Pulsed electrothermal space propulsion device

Abstract

The application provides a pulse electric heating type space propulsion device, which adopts a cathode emission based electron concentrated bombardment on a central area of a metal working substance surface, and the working substance material surface is further heated and decomposed to generate vapor discharge to generate thrust. The configuration provided by the application omits a pulse ignition power supply in an existing space propulsion device such as a pulse plasma electric propulsion, and a metal anode directly serves as a working substance, and a separate propellant and its storage and supply system are not needed, so that the structure is further simplified and miniaturization is easy to realize.

Description

Technical Field

[0001] This application relates to the field of space electric propulsion technology, specifically to a pulsed electrothermal space propulsion device. Background Technology

[0002] In recent years, micro-space vehicles (such as CubeSats) have shown great promise in communication, Earth observation, resource and mineral development, and disaster prevention and mitigation due to their advantages such as low development cost, short development cycle, light weight, ability to launch multiple satellites on a single launch, and ease of networking. Against this backdrop, universities and enterprises have been developing and launching experimental and commercial satellites, and conducting space experiments and on-orbit verification.

[0003] With the launch volume of micro-space vehicles increasing year by year, extending their on-orbit service time to further reduce satellite costs has become a crucial issue in their development. Due to atmospheric drag, low-Earth orbit (LEO) vehicles struggle to maintain a consistent attitude and orbit, and vehicles without propulsion systems typically only have a few months of on-orbit service time. Equipping them with propulsion systems can significantly extend their on-orbit service time. Furthermore, considering space power limitations and the need for precise thrust, using micro-propulsion systems for attitude and orbit adjustments is an effective way to improve the on-orbit lifespan and payload capacity of micro-space vehicles.

[0004] Currently, micro-propulsion systems with power outputs below 100 watts mainly fall into two categories. The first category consists of miniaturized versions of medium-to-high power propulsion systems. The second category comprises electric propulsion devices inherently characterized by low power and miniaturization, such as pulsed plasma thrusters. Ablative pulsed plasma thrusters (PPTs), using polytetrafluoroethylene (PTFE) as a solid propellant, offer advantages such as stable and easily stored propellant, no need for tanks or piping, and ease of integration with spacecraft. The thrust generated by a single pulsed discharge remains relatively stable, and pulse control facilitates precise manipulation of micro and nanosatellites. Within the power range below 200W, PPT-based propulsion systems typically maintain high specific impulse at low power consumption, making them suitable for various space missions, including attitude control, orbit transfer, position holding, drag compensation, and precise formation flying for microsatellite platforms.

[0005] Although pulsed plasma electric propulsion is a good option, the large pulse ignition power source (ignition circuit and spark plug) in the PPU is not conducive to system miniaturization, and there is an urgent need to develop new propulsion devices to meet the power requirements of micro-spacecraft applications. Summary of the Invention

[0006] To meet the propulsion technology requirements of micro-space vehicles and overcome the shortcomings of existing propulsion devices, this application aims to provide a pulsed electrothermal space propulsion device. This device employs electrons emitted from a cathode to bombard a metal anode working fluid, causing the surface of the working fluid material to heat and decompose, generating vapor that is then released to produce thrust. The configuration proposed in this application eliminates the pulsed ignition power source found in existing space propulsion devices such as pulsed plasma electric propulsion. Furthermore, the metal anode directly serves as the working fluid, eliminating the need for a separate propellant and its supply system, further simplifying the structure and facilitating miniaturization. The technical solution adopted in this application is as follows:

[0007] A pulsed electrothermal space propulsion device includes a cylinder, at least one emitting electrode, a metallic working fluid, a permanent magnet, a capacitor, a high-voltage power supply, a first switch, and a second switch.

[0008] The cylinder is a cylindrical body with a central cavity, which serves as the discharge cavity of the space propulsion device.

[0009] Permanent magnets are used to provide magnetic confinement so that electrons emitted by the emitting electrode can concentrate and bombard the central region of the metal working surface.

[0010] The metallic working fluid and the emitting electrode are installed inside the cylinder;

[0011] A high-voltage power supply is used to charge the capacitor pulse to a high voltage, so that an electric field is formed between the metal working medium and the emitting electrode, enabling electron emission from the needle-shaped end of the emitting electrode.

[0012] The metallic working medium is used as the anode of the discharge cavity, which is constructed of a cylinder.

[0013] Furthermore, the electrons emitted by the emitting electrode generate electron cyclotron motion under the constraint of the magnetic field lines formed by the permanent magnet, and are accelerated toward the surface of the metal working material under the combined action of the electric field. The electron cyclotron motion is Larmor cyclotron motion.

[0014] Furthermore, the permanent magnet is attached to the surface of the outer shell of the cylinder and is made of annular ferrite permanent magnet; one side of the permanent magnet is the S pole and the other side is the N pole, and the magnetic field lines formed show a layout that is concentrated in the central area of ​​the metal working surface and diffuses towards the N pole.

[0015] Furthermore, the permanent magnet provides a magnetic field of 0.1 to 0.2 T to confine the movement of electrons.

[0016] Furthermore, the metal working fluid is disc-shaped, with a diameter consistent with the inner diameter of the cylinder. It is installed on one side of the cylinder and connected to the positive terminal of a capacitor outside the cylinder via a wire and a first switch.

[0017] Furthermore, the diameter of the metal working fluid is 30mm to 50mm, the thickness is 5mm to 8mm, and the material of the metal working fluid is galvanized sheet.

[0018] Furthermore, the needle-like end of the emitting electrode is made of carbon nanotube material with a low field emission threshold electric field strength.

[0019] Furthermore, the number of emission electrodes is seven, which together with the array support and guide rod form an array of electron emission electrodes, which are installed inside the cylinder.

[0020] Furthermore, the array support is composed of a metal ring and three metal rods evenly distributed and intersecting inside the ring. The three metal rods divide the metal ring into six equal sectors. Six emission electrodes are installed at the six intersection points of the three metal rods and the metal ring. The intersection point of the three metal rods is the center of the metal ring, and one emission electrode is installed at the center of the ring. The emission electrode is perpendicular to the plane of the metal ring.

[0021] One end of the guide rod located on the plane of the array support is connected to the intersection of three metal rods, and the other end passes through a metal ring and is connected to the negative terminal of a capacitor via a wire.

[0022] Furthermore, the plane of the array support is parallel to the metal working medium, the tip of the emitting electrode faces the metal working medium, and the distance between the tip of the emitting electrode and the surface of the metal working medium is 1-2 mm.

[0023] Through the embodiments of this application, the following technical effects can be obtained: Compared with existing domestic and foreign solutions, the novel pulsed electrothermal power configuration based on electron bombardment of metal anode proposed in this application can realize the start-up operation mode of pulseless ignition power supply, and the basic technology is relatively mature, and the structure is simple and easy to miniaturize. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram illustrating the composition of the pulsed electrothermal space propulsion device of this application;

[0026] Figure 2 This is a schematic diagram illustrating the composition principle of an array-type electron emission electrode configuration.

[0027] Figure label:

[0028] 1. Cylinder, 2. Emitter electrode, 3. Metal working fluid, 4. Permanent magnet, 5. Capacitor, 6. High voltage power supply, 7. First switch and 8. Second switch. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] Figure 1 This is a schematic diagram illustrating the composition of the pulsed electrothermal space propulsion device of this application. The pulsed electrothermal space propulsion device includes a cylinder, at least one emitting electrode, a metallic working fluid, a permanent magnet, a capacitor, a high-voltage power supply, a first switch, and a second switch.

[0031] The cylinder is a cylindrical body with a central cavity, which serves as the discharge cavity of the space propulsion device.

[0032] Permanent magnets are used to provide magnetic confinement so that electrons emitted by the emitting electrode can concentrate and bombard the central region of the metal working surface.

[0033] The metallic working fluid and the emitting electrode are installed inside the cylinder;

[0034] A high-voltage power supply is used to charge the capacitor pulse to a high voltage, so that an electric field is formed between the metal working medium and the emitting electrode, enabling electron emission from the needle-shaped end of the emitting electrode.

[0035] The metallic working medium is used as the anode of the discharge cavity, which is constructed of a cylinder.

[0036] In the above scheme, the metal anode and working fluid are integrated into one design, eliminating the need for a storage and supply system.

[0037] The cylinder is closed on the left and open on the right, and is made of high-temperature resistant alumina ceramic insulation material;

[0038] The permanent magnet is attached to the surface of the outer shell of the cylinder and is a ring-shaped ferrite permanent magnet;

[0039] The permanent magnet has an S pole on the left and an N pole on the right, and the magnetic field lines formed are concentrated in the central area of ​​the metal working material surface and diffuse towards the N pole.

[0040] The permanent magnet provides a magnetic field of 0.1 to 0.2 T to confine the movement of electrons;

[0041] The metal working fluid is disc-shaped, with a diameter consistent with the inner diameter of the cylinder. It is installed on the left side of the cylinder and connected to the positive terminal of a capacitor outside the cylinder via a wire and a first switch.

[0042] The diameter of the metal working fluid is 30mm to 50mm and the thickness is 5mm to 8mm. The material of the metal working fluid is galvanized sheet. This is because zinc is easier to be heated by bombardment to generate vapor than other metals (which require a lower temperature for the same vapor pressure).

[0043] The needle-like end of the emitting electrode is made of carbon nanotube material with a low field emission threshold electric field strength.

[0044] like Figure 1 As shown, according to the emission IV curve of carbon nanotubes in the published literature "Field Emission Characteristics of Carbon Nanotubes" ("Journal of Semiconductors", Vol. 24, Supplement, 2003), in order to obtain a high field emission current (mA level), the electric field strength needs to reach 5kV / mm or above, and the high-voltage power supply output needs to reach 10kV. When the second switch is closed, the high-voltage power supply pulse-charges the capacitor to a high voltage; when the first switch is closed, the high voltage across the capacitor forms an electric field between the metal working medium and the emitting electrode and is released, realizing cathode electron emission and bombarding the metal working medium to generate vapor discharge;

[0045] This application employs a pulsed electrothermal space propulsion configuration based on electron bombardment of a metal anode, where the metal working fluid is used as the anode of a discharge cavity composed of a cylinder. To effectively concentrate electron bombardment on the surface region of the metal working fluid, the electron motion needs to be controlled and constrained. In this application, electrons emitted by the emitting electrode undergo electron cyclotron motion under the constraint of the magnetic field lines formed by the permanent magnet, and are accelerated towards the surface of the metal working fluid under the combined action of the electric field.

[0046] The electron cyclotron motion is a Larmor cyclotron motion with a radius r. c Represented as:

[0047] r c =m e v / qB

[0048] because The radius of motion r c The following relationship must be satisfied:

[0049]

[0050] Where m e Let represent the electron mass, q represent the electron charge, B represent the magnetic field strength, and v represent the velocity. Represents electric potential;

[0051] Based on the above relationship and related parameters, the radius of the region where electrons bombard the surface of the metal working material is on the order of millimeters, which is an order of magnitude smaller than the size of the metal working material disk. This indicates that the magnetic field confinement provided by the permanent magnet can concentrate the electrons emitted by the emitting electrode to bombard the central region of the metal working material surface.

[0052] The greatest advantage of this application lies in its design of a metal vapor formation method based on electron bombardment, enabling the start-up operation of a pulse-free ignition power supply. Firstly, an electric field is applied between the metal working medium and the emitting electrode, utilizing the field emission characteristics of the emitting electrode tip material to achieve electron emission, eliminating the need for traditional ignition circuits and spark plugs. Secondly, due to the integrated design of the metal anode and working medium, a storage and supply system is unnecessary, facilitating miniaturization. Thirdly, magnetic confinement causes the emitted electrons to move in a cyclotron-like manner around magnetic field lines towards the metal working medium, thereby constraining the accelerated diffusion process of electrons emitted from the cathode. This application demonstrates that it can concentrate the electron bombardment points on the surface of the metal working medium, promoting the formation of metal vapor.

[0053] Figure 2 This is a schematic diagram illustrating the composition principle of the array-type electron emission electrode configuration of this application. In the technical solution of this application, the array-type electron emission electrode consists of an array support, guide rods, and seven emission electrodes, which are installed inside a cylinder. The array support is composed of a metal ring and three intersecting metal rods evenly distributed within the ring. The three metal rods divide the metal ring into six equal sectors. Six emission electrodes are installed at the six intersection points of the three metal rods and the metal ring. The intersection point of the three metal rods is the center of the metal ring, and one emission electrode is installed at this center, perpendicular to the plane of the metal ring.

[0054] One end of the guide rod located on the plane of the array support is connected to the intersection of three metal rods, and the other end passes through the metal ring and is connected to the negative terminal of the capacitor through a wire;

[0055] The plane of the array support is parallel to the metal working medium, the tip of the emitting electrode faces the metal working medium, and the distance between the tip of the emitting electrode and the surface of the metal working medium is 1-2 mm.

[0056] The array-type electron emission electrode configuration, by employing seven electron emission electrodes, increases the surface area of ​​the electron bombardment metal anode, thereby generating a larger metal vapor power source and contributing to improved propulsion performance.

[0057] In summary, the novel pulsed electrothermal propulsion configuration based on electron bombardment of a metal anode proposed in this application employs an electron bombardment-based metal vapor working fluid formation method. Vapor is generated by the surface of the metal working fluid material through electron bombardment heating and decomposition. This device has a simple structure. Compared with traditional pulsed space propulsion devices such as pulsed plasma electric propulsion, it eliminates the need for a pulse ignition power supply due to the use of field emission principles for electron emission. Furthermore, the integrated design of the metal anode and working fluid eliminates the need for a storage and supply system. In addition, this application proposes a magnetic confinement method for the electron emission bombardment point. This method causes the electrons emitted from the cathode to accelerate in a cyclotron manner, thereby confining the accelerated diffusion process of the cathode-emitted electrons and concentrating the electron bombardment point on the surface of the metal working fluid material, promoting the formation of metal vapor. The array-type electron emission electrode configuration of this application uses multiple electron emission electrodes, thereby increasing the surface area of ​​the electron bombardment of the metal anode, further generating more metal vapor power sources, and improving propulsion performance.

[0058] While specific embodiments of this application have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this application, but all such changes and modifications fall within the scope of protection of this application.

Claims

1. A pulsed electrothermal space propulsion device, characterized in that, The pulsed electrothermal space propulsion device includes a cylinder, at least one emitting electrode, a metallic working fluid, a permanent magnet, a capacitor, a high-voltage power supply, a first switch, and a second switch. The cylinder is a cylindrical body with a central cavity, which serves as the discharge cavity of the space propulsion device. Permanent magnets are used to provide magnetic confinement so that electrons emitted by the emitting electrode can concentrate and bombard the central region of the metal working surface. The permanent magnet is attached to the surface of the outer shell of the cylinder and is made of annular ferrite permanent magnet; one side of the permanent magnet is the S pole and the other side is the N pole, and the magnetic field lines formed show a layout that is concentrated in the central area of ​​the metal working material surface and diffuses towards the N pole. The metallic working fluid and the emitting electrode are installed inside the cylinder; The metal working fluid is disc-shaped, with a diameter consistent with the inner diameter of the cylinder. It is installed on one side of the cylinder and connected to the positive terminal of a capacitor outside the cylinder via a wire and a first switch. The emitting electrode is connected to the negative terminal of the capacitor via a wire, with its tip pointing towards the metal working medium; A high-voltage power supply is used to charge the capacitor pulse to a high voltage, so that an electric field is formed between the metal working medium and the emitting electrode, enabling electron emission from the needle-shaped end of the emitting electrode. The metallic working medium is used as the anode of the discharge cavity, which is constructed of a cylinder.

2. The space propulsion device according to claim 1, characterized in that, Electrons emitted by the emitting electrode undergo electron cyclotron motion under the constraint of magnetic field lines formed by the permanent magnet, and are accelerated toward the surface of the metal working material under the combined action of the electric field. The electron cyclotron motion is Larmor cyclotron motion.

3. The space propulsion device according to claim 1, characterized in that, The permanent magnet provides a magnetic field of 0.1~0.2T to confine the movement of electrons.

4. The space propulsion device according to claim 1, characterized in that, The diameter of the metal working medium is 30mm~50mm and the thickness is 5mm~8mm. The material of the metal working medium is galvanized sheet.

5. The space propulsion device according to claim 1, characterized in that, The needle-like end of the emitting electrode is made of carbon nanotube material with a low field emission threshold electric field strength.

6. The space propulsion device according to claim 1, characterized in that, The number of emission electrodes is seven, which together with the array support and guide rod form an array of electron emission electrodes, which are installed inside the cylinder.

7. The space propulsion device according to claim 6, characterized in that, The array support consists of a metal ring and three intersecting metal rods evenly distributed within the ring. The three metal rods divide the metal ring into six equal sectors. Six emission electrodes are installed at the six intersection points of the three metal rods and the metal ring. The intersection point of the three metal rods is the center of the metal ring, and one emission electrode is installed at the center of the ring. The emission electrode is perpendicular to the plane of the metal ring. One end of the guide rod located on the plane of the array support is connected to the intersection of three metal rods, and the other end passes through a metal ring and is connected to the negative terminal of a capacitor via a wire.

8. The space propulsion device according to claim 6 or 7, characterized in that, The plane of the array support is parallel to the metal working medium, the tip of the emitting electrode faces the metal working medium, and the distance between the tip of the emitting electrode and the surface of the metal working medium is 1~2mm.

Images