Method for starting touch holding current of hollow cathode by utilizing Hall thruster to ignite

Abstract

The invention discloses a method for starting a touch holding current of a hollow cathode by sparking a Hall thruster, and relates to the field of sparking of spaceflight electric thrusters. The problem that in the prior art, a technology for restraining the thruster from being extinguished due to ignition is lacked, so that the cathode needs to be heated and ignited again, and the thruster needs to be restarted is solved. The method is used for transferring pulse energy of abrupt change current generated during ignition between an anode of an anode power supply of the thruster and an anode of the thruster in a power supply system to a contact pole of the hollow cathode in a self-sustaining state of the hollow cathode of the thruster, so that extinguishing of the Hall thruster is inhibited. The method is mainly used for being applied to the hollow cathode self-sustaining state in the stable operation stage after successful ignition of the Hall thruster.

Description

Technical Field

[0001] The present invention relates to the field of ignition of aerospace electric thrusters. Background Art

[0002] Hall thrusters are currently the most maturely applied electric propulsion devices in the world. Different from traditional chemical thrusters, Hall thrusters have the advantages of simple structure, high efficiency, high specific impulse, large thrust density, etc. They can greatly improve the payload rate of spacecraft, expand the scope of space missions, and are suitable for in-orbit missions with high control precision requirements such as attitude control, orbital maneuvering, and position keeping of spacecraft. A Hall thruster is a plasma discharge device that converts electrical energy into the kinetic energy of a working medium by the combined action of an electric field and a magnetic field.

[0003] After the Hall thruster ignites successfully, it will enter the stable operation stage. The plume of the Hall thruster is mainly composed of high-speed charged particles, neutral atoms, thruster sputtering products, etc. At this time, due to some sputtering products in the environment around the Hall thruster, for some reasons, they will enter the thruster channel. These substances will destroy the already stable magnetic filtering effect at the thruster outlet. It will affect the electron drift. They will be collided by high-energy ions, electrons and other particles, generating a spark phenomenon, which is the ignition of the thruster.

[0004] The occurrence of ignition is very likely to cause the thruster to extinguish during operation. Specifically: when the thruster is operating, sputtering products on the thruster wall or in some cabins will enter the thruster channel, affecting the electron drift. As a result, a spark phenomenon will occur inside the thruster channel. At this time, since the electron drift is disrupted, the ion current emitted by the channel is also affected, so that a short-time current pulse will be generated in the thruster discharge channel, which causes the discharge voltage of the thruster to drop rapidly at the same time. The pulse generated by the ignition sometimes extinguishes the thruster. After the thruster extinguishes, since the cathode generally closes the cathode hold-off electrode after the thruster ignites successfully, making the cathode in a self-sustaining state. Therefore, after the thruster extinguishes, it is necessary to reheat and ignite the cathode to make the thruster operate again. Therefore, how to suppress the extinguishing of the thruster due to ignition has important theoretical significance and application value. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem in the prior art that there is a lack of technology to suppress the extinguishing of the thruster caused by ignition, resulting in the need to reheat and ignite the cathode to restart the thruster. The present invention provides a method for starting the hollow cathode hold current by using the ignition of a Hall thruster.

[0006] Method for starting the holding current of a hollow cathode by using a Hall thruster to strike an arc. This method is used to transfer the pulse energy of the mutant current generated when striking an arc between the positive pole of the thruster anode power supply in the power supply system and the thruster anode to the holding electrode of the hollow cathode under the self-sustaining state of the thruster hollow cathode, thereby suppressing the extinction of the Hall thruster.

[0007] Preferably, the first circuit structure for realizing energy transfer includes: an inductor L1, a transformer T1, and a rectifier circuit;

[0008] One end of the inductor L1 is connected to the positive pole of the thruster anode power supply, the other end of the inductor L1 is connected to one end of the primary winding of the transformer T1, and the other end of the primary winding of the transformer T1 is connected to the thruster anode;

[0009] The two ends of the secondary winding of the transformer T1 are respectively connected to the two AC input terminals of the rectifier circuit, and the DC positive pole and the DC negative pole of the rectifier circuit are respectively connected to the holding electrode of the hollow cathode and the common negative electrode of the hollow cathode.

[0010] Preferably, the first circuit structure further includes a capacitor C1 and a TVS diode, both of which are connected in parallel between the DC positive pole and the DC negative pole of the rectifier circuit.

[0011] Preferably, the rectifier circuit is a full-bridge rectifier circuit composed of 4 diodes.

[0012] Preferably, the second circuit structure for realizing energy transfer includes a resistor R2, a capacitor C2, an inductor L2, an IGBT tube S1, and a constant voltage circuit VR;

[0013] One end of the resistor R2 is connected to the positive pole of the thruster anode power supply, the other end of the resistor R2 is connected to one end of the capacitor C2 and the collector of the IGBT tube S1 at the same time, the emitter of the IGBT tube S1 is connected to one end of the inductor L2 and the positive pole of the input voltage of the constant voltage circuit VR at the same time, and the other end of the inductor L2 is connected to the thruster anode;

[0014] The control pole of the IGBT tube S1 is used to receive an external drive signal;

[0015] The negative pole of the input voltage of the constant voltage circuit VR is connected to its output voltage negative pole, and the other end of the capacitor C2 and the common negative electrode of the hollow cathode at the same time; the positive pole of the output voltage of the constant voltage circuit VR is connected to the holding electrode of the hollow cathode.

[0016] Preferably, the third circuit structure for realizing energy transfer includes an inductor L3, resistors R3 and R4, and capacitors C3 and C4;

[0017] One end of the inductor L3 is connected to one end of the resistor R3, one end of the capacitor C4, and the positive pole of the thruster anode power supply at the same time;

[0018] The other end of the inductor L3 is connected to the anode of the thruster; the other end of the resistor R3 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to the common negative electrode of the hollow cathode; the other end of the capacitor C4 is connected to one end of the resistor R4, and the other end of the resistor R4 is connected to the keeper electrode of the hollow cathode.

[0019] Advantages of the present invention:

[0020] The present invention provides a method for using the ignition of a Hall thruster to start the keeper current of a hollow cathode. This method is used to transfer the pulse energy of the mutant current generated when a spark occurs between the positive electrode of the thruster anode power supply in the power supply system and the thruster anode to the keeper electrode of the hollow cathode under the self-sustaining state of the thruster hollow cathode, thereby suppressing the extinction of the Hall thruster. Transfer the energy generated at the moment of thruster ignition to the keeper electrode of the hollow cathode, so that the hollow cathode can emit enough electrons at that moment to maintain the operation of the thruster and prevent the thruster from extinguishing due to ignition.

[0021] And three circuits for transferring the energy generated when a spark occurs in the thruster to the cathode are provided. This circuit will suppress the occurrence of the phenomenon that the thruster extinguishes due to ignition.

[0022] The present invention attaches great importance to the problem that the thruster extinguishes due to ignition. Specifically:

[0023] For the first circuit structure, the circuit is a passive circuit. When a sparking phenomenon occurs, the inductor and the transformer can spontaneously transfer energy, and the greater the current impact during ignition, the more energy transfer is induced by the transformer and the inductor. In this structure, the impact energy generated by ignition is transferred to the hollow cathode through the transformer and the inductor by constructing a low-cost circuit, and the ignition is suppressed by the electron emission ability of the hollow cathode. Starting from the energy storage perspective and the excessive anode current impact, the impact current's damage to the power supply devices and the conversion and storage of the impact energy are reduced through the transformer and the inductor.

[0024] For the second circuit structure, the energy storage capacitor directly stores high-voltage energy, and the IGBT is used as a high-speed switch to achieve precise energy release, reducing conversion losses. During specific applications, the capacitor needs to be replaced regularly, and an external drive signal is required to control the switch state, and a voltage stabilizing circuit is also required. This circuit structure is slightly more complex than the first circuit structure.

[0025] For the third circuit structure, the structure is simple and the cost is low. During specific applications, the capacitor needs to be replaced regularly.

[0026] Considering the above three structures comprehensively, the first structure has the best effect. Description of the Drawings

[0027] Figure 1It is a schematic diagram of the principle of the first circuit structure for realizing energy transfer;

[0028] Figure 2 It is a schematic diagram of the principle of the second circuit structure for realizing energy transfer;

[0029] Figure 3 It is a schematic diagram of the principle of the third circuit structure for realizing energy transfer; Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0031] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0032] Detailed implementation manner 1. This implementation manner provides a method for using a Hall thruster to strike a fire to start the holding current of a hollow cathode. This method is used to transfer the pulse energy of the mutant current generated when striking a fire between the positive pole of the thruster anode power supply and the thruster anode in the self-sustaining state of the thruster hollow cathode to the holding electrode of the hollow cathode, thereby suppressing the extinction of the Hall thruster.

[0033] This implementation manner transfers the energy generated at the moment when the thruster strikes a fire to the holding electrode of the hollow cathode, so that the electron emission ability of the hollow cathode at that moment is sufficient, maintaining the operation of the thruster and preventing the thruster from extinguishing due to the fire.

[0034] See Figure 1 , the first circuit structure for realizing energy transfer is provided, including: inductor L1, transformer T1 and rectifier circuit;

[0035] One end of the inductor L1 is connected to the positive pole of the thruster anode power supply, the other end of the inductor L1 is connected to one end of the primary winding of the transformer T1, and the other end of the primary winding of the transformer T1 is connected to the thruster anode;

[0036] The two ends of the secondary winding of the transformer T1 are respectively connected to the two AC input ends of the rectifier circuit, and the DC positive pole and the DC negative pole of the rectifier circuit are respectively connected to the holding electrode of the hollow cathode and the common negative electrode of the hollow cathode.

[0037] In specific applications, the rectifier circuit is a full-bridge rectifier circuit composed of 4 diodes. The turn ratio range of the primary winding and the secondary winding of the transformer T1 depends on the thruster firing pulse range and the hollow cathode requirements.

[0038] Further, referring to Figure 1 , the first circuit structure further includes a capacitor C1 and a TVS diode, both of which are connected in parallel between the DC positive and negative poles of the rectifier circuit.

[0039] Figure 1 The principle adopted by the first circuit structure shown transfers the pulse energy of the mutant current to the holding electrode by means of energy conversion. Figure 1 , an inductor L1 is used to store energy according to the formula . When working normally, the energy is stored, where L is the inductance value of the inductor L1 and I is the current flowing through the inductor L1. When the ignition phenomenon occurs, due to the sudden increase in current, according to the formula , where V is the inductive electromotive force of the inductor, the current mutation will trigger L1 to generate a reverse electromotive force, and the energy will be coupled to the secondary winding of the transformer T1 through electromagnetic induction. In addition, the inductor L1 is connected in series near the anode power supply of the thruster, and can also suppress the current ripple and the impact of instantaneous changes on the power supply.

[0040] The primary winding of the transformer T1 is connected to the anode of the thruster, directly sensing the current change at the anode of the thruster and avoiding interfering with the main circuit path. The energy transfer efficiency of the transformer T1 depends on the magnetic flux change of the primary and secondary windings. According to the formula , connecting the primary winding directly to the anode of the thruster can ensure that the change in the current of the primary winding (i.e., the anode current of the thruster) is directly reflected in the magnetic core, so that a voltage can be efficiently induced in the secondary winding. Through the rectifier circuit (D1 - D4), regardless of the direction of the secondary winding voltage, a positive DC voltage is output to the holding electrode node to complete the energy transfer. N pri is the number of turns of the primary winding, N sec is the number of turns of the secondary winding, V pri is the voltage of the primary winding, V sec is the voltage of the secondary winding.

[0041] A capacitor C1 is connected in parallel on the adjustment circuit of the holding electrode to store the transferred energy and smooth the voltage fluctuation. A TVS diode DW1 is connected in parallel to absorb high - frequency transient spikes.

[0042] When ignition occurs, the primary winding of the transformer T1 will receive the ignition energy given by L1, and then it will transfer this energy to the holding electrode of the hollow cathode through the rectifier circuit, enabling the hollow cathode to emit more electrons in a short time and maintaining the stability of the thruster. When the thruster ignites, the current path is as follows:

[0043] L1 → T1 → rectifier circuit → cathode holding electrode

[0044] As an example, for a 400W Hall thruster, its ignition current can reach up to 120A, and the duration of a single pulse is 100 microseconds. Based on this, the components in Figure 1 are selected as follows:

[0045] Inductor L1: An inductor with an inductance of 50μH, a saturation current ≥160A, and a customized inductor with a magnetic core model of KOOLMμ77439 - A7;

[0046] Transformer T1: A customized high - frequency transformer TDKPC40EE42 / 21 / 20 with an inductance of 50μH and a turns ratio of 1:0.4, and a magnetic core model of TDKPC40EE42 / 21 / 20;

[0047] Full - bridge rectifier circuit (D1 - D4) connection method:

[0048] D1 (fast - recovery diode):

[0049] IXYS fast - recovery diode DSEI2X61 - 06C;

[0050] Anode: Connect to one end of the secondary winding of transformer T1.

[0051] Cathode: Connect to the keeper electrode.

[0052] D2 (fast - recovery diode):

[0053] IXYS fast - recovery diode DSEI2X61 - 06C.

[0054] Anode: Connect to the common negative electrode of the hollow cathode.

[0055] Cathode: Connect to one end of the secondary winding of transformer T1.

[0056] D3 (fast - recovery diode):

[0057] IXYS fast - recovery diode DSEI2X61 - 06C.

[0058] Anode: Connect to the other end of the secondary winding of the transformer T1.

[0059] Cathode: Connect to the keeper electrode node.

[0060] D4 (fast - recovery diode):

[0061] IXYS fast - recovery diode DSEI2X61 - 06C.

[0062] Anode: Connect to the common negative electrode of the hollow cathode.

[0063] Cathode: Connect to the other end of the secondary winding of the transformer T1.

[0064] Keeper electrode adjustment circuit:

[0065] Energy storage capacitor (C1):

[0066] Aluminum electrolytic capacitor, 250V 300UF;

[0067] Positive electrode: Connect to the holding electrode of the hollow cathode.

[0068] Negative electrode: Connect to the common negative electrode of the hollow cathode.

[0069] TVS diode (DW1):

[0070] 5KP440A is a transient voltage suppression diode (TVS) with a reverse breakdown voltage (VRWM) of 440V, a minimum breakdown voltage (VBR) of 492V, and a maximum clamping voltage (VC) of 713V.

[0071] Bidirectional parallel connection: Connect the holding electrode to the common negative electrode of the hollow cathode.

[0072] See Figure 2 , which further gives the implementation method of transferring the pulse energy of the mutant current to the holding electrode through a capacitor and a resistor, and specifically provides the second circuit structure for realizing energy transfer, including resistor R2, capacitor C2, inductor L2, IGBT tube S1, and constant voltage circuit VR;

[0073] One end of resistor R2 is connected to the positive electrode of the thruster anode power supply, and the other end of resistor R2 is simultaneously connected to one end of capacitor C2 and the collector of IGBT tube S1. The emitter of IGBT tube S1 is simultaneously connected to one end of inductor L2 and the positive input voltage of the constant voltage circuit VR. The other end of inductor L2 is connected to the thruster anode;

[0074] The control electrode of IGBT tube S1 is used to receive an external drive signal;

[0075] The negative input voltage of the constant voltage circuit VR is simultaneously connected to its negative output voltage, and the other end of capacitor C2 and the common negative electrode of the hollow cathode; The positive output voltage of the constant voltage circuit VR is connected to the holding electrode of the hollow cathode.

[0076] In this preferred embodiment, the constant voltage circuit VR is implemented using existing technology, and Figure 2 The core function of the circuit is to store energy through the energy storage capacitor C2 and control the release of the energy pulse by the IGBT tube S1 to drive the thruster to work. The constant voltage circuit VR obtains energy from the main circuit to the holding electrode and maintains the auxiliary electric field.

[0077] See Figure 3 , which gives the third circuit structure for realizing energy transfer, including inductor L3, resistors R3 and R4, and capacitors C3 and C4;

[0078] One end of the inductor L3 is simultaneously connected to one end of the resistor R3, one end of the capacitor C4, and the positive electrode of the thruster anode power supply;

[0079] The other end of the inductor L3 is connected to the thruster anode; the other end of the resistor R3 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to the common negative electrode of the hollow cathode; the other end of the capacitor C4 is connected to one end of the resistor R4, and the other end of the resistor R4 is connected to the keeper electrode of the hollow cathode.

[0080] The third circuit structure for realizing energy transfer can transfer part of the energy during thruster ignition to the keeper electrode through the passive design of the coupling capacitor C4 and the current-limiting resistor R4. The capacitor C3 and the resistor R3 store and provide the main pulse energy required for the thruster to operate. C4 and R4 act as "transient energy channels" to transfer the mutated energy during ignition to the keeper electrode. At the same time, relying on the inductor L3 to limit the current mutation, the active switch IGBT tube (S1) in the second circuit structure is omitted, and the structure is simpler.

[0081] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not deviate from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A method for starting a hollow cathode hold current by using a Hall thruster to strike an arc, characterized in that, This method is used to transfer the pulse energy of the mutant current generated when arcing occurs between the positive pole of the thruster anode power supply in the power supply system and the thruster anode to the keeper electrode of the hollow cathode under the self-sustaining state of the thruster hollow cathode, thereby suppressing the extinction of the Hall thruster.

2. The method for starting a hollow cathode by using a Hall thruster to generate a spark according to claim 1, wherein The first circuit structure for realizing energy transfer includes: inductor L1, transformer T1, and rectifier circuit; One end of inductor L1 is connected to the positive pole of the thruster anode power supply, the other end of inductor L1 is connected to one end of the primary winding of transformer T1, and the other end of the primary winding of transformer T1 is connected to the thruster anode; Both ends of the secondary winding of transformer T1 are respectively connected to the two AC input terminals of the rectifier circuit, and the DC positive pole and DC negative pole of the rectifier circuit are respectively connected to the keeper electrode of the hollow cathode and the common negative electrode of the hollow cathode.

3. The method for starting a hollow cathode by using a Hall thruster to generate a spark according to claim 2, characterized in that, The first circuit structure also includes capacitor C1 and TVS diode, both of which are connected in parallel between the DC positive pole and DC negative pole of the rectifier circuit.

4. The method for starting a hollow cathode by using a Hall thruster to generate a spark according to claim 2, wherein, The rectifier circuit is a full-bridge rectifier circuit composed of 4 diodes.

5. The method for starting a hollow cathode by using a Hall thruster to generate a spark according to claim 1, wherein The second circuit structure for realizing energy transfer includes resistor R2, capacitor C2, inductor L2, IGBT tube S1, and constant voltage circuit VR; One end of resistor R2 is connected to the positive pole of the thruster anode power supply, the other end of resistor R2 is simultaneously connected to one end of capacitor C2 and the collector of IGBT tube S1, the emitter of IGBT tube S1 is simultaneously connected to one end of inductor L2 and the positive pole of the input voltage of constant voltage circuit VR, and the other end of inductor L2 is connected to the thruster anode; The control pole of IGBT tube S1 is used to receive an external drive signal; The negative pole of the input voltage of constant voltage circuit VR is simultaneously connected to the negative pole of its output voltage, the other end of capacitor C2, and the common negative electrode of the hollow cathode; the positive pole of the output voltage of constant voltage circuit VR is connected to the keeper electrode of the hollow cathode.

6. The method for starting a hollow cathode by using the ignition phenomenon of a Hall thruster according to claim 1, characterized in that The third circuit structure for realizing energy transfer includes inductor L3, resistors R3 and R4, and capacitors C3 and C4; One end of inductor L3 is simultaneously connected to one end of resistor R3, one end of capacitor C4, and the positive pole of the thruster anode power supply; The other end of inductor L3 is connected to the thruster anode; the other end of resistor R3 is connected to one end of capacitor C3, the other end of capacitor C3 is connected to the common negative electrode of the hollow cathode; the other end of capacitor C4 is connected to one end of resistor R4, and the other end of resistor R4 is connected to the keeper electrode of the hollow cathode.

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