Coaxial liquid pulse plasma thruster

Abstract

The invention discloses a coaxial liquid pulse plasma thruster which comprises a cathode, an anode, a ceramic medium and an insulating ring, the cathode and the anode are coaxially arranged, the ceramic medium is located between the anode and the cathode, and the insulating ring is arranged between the anode and the ceramic medium; a porous capillary structure is arranged in the ceramic medium, ionic liquid is uniformly infiltrated on the porous capillary structure, the ionic liquid in the ceramic medium actively permeates to the end face of the ceramic medium through the capillary action to form a uniform liquid film, and the liquid film is punctured by pulse to form plasma. According to the application, the collaborative design of the ionic liquid working medium and the porous medium capillary supply system is adopted, the active infiltration of the ionic liquid is realized through the capillary force of the high borosilicate porous ceramic, a uniform liquid film is formed on a discharge interface, and the hysteresis ablation is eliminated; single pulse only consumes surface controllable mass, the utilization rate of a working medium is improved, and element impulse fluctuation is reduced.

Description

Technical Field

[0001] This invention relates to the field of spacecraft electric propulsion, and in particular to a coaxial liquid pulse plasma thruster. Background Technology

[0002] Pulsed plasma thrusters have become an ideal choice for micro and nano satellite propulsion systems due to their precise and controllable thrust, compact structure, and low power consumption. Current mainstream technologies use solid polytetrafluoroethylene (PTFE) as the working fluid. Spark plug ignition induces discharge between electrodes, ablates the working fluid to generate plasma, and accelerates its ejection under the influence of an electromagnetic field to produce thrust.

[0003] A Chinese invention patent with application number CN202211059378.X discloses a nozzle assembly for a micro-pulse plasma thruster with high discharge stability, comprising an anode plate, a polytetrafluoroethylene (PTFE) working fluid, a polyethylene (PE) working fluid, and a cathode plate. The anode and cathode plates are arranged parallel to each other in an upper and lower structure. The PE working fluid is placed between the anode and cathode plates. Two PTFE working fluids are symmetrically arranged on the left and right sides of the PE working fluid. Anode protrusions and cathode protrusions are symmetrically arranged in the middle of the upper and lower ends of the front side of the PE working fluid. The anode protrusions are fixed to the anode plate, and the cathode protrusions are fixed to the cathode plate. The discharge area is between the anode and cathode protrusions. This invention easily achieves the characteristic of conductive breakdown, has good vacuum arc constraint, reduces the dispersion between different pulses, and has good discharge stability of the micro-pulse plasma thruster. It achieves path constraint of the vacuum arc, reduces randomness, and enhances stability. By eliminating the need for a spark plug, the influence of random spark plug discharge on the main discharge between the anode and cathode plates is eliminated.

[0004] This technology has the following key problems: 1) Low working fluid utilization: There is a "hysteresis ablation" phenomenon in the solid ablation process, that is, the discharge arc causes unexpected ablation on the working fluid surface, resulting in unstable consumption of the single pulse and low working fluid utilization. 2) Poor ignition reliability: Spark plugs are prone to carbon buildup and failure, and fluctuations in discharge voltage lead to reduced thrust repeatability; 3) Uneven propellant ablation: After multiple discharges, the end face of the solid working fluid is severely concave, resulting in distorted electric field distribution and shortening the thruster's lifespan; 4) Significant plume contamination: Carbon particles generated by solid ablation deposit and contaminate satellite sensitive devices. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a coaxial liquid pulsed plasma thruster that achieves breakthroughs in thrust stability, ignition reliability, lifespan, and environmental friendliness, offering a new solution for the development of future satellite propulsion systems.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The present invention provides a coaxial liquid pulsed plasma thruster, comprising a cathode, an anode, a ceramic medium, and an insulating ring, wherein the cathode and anode are coaxially arranged, the ceramic medium is located between the anode and the cathode, and the insulating ring is disposed between the anode and the ceramic medium; The ceramic medium has a porous capillary structure, on which an ionic liquid is uniformly impregnated. The ionic liquid in the ceramic medium actively permeates to the end face of the ceramic medium through capillary action, forming a uniform liquid film. The pulse breaks down the liquid film to form plasma.

[0007] By adopting the above scheme, the present invention employs a synergistic design of an ionic liquid working medium and a porous medium capillary supply system. The ionic liquid achieves active wetting through the capillary force of high borosilicate porous ceramics, forming a uniform liquid film at the discharge interface and eliminating hysteresis ablation. Each pulse only consumes the controllable mass of the surface layer, improving the utilization rate of the working medium and reducing the fluctuation of the initial impulse.

[0008] The present invention discloses a coaxial liquid pulse plasma thruster, wherein the ceramic medium is selected from a high borosilicate porous material.

[0009] By adopting the above scheme and through the above porous capillary structure, the ionic liquid that is impregnated inside can actively permeate to the end face of the ceramic medium.

[0010] The present invention provides a coaxial liquid pulsed plasma thruster, wherein the porous capillary structure of the ceramic medium has a pore size of <2μm and a porosity of >60%.

[0011] By adopting the above scheme, the ionic liquid in the ceramic medium actively permeates to the end face of the ceramic medium through capillary action, forming a uniform liquid film of 0.1~0.3mm. A single pulse only consumes the controllable mass of the surface layer, improving the utilization rate of the working fluid and reducing the fluctuation of the impulse.

[0012] The present invention discloses a coaxial liquid pulse plasma thruster, wherein the insulating ring is made of alumina ceramic and is disposed inside the anode.

[0013] By adopting the above scheme, the insulating ring can prevent short circuits of the electrodes and maintain a discharge gap of 1~2mm.

[0014] The present invention provides a coaxial liquid pulse plasma thruster, wherein the cathode material is an aluminum alloy.

[0015] The above scheme is used as the negative electrode support structure of the discharge circuit.

[0016] The present invention provides a coaxial liquid pulse plasma thruster, wherein the anode material is copper.

[0017] By adopting the above scheme, a positive electrode of the discharge circuit is formed and a radial electric field is established.

[0018] The present invention discloses a coaxial liquid pulse plasma thruster, wherein the ionic liquid in the ceramic medium actively permeates to the end face of the ceramic medium through capillary action to form a uniform liquid film of 0.1~0.3mm.

[0019] By adopting the above scheme, a single pulse only consumes the controllable mass of the surface layer, saving working fluid materials.

[0020] The present invention provides a coaxial liquid pulse plasma thruster, wherein the dielectric strength of the insulating ring is >15kV / mm.

[0021] By adopting the above scheme, the insulating ring isolates the electrode, and the trigger pulse breaks down the liquid film to form plasma.

[0022] The present invention provides a coaxial liquid pulse plasma thruster, wherein the cathode is located on the central axis of the thruster.

[0023] Compared with the prior art, the present invention has the following beneficial effects: Improving working fluid utilization and thrust stability: Existing solid working fluid pulsed plasma thrusters suffer from delayed ablation, a defect stemming from the inability of the solid working fluid to replenish the ablation area in real time, causing random fluctuations in the initial impulse and severely restricting thrust accuracy. This invention employs a collaborative design of an ionic liquid working fluid and a porous medium capillary supply system. The ionic liquid achieves active wetting through the capillary force of high borosilicate porous ceramics, forming a uniform liquid film at the discharge interface and eliminating delayed ablation. Each pulse consumes only the controllable mass of the surface layer, improving working fluid utilization and reducing initial impulse fluctuations. Enhancing thruster ignition reliability and lifespan: Traditional spark plug ignition methods suffer from electrode carbon buildup and discharge voltage drift, leading to an increasing ignition failure rate with the cumulative number of pulses. Simultaneously, the solid working fluid end face undergoes concave deformation after multiple discharges, causing electric field distortion and accelerating electrode erosion, resulting in a short thruster lifespan that cannot meet the long-life requirements of modern constellation satellites with millions of pulses. The ionic liquid used in this invention is a room-temperature molten salt composed of anions and cations, which is directly ejected under the action of an electromagnetic field, eliminating the need for spark plugs for arc ignition and ensuring high ignition reliability. The ionic liquid working fluid exhibits no ablation deformation, and its porous ceramic structure maintains a constant electrode gap, thereby improving thruster lifespan. It also reduces plume contamination and compatibility issues: solid ablation produces a large number of carbon particles that deposit on sensitive surfaces such as satellite optical payloads and solar panels, causing performance degradation. While existing metal-doped PTFE can reduce carbon content, the introduced metal vapor still poses a risk of short circuits and has poor compatibility with highly integrated satellite platforms. This invention utilizes the complete evaporation characteristics of ionic liquids, achieving complete vaporization without solid residue during discharge, resulting in a plume carbon content approaching zero. Furthermore, the intrinsically low vapor pressure of the ionic liquid avoids space volatilization contamination, significantly improving compatibility with sensitive devices. The invention will be further described below with reference to the accompanying drawings. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention.

[0025] Figure label: 1. Cathode; 2. Ceramic dielectric; 3. Insulating ring; 4. Anode. Detailed Implementation

[0026] like Figure 1 As shown, the present invention discloses a coaxial liquid pulse plasma thruster, including a cathode 1, an anode 4, a ceramic dielectric 2 and an insulating ring 3. The cathode 1 and the anode 4 are coaxially arranged. The cathode 1 is located on the central axis of the thruster and is made of aluminum alloy, serving as the negative electrode support structure of the discharge circuit.

[0027] The ceramic medium 2 is disposed between the cathode 1 and the anode 4. The ceramic medium 2 has a porous capillary structure, on which an ionic liquid is uniformly impregnated. The ionic liquid in the ceramic medium 2 actively permeates to the end face of the ceramic medium 2 through capillary action, forming a uniform liquid film of 0.1~0.3mm. The ceramic medium 2 of this application is a high borosilicate porous material with a pore size <2μm and a porosity >60%. It is located between the cathode 1 and the anode 4 and is uniformly impregnated with an ionic liquid to form a discharge interface.

[0028] An insulating ring 3 is disposed inside the anode 4 and located between the ceramic dielectric 2 and the anode 4. In this embodiment, the material is alumina ceramic, which serves to prevent short circuits of the electrodes and maintain a discharge gap of 1~2mm. The dielectric strength of alumina ceramic is >15kV / mm, and it is used to isolate the electrodes.

[0029] The anode 4 is fitted outside the insulating ring 3. Its material is generally copper, which forms the positive electrode of the discharge circuit and establishes a radial electric field.

[0030] Ionic liquids such as EMI-BF4 and EMI-IM are selected as the working fluid for the thruster.

[0031] The ionic liquid immersed in the ceramic medium 2 actively permeates to the end face of the porous ceramic medium 2 through capillary action, forming a uniform liquid film. The insulating ring 3 isolates the electrode, and the trigger pulse breaks down the liquid film to form plasma. Under the action of the electric field between the anode and cathode 4, the plasma forms a closed loop with the discharge circuit, forming a current. The current induces a magnetic field, and the plasma cluster is accelerated and ejected under the action of the Lorentz force in the self-induced magnetic field, generating pulse thrust.

[0032] The above scheme has the following advantages: 1) Significantly improves thrust stability and propellant utilization. The active wetting and uniform liquid film formation of ionic liquids effectively solve the problem that solid working fluids cannot replenish the ablation area in real time, enabling precise control of mass consumption, improving working fluid utilization, reducing impulse fluctuations, and thus significantly improving thrust stability.

[0033] 2) Significantly improves ignition reliability and lifespan. Ionic liquids do not require spark plugs for arc ignition; they are ejected directly under the influence of an electromagnetic field. This overcomes the increased ignition failure rate caused by electrode carbon buildup and discharge voltage drift in traditional spark plug ignition methods, significantly improving ignition reliability. The ionic liquid working fluid exhibits no ablation deformation, and its porous ceramic structure maintains a constant electrode gap, effectively preventing electric field distortion and electrode erosion, thereby extending the thruster's lifespan.

[0034] 3) Significantly reduces plume contamination and improves compatibility Utilizing the total evaporation characteristics and low saturated vapor pressure of ionic liquids, the discharge process completely vaporizes without solid residue, and the carbon content of the plume approaches zero, reducing contamination of sensitive devices. At the same time, it avoids the risk of short circuits in circuits with metal-doped working fluids, achieving intrinsic safety compatibility with highly integrated satellite platforms.

[0035] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A coaxial liquid pulse plasma thruster, characterized in that, It includes a cathode (1), an anode (4), a ceramic medium (2), and an insulating ring (3). The cathode (1) and the anode (4) are coaxially arranged. The ceramic medium (2) is located between the anode (4) and the cathode (1). The insulating ring (3) is located between the anode (4) and the ceramic medium (2). The ceramic medium (2) is provided with a porous capillary structure, on which an ionic liquid is uniformly impregnated. The ionic liquid in the ceramic medium (2) actively permeates to the end face of the ceramic medium (2) through capillary action, forming a uniform liquid film. The pulse breaks through the liquid film to form plasma.

2. The coaxial liquid pulse plasma thruster according to claim 1, characterized in that, The ceramic medium (2) is made of high borosilicate porous material.

3. A coaxial liquid pulse plasma thruster according to claim 1, characterized in that, The porous capillary structure of the ceramic medium (2) has a pore size of <2μm and a porosity of >60%.

4. A coaxial liquid pulse plasma thruster according to claim 1, characterized in that, The insulating ring (3) is made of alumina ceramic and is located inside the anode (4).

5. A coaxial liquid pulse plasma thruster according to claim 1, characterized in that, The cathode (1) is made of aluminum alloy.

6. A coaxial liquid pulse plasma thruster according to claim 1, characterized in that, The anode (4) is made of copper.

7. A coaxial liquid pulse plasma thruster according to claim 1, characterized in that, The ionic liquid in the ceramic medium (2) actively permeates to the end face of the ceramic medium (2) through capillary action, forming a uniform liquid film of 0.1~0.3mm.

8. A coaxial liquid pulse plasma thruster according to claim 4, characterized in that, The dielectric strength of the insulating ring (3) is >15kV / mm.

9. A coaxial liquid pulse plasma thruster according to claim 1, characterized in that, The cathode (1) is located on the central axis of the thruster.

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