Hall thruster discharging circuit and Hall thruster ignition starting method

Abstract

The invention discloses a Hall thruster discharge circuit and a Hall thruster ignition starting method, and relates to the technical field of electric propulsion, the Hall thruster discharge circuit comprises a discharge channel and an anode of a Hall thruster, the upstream wall surface of the discharge channel is a metal wall surface, and the upstream wall surface of the discharge channel is a metal wall surface. The metal wall surface and the anode are respectively connected to a common connection point outside the discharge channel through wires, and a switch is arranged on the wire between the metal wall surface and the common connection point. The reliability of ignition starting of the Hall thruster is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric propulsion, and particularly to a Hall thruster discharge circuit and a Hall thruster ignition starting method. Background Art

[0002] A Hall thruster is a space electric propulsion device. Its discharge channel is annular, and the gas distributor is located at the bottom of the channel, which is generally also used as the anode. The cathode is located outside the discharge channel, and an electromagnetic field is used to ionize and accelerate the working medium between the cathode and the anode. It has the advantages of simple structure, long service life, good reliability, etc., and is thus widely used in various space missions. In recent years, with the rise of low-earth orbit communication satellite constellation missions, the total number of satellites reaches tens of thousands. Hall thrusters are required to provide power during stages such as orbit raising, attitude adjustment, and deorbiting. The increasing application requirements and frequencies have put forward higher requirements for the reliability of the Hall propulsion system.

[0003] Before the Hall thruster starts, the ionization process has not been established, and the working medium atoms reach a stable flow state in the discharge channel. At this time, the atomic density is much higher than that in the steady-state discharge process. During the ignition start moment, a large number of atoms in the entire channel participate in the ionization process, and then a discharge current much larger than that in the steady-state discharge state is generated, which is generally called the impact current. This transient impact current will cause electromagnetic interference to the satellite bus, put forward higher requirements for the electrical insulation of the entire satellite platform, and even if the impact current is too large, it will damage the internal components of the power supply and reduce the system reliability.

[0004] Generally, a filter circuit is added between the anode of the Hall thruster and the power supply to suppress the ignition impact current fed back to the power supply end. The larger the capacitance in the filter circuit, the smaller the ignition impact current fed back to the power supply, which is beneficial to improving the system reliability. On the other hand, increasing the capacitance value in the filter circuit also increases the oscillation amplitude of the discharge current in the steady-state operation of the thruster, and the discharge stability decreases, which is not conducive to improving the system reliability. Therefore, the existing methods cannot take into account the reliability during the ignition start and steady-state discharge processes of the Hall thruster, and can only adopt a compromise strategy. Thus, new methods are needed to suppress the Hall thruster ignition impact current. Summary of the Invention

[0005] The purpose of the present invention is to provide a Hall thruster discharge circuit and a Hall thruster ignition starting method to improve the reliability of the Hall thruster ignition start.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A Hall thruster discharge circuit includes: a discharge channel and an anode of the Hall thruster. The upstream wall surface of the discharge channel is a metal wall surface. The metal wall surface and the anode are respectively connected to a common connection point outside the discharge channel by wires, and a switch is provided on the wire between the metal wall surface and the common connection point.

[0008] Optionally, the Hall thruster discharge circuit further includes a cathode, which includes a heating wire, a holding electrode, and a cathode emitter; the heating wire is used to heat the cathode emitter, and one end of the holding electrode is connected to a holding electrode power supply, and the other end is connected to the cathode emitter.

[0009] Optionally, the Hall thruster discharge circuit further includes a filter circuit, and the filter circuit is connected between the anode power supply and the anode.

[0010] Optionally, the materials of the metal wall surface and the anode are both 1Gr18Ni9Ti.

[0011] A Hall thruster ignition and startup method, which applies the Hall thruster discharge circuit, includes:

[0012] Power on the cathode;

[0013] Close the switch connected to the metal wall surface, and power on the anode using the anode power supply;

[0014] When the discharge current of the Hall thruster is stable, disconnect the switch.

[0015] Optionally, powering on the cathode specifically includes:

[0016] Heat the cathode emitter through the heating wire, and when the temperature of the cathode emitter rises to a set temperature, use the holding electrode to maintain the discharge of the cathode emitter.

[0017] Optionally, the current of the holding electrode is greater than the discharge current of the anode during the steady-state operation of the Hall thruster.

[0018] Optionally, when the discharge current of the Hall thruster is stable, disconnecting the switch specifically includes:

[0019] When the discharge current of the Hall thruster does not change within a set time period, disconnect the switch.

[0020] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0021] In the present invention, the upstream wall surface of the discharge channel of the traditional Hall thruster is modified to a metal wall surface, and a switch is used to realize the switching between the metal wall surface and the anode. When the metal wall surface is electrically connected to the anode, the distance between the anode and the cathode in the discharge circuit is shorter, the impedance is smaller, and it is easier to break down to form a discharge circuit, reducing the difficulty of ignition and startup of the Hall thruster. When the metal wall surface is electrically connected to the anode, it is equivalent to moving the anode end face from the bottom of the discharge channel to near the outlet of the discharge channel, compressing the space of the ionization region at the moment of ignition and startup. Therefore, the number of atoms participating in ionization is less, which can reduce the impact current at the moment of ignition and startup and improve the reliability of ignition and startup of the Hall thruster. Brief Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 It is a schematic diagram of the discharge circuit structure of a Hall thruster provided by an embodiment of the present invention;

[0024] Figure 2 It is a schematic diagram of the process flow of a Hall thruster ignition and startup method provided by an embodiment of the present invention;

[0025] Figure 3 It is a schematic diagram of the ionization process at the moment of startup of a Hall thruster when the metal wall surface is suspended provided by an embodiment of the present invention;

[0026] Figure 4 It is a schematic diagram of the ionization process at the moment of startup of a Hall thruster when the metal wall surface is electrically connected to the anode provided by an embodiment of the present invention;

[0027] Figure 5 It is a schematic diagram of the experimental results of the startup impact signal of a Hall thruster when the metal wall surface is suspended provided by an embodiment of the present invention;

[0028] Figure 6 It is a schematic diagram of the experimental results of the startup impact signal of a Hall thruster when the metal wall surface is electrically connected to the anode provided by an embodiment of the present invention. Detailed Embodiments

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0030] The object of the present invention is to provide a Hall thruster discharge circuit and a Hall thruster ignition and startup method to improve the reliability of Hall thruster ignition and startup.

[0031] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Embodiment 1

[0033] As Figure 1 shown, a Hall thruster discharge circuit in this embodiment includes: a discharge channel and an anode of the Hall thruster. The upstream wall surface of the discharge channel is a metal wall surface. The metal wall surface and the anode are respectively connected to a common connection point outside the discharge channel by wires, and a switch S is provided on the wire between the metal wall surface and the common connection point. The common connection point is the Figure 1 point A in

[0034] The wires for leading out the electrical signals of the metal wall surface and the anode to the outside of the Hall thruster (outside the discharge channel) are all made of high-temperature resistant wires.

[0035] When the switch S is off, the metal wall surface is in an electrically floating state, and only the anode receives the discharge current. When the switch S is on, the metal wall surface and the anode are conducted, and both receive the discharge current.

[0036] In this embodiment, the material of the upstream wall surface of the discharge channel is replaced from boron nitride ceramic to metal to form a metal wall surface. Except for the upstream wall surface, other parts of the discharge channel still maintain the original insulating wall surface. The upstream wall surface is the wall surface within a set distance range from the bottom of the discharge channel, and the anode is arranged at the bottom of the discharge channel.

[0037] In this embodiment, the metal wall surface is connected to the Hall thruster discharge circuit (discharge circuit), and the switching of the connection mode between the metal wall surface and the anode is realized through the switch S. The relationship between the metal wall surface and the anode is a parallel relationship.

[0038] In this embodiment, the anode is used as the main electrode, and the metal wall surface is connected to the discharge circuit as an additional electrode.

[0039] The Hall thruster discharge circuit further includes a cathode, and the cathode includes a heating wire, a holding electrode, and a cathode emitter (negative electrode); the heating wire is used to heat the cathode emitter, and one end of the holding electrode is connected to the holding electrode power supply, and the other end is connected to the cathode emitter.

[0040] The heating wire heats the cathode emitter to a sufficient temperature to enable it to emit electrons, providing electrons for the operation of the Hall thruster. The heating wire is connected to the positive terminal of the cathode heating power supply, and the cathode emitter is connected to the negative terminal of the cathode heating power supply, so that a heating circuit is formed between the cathode heating wire and the cathode emitter. The function of the cathode holding electrode is to draw out the electrons emitted by the cathode when the cathode works alone to form a self-sustaining circuit. Therefore, the holding electrode is connected to the positive terminal of the holding electrode power supply, and the negative terminal of the holding electrode power supply is connected to the negative electrode of the cathode. During the ignition startup process, the cathode provides electrons for the Hall thruster, and a plasma is generated between the cathode and the anode and the metal wall of the Hall thruster. The two can form a path relying on the free electrons in the plasma, and the current received by the anode and the metal wall passes through the filter circuit, the anode power supply, and the negative electrode of the cathode to form a closed circuit.

[0041] In this embodiment, the cathode is ignited separately before the anode is ignited, that is, the temperature of the negative electrode of the cathode is increased to the thermionic emission state by the heating wire, and then the holding electrode is used to maintain the separate discharge of the cathode. The holding electrode current needs to be greater than the anode discharge current in the steady-state operation of the thruster.

[0042] Close the switch S to conduct the metal wall and the anode, then perform anode ignition. After successful ignition, wait for the thruster to operate stably and then disconnect the switch S to make the metal wall in a floating state.

[0043] The discharge circuit of the Hall thruster further includes a filter circuit, and the filter circuit is connected between the anode power supply and the anode. The metal wall and the anode are connected in parallel and then connected to the connection point of the inductor, resistor, and capacitor in the filter circuit.

[0044] The materials of the metal wall and the anode are both 1Gr18Ni9Ti.

[0045] The discharge circuit of the Hall thruster includes three components: a filter circuit, a Hall thruster, and a cathode. The required power supplies include an anode power supply, a cathode heating power supply for supplying power to the heating wire, and a cathode holding electrode power supply for supplying power to the holding electrode.

[0046] The filter circuit is composed of a resistor and an inductor connected in parallel and then connected in series with a capacitor. One end of the capacitor is connected to the negative terminal of the anode power supply, and the other end is connected to the anode of the Hall thruster. One end of the parallel connection of the resistor and the inductor is connected to the positive terminal of the anode power supply, and the other end is also connected to the anode of the Hall thruster. During the ignition startup process, there is a large pulse current on the anode or the metal wall of the Hall thruster, and the filter circuit plays a role in suppressing the peak value of the current returning to the anode power supply.

[0047] Embodiment 2

[0048] As Figure 2As shown in the figure, this embodiment provides a method for igniting and starting a Hall thruster. The method for igniting and starting a Hall thruster applies the Hall thruster discharge circuit described in Embodiment 1. The method for igniting and starting a Hall thruster includes:

[0049] Step 101: Energize the cathode.

[0050] Step 102: Close the switch connected to the metal wall surface and energize the anode using the anode power supply.

[0051] Step 103: After the discharge current of the Hall thruster stabilizes, disconnect the switch.

[0052] Among them, Step 101 ignites the cathode alone, specifically including: heating the cathode emitter through a heating wire. After the temperature of the cathode emitter increases to the set temperature (thermal emission state), the hold electrode is used to maintain the individual discharge of the cathode emitter.

[0053] The current of the hold electrode is greater than the discharge current of the anode when the Hall thruster operates in a steady state. The discharge current of the anode when the Hall thruster operates in a steady state is known.

[0054] Among them, in Step 102, the metal wall surface is conducted to the anode, and then the anode is ignited.

[0055] Among them, Step 103 specifically includes: after the anode is successfully ignited, when the discharge current of the Hall thruster does not change within a set time period (the Hall thruster operates stably), then disconnect the switch S.

[0056] As Figure 3 and Figure 4 shown, when the metal wall surface is conducted to the anode, the distance between the anode and the cathode in the discharge circuit is shorter, the impedance is smaller, and it is easier to break down to form a discharge circuit, reducing the difficulty of igniting and starting the Hall thruster. Most of the neutral atoms staying between the anode and the channel outlet will be ionized instantaneously during ignition and start-up, which is also the reason for the ignition impact current commonly existing in Hall thrusters. When the metal wall surface is conducted to the anode, it is equivalent to moving the anode end face from the bottom of the channel to near the channel outlet, compressing the space of the ionization region during ignition and start-up. Therefore, the number of atoms participating in ionization is less, which can reduce the ignition and start-up impact current.

[0057] During the steady-state discharge stage of the Hall thruster, when the metal wall surface is conducted to the anode, the end of the metal wall surface (anode) is close to the ionization region, and electrons are more likely to be directly received by the anode, resulting in an increase in the electron current and a decrease in the discharge efficiency.

[0058] Therefore, during the ignition start-up phase, the metal wall is electrically connected to the anode, and the connection between the two is disconnected during the steady-state discharge phase of the thruster. The metal wall is in a floating state. The present invention is configured to balance high steady-state discharge efficiency and low ignition impact current.

[0059] The method of the present invention can effectively reduce the ignition impact current of the Hall thruster at the source, reduce the impact on the power supply system during the start-up process and the difficulty of power supply design. It can even remove the filter circuit, improving the system reliability. By switching the switch S in the external circuit, the impact on the steady-state discharge process can be avoided. The method is simple and practical.

[0060] The following uses specific examples to illustrate the technical effects of a Hall thruster ignition start-up method of the present invention.

[0061] Example 1

[0062] An anode ignition experiment was conducted using a 1.35 kW hybrid wall (metal wall + insulating wall) Hall thruster. The ignition parameters were fixed as anode flow rate of 4 mg / s, anode voltage of 300 V, and characteristic magnetic field strength of 200 Gauss. Before the anode ignition start-up, the cathode and the keeper maintained stable discharge, and the keeper current of 5 A and the cathode flow rate of 0.3 mg / s remained unchanged. During the experiment, the voltage and current signals between the anode and the metal wall at the moment of anode ignition start-up of the Hall thruster were collected in the states where the switch S in the [[]] was open (the metal wall was floating) and closed (the metal wall served as the anode). The results are shown in Figure 1 and Figure 5 respectively, Figure 6 where the green line in Figure 6 is the discharge voltage and the blue line is the discharge current. The discharge current was collected at point A in Figure 1 . As shown in Figure 5 , using the conventional method, the peak value of the impact current at the moment of anode ignition start-up reached as much as 60 A, even exceeding the range of the measuring instrument; using the method of the present invention, as shown in Figure 6 (a) and (b), no obvious peak value of the impact current was seen, and the anode current gradually transitioned from 0 A to a stable discharge state, proving the effect of the method of the present invention in reducing the ignition start-up impact current of the Hall thruster.

[0063] Example 2

[0064] A steady-state discharge experiment was conducted using a 1.35 kW hybrid wall Hall thruster. The discharge parameters were fixed as anode flow rate of 4 mg / s, anode voltage of 500 V, and characteristic magnetic field strength of 200 Gauss, and Figure 2The steady-state discharge performance parameters in the states where the middle switch S is open (the metal wall surface is suspended) and closed (the metal wall surface serves as an additional anode) are shown in Table 1 below. It can be seen that the discharge performance of the thruster, including the thrust and anode efficiency, is higher in the state where the metal wall surface is suspended (switch S is open), which proves that the method of the present invention can not only suppress the ignition start impact current of the thruster but also ensure excellent steady-state discharge performance.

[0065] Table 1 Steady-state discharge performance parameters in the states where switch S is open and closed

[0066] Switch S state Anode discharge current (A) Thrust (mN) Anode efficiency (%) Open 3.44 88.6 58.8 Closed 3.54 88.1 56.7

[0067] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0068] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, there will be changes in the specific implementation manners and application scopes according to the idea of the present invention. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A Hall thruster discharge circuit, characterized in that Including: The discharge channel and anode of the Hall thruster, the upstream wall surface of the discharge channel is a metal wall surface, the metal wall surface and the anode are respectively connected to a common connection point outside the discharge channel by wires, and a switch is arranged on the wire between the metal wall surface and the common connection point.

2. The Hall thruster discharge circuit according to claim 1, wherein It further includes a cathode, and the cathode includes a heating wire, a holding electrode and a cathode emitter; the heating wire is used to heat the cathode emitter, one end of the holding electrode is connected to the holding electrode power supply, and the other end is connected to the cathode emitter.

3. The Hall thruster discharge circuit according to claim 1, characterized in that, It further includes a filter circuit, and the filter circuit is connected between the anode power supply and the anode.

4. The Hall thruster discharge circuit according to claim 1, characterized in that, The materials of the metal wall surface and the anode are both 1Gr18Ni9Ti.

5. A Hall thruster ignition and startup method, characterized in that, The Hall thruster ignition start method uses the Hall thruster discharge circuit according to any one of claims 1-4, and the Hall thruster ignition start method includes: Applying power to the cathode; Closing the switch connected to the metal wall surface and applying power to the anode using the anode power supply; When the discharge current of the Hall thruster is stable, disconnect the switch.

6. The Hall thruster ignition start method according to claim 5, characterized in that Applying power to the cathode specifically includes: Heating the cathode emitter through the heating wire, and when the temperature of the cathode emitter rises to the set temperature, using the holding electrode to maintain the discharge of the cathode emitter.

7. The Hall thruster ignition start method according to claim 6, wherein The current of the holding electrode is greater than the discharge current of the anode during the steady-state operation of the Hall thruster.

8. The Hall thruster ignition start method according to claim 5, characterized in that When the discharge current of the Hall thruster is stable, disconnecting the switch specifically includes: When the discharge current of the Hall thruster does not change within the set time period, disconnect the switch.

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