A micro-cathode arc thruster

Abstract

The application discloses a micro-cathode arc thruster and belongs to the technical field of micro-cathode arc thrusters. The micro-cathode arc thruster comprises a cathode, an insulator and an anode. The insulator is arranged between the cathode and the anode, and the top surface of the insulator is a slope located between the anode and the cathode. The cathode comprises a base body and a reinforcing body arranged on the top surface of the base body. One end of the slope is connected with the base body, and the other end of the slope is connected with the anode. The shortest distance between the anode and the cathode is located between the anode and the reinforcing body, and the shortest distance is smaller than the length of the slope. In this way, the application has a gas discharge channel L2 in addition to a surface discharge channel L1 along the surface of the insulator, so that the ablation position of the cathode is transferred from the joint between the base body and the insulator to the reinforcing body, the ablation area of the cathode is increased, the service life of the thruster is prolonged, and the total impulse of the thruster is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-cathode arc thruster, in particular to a micro-cathode arc thruster. BACKGROUND

[0002] The micro-cathode arc thruster has the characteristics of high specific impulse, low power, small volume and low mass, and is suitable for being used as a cubic satellite propulsion device, and has a good development prospect. The cathode is the most important part of the micro-cathode arc thruster as the conductive structure and the working medium. The head of the cathode structure of the existing micro-cathode arc thruster is a cylindrical structure. When the discharge frequency of the micro-cathode arc thruster is small, the cathode structure is complete, and the cathode and the anode can maintain stable discharge. With the continuous increase of the inter-electrode discharge frequency of the micro-cathode arc thruster, the cylindrical structure is seriously ablated, so that the cathode structure is difficult to maintain integrity, causing the thruster to fail to discharge, thereby causing the total impulse of the micro-cathode arc thruster to be difficult to reach a high level.

[0003] Therefore, how to design a micro-cathode arc thruster to improve the service life and total impulse of the micro-cathode arc thruster is a technical problem to be solved by those skilled in the art. SUMMARY

[0004] The present application aims at the defects and deficiencies in the prior art, and provides a micro-cathode arc thruster, which increases the ablation area of the cathode and improves the service life and total impulse of the thruster.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0006] The present application provides a micro-cathode arc thruster, which comprises a cathode, an insulator and an anode, the insulator is arranged between the cathode and the anode, and the top surface of the insulator is a slope in the region between the anode and the cathode.

[0007] The cathode comprises a base body and a reinforcing body arranged on the top surface of the base body, one end of the slope is connected with the base body, the other end of the slope is connected with the anode, the shortest distance between the anode and the cathode is located between the anode and the reinforcing body, and the shortest distance is smaller than the length of the slope.

[0008] Preferably, the cathode, the insulator and the anode are arranged in sequence from inside to outside, the position where the base body intersects with the slope is lower than the position where the anode intersects with the slope, and the shortest distance between the anode and the cathode is a horizontal line segment passing through the intersection point of the slope and the anode.

[0009] Preferably, the reinforcing body is a conical structure with a small upper part and a large lower part.

[0010] Preferably, the base body and the reinforcing body are integrally formed.

[0011] Preferably, the angle between the inclined surface and the horizontal direction is 15-30 degrees.

[0012] Preferably, the end of the base body away from the reinforcing body is provided with a support structure, and the end of the support structure away from the base body is provided with an external thread.

[0013] Preferably, the outer portion of the anode is provided with a shell, the inner portion of the shell is provided with a third through hole for accommodating the anode, the anode is located in the third through hole, and the top surface of the anode, the insulator located in the anode and the top surface of the cathode do not protrude out of the third through hole.

[0014] Preferably, the outer portion of the shell is provided with a permanent magnet for accelerating plasma, and the permanent magnet at least entirely covers the inclined surface in the height direction.

[0015] Preferably, the bottom portion of the shell is provided with a base, and the base is detachably connected with the shell.

[0016] The present application has the following technical effects relative to the prior art:

[0017] 1. By setting the cathode to include a base body and a reinforcing body, and setting the shortest distance between the anode and the cathode to be between the anode and the reinforcing body, and the shortest distance being smaller than the length of the inclined surface, the present application has discharge channels L1 along the surface of the insulator and discharge channels L2, so that the ablation position of the cathode is transferred from the junction of the base body and the insulator to the reinforcing body, thereby increasing the ablation area on the cathode, prolonging the service life of the thruster, and improving the total impulse of the thruster.

[0018] The other technical solutions of the present application have the following technical effects relative to the prior art:

[0019] 2. By setting the reinforcing body to be a conical structure with a small upper portion and a large lower portion, in the gas discharge stage, the electric arc ablates the reinforcing body and the base body first, and as the ablation proceeds, the diameters of the two gradually decrease, thereby making the portion of the cathode on the insulator gradually tend to be a cylinder, and then the ablation position is transferred to the cylinder with a small diameter, until the cylinder with a small diameter cannot maintain integrity and causes the thruster to fail to discharge, thereby achieving the technical effects of greatly increasing the ablation area, prolonging the service life of the thruster and the total impulse. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments will be briefly introduced. Obviously, the accompanying drawings in the following description only need to be some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0021] Figure 1 It is a structural schematic diagram of a micro-cathode arc thruster.

[0022] Figure 2 It is a structural schematic diagram of a cathode.

[0023] Figure 3 It is a structural schematic diagram of different discharge paths.

[0024] Figure 4 It is a structural schematic diagram of an insulator before modification.

[0025] Figure 5 It is a structural schematic diagram of an insulator after modification.

[0026] Figure 6 It is a schematic diagram of ion collision frequency on the surface of the insulator under different inner recess angles.

[0027] In the figure, 1 is a cathode, 2 is an insulator, 3 is an anode, 4 is a first through hole, 5 is a second through hole, 6 is a bevel, 7 is a base body, 8 is a reinforcing body, 9 is a relationship curve when α is 15°, 10 is a relationship curve when α is 30°, 11 is a support structure, 12 is an outer shell, 13 is a third through hole, 14 is a permanent magnet, 15 is a base, and 16 is a cylinder with a smaller diameter. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art on the basis of the embodiments in the present application without any creative effort belong to the scope of protection of the present application.

[0029] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] As Figures 1 to 6As shown, the present application provides a micro-cathode arc thruster, which comprises a cathode 1, an insulator 2 and an anode 3, the insulator 2 is arranged between the cathode 1 and the anode 3, and the top surface of the insulator 2 is a bevel 6 between the anode 3 and the cathode 1, further, the bevel 6 is a torus, the cathode 1 comprises a base 7 and a reinforcing body 8 arranged on the top surface of the base 7, one end of the bevel 6 is connected with the base 7, and the other end of the bevel 6 is connected with the anode 3, so that in the initial stage of discharge, the high voltage applied between the anode 3 and the cathode 1 can break through the conductive coating on the surface of the insulator 2 and form an initial micro-plasma, so as to form a path between the cathode 1 and the anode 3 and then arc, and then the arc ablates the cathode 1 to make the metal of the cathode 1 evaporate into metal vapor, at this time, since the metal vapor concentration is the largest at the junction of the base 7 and the insulator 2, the discharge form at this time is mainly surface discharge along the surface of the insulator 2, and the discharge channel is Figure 3 L1 in the formula, the ablation site is concentrated at the junction of the base 7 and the insulator 2; with the accumulation of the number of discharges, there is a certain concentration of metal vapor between the reinforcing body 8 and the anode 3, and at the same time, the arc tends to select the smallest arc distance, so the present application sets the shortest distance between the anode 3 and the cathode 1 to be between the anode 3 and the reinforcing body 8, and the shortest distance is smaller than the length of the bevel 6, so as to establish a discharge channel L2 between the reinforcing body 8 and the anode 3, thereby making the ablation site transfer from the junction of the base 7 and the insulator 2 to the reinforcing body 8, so as to increase the ablation area and prolong the service life of the thruster.

[0031] The positional relationship of the cathode 1, the insulator 2 and the anode 3 can be that the cathode 1, the insulator 2 and the anode 3 are arranged in turn from inside to outside, or the anode 3, the insulator 2 and the cathode 1 are arranged in turn from inside to outside, as a preferred embodiment of the present application, the cathode 1, the insulator 2 and the anode 3 are arranged in turn from inside to outside, that is, the inside of the insulator 2 is provided with a first through hole 4, the inside of the anode 3 is provided with a second through hole 5, the cathode 1 is arranged in the first through hole 4, the insulator 2 is arranged in the second through hole 5, and the position where the base 7 intersects with the bevel 6 is lower than the position where the anode 3 intersects with the bevel 6, and the shortest distance between the anode 3 and the cathode 1 is a horizontal line segment passing through the intersection point of the bevel 6 and the anode 3, since the top surface of the base 7 is lower than the highest point of the bevel 6, the horizontal line segment passing through the intersection point of the bevel 6 and the anode 3 must intersect with the reinforcing body 8, so that in the gas discharge stage, the ablation site can be transferred from the junction of the base 7 and the bevel 6 to the reinforcing body 8.

[0032] If the reinforcing body 8 is an inverted cone with a large top and a small bottom, the shortest distance between the anode 3 and the cathode 1 is the horizontal line segment passing the top surface of the reinforcing body 8. Since the metal vapor concentration and temperature are both low at the top surface of the reinforcing body 8, the arc is not easy to break through the gas to discharge, so the reinforcing body 8 in this shape cannot effectively increase the ablation area of the cathode 1. In addition, if the bottom surface of the inverted cone structure is ablated, it will further reduce the size of the bottom surface of the reinforcing body 8, which is not conducive to maintaining the structural integrity of the cathode 1. Therefore, the reinforcing body 8 is set to be a non-inverted cone structure in the present application. If the reinforcing body 8 is a cylinder, it has been proved by experiments that after a certain concentration of metal vapor is accumulated between the cathode 1 and the anode 3, there will be gas discharge between the cathode 1 and the anode 3, but the main discharge form is still surface discharge along the surface of the insulator 2, that is, the reinforcing body 8 in the shape of a cylinder also has limited effect on increasing the ablation area of the cathode 1. Therefore, as a preferred embodiment of the present application, the reinforcing body 8 is in the shape of a cone with a small top and a large bottom, so that the shortest distance between the anode 3 and the cathode 1 is the line segment parallel to the horizontal line in the line connecting the outer surface of the reinforcing body 8 and the anode 3. Since the closer to the bottom surface of the reinforcing body 8, the shorter the horizontal line connecting the reinforcing body 8 and the anode 3, the line segment with the shortest distance between the reinforcing body 8 and the anode 3 is relatively close to the intersection position of the base 7 and the inclined surface 6, the concentration of metal vapor is high, and the temperature is also relatively high, so the arc is easy to break through the gas to discharge to form a discharge channel L2, thereby making the arc ablate the reinforcing body 8 first during the gas discharge stage. When the shortest distance between the outer surface of the reinforcing body 8 and the anode 3 is less than the shortest distance between the outer surface of the base 7 and the anode 3, the base 7 is ablated in turn. When the shortest distance between the base 7 and the anode 3 is less than the shortest distance between the reinforcing body 8 and the anode 3, the reinforcing body 8 is ablated in turn. With the arc ablated back and forth between the reinforcing body 8 and the base 7, the diameters of the two gradually decrease, so that the part of the cathode 1 on the insulator 2 gradually tends to be a cylinder 16 with a small diameter (see Figure 3 ), until the cylinder 16 with a small diameter is ablated to the extent that it cannot maintain its integrity and causes the thruster to fail to discharge. In summary, the present application sets the reinforcing body 8 in the shape of a truncated cone on the base 7, which can greatly increase the ablation area and prolong the service life and total impulse of the thruster. As a preferred embodiment of the present application, the base 7 is in the shape of a cylinder. In addition, in order to increase the ablation area, the width of the bottom of the reinforcing body 8 should be increased as much as possible. In order to improve the connection firmness between the base 7 and the reinforcing body 8, the base 7 and the reinforcing body 8 are set to be integrally formed.

[0033] In addition, since the inter-electrode ions generated by the discharge between the cathode 1 and the anode 3 flow upward to be ejected from the thruster, the position where the inclined surface 6 intersects with the cathode 1 is set to be lower than the position where the inclined surface 6 intersects with the anode 3, which can also be understood as that the top surface of the insulator 2 in Figure 4 is originally a horizontal surface that is inwardly recessed to form the inclined surface 6 (see Figure 5), and the collision probability of the inter-electrode ions with the insulator 2 is increased, and the metal ions colliding on the surface of the insulator 2 are more likely to lose energy and become metal atoms to deposit on the surface of the insulator 2 to form a new conductive coating, thereby reducing the impedance between the anode 3 and the cathode 1.

[0034] Since the probability of the inter-electrode ions colliding with the insulator 2 is related to the angle α between the inclined surface 6 and the horizontal surface, when the angle α is small, the probability of the inter-electrode ions colliding with the insulator 2 is high, but the discharge channel tends to be along the surface of the insulator 2, resulting in that the conductive coating on the surface of the insulator 2 is seriously ablated; when the angle α is large, the probability of the inter-electrode ions colliding with the insulator 2 is low, but the discharge channel tends to be away from the surface of the insulator 2, thereby prolonging the service life of the thruster, and therefore a suitable angle α has a great influence on the deposition effect of the inter-electrode ions, and the relationship between the collision frequency of the inter-electrode ions on the surface of the insulator 2 under different angles α is as shown in Figure 6 , wherein the abscissa X represents the distance between the outer surface of the cathode 1 and the upper surface of the insulator 2, and the ordinate represents the collision frequency of the atoms with the wall surface (i.e. the inner surface of the inclined surface 6), and the higher the collision frequency represents the greater the ion density on the surface of the insulator 2, 9 represents the relationship curve when α is 15°, and 10 represents the relationship curve when α is 30°, and it can be seen that compared with the 30° concave insulator 2 (i.e. α is 30°), when the 15° concave insulator 2 (i.e. α is 15°) is used for discharging, the coverage of the inter-electrode ions on the surface of the insulator 2 is more uniform, and therefore the application preferably adopts the angle α between the inclined surface 6 and the horizontal direction as 15°.

[0035] As shown in Figure 2 , the cathode 1 comprises a reinforcing body 8, a base body 7 and a support structure 11, the support structure 11 is located on the side of the base body 7 away from the reinforcing body 8, the outer contour of the support structure 11 is matched with the inner contour of the first through hole 4, and preferably, the support structure 11 is a cylindrical structure with an outer diameter matched with the inner diameter of the first through hole 4, and an outer thread is further arranged at the end of the support structure 11 away from the base body 7, so as to facilitate the assembly with other components. In order to improve the compactness of the structure and improve the contact stability of the insulator 2 with the cathode 1 and the insulator 2 with the anode 3, the application sets that the contact surfaces between the insulator 2 and the cathode 1 and between the insulator 2 and the anode 3 are all planes, and the insulator 2 is an insulating ceramic.

[0036] As shown in Figure 1 , the application is provided with an outer shell 12 outside the anode 3, the inner part of the outer shell 12 is provided with a third through hole 13 for accommodating the anode 3, the anode 3 is arranged in the third through hole 13, and the top surface of the anode 3 and the top surfaces of the insulator 2 and the cathode 1 arranged in the anode 3 all do not protrude out of the third through hole 13, so that the outer shell 12 plays a role in protecting the anode 3, the insulator 2 and the cathode 1. The outer part of the outer shell 12 is provided with a permanent magnet 14 for accelerating plasma, and in the height direction, i.e. Figure 1In the direction of the arrow shown in the figure, the permanent magnet 14 covers at least all of the inclined surface 6 on the insulator 2, so that the permanent magnet 14 can accelerate all the plasma generated between the anode 3 and the cathode 1. The bottom of the shell 12 is also provided with a base 15, which is detachably connected with the shell 12. As a preferred embodiment of the present application, the base 15 is connected with the shell 12 by means of bolts and nuts.

[0037] It is to be understood that the application is not limited to the details of the above-exemplified embodiments and can be implemented in various other forms without departing from the spirit or essential characteristics of the application. The embodiments should therefore be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein and are part of the application.

Claims

1. A micro-cathode arc thruster characterized by: The cathode, the insulator and the anode are arranged in order from inside to outside, one end of the inclined surface is connected with the base, the other end of the inclined surface is connected with the anode, the shortest distance between the anode and the cathode is located between the anode and the reinforcing body, and the shortest distance is smaller than the length of the inclined surface. The reinforcing body is a conical structure with a small top and a large bottom. The base and the reinforcing body are integrally formed.

2. The micro-cathode arc thruster of claim 1, wherein: The angle between the inclined surface and the horizontal direction is 15-30 degrees.

3. The micro-cathode arc thruster of claim 2, wherein: The end of the base away from the reinforcing body is provided with a support structure, and the end of the support structure away from the base is provided with an external thread.

4. The micro-cathode arc thruster of claim 3, wherein: The anode is provided with an outer shell, the inner part of the outer shell is provided with a third through hole for accommodating the anode, the anode is located in the third through hole, and the top surface of the anode and the top surfaces of the insulator and the cathode located in the anode do not protrude out of the third through hole.

5. The micro-cathode arc thruster of claim 1, wherein: The outer part of the outer shell is provided with a permanent magnet for accelerating plasma, and in the height direction, the permanent magnet at least covers the inclined surface.

6. The micro-cathode arc thruster of claim 1, wherein: The bottom of the outer shell is provided with a base, and the base is detachably connected with the outer shell.

7. The micro-cathode arc thruster of claim 6, wherein: ​ 8. The micro-cathode arc thruster of claim 7, wherein: ​

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