A microcathodic arc thruster cathode injection device

Abstract

The application discloses a micro-cathode arc thruster cathode injection device, which comprises a core guide shell, a core, a solenoid, a permanent magnet, a propelling column, an insulating protective shell and a double-end clamp; one end of the core is located in the core guide shell, and the other end of the core extends out of the core guide shell and is wound with the solenoid; the permanent magnet is opposite to the core and located at the tail end of the core; the head end of the propelling column is connected with the permanent magnet, and the tail end of the propelling column extends into the insulating protective shell and is opposite to the double-end clamp; the cathode sequentially passes through the center through hole of the protective shell, the core, the permanent magnet and the propelling column, and is clamped and fixed by the double-end clamp; the tail end of the cathode is opposite to the conductive carbon film; the application compensates the loss caused by cathode ablation in the working process by adding cathode material, prolongs the service life of the cathode and further prolongs the service life of the thruster; the working time of the micro-cathode arc thruster is greatly prolonged, and the economic benefit of the micro-cathode arc thruster is increased.

Description

Technical Field

[0001] This invention relates to the field of electric propulsion technology, and in particular to a cathode injection device for a microcathode arc thruster. Background Technology

[0002] Microcathode arc thrusters are an emerging electromagnetic propulsion method, promising for orbit maintenance of various microsatellites. They offer advantages such as high specific impulse, simple structure, low power consumption, and the elimination of the need for a gas supply system.

[0003] The propulsion principle of the microcathode arc thruster is:

[0004] 1. Ignition is achieved by ionizing conductive carbon paint through short-term high-voltage pulse discharge between the anode and cathode to generate plasma and form a circuit.

[0005] 2. The deflection of particles by a magnetic field generates an outward jet of thrust. After successful ignition, plasma is generated at the outer anode, which acts as a corrosion electrode. Both positively charged metal ions and negatively charged electrons produced by ionization are ejected, eliminating the need for an additional electron gun to balance the charge and simplifying the complex structure.

[0006] 3. Observable rotation of the cathode discharge point. At this time, corrosion occurs on the outer annular cathode. At the same time, under the influence of the magnetic field, the rotation of the cathode discharge point, also known as the cathode spot, can bring great benefits: making the corrosion more uniform, giving it a longer service life, and allowing it to maintain its shape to a greater extent to ensure the stability of its discharge characteristics.

[0007] However, some problems still exist in practical applications, especially:

[0008] 1. Due to its small size, the parts are prone to relative movement, which can cause installation difficulties and structural instability.

[0009] 2. Because extremely high voltage pulses are generated between the anode and cathode, discharges may occur between some structures, which may lead to the melting of the thruster structure.

[0010] 3. Because the cathode corrodes while other components remain intact during operation, the lifespan of the thruster is largely limited by the lifespan of the cathode. Summary of the Invention

[0011] The purpose of this invention is to provide a cathode injection device for a microcathode arc thruster to solve the problems existing in the prior art. This device can stably clamp and push the cathode, increase the working time of the microcathode thruster, and increase its economic benefits.

[0012] To achieve the above objectives, the present invention provides the following solution:

[0013] This invention provides a cathode injection device for a micro cathode arc thruster, comprising an iron core guide shell, an iron core, a solenoid, a permanent magnet, a thrust column, an insulating protective shell, and a double-headed clamp;

[0014] One end of the iron core is located inside the iron core guide shell, and the other end of the iron core extends out of the iron core guide shell and is wound with the solenoid. The solenoid can be used to input an adjustable current.

[0015] The permanent magnet is opposite to the iron core and located at the tail end of the iron core. The first end of the push column is connected to the permanent magnet, and the tail end of the push column extends into the insulating protective shell. The insulating protective shell contains, from the first end to the tail end, a spring cavity, a guide cavity, and a double-headed clamp limiting cavity. A spring is provided in the spring cavity. The spring is sleeved outside the push column, and the two ends of the spring abut against the limiting block provided on the push column and the bottom of the spring cavity, respectively. The tail end of the push column passes through the spring cavity and extends into the guide cavity. One end of the double-headed clamp is located in the guide cavity opposite to the tail end of the push column, and the other end of the double-headed clamp is adapted to the double-headed clamp limiting cavity. A conductive carbon film connected to the anode is installed at the tail end opening of the insulating protective shell.

[0016] The cathode passes sequentially through the central through hole of the protective shell, the iron core, the permanent magnet, and the propulsion column, and is held and fixed by the double-headed clamp. The tail end of the cathode is opposite to the conductive carbon film.

[0017] Preferably, a second spring is connected between the iron core and the iron core guide shell.

[0018] Preferably, the solenoid is connected to a power source, and a sliding rheostat is provided in the circuit between the solenoid and the power source. The sliding rheostat is used to change the magnitude of the current flowing into the solenoid.

[0019] Preferably, a rubber pad is provided on the end face of the permanent magnet opposite to the iron core.

[0020] Preferably, the double-headed clamp includes two symmetrically arranged clamping blocks, with the cathode clamped between the two clamping blocks. The head of the double-headed clamp is a cone shape with a diameter that gradually increases towards the push column, and the inner wall of the head of the double-headed clamp is flared. The middle part of the double-headed clamp is cylindrical. The head and middle part of the double-headed clamp are located in the guide cavity, and the tail part of the double-headed clamp is located in the double-headed clamp limiting cavity. The double-headed clamp limiting cavity includes a conical cavity at the front end and a cylindrical cavity at the rear end. The outer contour of the tail part of the double-headed clamp is adapted to the double-headed clamp limiting cavity, and a spring is sleeved on the outside of the middle part of the double-headed clamp.

[0021] Preferably, the diameter of the central through hole through which the cathode passes in the core guide shell, the core, the rubber pad, and the permanent magnet is greater than the diameter of the cathode.

[0022] Preferably, the propulsion column is made of insulating material.

[0023] The present invention achieves the following beneficial technical effects compared to the prior art:

[0024] The cathode injection device for the microcathode arc thruster provided by this invention can firmly clamp and push the cathode for injection. The cathode contacts the insulating material, preventing discharge between the device structures, ensuring the overall device structure is stable and reliable. Adding cathode material compensates for losses caused by cathode erosion during operation, extending the cathode's lifespan and thus the thruster's lifespan. The input thrust time is controlled by a PPU system (where IGBTs are switches, specifically insulated-gate bipolar transistors, whose opening and closing are indicated by the input signal. When closed, the power supply charges the inductor; when open, the inductor discharges, thus applying a high-voltage alternating current between the anode and cathode). The input current is controlled by a sliding rheostat, thereby controlling the input thrust and thus the lower limit of the cathode material input. A clamping system is designed at the feed channel, utilizing its clamping mechanical characteristics to control the upper limit of the cathode material input while simultaneously fixing the cathode. This allows the microcathode thruster to operate for a longer period even with significant cathode loss. Compared to existing technologies, this invention significantly extends the operating time of the microcathode arc thruster and increases its economic benefits. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the cathode injection device of the micro cathode arc thruster in this invention;

[0027] Figure 2 This is a schematic diagram of the structure of the double-headed clamp in this invention;

[0028] Figure 3 This is a schematic diagram of the clamping block in the present invention;

[0029] Figure 4 This is a side view of the clamping block in this invention;

[0030] Figure 5 This is a circuit diagram of the solenoid in this invention;

[0031] In the diagram: 1-Iron core guide shell, 2-Iron core, 3-Solenoid, 4-Permanent magnet, 5-Rubber pad, 6-Propeller column, 7-Insulating protective shell, 8-Double-headed clamp, 9-Spring 1, 10-Conductive carbon film, 11-Anode, 12-Spring 2, 13-Sliding rheostat, 14-Head, 15-Middle, 16-Tail, 17-Cathode, 18-Spring 3. Detailed Implementation

[0032] 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, and 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.

[0033] The purpose of this invention is to provide a cathode injection device for a microcathode arc thruster to solve the problems existing in the prior art.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] The microcathode arc thruster cathode injection device in this embodiment, such as Figures 1-5 As shown, it includes an iron core guide shell 1, an iron core 2, a solenoid 3, a permanent magnet 4, a push column 6, an insulating protective shell 7, and a double-headed clamp 8;

[0036] One end of the iron core 2 is located inside the iron core guide shell 1, and the other end of the iron core 2 extends out of the iron core guide shell 1 and is wound with a solenoid 3. The solenoid 3 can be used to input an adjustable current.

[0037] The permanent magnet 4 is opposite to the iron core 2 and located at the tail end of the iron core 2. The first end of the push column 6 is connected to the permanent magnet 4, and the tail end of the push column 6 extends into the insulating protective shell 7. The insulating protective shell 7 contains a spring cavity, a guide cavity, and a double-headed clamp limiting cavity from the first end to the tail end. A spring 9 is provided in the spring cavity. The spring 9 is sleeved on the outside of the push column 6, and the two ends of the spring 9 abut against the limiting block provided on the push column 6 and the bottom of the spring cavity, respectively. The tail end of the push column 6 passes through the spring cavity and extends into the guide cavity. One end of the double-headed clamp 8 is located in the guide cavity opposite to the tail end of the push column 6, and the other end of the double-headed clamp 8 is adapted to the double-headed clamp limiting cavity. A conductive carbon film 10 connected to the anode 11 is installed at the opening of the tail end of the insulating protective shell 7.

[0038] The cathode 17 passes through the central through hole of the protective shell, iron core 2, permanent magnet 4, and push column 6 in sequence, and is held and fixed by the double-headed clamp 8. The tail end of the cathode 17 is opposite to the conductive carbon film 10.

[0039] In this specific embodiment, a second spring 12 is connected between the iron core 2 and the iron core guide shell 1. The second spring 12 is used to pull back the popped-out iron core 2.

[0040] In this specific embodiment, the solenoid 3 is connected to a power source, and a sliding rheostat 13 is provided on the circuit between the solenoid 3 and the power source. The sliding rheostat 13 is used to change the magnitude of the current flowing into the solenoid 3.

[0041] In this specific embodiment, a rubber pad 5 is provided on the end face of the permanent magnet 4 opposite to the iron core 2.

[0042] In this specific embodiment, the double-headed clamp 8 includes two symmetrically arranged clamping blocks, with the cathode 17 clamped between the two clamping blocks. The head 14 of the double-headed clamp 8 is a cone shape with a diameter that gradually increases towards the push column 6, and the inner wall of the head of the double-headed clamp 8 is flared. The middle part of the double-headed clamp 8 is cylindrical. The head 14 and the middle part 15 of the double-headed clamp 8 are located in the guide cavity, and the tail 16 of the double-headed clamp 8 is located in the double-headed clamp limiting cavity. The double-headed clamp limiting cavity includes a conical cavity at the front end and a cylindrical cavity at the rear end. The outer contour of the tail 16 of the double-headed clamp 8 is adapted to the double-headed clamp limiting cavity, and a spring 18 is sleeved on the outside of the middle part 15 of the double-headed clamp 8.

[0043] The diameter of the central through-hole through which the cathode 17 passes—the iron core guide shell 1, the iron core 2, the rubber pad 5, and the permanent magnet 4—is larger than the diameter of the cathode 17. The propulsion column 6 is made of insulating material. The length of the cathode 17 can be selected according to the lifespan of the front-end discharge chamber. The entire system adopts a through-hole design, and the cathode 17 does not contact the protective shell, solenoid 3, rubber pad 5, or permanent magnet 4. Since the propulsion column 6 is made of insulating material, the length of the cathode 17 is not limited.

[0044] The working principle of the microcathode arc thruster cathode injection device in this invention is as follows:

[0045] When cathode material injection is required, the switch on the solenoid 3 circuit is closed, and the current through the solenoid 3 induces a magnetic field, which causes the iron core 2 to be attracted by the permanent magnet 4. Overcoming the tension of the second spring 12, it hits the rubber pad 5 behind the permanent magnet 4. The permanent magnet 4 is pushed by the thrust to drive the push column 6. The push column 6 overcomes the elasticity of the first spring 9 and squeezes the double-headed clamp 8. The double-headed clamp 8 moves forward, and the third spring 18 on the double-headed clamp 8 is compressed. The head 14 and the tail 16 of the double-headed clamp 8 are both designed to be inclined. Therefore, the head 14 near the end of the push column is squeezed by the third spring 18, and the tail 16 away from the push column 6 opens. At the same time, the double-headed clamp 8 moves forward, and the head 14 near the push column 6 clamps the cathode 17 and drives it forward.

[0046] When the push is finished, the branch switch of solenoid 3 is turned off, solenoid 3 returns to its original position under the action of spring 12, push column 6 returns to its original position under the action of spring 9, and double-headed clamp 8 also moves backward under the elastic force of spring 9. The head 14 near the push column 6 is released and the tail 16 away from the push column 6 is clamped, fixing the cathode 17 so that it cannot move axially.

[0047] According to the design requirements of the thruster, the present invention changes the excitation current of the solenoid 3 by changing the resistance of the sliding rheostat 13R2, thereby changing the thrust, so as to ensure that the length of the cathode 17 material injected each time meets the requirements of the discharge chamber.

[0048] The formula for calculating the excitation magnetic field is:

[0049]

[0050] B = μ0 × H

[0051] Where H is the magnetic field strength; n is the number of turns of the excitation coil; I is the excitation current; l is the effective magnetic path length; B is the magnetic flux density; and u0 is the free permeability.

[0052] The number of turns and the current amplitude here are designed based on the degree of loss of the cathode 17 in the discharge chamber.

[0053] This invention has illustrated its principles and implementation methods using specific examples. The descriptions of these embodiments are merely illustrative of the method and its core ideas; furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the principles of this invention. Therefore, the content of this specification should not be construed as limiting the invention.

Claims

1. A cathode injection device for a microcathode arc thruster, characterized in that: Includes core guide shell, core, solenoid, permanent magnet, push column, insulating protective shell and double-headed clamp; One end of the iron core is located inside the iron core guide shell, and the other end of the iron core extends out of the iron core guide shell and is wound with the solenoid. The solenoid can be used to input an adjustable current. The permanent magnet is opposite to the iron core and located at the tail end of the iron core. The first end of the push column is connected to the permanent magnet, and the tail end of the push column extends into the insulating protective shell. The insulating protective shell contains, from the first end to the tail end, a spring cavity, a guide cavity, and a double-headed clamp limiting cavity. A spring is provided in the spring cavity. The spring is sleeved outside the push column, and the two ends of the spring abut against the limiting block provided on the push column and the bottom of the spring cavity, respectively. The tail end of the push column passes through the spring cavity and extends into the guide cavity. One end of the double-headed clamp is located in the guide cavity opposite to the tail end of the push column, and the other end of the double-headed clamp is adapted to the double-headed clamp limiting cavity. A conductive carbon film connected to the anode is installed at the tail end opening of the insulating protective shell. The cathode passes sequentially through the central through hole of the protective shell, the iron core, the permanent magnet, and the propulsion column, and is held and fixed by the double-headed clamp. The tail end of the cathode is opposite to the conductive carbon film.

2. The microcathode arc thruster cathode injection device of claim 1, wherein: A spring is connected between the iron core and the iron core guide shell.

3. The microcathode arc thruster cathode injection device of claim 1, wherein: The solenoid is connected to a power source, and a sliding rheostat is installed in the circuit between the solenoid and the power source. The sliding rheostat is used to change the magnitude of the current flowing into the solenoid.

4. The cathode injection device for the microcathode arc thruster according to claim 1, characterized in that: A rubber pad is provided on the end face of the permanent magnet opposite to the iron core.

5. The cathode injection device for the microcathode arc thruster according to claim 1, characterized in that: The dual-head clamp includes two symmetrically arranged clamping blocks, with the cathode clamped between the two clamping blocks. The head of the dual-head clamp is a cone shape with a diameter that gradually increases towards the push column, and the inner wall of the head of the dual-head clamp is flared. The middle part of the dual-head clamp is cylindrical. The head and middle part of the dual-head clamp are located in the guide cavity, and the tail part of the dual-head clamp is located in the dual-head clamp limiting cavity. The dual-head clamp limiting cavity includes a conical cavity at the front end and a cylindrical cavity at the rear end. The outer contour of the tail part of the dual-head clamp is adapted to the dual-head clamp limiting cavity. A spring is sleeved on the outside of the middle part of the dual-head clamp.

6. The microcathode arc thruster cathode injection device of claim 4, wherein: The diameter of the central through-hole through which the cathode passes in the core guide shell, the core, the rubber pad, and the permanent magnet is larger than the diameter of the cathode.

7. The microcathode arc thruster cathode injection device of claim 1, wherein: The propulsion column is made of insulating material.

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