阅读说明：本技术 双极多模式微阴极弧推力器 (Bipolar multimode micro-cathode arc thruster ) 是由 章喆 汤海滨 许舒婷 张尊 于 2019-09-04 设计创作，主要内容包括：本发明公开了一种双极多模式微阴极弧推力器,其特征在于,包括绝缘圆柱外壳(1)、绝缘板(2)、同轴形阳极(3)、中空同轴形绝缘件(4)、环形阴极(5)、环形阳极(6)、环形绝缘件(7)、电磁线圈(8)和永磁铁(9)。本发明的双极多模式微阴极弧推力器的双阳极结构存在两种不同构型的阳极结构,即同轴形阳极和环形阳极,随着推力器工作寿命的变化,可以切换选择使用同轴形阳极或环形阳极进行工作,从而实现推力器寿命期间内的两种模式的工作状态。(The invention discloses a bipolar multimode micro-cathode arc thruster which is characterized by comprising an insulating cylindrical shell (1), an insulating plate (2), a coaxial anode (3), a hollow coaxial insulating part (4), an annular cathode (5), an annular anode (6), an annular insulating part (7), an electromagnetic coil (8) and a permanent magnet (9). The double-anode structure of the bipolar multi-mode micro-cathode arc thruster has two anode structures with different configurations, namely a coaxial anode and an annular anode, and the coaxial anode or the annular anode can be switched and selectively used for working along with the change of the service life of the thruster, so that the working states of two modes in the service life of the thruster are realized.)

1. A bipolar multimode micro-cathode arc thruster is characterized by comprising an insulating cylindrical shell (1), an insulating plate (2), a coaxial anode (3), a hollow coaxial insulating part (4), an annular cathode (5), an annular anode (6), an annular insulating part (7), an electromagnetic coil (8) and a permanent magnet (9);

the insulating plate (2) is connected with the rear end of the insulating cylindrical shell (1) to form a semi-closed cylindrical structure; the discharge end of the coaxial anode (3) is inserted into the hollow coaxial insulator (4), the hollow coaxial insulator (4) is inserted into the annular cathode (5), and the hollow coaxial insulator (4) ensures the distance and the insulation between the coaxial anode (3) and the annular cathode (5); the discharge end of the coaxial anode (3) extends out of the hollow coaxial insulating piece (4);

the annular anode (6), the annular insulator (7) and the annular cathode (5) are positioned inside the front end of the insulating cylindrical shell (1) in a close-stacked manner; the annular anode (6) is positioned at the foremost end of the insulating cylindrical shell (1); the annular insulating piece (7) is arranged between the annular anode (6) and the annular cathode (5) to ensure the distance and the insulativity between the annular anode (6) and the annular cathode (5);

the front end of the insulating cylindrical shell (1) extends into a cylindrical structure formed by overlapping the electromagnetic coil (8) and the permanent magnet (9), so that the discharge end of the coaxial anode (3) is just positioned in the range of a magnetic field formed by the electromagnetic coil (8) and the permanent magnet (9).

2. The bipolar multimode micro-cathodic arc thruster as claimed in claim 1, characterized in that the insulating plate (2) is centrally provided with a through hole through which the end of the coaxial anode (3) opposite to the discharge end is fixedly connected to the insulating plate (2).

3. The bipolar multimode micro-cathodic arc thruster according to claim 1, characterized in that between the insulating plate (2) and the annular cathode (5) there is provided a spring ensuring that the annular cathode (5), the annular insulator (7) and the annular anode (6) are always positioned inside the front end of the insulating cylindrical shell (1).

4. The bipolar multimode micro-cathodic arc thruster of claim 1, characterized in that the outer diameters of the annular anode (6), the annular insulator (7) and the annular cathode (5) are clearance fitted with the inner diameter of the insulating cylindrical casing (1).

5. The bipolar multimode micro-cathodic arc thruster of claim 1, characterized in that the insulating plate (2) is attached to the rear end of the insulating cylindrical shell (1) by epoxy glue.

6. The bipolar multimode micro-cathodic arc thruster of claim 1, characterized in that the outer diameter of the coaxial anode (3) is interference fitted with the inner diameter of the hollow coaxial insulator (4), the outer diameter of the hollow coaxial insulator (4) being clearance fitted with the inner diameter of the annular cathode (5).

7. The bipolar multimode micro-cathodic arc thruster according to claim 1, characterized in that the insulating cylindrical housing (1) is fixedly mounted inside the cylindrical structure formed by the superposition of the electromagnetic coil (8) and the permanent magnet (9) by means of epoxy glue.

8. The bipolar multimode micro-cathodic arc thruster of claim 1, characterized in that the wall thickness of the hollow coaxial insulator (4) is 4-10 mm.

9. The bipolar multi-mode micro-cathodic arc thruster of claim 1, wherein the thickness of the annular insulating member (7) is 2-4 mm.

10. The bipolar multimode micro-cathodic arc thruster according to claim 1, characterized in that the insulating cylindrical shell (1) is made of ceramic material.

Technical Field

The invention belongs to the field of electric propulsion plasma application, and particularly relates to a two-stage multi-mode micro-cathode arc thruster applied to space propulsion tasks of micro and nano satellites.

Background

The electric propulsion is an advanced propulsion mode which utilizes electric energy to directly heat the propellant or utilizes electromagnetic action to ionize and accelerate the propellant so as to obtain propulsion power, has higher specific impulse, thrust and efficiency, and has wide application prospect in space tasks of orbit control, deep space exploration, interstellar navigation and the like of large-scale spacecrafts. The Micro-Cathode arc thruster (mu CAT for short) is a small-thrust electromagnetic Micro thruster specially designed for a cube star, is mainly characterized by pulse operation, small volume, low power (0.1W magnitude) and high specific impulse (2000-plus 3000s), and can be widely applied to attitude adjustment and orbit maintenance tasks of small-volume satellites such as Micro, nano and cube stars.

The existing known micro-cathode arc thruster has the problems that performance parameters are reduced after long-time ignition, discharge erosion and failure easily occur at the later stage of service life. The main reason is that the discharging mode of the thruster is single, after long-time ignition, the erosion degree of the discharging surface and the wall surface can be greatly changed, but the discharging mode cannot be correspondingly adjusted, and further the performance of the thruster is reduced or fails.

Disclosure of Invention

In order to overcome at least the above-mentioned drawbacks of the prior art, the present invention provides a micro-cathode arc thruster having a dual-electrode structure to implement a dual-electrode switchable multi-mode discharge operation of μ CAT.

According to an aspect of the present invention, there is provided a bipolar multimode micro-cathodic arc thruster, comprising an insulating cylindrical casing, an insulating plate, a coaxial anode, a hollow coaxial insulator, an annular cathode, an annular anode, an annular insulator, an electromagnetic coil, and a permanent magnet;

the insulating plate is connected with the rear end of the insulating cylindrical shell to form a semi-closed cylindrical structure; the discharge end of the coaxial anode is inserted into the hollow coaxial insulating piece, the hollow coaxial insulating piece is inserted into the annular cathode, and the hollow coaxial insulating piece ensures the distance and the insulativity between the coaxial anode and the annular cathode; the discharge end of the coaxial anode extends out of the hollow coaxial insulating part;

the annular anode, the annular insulator and the annular cathode are positioned inside the front end of the insulating cylindrical shell in a tightly stacked manner; the annular anode is positioned at the foremost end of the insulating cylindrical shell; the annular insulating part is arranged between the annular anode and the annular cathode, so that the distance and the insulativity between the annular anode and the annular cathode are ensured;

the front end of the insulating cylindrical shell extends into a cylindrical structure formed by overlapping the electromagnetic coil and the permanent magnet, so that the discharge end of the coaxial anode is just positioned in the magnetic field range formed by the electromagnetic coil and the permanent magnet.

In some embodiments, the insulating plate may be provided at the center thereof with a through-hole, and an end of the coaxial anode opposite to the discharge end may be fixedly coupled to the insulating plate through the through-hole.

In some embodiments, a spring may be provided between the insulating plate and the annular cathode, ensuring that the annular cathode, the annular insulator and the annular anode are always positioned inside the front end of the insulating cylindrical housing.

In some embodiments, the outer diameters of the annular anode, the annular insulator, and the annular cathode may be clearance fit with the inner diameter of the insulating cylindrical housing.

In some embodiments, the insulating plate may be attached to the rear end of the insulating cylindrical housing by epoxy glue.

In some embodiments, the outer diameter of the co-axial anode may be an interference fit with the inner diameter of the hollow co-axial insulator, which is a clearance fit with the inner diameter of the annular cathode.

In some embodiments, the insulating cylindrical housing may be fixedly mounted in a cylindrical structure formed by overlapping the electromagnetic coil and the permanent magnet by epoxy glue.

In some embodiments, the wall thickness of the hollow coaxial insulator may be 4-10 mm.

In some embodiments, the thickness of the annular insulator may be 2-3 mm.

In some embodiments, the insulating cylindrical housing may be made of a ceramic material.

The invention has the beneficial effects that:

the double-anode structure of the mu CAT has two anode structures (a coaxial anode and an annular anode) with different configurations, and the coaxial anode or the annular anode can be switched and selected to work along with the change of the working life of the mu CAT, so that the working states of two modes in the service life period (about 100 ten thousand ignitions) of the mu CAT thruster are realized:

working mode 1: at the initial stage of the mu CAT service life, the cathode surface is smooth, and the mu CAT of the coaxial electrode structure has relatively high specific impulse and efficiency, so that power is supplied to the coaxial anode selectively, and the working mode of the thruster is the coaxial mu CAT;

the working mode 2 is as follows: in the middle and later period of the life of the mu CAT, spots caused by discharge concentration appear on the surface of a cathode due to the defect that the ablation surface of the coaxial mu CAT is uneven (the service life and the performance of the thruster can be reduced), and the mu CAT with the annular anode structure has the characteristics of uniform ablation, long service life and good ignition stability, so that power is supplied to the annular anode selectively, and the working mode of the thruster is the annular mu CAT at the moment.

Drawings

Fig. 1(a) - (b) are schematic structural views of a bipolar multi-mode micro-cathode arc thruster of the present invention, in which fig. 1(a) is a front view, and fig. 1(b) is a sectional view taken along a-a of fig. 1 (a).

Detailed Description

The invention is further described below with reference to the accompanying drawings and examples, it being understood that the examples described below are intended to facilitate the understanding of the invention, and are not intended to limit it in any way.

As shown in fig. 1, the bipolar multimode micro-cathode arc thruster of the present invention includes an insulating cylindrical casing 1, an insulating plate 2, a coaxial anode 3, a hollow coaxial insulator 4, an annular cathode 5, an annular anode 6, an annular insulator 7, an electromagnetic coil 8, and a permanent magnet 9.

The insulating cylindrical shell 1 can be made of machinable ceramic materials, and the insulating plate 2 is connected with the rear end of the insulating cylindrical shell 1 to form a semi-closed cylindrical structure. In particular, the insulating plate is connected to the rear end of the insulating cylindrical shell through epoxy resin adhesive, so that the insulativity of the internal annular cathode 5 and the annular anode 6 with the external environment is ensured, and the detachability of the whole structure is also ensured. In this example, the insulating plate 2 is provided with a through hole in the centre through which the end of the coaxial anode 3 opposite its discharge end is fixedly connected (e.g. by interference fit) to the insulating plate.

The discharge end of the coaxial anode 3 is inserted into the hollow coaxial insulator 4 in a close fit manner, and the hollow coaxial insulator 4 is inserted into the annular cathode 5 in a clearance fit manner, so that the hollow coaxial insulator 4 is positioned between the coaxial anode 3 and the annular cathode 5, and the accurate distance and the insulativity between the coaxial anode 3 and the annular cathode 5 are ensured. In some embodiments, the wall thickness of the hollow coaxial insulator 4 may be 4-10 mm, preferably 6mm, to ensure a specific spacing between the coaxial anode 3 and the annular cathode 5.

In particular, the discharge end of the coaxial anode 3 should extend to protrude through the hollow coaxial insulator 4 to achieve discharge.

As shown in the figure, the front end of the insulating cylindrical casing 1 has a positioning step by which the ring-shaped anode 6 is positioned at the foremost end of the insulating cylindrical casing 1. The annular anode 6, the annular insulator 7 and the annular cathode 5 are positioned inside the front end of the insulating cylindrical housing 1 in a close stacked manner, wherein the annular insulator 7 is disposed between the annular anode 6 and the annular cathode 5 to ensure accurate spacing and insulation between the annular anode 6 and the annular cathode 5. In some embodiments, the thickness of the annular insulator 7 may be 2-4 mm, preferably 2mm, to ensure a certain spacing between the annular anode 6 and the annular cathode 5.

The distance between the coaxial anode 3 and the annular cathode 5 and the distance between the annular anode 6 and the annular cathode 5 directly determine the length of the arc between the anode and the cathode, and good arc morphology can be obtained by controlling the distance of the distances.

In this example, a spring 10 is provided between the insulating plate 2 and the annular cathode 5 to ensure that the annular cathode 5, the annular insulator 7 and the annular anode 6 are always positioned inside the front end of the insulating cylindrical housing 1. In particular, the outer diameters of the annular anode 6, annular insulator 7 and annular cathode 5 are clearance fit with the inner diameter of the insulating cylindrical housing 1.

The front end of the insulating cylindrical shell 1 extends into a cylindrical structure formed by overlapping the electromagnetic coil 8 and the permanent magnet 9, the extending length of the insulating cylindrical shell is influenced by the length of the coaxial anode 3, and the discharging end of the coaxial anode 3 is required to be ensured to be just within the magnetic field range formed by the electromagnetic coil 8 and the permanent magnet 9, so that the appearance of the electric arc can be controlled by the magnetic field. After the distance between the insulating cylindrical case 1 and the electromagnetic coil 8 and the permanent magnet 9 is controlled, the relative position of the cylindrical structure formed by overlapping the insulating cylindrical case 1 and the electromagnetic coil 8 and the permanent magnet 9 may be fixed, for example, by epoxy resin glue.

With the structure, the μ CAT of the invention can realize the following two modes of working states in the life period (100 ten thousand ignitions) of the μ CAT thruster:

working mode 1: at the initial stage of the mu CAT service life, the cathode surface is smooth, and the mu CAT of the coaxial electrode structure has relatively high specific impulse and efficiency, so that power is supplied to the coaxial anode selectively, and the working mode of the thruster is the coaxial mu CAT;

the working mode 2 is as follows: in the middle and later period of the life of the mu CAT, spots caused by discharge concentration appear on the surface of a cathode due to the defect that the ablation surface of the coaxial mu CAT is uneven (the service life and the performance of the thruster can be reduced), and the mu CAT with the annular anode structure has the characteristics of uniform ablation, long service life and good ignition stability, so that power is supplied to the annular anode selectively, and the working mode of the thruster is the annular mu CAT at the moment.

It will be apparent to those skilled in the art that various modifications and improvements can be made to the embodiments of the present invention without departing from the inventive concept thereof, and these modifications and improvements are intended to be within the scope of the invention.