CN117128150A - Working medium-free miniature thermionic emission device - Google Patents

Working medium-free miniature thermionic emission device Download PDF

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Publication number
CN117128150A
CN117128150A CN202311015101.1A CN202311015101A CN117128150A CN 117128150 A CN117128150 A CN 117128150A CN 202311015101 A CN202311015101 A CN 202311015101A CN 117128150 A CN117128150 A CN 117128150A
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China
Prior art keywords
electron emitter
electron
supporting cylinder
emission device
emitter
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CN202311015101.1A
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Inventor
乔彩霞
张岩
王亚楠
梁伟
李思贝
夏启蒙
祁瑾
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Shanghai Institute of Space Propulsion
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Shanghai Institute of Space Propulsion
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Priority to CN202311015101.1A priority Critical patent/CN117128150A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H—PRODUCING A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H1/00—Using plasma to produce a reactive propulsive thrust
    • F03H1/0093—Electro-thermal plasma thrusters, i.e. thrusters heating the particles in a plasma
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
    • B64G1/00—Cosmonautic vehicles
    • B64G1/22—Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
    • B64G1/40—Arrangements or adaptations of propulsion systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H—PRODUCING A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H1/00—Using plasma to produce a reactive propulsive thrust
    • F03H1/0006—Details applicable to different types of plasma thrusters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H—PRODUCING A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H1/00—Using plasma to produce a reactive propulsive thrust
    • F03H1/0006—Details applicable to different types of plasma thrusters
    • F03H1/0025—Neutralisers, i.e. means for keeping electrical neutrality
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H—PRODUCING A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H1/00—Using plasma to produce a reactive propulsive thrust
    • F03H1/0006—Details applicable to different types of plasma thrusters
    • F03H1/0031—Thermal management, heating or cooling parts of the thruster

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Electron Sources, Ion Sources (AREA)

Abstract

The application provides a working medium-free miniature thermionic emission device, which comprises: the electron emitter comprises an extraction electrode, an electron emitter, a heating assembly, a shielding cover, an insulating connecting piece and a supporting cylinder; the extraction electrode is arranged outside the supporting cylinder, and the electron emitter and the heating component are arranged in the supporting cylinder; the heating component is used for heating the electron emitter to enable the electron emitter to emit hot electron current; the central axis of the electron emitter is arranged corresponding to the extraction hole on the extraction electrode, and a gap exists between the emission end face of the electron emitter and the extraction electrode; the both ends of insulating connecting piece connect respectively the lateral wall of support section of thick bamboo and the inside wall of leading-out pole, and the shield cover sets up in the week side of support section of thick bamboo, has the clearance between shield cover and the support section of thick bamboo. The electron emission device is used as an electron source for a tethered propulsion system, does not need to consume propellant working medium, can greatly improve the performance of the propulsion system, simplifies the system structure, lightens the weight and completes space tasks such as orbit transfer or end-of-life off orbit of a spacecraft.

Description

Working medium-free miniature thermionic emission device
Technical Field
The application relates to the technical field of aerospace propulsion, in particular to a working medium-free miniature thermionic emission device, and especially relates to a working medium-free miniature thermionic emission device of a rope propulsion system.
Background
In the conventional space propulsion technology, both chemical propulsion and electric propulsion are completed by adopting the reaction force of the propellant sprayed backwards. With the increase in the geometric cardinality of space debris and space debris, spacecraft are required to have end-of-life off-orbit functionality. The need for these space propulsion tasks makes the propellant carry-over one of the decisive factors limiting spacecraft orbit maneuver capability and on-orbit life. Therefore, the working medium-free electric power rope propulsion technology without consuming propellant becomes a hot spot for competitive exploration in various countries.
Space tethered propulsion is a novel propulsion technique that cuts a space magnetic field through a conductive flexible tether to generate thrust. The technology utilizes the conductive flexible tether to connect two or more spacecrafts together, current with a certain size and direction is introduced into the conductive tether, a closed loop is formed between the conductive tether and a plasma layer in a space environment, the conductive tether can generate Lorentz force in the geomagnetic field, as shown in figure 2, the Lorentz force can provide thrust for the spacecrafts, and when the Lorentz force is the same as the track speed direction of the system, the track lifting is realized. When the current in the tether is reversed, the generated Lorentz force is opposite to the orbit speed direction of the spacecraft, so that the orbit of the spacecraft can be reduced, and the off-orbit function at the end of the service life is completed.
During in-orbit operation of the space tether propulsion system, electrons of low energy are emitted into the space environment at one end of the tether by means of an electron emission device and coupled with surrounding plasma, while electrons of the space are collected at the other end by means of an electron collection device, so that an electric current is formed in the tether, thereby generating Lorentz force.
The magnitude of the lorentz force corresponds to the equation (1):
wherein F is Lorentz force, B is space geomagnetic field intensity, I is electronic current flowing through the conductive tether, l is conductive tether length, dl is conductive tether infinitesimal length;
wherein the intensity of the geomagnetic field in space is 5×10 -5 ～5×10 -7 Tesla, rope length is generally 1-10 km according to system design, for a specific spacecraft off-orbit task, lorentz force is proportional to electron current, off-orbit time is inversely proportional to electron current, for example, a satellite with the mass of 500kg and orbit height of 350km is off-orbit, if a space rope propulsion system with the length of 2km and the electron current of 20mA is adopted for off-orbit at the end of life, thrust of 1-2 mN can be generated, and the orbit needs to be reduced to the orbit height of 200km for about 1 year, so that the off-orbit task is completed.
At present, the research of space tethered propulsion mostly adopts a hollow cathode of an electric propulsion system as an electron source. The hollow cathode technology is mature, the emission current is large, the electron energy is low, but inert gas working media such as xenon are consumed, a complex storage tank, a valve and a flow control system are required to be configured, and the defects are large power consumption (hundreds of watts), large weight (tens of kilograms) and complex system.
Therefore, there is an urgent need for an electronic current emission device with low power consumption, small size, no working medium, light weight and simple structure, which meets the requirements of functional implementation, service life and reliability of a space tethered propulsion system.
The patent document with the publication number of CN109050994A discloses a working medium-free active controller for the surface potential of an electron emission type spacecraft, which comprises a photocathode, a light source, an outer cylinder body and an extraction electrode, wherein two ends of the outer cylinder body are provided with openings, one end of the outer cylinder body is provided with the transmission type photocathode, the other end of the outer cylinder body is provided with the extraction electrode with a central opening, and the photocathode and the extraction electrode are insulated with the outer cylinder body; the light source is arranged outside the outer cylinder body, and the photocathode generates photoelectrons under the irradiation of the light source; the extraction electrode and the outer cylinder are respectively loaded with positive and negative voltages. The patent document uses photocathodesThe basic principle is that the external light source energy is absorbed by a specific photoelectric material to excite the process of electron emission, and the patent document is applicable to the emission current of nano-to microamperes (10 -9 ～10 -6 A) Application fields of photocells, photomultiplier tubes and the like of range electron current belong to another field of cathode electronics, and reference is made in the following literature: lin Zulun, wang Xiaoju, cathode electronics, national defense industry press, beijing, first edition, month 1 2013, P154; if the space tethered propulsion system adopts photocathodes of the patent document, assuming that the current is microampere, the thrust is in the order of mu N (thousandth) for similar configuration and tasks, the off-track time is about 1000 years (thousands times), if the photocathodes provide electron currents of milliamperes (mA) or even more, the emission size of the photocathodes must be increased to thousands times, or an array of thousands of photocathodes is made to meet the task requirements, and meanwhile, a huge specific light source is required to meet the illumination requirements, which greatly increases the difficulty of the preparation process and makes engineering difficult to realize.
Disclosure of Invention
Aiming at the defects in the prior art, the application aims to provide a working medium-free miniature thermionic emission device.
The application provides a working medium-free miniature thermionic emission device, which comprises: the electron emitter comprises an extraction electrode, an electron emitter, a heating assembly, a shielding cover, an insulating connecting piece and a supporting cylinder;
the electron emitter and the heating component are arranged in the supporting cylinder; the heating component is used for heating the electron emitter to enable the electron emitter to emit hot electron current; the central shaft of the electron emitter is arranged corresponding to the extraction hole on the extraction electrode, and a gap exists between the emission end face of the electron emitter and the extraction electrode;
the both ends of insulating connecting piece are connected respectively the lateral wall of support section of thick bamboo with the inside wall of leading-out pole, the shield cover sets up the week side of support section of thick bamboo, the shield cover with there is the clearance between the support section of thick bamboo.
Preferably, one opening end of the supporting cylinder is positioned in the extraction electrode, and the other opening end of the supporting cylinder is positioned outside the extraction electrode;
the electron emitter is arranged at the opening end of the supporting cylinder, which is positioned in the leading-out electrode, and the power supply connecting end of the heating component extends out of the opening end of the supporting cylinder, which is positioned outside the leading-out electrode.
Preferably, the electron emitter is made of an electron emission material with a low work function;
the electron emitter is any one of the following: oxide emitter, barium tungsten emitter, lanthanum boride emitter.
Preferably, the emission surface of the electron emitter is a spherical concave surface, a circular plane or a polygonal plane.
Preferably, the device also comprises an outgoing power supply and a heating power supply;
the positive electrode of the extraction power supply is connected with the extraction electrode; the negative electrode of the lead-out power supply is respectively connected with the negative electrode of the heating power supply and the negative electrode of the heating component; the positive electrode of the heating power supply is connected with the positive electrode of the heating component.
Preferably, the heating component is a spiral heater, and the configuration is any one of the following: plane single screw, plane double screw, three-dimensional single screw, three-dimensional double screw and three-dimensional single screw structure with variable pitch.
Preferably, the insulating connector is a ceramic insulator.
Preferably, the heater is made of any one of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium, and alloys;
the alloy comprises any two or more of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium.
Preferably, the supporting cylinder is made of any one of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium, and alloys;
the alloy comprises any two or more of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium.
Preferably, the shielding case is made of a strip or foil of any one of the following materials: tantalum, niobium, tantalum-niobium alloys, molybdenum-rhenium alloys, foils, strips.
Compared with the prior art, the application has the following beneficial effects:
1. the thermionic emission device has the advantages of small volume, light weight, low power consumption and capability of emitting electron current of hundred milliamperes, is used as an electron source for a tethered propulsion system, does not need to consume propellant working medium, can greatly improve the performance of the propulsion system, simplifies the system structure, lightens the weight, and completes space tasks such as orbit transfer or end-of-life off orbit of a spacecraft;
2. the application can be used for an electron source of a space rope propulsion system to actively emit electron current of tens milliamperes to hundred milliamperes into a space environment, electrons in a space plasma environment can be collected through electron collection and impact, current with a certain size and direction can be formed in a conductive rope and form a passage with a charged ion layer in the space environment, the conductive rope generates Lorentz force when cutting geomagnetic fields, the Lorentz force can provide thrust for a connected spacecraft, and when the Lorentz force is the same as the track speed direction of the system, the thrust can be provided for the spacecraft without consuming any fuel, so that track lifting is realized; when the current direction in the tether is changed, the induced Lorentz force is opposite to the orbit speed direction of the spacecraft, so that the resistance function of space tether propulsion can be realized, and the orbit of the spacecraft is reduced; therefore, the magnitude and the direction of the thrust generated by the propulsion of the space ropes can be changed by adjusting the magnitude and the direction of the current which is introduced into the ropes, and the thrust is adjusted within a certain range;
3. the device does not need to consume working medium, has simple structure, small volume, light weight and low energy of emitted electronic current, and the electronic current can be actively regulated through heating power and leading-out voltage, so that great economic benefit is brought to a tethered propulsion system;
4. the working medium-free electron source can be used as a neutralizer of a low-power electric thruster (such as an ion, a Hall, a field emission thruster and the like) and is used for plume neutralization of the thruster so as to avoid electrification of a spacecraft;
5. the working medium-free electron source can be used as a plasma contactor for actively controlling the surface potential of spacecrafts such as space stations and the like in space operation, preventing static discharge caused by local charge accumulation on the surface of the spacecrafts, and preventing the safety of the surface materials and key equipment of the spacecrafts from being damaged by spark, ablation and the like caused by the static discharge.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
FIG. 1 is a schematic diagram of a working medium-free miniature thermionic emission device of the present application;
FIG. 2 is a physical schematic of a space tethered propulsion system for use with the present application;
fig. 3 is a schematic diagram of an end surface shape of an electron emitter according to the present application;
FIG. 4 is a configuration view of the heater of the present application;
fig. 5 is a schematic circuit diagram of the present application.
The figure shows:
lead-out electrode 1 shielding case 4
Insulated connector 5 for leading out power supply 101
Heating power supply 102 supports barrel 6
Extraction hole 7 of electron emitter 2
Heating assembly 3
Detailed Description
The present application will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present application, but are not intended to limit the application in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present application.
Example 1:
as shown in fig. 1 to 5, this embodiment provides a working medium-free micro thermionic emission device, including: the electron emitter 2 and the heating component 3 are arranged in the supporting cylinder 6, the heating component 3 is used for heating the electron emitter 2, so that the electron emitter 2 emits hot electron current, a central shaft of the electron emitter 2 corresponds to an extraction hole 7 on the extraction electrode 1, a gap exists between the emission end face of the electron emitter 2 and the extraction electrode 1, two ends of the insulating connecting piece 5 are respectively connected with the outer side wall of the supporting cylinder 6 and the inner side wall of the extraction electrode 1, the shielding cover 4 is arranged on the periphery of the supporting cylinder 6, and a gap exists between the shielding cover 4 and the supporting cylinder 6.
The electron emitter 2, the heating element 3 and the support cylinder 6 are welded together by flanges to form a unitary structure. The insulating connector 5 is a ceramic insulator.
The extraction hole 7 is disposed opposite to the central axis of the electron emitter 2. A gap exists between the emission end face of the electron emitter 2 and the extraction electrode 1.
The electron emitter 2 adopts electron emission materials with low work function, and the electron emitter 2 is any one of the following: oxide emitter, barium tungsten emitter, lanthanum boride emitter. The emission surface of the electron emitter 2 is a plane or a concave spherical cap. In this embodiment, the emission surface of the electron emitter 2 is a spherical concave surface, a circular plane, or a polygonal plane.
The working medium-free miniature thermionic emission device of the embodiment further comprises an extraction power supply 101 and a heating power supply 102, wherein the positive electrode of the extraction power supply 101 is connected with the extraction electrode 1, the negative electrode of the extraction power supply 101 is respectively connected with the negative electrode of the heating power supply 102 and the negative electrode of the heating component 3, and is grounded, and the positive electrode of the heating power supply 102 is connected with the positive electrode of the heating component 3.
One opening end of the supporting cylinder 6 is positioned in the lead-out electrode 1, the other opening end of the supporting cylinder 6 is positioned in the lead-out electrode 1, the electron emitter 2 is arranged at the opening end of the supporting cylinder 6 positioned in the lead-out electrode 1, and the power supply connecting end of the heating component 3 extends out of the opening end of the supporting cylinder 6 positioned outside the lead-out electrode 1.
The heating element 3 is a screw heater. The heater is made of any one of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium, alloys comprising any two or more of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium. The heater is configured as any one of the following: plane single screw, plane double screw, three-dimensional single screw, three-dimensional double screw and three-dimensional single screw structure with variable pitch.
The supporting cylinder 6 is made of any one of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium, alloys comprising any two or more of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium. The shielding case 4 is made of a strip or foil of any one of the following materials: tantalum, niobium, tantalum-niobium alloys, molybdenum-rhenium alloys.
Example 2:
the present embodiment will be understood by those skilled in the art as a more specific description of embodiment 1.
The technical scheme of the embodiment relates to the technical field of aerospace propulsion, in particular to a structural design of an electronic source of a space spacecraft, which is particularly suitable for a tethered propulsion system, and can form a propulsion system without consuming propellant working media, with low power consumption, so as to finish tasks of spacecraft orbit transfer, end-of-life off orbit and the like.
The embodiment provides a working medium-free miniature thermionic emission device of a tethered propulsion system, which comprises a lead-out electrode, an electron emitter, a heater, a shielding cover, a ceramic insulator and a supporting cylinder.
The heater is powered by an external power supply to raise the temperature, and transmits heat to the electron emitter to achieve the working temperature and emit hot electron current. The extraction electrode is electrically insulated from the electron emitter by the ceramic insulator, and proper extraction voltage is increased on the extraction electrode to form an electric field, so that the electron extraction is facilitated. The working medium-free miniature thermionic emission device can obtain tens to hundreds of milliamperes of electron current by supplying heating power of 5-20W through miniaturized design and material optimization.
The electron emitter is arranged at one end of the supporting cylinder, and the spiral heater is arranged next to the emitter in the supporting cylinder, so that heat of the heater is conveniently transferred to the electron emitter through conduction. An external power supply supplies power to the heater to heat the heater, and heat is transferred to the electron emitter to reach the working temperature through conduction, so that hot electron current is emitted. The shielding cover is arranged outside the supporting cylinder, and a gap is formed between the shielding cover and the supporting cylinder, so that heat radiation loss can be reduced, and power loss is reduced. The extraction electrode is electrically insulated from the electron emitter by the ceramic insulator, and the small holes on the extraction electrode are opposite to the central axis of the emitter, thereby being beneficial to electron extraction. The electron emitter, the heater, the supporting cylinder and the flange of the working medium-free miniature thermionic emission device are welded into an integral structure, which is beneficial to improving the structural strength and the resistance to the mechanical environment.
The working medium-free miniature thermionic emission device of the tethered propulsion system is a thermionic source, and the vacuum degree of the working environment is better than 2 multiplied by 10 -2 Pa。
The emitter adopts electron emission material with low work function, the emitter material can be one of oxide emitter, barium tungsten emitter or lanthanum boride emitter, or other materials with low work function, and the emission current density j 0 [A/cm 2 ]Can be described by the chalcosen formula:
wherein A is 0 For the theoretical value of the emission constant, 120.4A.cm was taken for the barium tungsten emitter -2 ·K -2 T is the working temperature of the emitter [ K ]]，φ c Surface work function [ eV ] of cathode emitter]For barium tungsten emitters, 2.12eV (1 ev=1.6x10-19J) is taken, k is the boltzmann constant 1.38x10 -23 J/K, when the working temperature of the barium-tungsten emitter is 950-1100 ℃, the emission current density is calculated according to Charles' equation:
j 0 ＝0.33～3.8A/cm 2 。
the emission surface of the electron emitter can be a spherical crown concave surface, a round plane or a polygonal plane, and the concave surface is favorable for focusing and emission of electrons.
The heater is prepared from high-temperature resistant molybdenum, tantalum, niobium, tungsten and rhenium or alloy materials of the materials.
The heater is configured as any one of the following: plane single screw, plane double screw, three-dimensional single screw, three-dimensional double screw and three-dimensional single screw structure with variable pitch.
The supporting cylinder is prepared from high-temperature-resistant molybdenum, tantalum, niobium, tungsten and rhenium or alloy materials of the materials.
The heat shield is made of high temperature resistant materials, preferably tantalum, niobium, tantalum-niobium alloy, molybdenum-rhenium alloy foil or strip.
And a certain gap is kept between the extraction electrode and the emission end face of the electron emitter, and positive voltage is applied to extract electrons.
Example 3:
the present embodiment will be understood by those skilled in the art as a more specific description of embodiment 1.
The application provides a working medium-free miniature thermionic emission device of a tethered propulsion system, which has a structure shown in figure 1 and comprises an extraction electrode 1, an electron emitter 2, a heating component 3, a shielding cover 4, an insulating connecting piece 5 and a supporting cylinder 6. The heating element 3 is a heater and the insulating connector 5 is a ceramic insulator.
The planar electron emitter 2 is mounted at one end of the support cylinder 6, and the spiral heating element 3 is mounted next to the emitter in the support cylinder 6, so that heat of the heating element 3 is conveniently transferred to the electron emitter 2 through conduction. The shielding cover 4 is arranged outside the supporting cylinder 6, and a gap is formed between the shielding cover 4 and the supporting cylinder 6, so that heat radiation loss can be reduced, and power loss is reduced. The extraction electrode 1 is electrically insulated from the electron emitter 2 through an insulating connecting piece 5, and the extraction electrode 1 is provided with a small hole which is opposite to the central axis of the emitter, thereby being beneficial to the extraction of electrons. The electron emitter, the heater and the supporting cylinder of the working medium-free miniature thermionic emission device are welded into an integral structure, which is beneficial to improving the structural strength and the resistance to the chemical environment.
The emitter adopts electron emission material with low work function to emitThe current density can be described by the Charles equation, the emitter material adopts a barium tungsten emitter, and the emitted current density j 0 [A/cm 2 ]Can be calculated from formula (2):
wherein A is 0 For the theoretical value of the emission constant, 120.4A.cm was taken for the barium tungsten emitter -2 ·K -2 T is the working temperature of the emitter [ K ]]，φ c Surface work function [ eV ] of cathode emitter]For barium tungsten emitters, 2.12eV (1 ev=1.6x10-19J) is taken, k is the boltzmann constant 1.38x10 -23 J/K, when the working temperature of the barium-tungsten emitter is 950-1100 ℃, the emission current density is calculated according to Charles' equation:
j 0 ＝0.33～3.8A/cm 2 。
the electron emitter is a circular plane having a diameter of 5mm, as shown in fig. 3 (2).
The heater heating wire is wound by tungsten rhenium wire with the diameter of 0.2-0.4 mm, and is one of a plane single screw, a plane double screw, a three-dimensional single screw, a three-dimensional double screw and a variable pitch three-dimensional single screw structure, as shown in figure 4.
The supporting cylinder is made of molybdenum, and the shielding cover is made of tantalum foil or molybdenum-rhenium foil.
And a gap of 1-2 mm is kept between the extraction electrode and the emission end face of the electron emitter, and positive voltage is applied to extract electrons.
Working circuit schematic diagram of working medium-free miniature thermionic emission device is shown in figure 5, and working environment vacuum degree is not lower than 2×10 -2 Pa. When the heating power is 5-20W and the heating time is about 5 minutes, the temperature of the electron emitter reaches 950-1150 ℃, the voltage of 100-500V is applied to the leading-out electrode, the generation of electron current can be observed, and when the emitted electron current can reach 5-100 mA, the electron source requirement of the tethered propulsion system can be met.
The electron emission device has the advantages of small volume, light weight, low power consumption and capability of emitting electron current of hundred milliamperes, is used as an electron source for a tethered propulsion system, does not need to consume propellant working medium, can greatly improve the performance of the propulsion system, simplifies the system structure, lightens the weight, and completes space tasks such as orbit transfer or end-of-life off orbit of a spacecraft.
In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.
The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the application. The embodiments of the application and the features of the embodiments may be combined with each other arbitrarily without conflict.

Claims (10)

1. A working-medium-free miniature thermionic emission device, comprising: the electron emitter comprises an extraction electrode (1), an electron emitter (2), a heating component (3), a shielding cover (4), an insulating connecting piece (5) and a supporting cylinder (6);
the extraction electrode (1) is arranged outside the supporting cylinder (6), and the electron emitter (2) and the heating component (3) are arranged in the supporting cylinder (6); the heating component (3) is used for heating the electron emitter (2) to enable the electron emitter (2) to emit hot electron current; the central axis of the electron emitter (2) is arranged corresponding to the extraction hole (7) on the extraction electrode (1), and a gap exists between the emission end surface of the electron emitter (2) and the extraction electrode (1);
the two ends of the insulating connecting piece (5) are respectively connected with the outer side wall of the supporting cylinder (6) and the inner side wall of the lead-out pole (1), the shielding cover (4) is arranged on the periphery of the supporting cylinder (6), and a gap exists between the shielding cover (4) and the supporting cylinder (6).
2. The working substance-free miniature thermionic emission device according to claim 1, characterized in that one open end of the supporting cylinder (6) is located in the extraction electrode (1), and the other open end of the supporting cylinder (6) is located outside the extraction electrode (1);
the electron emitter (2) is arranged at the opening end of the supporting cylinder (6) positioned in the lead-out electrode (1), and the power supply connecting end of the heating component (3) extends out of the opening end of the supporting cylinder (6) positioned outside the lead-out electrode (1).
3. The working substance-free miniature thermionic emission device according to claim 1, characterized in that the electron emitter (2) is made of electron emission material with low work function;
the electron emitter (2) is any one of the following: oxide emitter, barium tungsten emitter, lanthanum boride emitter.
4. The working-medium-free miniature thermionic emission device according to claim 1, characterized in that the emission surface of the electron emitter (2) is a spherical crown concave surface, a circular plane or a polygonal plane.
5. The working substance-free miniature thermionic emission device according to claim 1, further comprising an extraction power supply (101) and a heating power supply (102);
the positive electrode of the extraction power supply (101) is connected with the extraction electrode (1); the negative electrode of the extraction power supply (101) is respectively connected with the negative electrode of the heating power supply (102) and the negative electrode of the heating component (3); the positive electrode of the heating power supply (102) is connected with the positive electrode of the heating component (3).
6. The working substance-free miniature thermionic emission device according to claim 1, characterized in that the heating component (3) is a spiral heater, and is configured as any one of the following: plane single screw, plane double screw, three-dimensional single screw, three-dimensional double screw and three-dimensional single screw structure with variable pitch.
7. The working substance-free miniature thermionic emission device as claimed in claim 1, characterized in that the insulating connection (5) is a ceramic insulator.
8. The working-medium-free miniature thermionic emission device of claim 4, wherein the heater is made of any one of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium, and alloys;
the alloy comprises any two or more of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium.
9. The working substance-free miniature thermionic emission device as claimed in claim 1, characterized in that the support cylinder (6) is made of any one of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium, and alloys;
the alloy comprises any two or more of the following materials: molybdenum, tantalum, niobium, tungsten, rhenium.
10. The working substance-free miniature thermionic emission device according to claim 1, characterized in that the shielding cover (4) is made of a strip or foil of any one of the following materials: tantalum, niobium, tantalum-niobium alloys, molybdenum-rhenium alloys.
CN202311015101.1A 2023-08-11 2023-08-11 Working medium-free miniature thermionic emission device Pending CN117128150A (en)

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Publications (1)

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CN117128150A true CN117128150A (en) 2023-11-28

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