A multi-stage tangential field thruster of focused plumes

Abstract

A multi-stage tangential field thruster of focused plume comprises: a plurality of permanent magnets sleeved on the outer wall of a main discharge structure; the tail end surface of an anode structure is perpendicular to the axis of the main discharge structure, the axis of the anode structure is coaxial with the axis of the discharge structure, and the center point of the tail end surface of the anode structure coincides with the highest point of the magnetic field strength of the tangential magnetic field of the first-stage permanent magnet on the axis; wherein the permanent magnet closest to the inlet end of the main discharge structure is the first-stage permanent magnet; a plurality of wedge-shaped ring structures are fixedly installed in the main discharge structure in the axial direction; the wedge-shaped ring structure is preferentially arranged by the permanent magnet located at the tail end (i.e. downstream) of the main discharge structure. The channel configuration of the present application can overcome the shortcomings of the existing plume optimization technology of the thruster, fundamentally solve the engineering and technical problems of the hollow plume of the thruster (the plume divergence efficiency can be improved by about 30%), and can be widely applied to different power levels of the tangential magnetic field thruster.

Description

Technical Field

[0001] This invention relates to a multi-stage tangential thruster for focusing plumes, belonging to the field of electric propulsion technology. Background Technology

[0002] The multistage tangential magnetic field thruster is a novel type of plasma electric propulsion device. This thruster utilizes the confinement of plasma by a tangential magnetic field to significantly reduce ion erosion of the thruster walls, resulting in a remarkable long-life performance advantage. Looking at various multistage tangential magnetic field thrusters with different structures developed by research institutions both domestically and internationally, from Thales' HEMP-T (High-Efficient Multistage Plasma thruster) to MIT's DCFT (Diverging Cusped Field Thruster) and Stanford University's CCFT (Cylindrical Cusped Field Thruster), a severe hollow plume phenomenon is prevalent under different discharge conditions. The emitted high-energy ion beam is mainly distributed in the large-angle region, while the ion flux near the thruster axis is extremely low. This hollow plume leads to reduced thruster plume divergence efficiency. The high-energy ion beam not only causes severe corrosion of the thruster cathode, greatly shortening the thruster's lifespan, but also causes severe corrosion and damage to surrounding components. Therefore, optimizing the thrust plume is an important issue that needs to be addressed in the engineering application of multi-stage tangential thrusters.

[0003] Dr. Taylor from MIT optimized the thruster's plume structure by adding magnetic shielding and additional coils. Based on experimental results from his doctoral dissertation, "An Exploration of Prominent Cusped-Field Thruster Phenomena: The Hollow Conical Plume and Anode Current Bifurcation," he found that magnetic shielding exacerbates plume divergence, while additional coils only shift the ion current density peak near 35° to smaller angles, while the ion current density at other angles remains essentially unchanged. Therefore, the divergent hollow plume structure persists. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of existing thruster plume optimization technology and propose a multi-stage tangential field thruster with a focusing plume. The channel configuration has a simple structure and can fundamentally solve the engineering and technical problems of hollow thruster plumes. It can be widely used in tangential magnetic field thrusters of different power levels.

[0005] The technical solution of this invention is:

[0006] A multi-stage tangential thruster for focusing plumes includes: a main discharge structure, a wedge-shaped ring structure, a permanent magnet, an anode structure, and a housing;

[0007] The permanent magnet and the main discharge structure are respectively fixedly mounted on the housing;

[0008] Multiple permanent magnets are fitted on the outer wall of the main discharge structure, and the permanent magnets are coaxial with the axis of the main discharge structure.

[0009] The multiple permanent magnet segments do not contact each other, and the inner wall of the permanent magnets does not contact the main discharge structure;

[0010] The main discharge structure is a cylindrical structure, and a tapered expansion section is machined at the outlet end of the main discharge structure.

[0011] An anode structure is fixedly installed inside the inlet end of the main discharge structure; the head end face of the anode structure is machined with a central through hole as an inlet through hole, and the tail end face of the anode structure is machined with multiple circumferentially distributed through holes as outlet through holes.

[0012] The anode structure has a gas buffer chamber inside, which is used to connect the inlet and outlet through holes;

[0013] The tail end face of the anode structure is perpendicular to the axis of the main discharge structure. The axis of the anode structure is coaxial with the axis of the discharge structure. The center point of the tail end face of the anode structure coincides with the point where the magnetic field strength of the first-stage permanent magnet is the highest at the axis. The permanent magnet closest to the entrance end of the main discharge structure is the first-stage permanent magnet.

[0014] Multiple wedge-shaped ring structures are fixedly installed inside the main discharge structure along the axial direction; the center of the wedge-shaped ring structure is machined with a tapered hole section and a through hole section, the tapered hole section is located at the front end of the through hole section, and the opening of the tapered hole section of the wedge-shaped ring structure faces the anode structure;

[0015] The total number of wedge ring structures is less than the total number of permanent magnets; the wedge ring structures are preferentially set starting from the permanent magnets located at the tail (i.e., downstream) of the main discharge structure, and a maximum of one wedge ring structure is set within the axial length range of each permanent magnet.

[0016] Preferably, the axial gap between two adjacent permanent magnets is in the range of 2-3 mm.

[0017] Preferably, the single-sided gap between the inner wall of the permanent magnet and the outer wall of the main discharge structure is in the range of 1 to 2.5 mm.

[0018] Preferably, the axial length of the tapered expansion section is in the range of 6-8 mm.

[0019] Preferably, the diameter of the outlet through hole at the tail end face of the anode structure is in the range of 0.5 to 1 mm.

[0020] Preferably, the diameter of the circumference of the multiple circumferentially distributed outlet through holes is greater than the inner diameter of the wedge-shaped ring structure.

[0021] Preferably, the anode structure is made of a metallic material; the wedge-shaped ring structure and the main discharge structure are made of boron nitride.

[0022] Preferably, the radial thickness H of the wedge-shaped ring structure i (i.e., wall thickness) and wedge angle α of the tapered hole section i The calculation formula is as follows:

[0023] The wedge-shaped ring structures are sequentially numbered from the inlet end to the outlet end of the main discharge structure.

[0024] When i = 1, that is, the radial thickness H of the first-stage wedge ring structure i =2R a -R; wedge angle of the tapered section of the first-stage wedge ring structure.

[0025] Among them, R a R is the radius of the circumference of the multiple circumferentially distributed through holes on the tail end face of the anode structure, R is the inner diameter of the main discharge structure, and L is the radius of the circumference of the anode structure. i The axial length of the permanent magnet corresponding to the i-th wedge ring structure is given by k, which is the ratio of the axial distance between the front end face of the wedge ring structure and the front end face of the corresponding permanent magnet, and the value ranges from 1 / 3 to 1 / 2.

[0026] For i = 2, 3, 4, ..., M, that is, the wall thickness H of the wedge ring structures other than the first-level wedge ring structure. i =2H i-1 -R; For the wedge angle of the tapered section of the wedge ring structure other than the first-stage wedge ring structure.

[0027]

[0028] Preferably, the axial length Z of the through-hole section of the wedge-shaped ring structure is... 内i The calculation formula is as follows:

[0029] Z 内i =Z 外i -H i tanα i

[0030] Where i = 1, 2, 3, 4, ..., M, Z 外i This is the axial length of the outer wall surface of the wedge-shaped ring structure.

[0031] Preferably, the axial length Z of the outer wall surface of the wedge-shaped ring structure 外i The value range is 5 to 8 mm.

[0032] The advantages of this invention compared to the prior art are:

[0033] 1) The main discharge structure of the thruster of the present invention has a variable cross-section structure at the exit magnetic tip, which can reduce the degree of interaction between plasma and wall, thereby reducing the channel corrosion rate and improving the service life of the thruster.

[0034] 2) The final stage magnetic tip of the thruster of the present invention is provided with a wedge-shaped ring structure, which can reduce the probability of working fluid atoms leaking near the wall of the main discharge structure and make the atoms focus on the main ionization region of the channel axis, thereby effectively improving the ionization efficiency of the thruster.

[0035] 3) The main discharge structure of the thruster of the present invention is provided with a multi-wedge ring structure, which can reduce the plasma density in the ionization region of the thruster outlet plume, thereby suppressing the plume divergence of the thruster and realizing plume focusing.

[0036] 4) By changing the number and wedge angle of the wedge ring structure, the radial scale of multiple ionization regions in the thruster can be adjusted step by step, thereby reducing the wall loss of the plasma and increasing the output flux of ions at the thruster outlet, thus improving the overall efficiency. Attached Figure Description

[0037] Figure 1 This is a structural diagram of the focusing plume channel of the present invention;

[0038] Figure 2(a) is a schematic diagram of a multi-stage tangential thruster for focusing plumes;

[0039] Figure 2(b) is a schematic diagram of the distribution of a focused plume;

[0040] Figure 3 This is a schematic diagram showing the position and structure of the thruster wedge ring;

[0041] Figure 4 This is a plume distribution diagram of the focusing multi-stage tangential thruster of the present invention under different operating conditions. Detailed Implementation

[0042] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and specific examples.

[0043] This invention provides a multi-stage tangential thruster for focusing plumes, such as... Figure 1 As shown, it includes: a main discharge structure 1, a wedge-shaped ring structure 2, a permanent magnet 3, an anode structure 4, and a housing. The permanent magnet 3 and the main discharge structure 1 are fixedly mounted on the housing. Multiple segments of the permanent magnet 3 are fitted on the outer wall of the main discharge structure 1, and the axes of the permanent magnet 3 and the main discharge structure 1 are coaxial. The multiple segments of the permanent magnet 3 do not contact each other, and the inner wall of the permanent magnet 3 does not contact the main discharge structure 1. The main discharge structure 1 is a cylindrical structure, and a tapered expansion section is machined at the outlet end of the main discharge structure 1 to avoid the high-energy ion beam.

[0044] An anode structure 4 is fixedly installed inside the inlet end of the main discharge structure 1. A central through-hole is machined on the head end face of the anode structure 4 as an inlet through-hole, and multiple circumferentially distributed through-holes are machined on the tail end face of the anode structure 4 as outlet through-holes. A gas buffer chamber is machined inside the anode structure 4 to connect the inlet and outlet through-holes. The working gas enters the gas buffer chamber from the inlet through-hole on the head end face of the anode structure 4. After homogenization in the gas buffer chamber, the working gas enters the main discharge structure 1 through the circumferentially distributed outlet through-holes on the tail end face.

[0045] The tail end face of the anode structure 4 serves as the discharge end face. The tail end face of the anode structure 4 is perpendicular to the axis of the main discharge structure 1. The axis of the anode structure 4 is coaxial with the axis of the discharge structure 1. The center point of the tail end face of the anode structure 4 coincides with the point where the magnetic field strength of the first-stage permanent magnet 3 is the highest at the axis. Among them, the permanent magnet 3 closest to the entrance end of the main discharge structure 1 serves as the first-stage permanent magnet 3.

[0046] Multiple wedge-shaped ring structures 2 are fixedly installed inside the main discharge structure 1 along the axial direction; the wedge-shaped ring structure 2 has a conical hole section and a through hole section machined in the center, the conical hole section is located at the front end of the through hole section, and the opening of the conical hole section of the wedge-shaped ring structure 2 faces the anode structure 4;

[0047] The total number of wedge ring structures 2 is less than the total number of permanent magnets 3; the wedge ring structures 2 are preferentially set starting from the permanent magnets 3 located at the tail (i.e. downstream) of the main discharge structure 1, and at most one wedge ring structure 2 is set within the axial length range of each permanent magnet 3.

[0048] The axial gap between two adjacent permanent magnets 3 ranges from 2 to 3 mm. The single-sided gap between the inner wall of the permanent magnet 3 and the outer wall of the main discharge structure 1 ranges from 1 to 2.5 mm. The axial length of the tapered expansion section ranges from 6 to 8 mm. The diameter of the outlet through hole at the tail end face of the anode structure 4 ranges from 0.5 to 1 mm.

[0049] The diameter of the circumference of the multiple circumferentially distributed outlet holes is larger than the inner diameter of the wedge-shaped ring structure 2.

[0050] The anode structure 4 is made of metallic material; the wedge-shaped ring structure 2 and the main discharge structure 1 are made of boron nitride.

[0051] The main discharge structure 1 has M wedge-shaped ring structures 2 fixedly installed inside. N permanent magnets 3 are coaxially mounted on the outer wall of the main discharge structure 1, and the magnetic lines of force generated form N magnetic tips. The mathematical relationship between M and N is as follows:

[0052] 1≤M≤N-1

[0053] M wedge-shaped ring structures 2 are arranged inside the main discharge structure 1, causing the working fluid atoms near the wall of the main discharge structure 1 to move towards the zero magnetic point P on the axis. iFocusing on the radial thickness H of the corresponding wedge-shaped ring structure 2 i (i.e., wall thickness) and wedge angle α of the tapered hole section i The calculation formula is as follows:

[0054] From the inlet end of the main discharge structure 1 to the outlet end, the wedge-shaped ring structure 2 is sequentially labeled with levels;

[0055] When i = 1, that is, the radial thickness H of the first-stage wedge ring structure 2 i =2R a -R; Wedge angle of the tapered section of the first-stage wedge ring structure 2

[0056] Among them, R a R is the radius of the circumference of the multiple circumferentially distributed through holes on the tail end face of anode structure 4, R is the inner diameter of main discharge structure 1, and L is the radius of the circumference ... i The axial length of the permanent magnet 3 corresponding to the i-th wedge ring structure 2 is given by k, which is the ratio of the axial distance between the front end face of the wedge ring structure 2 and the front end face of the corresponding permanent magnet 3, and the value ranges from 1 / 3 to 1 / 2.

[0057] For i = 2, 3, 4, ..., M, that is, the wall thickness H of the wedge ring structures 2 other than the first-level wedge ring structure 2. i =2H i-1 -R; For the wedge angle of the tapered section of the wedge ring structure 2 other than the first-stage wedge ring structure 2.

[0058] Axial length Z of the through-hole section of the wedge ring structure 内i The calculation formula is as follows:

[0059] Z 内i =Z 外i -H i tanα i

[0060] Where i = 1, 2, 3, 4, ..., M, Z 外i denoted as axial length of the outer wall of wedge-shaped ring structure 2.

[0061] Axial length Z of the outer wall of the wedge-shaped ring structure 2 外i The value range is 5 to 8 mm.

[0062] Example

[0063] In this embodiment of the invention, the upstream port of the main discharge structure 1 is a semi-enclosed structure, the middle part is a cylindrical structure, and the downstream end is a variable cross-section open structure. M wedge-shaped ring structures 2 are coaxially arranged downstream of the thruster's annular magnetic tip. Taking the three-level magnetic field (M=1, N=3) shown in Figures 2(a) and (b) as an example, the length of the main discharge structure 1 is consistent with the axial length of the thruster, and the wall thickness is 3-4 mm. Its upstream semi-enclosed structure is coaxially fitted with the anode of the thruster, and its downstream variable cross-section open structure is coaxially installed with the outer magnetic stage of the thruster without contact. The gap between the variable cross-section open structure and the outer magnetic stage of the thruster is controlled within the range of 0.5-1.0 mm, and the angle between the surface of the variable cross-section open structure and the axis of the thruster is 30°-60°, with the cone opening facing downstream. The radial height of the wedge-shaped ring structure 2 is controlled within the range of 3-5 mm, and the angle between the wedge surface and the axis is 45°-60°. The wedge-shaped ring structure 2 is coaxially inserted into the discharge channel from the variable cross-section opening side of the main discharge structure 1. Its annular conical surface is located upstream of the main discharge structure 1, and its annular plane is located downstream of the main discharge structure 1. The wedge-shaped ring structure 2 is placed downstream of the annular magnetic tip of the thruster. In this embodiment of the invention, the distance between its position and the annular magnetic tip at the upstream end face of the corresponding permanent magnet 3 is controlled within the range of 5 to 10 mm.

[0064] Under this channel configuration, the ionization of the thrust working fluid and the acceleration of ions undergo significant changes, which are key to the generation of a focused plume by the thruster:

[0065] First, the wedge-shaped ring structure 2 reduces the leakage probability of working propellant atoms near the wall. After the working propellant atoms collide with the conical surface of the wedge-shaped ring, they are reflected to the main ionization region near the axis, thereby improving the ionization efficiency of the main ionization region within the channel. Figure 3 As shown; at the same time, enhanced ionization in the ionization region can reduce the density of working propellant atoms in the plume region, thereby suppressing the ionization process in the diverging magnetic field of the plume ionization region.

[0066] Second, the wedge-shaped ring structure 2 restricts the radial expansion of the ionization region while expanding its axial distribution, resulting in a high-density ion jet with ion aggregation at the axis, forming a focused plume distribution, such as... Figure 4 As shown.

[0067] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make possible variations and modifications to the technical solutions of the present invention using the disclosed methods and techniques without departing from the spirit and scope of the invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall fall within the protection scope of the present invention. Where there is no conflict, the embodiments of this application and the technical features thereof can be combined with each other.

[0068] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A multi-stage tangential thruster for focusing plumes, characterized in that, include: The main discharge structure (1), the wedge ring structure (2), the permanent magnet (3), the anode structure (4), and the shell; The permanent magnet (3) and the main discharge structure (1) are respectively fixedly installed on the housing; Multiple permanent magnets (3) are mounted on the outer wall of the main discharge structure (1), and the axes of the permanent magnets (3) and the main discharge structure (1) are coaxial. The multiple permanent magnets (3) do not contact each other, and the inner wall of the permanent magnets (3) does not contact the main discharge structure (1); The main discharge structure (1) is a cylindrical structure, and a tapered expansion section is machined at the outlet end of the main discharge structure (1); An anode structure (4) is fixedly installed inside the inlet end of the main discharge structure (1); a central through hole is machined on the head end face of the anode structure (4) as an inlet through hole, and multiple circumferentially distributed through holes are machined on the tail end face of the anode structure (4) as outlet through holes. The anode structure (4) has a gas buffer chamber inside, which is used to connect the inlet and outlet through holes; The tail end face of the anode structure (4) is perpendicular to the axis of the main discharge structure (1). The axis of the anode structure (4) is coaxial with the axis of the main discharge structure (1), and the center point of the tail end face of the anode structure (4) coincides with the point of highest tangential magnetic field strength of the first-stage permanent magnet (3). Among them, the permanent magnet (3) closest to the entrance end of the main discharge structure (1) is the first-stage permanent magnet (3). Multiple wedge-shaped ring structures (2) are fixedly installed inside the main discharge structure (1) along the axial direction; the wedge-shaped ring structure (2) has a conical hole section and a through hole section machined in the center, the conical hole section is located at the front end of the through hole section, and the opening of the conical hole section of the wedge-shaped ring structure (2) faces the anode structure (4); The total number of wedge ring structures (2) is less than the total number of permanent magnets (3); the wedge ring structures (2) are set starting from the permanent magnet (3) located at the tail of the main discharge structure (1), and at most one wedge ring structure (2) is set within the axial length range of each permanent magnet (3).

2. The multi-stage convergence thruster for focusing plumes according to claim 1, characterized in that, The axial gap between two adjacent permanent magnets (3) is 2-3 mm.

3. A multi-stage convergence thruster for focusing plumes according to claim 2, characterized in that, The single-sided gap between the inner wall of the permanent magnet (3) and the outer wall of the main discharge structure (1) ranges from 1 to 2.5 mm.

4. A multi-stage convergence thruster for focusing plumes according to claim 1, characterized in that, The axial length of the tapered expansion section ranges from 6 to 8 mm.

5. A multi-stage convergence thruster for focusing plumes according to claim 1, characterized in that, The diameter of the outlet through hole at the tail end face of the anode structure (4) ranges from 0.5 to 1 mm.

6. A multi-stage convergence thruster for focusing plumes according to claim 5, characterized in that, The diameter of the circumference of the multiple circumferentially distributed outlet holes is greater than the inner diameter of the wedge-shaped ring structure (2).

7. A multi-stage convergence thruster for focusing plumes according to any one of claims 1 to 6, characterized in that, The anode structure (4) is made of metallic material; the wedge ring structure (2) and the main discharge structure (1) are made of boron nitride.

8. A multi-stage convergence thruster for focusing plumes according to claim 7, characterized in that, The radial thickness H of the wedge-shaped ring structure (2) i and the wedge angle α of the conical hole section i The calculation formula is as follows: From the inlet end of the main discharge structure (1) to the outlet end, the wedge-shaped ring structure (2) is sequentially numbered. When i = 1, that is, the radial thickness H of the first-stage wedge ring structure (2) i =2R a -R, the wedge angle of the tapered section of the first-stage wedge ring structure (2). Among them, R a R is the radius of the circumference of the multiple circumferentially distributed through holes on the tail end face of the anode structure (4), R is the inner radius of the main discharge structure (1), and L is the radius of the circumference of the anode structure (4). i The axial length of the permanent magnet (3) corresponding to the i-th wedge ring structure (2) is given by k, which is the ratio of the axial distance between the front end face of the wedge ring structure (2) and the front end face of the corresponding permanent magnet (3), and the value ranges from 1 / 3 to 1 / 2. For i = 2, 3, 4, ..., M, that is, the wall thickness H of the wedge ring structures (2) other than the first-level wedge ring structure (2) i =2H i-1 -R, for the wedge angle of the tapered segment of the wedge ring structure (2) other than the first-stage wedge ring structure (2).

9. A multi-stage convergence thruster for focusing plumes according to claim 8, characterized in that, The axial length Z of the through-hole section of the wedge ring structure (2) 内i The calculation formula is as follows: Z 内i =Z 外i -H i tanα i Where i = 1, 2, 3, 4, ..., M, Z 外i The axial length of the outer wall of the wedge-shaped ring structure (2) is given.

10. A multi-stage convergence thruster for focusing plumes according to claim 9, characterized in that, The axial length Z of the outer wall of the wedge-shaped ring structure (2) 外i The value range is 5 to 8 mm.

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