component in the microwave signal and send the microwave signal with the DC component isolated to the thruster ionization chamber.

5. The fluid-free cathode neutralization circuit for a microwave ion thruster according to claim 1, characterized in that: The filling ceramic is alumina-filled ceramic.

6. The fluid-free cathode neutralization circuit for a microwave ion thruster according to claim 2, characterized in that: Set the gas to xenon.

7. The fluidless cathode neutralization circuit for a microwave ion thruster according to claim 1, characterized in that: The bias power supply is an adjustable bias power supply.

8. The fluidless cathode neutralization circuit for a microwave ion thruster according to claim 1, characterized in that: The touch-holding electrode power supply is an adjustable power supply; the heating power supply is an adjustable power supply.

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