Focusing type electrospray thruster

Abstract

The invention relates to a focusing type electrospray thruster, which relates to the technical field of electric propulsion, and comprises an emitting electrode with a tip, a leading-out electrode with an equal-width notch, a focusing electrode with an equal-width rotary expanding notch and an accelerating electrode with an equal-width rotary expanding notch which are arranged in sequence, the notch centers of the leading-out electrode, the focusing electrode and the accelerating electrode and the tip of the emitting electrode are positioned on the same straight line; the emitting electrode and the focusing electrode are connected to a high-voltage direct-current power supply with the same electrical property, the leading-out electrode and the accelerating electrode are grounded, the emitting electrode and the leading-out electrode lead out an ion beam, the leading-out electrode and the focusing electrode focus the ion beam to reduce a divergence angle, and the focusing electrode and the accelerating electrode accelerate the ion beam with the reduced divergence angle. The method has the advantages that an ion accelerated divergent electric field of the electrospray thruster is converted into a divergent-focused electric field, and the plume divergence angle and the non-axial loss of a beam are reduced.

Description

Technical Field

[0001] This invention relates to the field of electric propulsion technology, and more particularly to a focusing type electro-spray thruster. Background Technology

[0002] Electrospray thrusters are devices that use conductive media such as ionic liquids as propellant, and utilize the electrostatic field between the emitter and the extractor to extract ions or charged droplets from the liquid working medium and accelerate them to generate thrust. They have advantages such as small size, light weight, high specific impulse, and high control precision, and are an important preferred solution for micro and nano satellite propulsion systems.

[0003] Extracting ions or charged liquids from the propellant requires an extremely high electric field strength at the liquid surface. To address this, electrospray thrusters typically employ a pin-hole or prismatic structure. The emitter tip uses a needle-shaped or prismatic structure with an extremely small radius of curvature (several micrometers to tens of micrometers), while the lead-out electrode uses a pinhole or prismatic structure with a scale of hundreds of micrometers. Through the high voltage between the electrodes and the tip effect of the electric field distribution, an electric field strength greater than 10 is generated at the emitter tip. 8 An axial electric field distribution of V / m is used to extract ions or charged droplets. This electrode structure generates an axial electric field while also creating a field strength perpendicular to the axial direction, which is a typical diffusion-type electric field distribution. Ions or charged droplets are accelerated under the action of the axial electric field, converting electrical energy into propulsive kinetic energy. Simultaneously, under the action of the field strength perpendicular to the axis, they diffuse rapidly, forming a plume distribution with a large divergence angle (e.g., V / m). Figure 3 (As shown). The large divergence angle characteristic of the electro-spray thruster not only indicates a certain non-axial loss, but also limits its installation direction on the spacecraft due to the interaction effect between the thruster plume and the spacecraft, thus reducing its competitiveness among similar electric propulsion devices.

[0004] Therefore, to address the above shortcomings, a focused electro-spray thruster is needed. Summary of the Invention

[0005] (a) Technical problems to be solved The technical problem to be solved by the present invention is to address the issue of large plume divergence angle in existing electrospray thrusters.

[0006] (II) Technical Solution To address the aforementioned technical problems, this invention provides a focusing electrospray thruster, comprising, sequentially arranged, an emitter with a pointed tip, an extractor with an equal-width slot, a focusing electrode with an equal-width to expansion slot, and an accelerating electrode with an equal-width to expansion slot. The centers of the slots of the extractor, focusing electrode, and accelerating electrode are aligned with the tip of the emitter. The emitter and focusing electrode are connected to a high-voltage DC power supply of the same polarity, while the extractor and accelerating electrode are grounded. The emitter and extractor extract ion beams, the extractor and focusing electrode focus the ion beams to reduce the divergence angle, and the focusing electrode and accelerating electrode accelerate the ion beams whose divergence angle has been reduced.

[0007] As a further explanation of the present invention, preferably, the absolute value of the focusing electrode voltage is less than that of the emitter voltage.

[0008] As a further explanation of the present invention, preferably, an insulating gasket is fixedly connected between the lead-out electrode and the focusing electrode, and between the focusing electrode and the accelerating electrode. The insulating gasket has a slot of equal width in the middle, and the center of the slot of the insulating gasket is on the same straight line as the center of the slots of the lead-out electrode, the focusing electrode and the accelerating electrode.

[0009] As a further explanation of the present invention, preferably, the emitter is provided with an outer shell, the outer shell has a hexahedral structure and a cylindrical groove in the middle, and the bottom of the emitter is provided with a cylindrical base, the outer diameter of the base is smaller than the inner diameter of the cylindrical groove in the outer shell, and the base is embedded in the cylindrical groove of the outer shell.

[0010] As a further explanation of the present invention, preferably, a square platform is connected between the bottom of the emitter and the top of the base, and a support is fitted over the square platform. The support is embedded in the cylindrical groove of the outer shell and is fixedly connected to the outer shell by bolts.

[0011] As a further explanation of the present invention, preferably, a rubber ring is embedded between the support and the outer shell for sealing.

[0012] As a further explanation of the present invention, preferably, the top surface of the outer shell is provided with a plurality of symmetrical threaded holes, and the lead-out electrode, focusing electrode, accelerating electrode and insulating gasket are provided with cylindrical holes at corresponding positions, so that the lead-out electrode, focusing electrode, accelerating electrode and insulating gasket are fixed to the top surface of the outer shell by bolt pairs.

[0013] (III) Beneficial Effects The above-described technical solution of the present invention has the following advantages: This invention introduces a focusing electrode, transforming the accelerating electric field configuration of the electrospray thruster from a divergent type to a divergent-focused type. The focused electric field distribution suppresses the radial velocity of ions or charged droplets downstream of the extraction electrode, significantly reducing the beam divergence angle. An accelerating electrode is further introduced after the focusing electrode to further accelerate the focused beam of ions or charged droplets axially, improving the propellant ejection velocity, i.e., the specific impulse, of the thruster. Simultaneously, the slotted profiles of both the focusing and accelerating electrodes employ a constant-width to-expansion surface, ensuring ease of fabrication and resistance to sputtering erosion while achieving the focused electric field configuration. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the working principle of the present invention; Figure 3 This is a plume diagram of an existing electrospray thruster; Figure 4 This is a plume diagram of the electro-spray thruster of the present invention; Figure 5 This is a comparison diagram of the divergence half-angle of the present invention and the prior art under different operating voltages.

[0015] In the diagram: 1. Emitter; 11. Base; 12. Support; 2. Lead-out electrode; 3. Focusing electrode; 4. Accelerating electrode; 5. Insulating gasket; 6. Outer shell. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] A type of focused electro-spray thruster, such as Figure 1 As shown, it includes an emitter 1, a lead 2, a focusing electrode 3, an accelerating electrode 4, an insulating pad 5, and a housing 6. The emitter 1 is arranged inside the housing 6, the lead 2 is fixed to the housing 6, the focusing electrode 3 is mounted on the lead 2, and an insulating pad 5 is fixed between the lead 2 and the focusing electrode 3 to achieve potential isolation; the accelerating electrode 4 is mounted on the focusing electrode 3, and an insulating pad 5 is also fixed between the focusing electrode 3 and the accelerating electrode 4 to achieve potential isolation.

[0018] Combination Figure 1 , Figure 2The emitter 1 is a prismatic structure formed by processing porous material. The radius of curvature at the tip of the prismatic structure is several micrometers to tens of micrometers. The bottom of the emitter 1 has a boss-type base 11 with a lower circle and a top. The outer shell 6 is a hexahedral structure with a cylindrical groove in the middle. The outer diameter of the cylindrical part of the base 11 is smaller than the inner diameter of the cylindrical groove in the outer shell 6, so that the base 11 can be embedded in the cylindrical groove of the outer shell 6. Between the emitter 1 and the cylindrical part of the base 11 is a square platform. A support 12 is fitted over the square platform. The support 12 is a T-shaped rotating structure. The top of the support 12 has a square hole to engage the square platform. The support 12 is embedded in the cylindrical groove of the outer shell 6 and is fixed to the outer shell 6 by bolts to press the base 11 into the outer shell 6, thereby fixing the emitter 1 inside the outer shell 6. Since the outer shell 6 is both a structural component of the thruster and an ionic liquid propellant storage device, a rubber ring can also be embedded between the support 12 and the outer shell 6 for sealing.

[0019] Combination Figure 1 , Figure 2 Both the lead-out electrode 2 and the insulating pad 5 are plate-shaped structures, while the focusing electrode 3 and the accelerating electrode 4 are block-shaped structures. Each of the lead-out electrode 2, focusing electrode 3, accelerating electrode 4, and insulating pad 5 has a through-groove in its center. The lead-out electrode 2 and insulating pad 5 have grooves of equal width. The groove width of the lead-out electrode 2 is 400–800 μm. The focusing electrode 3 and accelerating electrode 4 have grooves of equal width that expand towards the exit end; that is, the width is equal near the inlet end, and increases towards the outlet end. This type of groove, while achieving a focused electric field configuration, also ensures ease of processing and resistance to sputtering erosion of the electrode plates. The center of the groove openings of the lead-out electrode, focusing electrode, accelerating electrode, and insulating pad 5 is on the same straight line as the tip of the emitter electrode 1. The top surface of the outer casing 6 has several symmetrical threaded holes, and the lead electrode 2, focusing electrode 3, accelerating electrode 4 and insulating gasket 5 are all provided with cylindrical holes at corresponding positions, so that the lead electrode 2, focusing electrode 3, accelerating electrode 4 and insulating gasket 5 are fixed to the top surface of the outer casing 6 by bolt pairs.

[0020] like Figure 2 As shown, emitter 1 and focusing electrode 3 are connected to a high-voltage DC power supply of the same polarity, with the absolute value of the voltage at focusing electrode 3 being less than that at emitter 1. Lead-out electrode 2 and accelerating electrode 4 are grounded. The thruster's working fluid, ionic liquid, is passively supplied through the pores in emitter 1 and transported to its tip. Lead-out electrode 2, serving as the first electrode, induces the ionic liquid to form a Taylor cone at the tip of emitter 1 due to the high-intensity electric field between it and emitter 1, achieving ion evaporation and accelerated extraction at the top of the Taylor cone. Focusing electrode 3, serving as the second electrode, provides the ions or charged droplets with an acceleration perpendicular to the axial direction, tending towards the axial direction, thus focusing the plume towards the axial direction and reducing the plume divergence angle. Accelerating electrode 4, serving as the third electrode, forms a secondary accelerating electric field with focusing electrode 3 to accelerate the ion beam. The final result is as follows: Figure 4The effect, compared to Figure 3 The plume morphology of the present invention significantly reduces the plume divergence angle.

[0021] like Figure 5 As shown, the plume divergence half-angle measurement results of the focusing electrospray thruster of the present invention under different operating voltages are compared with those of existing electrospray thrusters. The divergence half-angle of the electrospray thruster of the present invention is reduced by about 2 / 3 compared with that of existing electrospray thrusters. This demonstrates that the present invention can achieve good focusing performance under various voltages.

[0022] In summary, this invention, by introducing a focusing electrode 3, transforms the divergent electric field of ion acceleration in an electrospray thruster into a divergent-focused electric field, reducing the plume divergence angle and the non-axial loss of the beam. Even if those skilled in the art were motivated to simply add a focusing electrode 3 for focusing, it would likely weaken the electric field on the thruster emitter surface, decrease the acceleration voltage, and result in a significant drop in emission current and severe loss of thrust performance. However, this invention, relying on the equal-width to expansion-type surface design of the focusing electrode 3, suppresses emission current loss. Combined with the subsequent addition of a velocity electrode 4, it avoids thrust performance loss, overcoming the technical difficulties of decreased emission current and thrust loss caused by arbitrarily adding a focusing electrode 3. Furthermore, it allows the divergence angle to be controlled within a small range, representing a significant technological advancement.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A focusing electro-spray thruster, characterized in that: It includes an emitter (1) with a pointed tip, an extractor (2) with an equal-width slot, a focusing electrode (3) with an equal-width to expansion slot, and an accelerating electrode (4) with an equal-width to expansion slot arranged in sequence. The center of the slots of the extractor (2), focusing electrode (3), and accelerating electrode (4) are on the same straight line as the tip of the emitter (1). The emitter (1) and focusing electrode (3) are connected to a high-voltage DC power supply of the same polarity. The extractor (2) and accelerating electrode (7) are grounded. The emitter (1) and extractor (2) extract the ion beam. The extractor (2) and focusing electrode (3) focus the ion beam to reduce the divergence angle. The focusing electrode (3) and accelerating electrode (4) accelerate the ion beam whose divergence angle has been reduced.

2. The focusing electro-spray thruster according to claim 1, characterized in that: The absolute value of the voltage at the focusing electrode (3) is less than that at the emitter electrode (1).

3. A focusing electro-spray thruster according to claim 1, characterized in that: An insulating pad (5) is fixed between the lead electrode (2) and the focusing electrode (3), and between the focusing electrode (3) and the accelerating electrode (4). The insulating pad (5) has a slot of equal width in the middle. The center of the slot of the insulating pad (5) is on the same straight line as the center of the slots of the lead electrode (2), the focusing electrode (3) and the accelerating electrode (4).

4. A focusing electro-spray thruster according to claim 1, characterized in that: The emitter (1) is provided with a shell (6), which is a hexahedral structure with a cylindrical groove in the middle. The emitter (1) is provided with a cylindrical base (11) at the bottom. The outer diameter of the base (11) is smaller than the inner diameter of the cylindrical groove in the shell (6). The base (11) is embedded in the cylindrical groove of the shell (6).

5. A focusing electro-spray thruster according to claim 4, characterized in that: A square platform is connected between the bottom of the emitter (1) and the top of the base (11). A support (12) is attached to the square platform. The support (12) is embedded in the cylindrical groove of the outer shell (6) and is fixed to the outer shell (6) by bolts.

6. A focusing electro-spray thruster according to claim 5, characterized in that: A rubber ring is embedded between the support (12) and the outer shell (6) for sealing.

7. A focusing electro-spray thruster according to claim 6, characterized in that: The top surface of the outer shell (6) has several symmetrical threaded holes. The lead-out electrode (2), focusing electrode (3), accelerating electrode (4) and insulating pad (5) are all provided with cylindrical holes at corresponding positions, so that the lead-out electrode (2), focusing electrode (3), accelerating electrode (4) and insulating pad (5) are fixed to the top surface of the outer shell (6) by bolt pairs.

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