CN115750252B

CN115750252B - Working medium-free cathode, hall thruster comprising same and space equipment

Info

Publication number: CN115750252B
Application number: CN202310000673.6A
Authority: CN
Inventors: 徐禄祥; 卢世旭
Original assignee: Hangzhou Institute of Advanced Studies of UCAS
Current assignee: Hangzhou Institute of Advanced Studies of UCAS
Priority date: 2023-01-03
Filing date: 2023-01-03
Publication date: 2023-04-28
Anticipated expiration: 2043-01-03
Also published as: CN115750252A

Abstract

The invention relates to a working medium-free cathode, a Hall thruster comprising the working medium-free cathode and space equipment. The working substance-free cathode has: the annular emitter is made of electron emission materials and is of a hollow annular structure; and the supporting ring seat is internally limited with a Hall thruster body accommodating space, and the annular emitter is fixed in the supporting ring seat. The invention has the advantages of simple structure, high reliability, no working medium, high efficiency and the like.

Description

Working medium-free cathode, hall thruster comprising same and space equipment

Technical Field

The invention relates to the technical field of space propulsion; in particular, the invention relates to a working medium-free cathode, a Hall thruster comprising the working medium-free cathode, and space equipment.

Background

The Hall thruster is a space electric propulsion device, is widely applied to the field of space propulsion, and is also one of the preferred propulsion devices of the current space aircraft. For example, typical applications include, but are not limited to, attitude control and deep space exploration main propulsion devices for satellites.

Fig. 1 shows the working principle of a conventional steady-state plasma hall thruster. As shown in the figure, inside the thruster there is a pair of mutually perpendicular electric and magnetic fields F1 and F2, the electric field being in the axial direction and the magnetic field being in the radial direction. The cathode A is an electron source for maintaining stable discharge, electrons generated by the cathode A enter a radial magnetic field area under the attraction of high potential of the anode, and the electrons do circumferential drifting movement under the action of electromagnetic force of E multiplied by B of a radial magnetic field and an axial electric field, so that circumferential electron current is formed. The working medium gas enters the annular discharge chamber through the anode gas distributor B and then reaches the radial electron drift region, and electrons are collided with neutral atoms in the working medium gas and ionized. Under the action of the axial electric field, ions in the thruster generate axial acceleration and are finally ejected at a high speed to form reverse thrust.

The cathode is an important component of the Hall thruster, and provides ionized electrons and neutralizing electrons for the thruster. The cathode structure and the installation of the Hall thruster in the prior art are complex, the reliability is low, the heating temperature is high, a large amount of working medium is required to be consumed, and the efficiency is required to be improved.

Disclosure of Invention

In view of the above, the present invention provides a working-medium-free cathode, and a hall thruster, a space apparatus comprising the same, which solve or at least alleviate one or more of the above-mentioned problems and other problems with the prior art.

To achieve the foregoing object, according to a first aspect of the present invention, there is provided a working-substance-free cathode, wherein the working-substance-free cathode has:

the annular emitter is made of electron emission materials and is of a hollow annular structure; and

the support ring seat, the inside thruster body accommodation space that is limited with of support ring seat, the cyclic annular emitter is fixed in the support ring seat.

Optionally, in the working-medium-free cathode as described above, the inner ring of the annular emitter has a taper angle facing the accommodating space.

Optionally, in the working-medium-free cathode as described above, the inner ring of the annular emitter has a taper angle of 5 degrees to 15 degrees facing the accommodating space.

Optionally, in the working-substance-free cathode as described above, the working-substance-free cathode has a heater placed in the support ring seat and a heater housing, the heater housing is of an annular grooved structure, the heater is wound in the groove, and the annular emitter is mounted into the heater housing so that the heater can heat the annular emitter through the heater housing.

Optionally, in the working-medium-free cathode as described above, the working-medium-free cathode has an upper ceramic ring and a lower ceramic ring, each of which has a vertical annular side wall and a planar bottom wall with a through hole so that each of the upper ceramic ring and the lower ceramic ring constitutes a hollow ceramic ring having a concave shape, the heater housing, the heater, and the annular emitter being interposed therebetween;

and an outer diameter of the annular sidewall of the lower ceramic ring is equal to an inner diameter of the annular sidewall of the upper ceramic ring, the lower ceramic ring is mounted to the upper ceramic ring to thereby complete radial positioning of the lower ceramic ring, and a depth of the upper ceramic ring is equal to a height of the lower ceramic ring.

Optionally, in the working-medium-free cathode as described above, the inner diameter of the through hole of the planar bottom wall of the lower ceramic ring is smaller than the outer diameter of the bottom surface of the annular emitter and larger than the inner diameter of the bottom surface of the annular emitter, and the inner diameter of the through hole of the planar bottom wall of the upper ceramic ring is smaller than the outer diameter of the top surface of the annular emitter and larger than the inner diameter of the top surface of the annular emitter;

the annular sidewall of the lower ceramic ring has an inner diameter equal to the outer diameter of the heater housing to radially position the heater housing around the annular emitter, and the thickness of the annular emitter, the heater housing is equal to the depth of the groove between the upper ceramic ring and the lower ceramic ring.

Optionally, in the working-medium-free cathode as described above, an inner protrusion is formed on an inner sidewall of the support ring seat, the inner protrusion is defined at a top of the accommodating space, an inner diameter of the inner protrusion is smaller than an outer diameter of the lower ceramic ring, and the outer diameter of the support ring seat is equal to the outer diameter of the upper ceramic ring so as to be able to complete radial positioning of the lower ceramic ring, the upper ceramic ring, the annular emitter and the heater housing.

Optionally, in the working-medium-free cathode as described above, the working-medium-free cathode includes an upper fixing ring and a fixing base, the upper fixing ring is fixed on the top of the supporting ring seat, the fixing base is fixed on the bottom of the supporting ring seat,

the upper fixing ring is of a convex structure, the outer diameter of a convex part of the convex structure is equal to the outer diameter of the upper ceramic ring, the outer diameter of the bottom of the convex structure is equal to the outermost diameter of the support seat, the convex part of the upper fixing ring keeps the lower ceramic ring, the heater housing and the annular emitter on the inner convex through the upper ceramic ring,

and the fixed base is of an annular structure, and the outer diameter of the annular structure is equal to the outermost diameter of the supporting ring seat.

In order to achieve the foregoing object, according to a second aspect of the present invention, there is provided a hall thruster comprising the working substance-free cathode of any one of the foregoing first aspects and a thruster body mounted to the stationary base and located in the accommodation space.

In order to achieve the aforementioned object, according to a third aspect of the present invention, there is provided a space apparatus, wherein a thruster of the space apparatus comprises a hall thruster as described in the aforementioned second aspect.

The working medium-free cathode and the Hall thruster and the space equipment comprising the working medium-free cathode have the advantages of simple structure and installation, high reliability, no working medium, high efficiency and the like. Further, the hall thruster in some aspects can realize a dual working mode (a passive working mode and an active working mode), can be switched between the two modes according to the situation, has short starting time in the passive working mode, does not need power consumption, improves the efficiency of a propulsion system, saves the total power, and is suitable for working conditions of small current and small thrust.

Drawings

The present disclosure will become more apparent with reference to the accompanying drawings. It is to be understood that these drawings are solely for purposes of illustration and are not intended as a definition of the limits of the invention. In the figure:

FIG. 1 is a schematic diagram of a prior art Hall thruster;

FIG. 2 is a schematic cross-sectional view of one embodiment of a non-working substance cathode according to the present invention;

FIG. 3 is a partial schematic view of the non-working substance cathode of FIG. 2;

FIG. 4 is a schematic perspective view of the non-working substance cathode of FIG. 2;

FIG. 5 is a schematic cross-sectional view of a Hall thruster comprising the working substance-less cathode of FIG. 2, a circuit connection diagram in active mode of operation;

FIG. 6 is a schematic cross-sectional view of a Hall thruster comprising the non-working substance cathode of FIG. 2, a circuit connection diagram in a passive mode of operation; and

fig. 7 is an enlarged partial cross-sectional view of the cathode and hall thruster combination showing ion, electron, neutral atom trajectories and associated operating mechanisms and processes.

Reference numerals: a-a cathode; a B-anode gas distributor; 1-fixing a base; 2-a support ring seat; 3-a lower ceramic ring; 4-ceramic rings; 5-an upper retaining ring; a 6-ring emitter; 7-a heater; 8-a heater housing; 9-accommodating space; 10-internal protrusions; 11-anode; 12-magnetic coils; 13-thruster casing.

Detailed Description

The working substance-free cathode and the hall thruster comprising the same, the structural composition, features and advantages of the space device, etc. according to the present invention will be described below by way of example with reference to the accompanying drawings and specific embodiments, however, all descriptions should not be taken to limit the invention in any way.

Furthermore, to the extent that any individual feature described or implied in the embodiments set forth herein, or any individual feature shown or implied in the figures, the invention still allows any combination or deletion of such features (or equivalents thereof) without any technical hurdle, and further embodiments according to the invention are considered to be within the scope of the disclosure herein.

It should also be noted that, in the description of the present invention, terms such as "upper," "lower," "inner," "outer," and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, which are merely for convenience of description, and do not indicate or imply that the apparatus or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

Figure 2 is a schematic cross-sectional view of one embodiment of a non-working substance cathode according to the present invention.

As shown in the figure, the working medium-free cathode comprises a fixed base 1, a supporting ring seat 2, a lower ceramic ring 3, an upper ceramic ring 4, an upper fixed ring 5, an annular emitter 6, a heater 7, a heater shell 8 and the like. The whole body of the working medium-free cathode is of a hollow annular structure, can be externally used for a Hall thruster, and wraps the thruster body. In use, the thruster body may be housed in the housing space 9.

In the example shown, the working substance-free cathode has an annular emitter 6 and a support ring holder 2.

The material of the ring-shaped emitter 6 is an electron emitting material. The electron emission material ring can generate electrons under the bombardment effect of ions, and the generated electrons can basically meet the requirements of the thruster on the electrons, and the electron emission material ring is particularly suitable for a micro-power Hall thruster.

In this embodiment, the annular emitter 6 is also a hollow annular structure. In order to increase the electron emissivity, the inner ring of the ring-shaped emitter has a cone angle facing the receiving space 9, which can be, for example, 5 to 15 degrees. In a further embodiment, the taper angle may be 10 degrees. By the arrangement, a small part of beam ions can be sacrificed to exchange for a larger contact area between the beam ions and the annular emitter 6, so that the bombardment heating effect is more obvious, and the electron emissivity is improved.

The support ring seat 2 is internally limited with a Hall thruster body accommodating space 9, and the annular emitter 6 is fixed in the support ring seat 2. The annular emitter 6 is electrically insulated from the support ring seat 2, the upper fixing ring 5 and the fixing base 1. The thruster body is accommodated in the accommodating space 9, so that the thruster body and the working medium-free cathode can be combined together to form a Hall propulsion system.

As shown, in this embodiment the working substance-free cathode also has a heater 7 placed in the support ring seat 2 and a heater housing 8. The heater housing 8 is of an annular grooved structure, the heater is wound in the groove, and the annular emitter 6 is mounted into the heater housing 8 so that the heater 7 can heat the annular emitter 6 through the heater housing 8 to reach an electron emission temperature.

For example, the outer diameter of the annular emitter 6 may be equal to the inner diameter of the heater housing 8, and the annular emitter 6 is installed into the heater housing 8 to complete the radial positioning of the annular emitter 6. The height of the annular emitter 6 may be equal to the thickness of the heater housing 8.

Fig. 3 is a partial schematic view of the non-working substance cathode of fig. 2. As can be seen from the figure, the heater housing 8 is U-shaped in cross section with a recess opening at one end of the annular heater housing. The heater may be placed in the recess through the opening and separated from the annular emitter 6 and other components by the side walls of the heater housing, respectively.

As can be seen in connection with fig. 2 and 3, in this embodiment the working substance-free cathode may also have an upper ceramic ring 4 and a lower ceramic ring 3. For example, the material of the lower ceramic ring 3 and the upper ceramic ring 4 may be boron nitride ceramics. The lower ceramic body 3 and the upper ceramic ring 4 ensure the insulation between the annular emitter 6 and the fixed base 1, the support ring seat 2 and the upper fixed ring 5, and the like.

As shown in the figure, the upper ceramic ring 4 and the lower ceramic ring 3 are provided with vertical annular side walls and a plane bottom wall with through holes, so that the upper ceramic ring 4 and the lower ceramic ring 3 form a concave hollow ceramic ring, the axial opening directions of the upper ceramic ring 4 and the lower ceramic ring 3 are oppositely arranged, and the lower ceramic ring 3 is positioned in the concave hollow space of the upper ceramic ring 4. The heater housing 8, the heater 7, and the annular emitter 6 are sandwiched between the upper ceramic ring 4 and the lower ceramic ring 3 in a space collectively defined by the concave hollow spaces of the upper ceramic ring 4 and the lower ceramic ring 3, respectively.

In this embodiment, the outer diameter of the annular sidewall of the lower ceramic ring 3 is equal to the inner diameter of the annular sidewall of the upper ceramic ring 4, and the lower ceramic ring 3 is mounted to the upper ceramic ring 4 so as to complete radial positioning of the lower ceramic ring 3, and the depth of the upper ceramic ring 4 is equal to the height of the lower ceramic ring 3. In alternative embodiments, the lower ceramic ring 3 and the upper ceramic ring 4 may be an interference fit therebetween, so that the two are securely mated, and assembled as a module.

Further, in the illustrated embodiment, the through-hole inner diameter of the planar bottom wall of the lower ceramic ring 3 is smaller than the bottom outer diameter of the annular emitter 6 and larger than the bottom inner diameter of the annular emitter 6, and thus the annular emitter 6 can be held on the lower ceramic ring 3. The through-hole inner diameter of the planar bottom wall of the upper ceramic ring 4 is smaller than the top outer diameter of the annular emitter 6 and larger than the top inner diameter of the annular emitter 6, and thus the annular emitter 6 can be held under the upper ceramic ring 4. Thereby, the annular emitter 6 is held between the upper ceramic ring 4 and the lower ceramic ring 3.

In addition, the inner diameter of the annular side wall of the lower ceramic ring 3 is equal to the outer diameter of the heater housing 8 so that the heater housing 8 surrounding the annular emitter 6 is radially positioned, and the thickness of the annular emitter 6, the heater housing 8 is equal to the depth of the groove between the upper ceramic ring 4 and the lower ceramic ring 3. In alternative embodiments, the lower ceramic ring 3 and the heater housing 8 may be an interference fit so that they may be modularly mounted together for ease of assembly.

In order to fix the heater 7, the ring-shaped emitter 6, etc. to the support ring holder 2, an inner protrusion 10 may be formed on an inner sidewall of the support ring holder 2, the inner protrusion 10 being defined at the top of the receiving space 9. The inner diameter of the inner protrusion 10 is smaller than the outer diameter of the lower ceramic ring 3, and the outer diameter of the support ring seat 2 is equal to the outer diameter of the upper ceramic ring 4 so that radial positioning of the lower ceramic ring 3, the upper ceramic ring 4, the annular emitter 6 and the heater housing 8 can be accomplished.

According to the illustrated embodiment, it can be seen that the working substance-free cathode comprises an upper fixing ring 5 and a fixing base 1. As shown in the figure, the upper fixing ring 5 is fixed on the top of the supporting ring seat 2, and the fixing base 1 is fixed on the bottom of the supporting ring seat 2. The material of the support ring seat 2, the fixing base 1 and the upper fixing ring 5 can be stainless steel.

The upper fixing ring 5 and the supporting ring seat 2 can be connected together through bolts, and the supporting ring seat 2 and the fixing base 1 can be connected together through bolts, so that tight connection of the whole cathode internal components (such as the lower ceramic ring 3, the upper ceramic ring 4, the upper fixing ring 5, the annular emitter 6, the heater 7, the heater housing 8 and the like) is ensured.

The upper fixing ring 5 is of a convex structure, the outer diameter of the convex part of the convex structure can be equal to the outer diameter of the upper ceramic ring 4, the outer diameter of the bottom of the convex structure can be equal to the outermost diameter of the supporting ring seat 2, and the convex part of the upper fixing ring 5 holds the lower ceramic ring 3, the heater 7, the heater housing 8, the annular emitter 6 on the inner bulge 10 through the upper ceramic ring 4, so that the axial positioning of the upper ceramic ring 4, the lower ceramic ring 3, the heater 7, the heater housing 8, the annular emitter 6 and the like is realized. The height of the protruding structure of the upper fixing ring 5 plus the height of the ceramic ring 4 may be equal to the depth of the recess from the inside of the support ring seat 2 to the inner protrusion 10.

The fixing base 1 is of an annular structure, and the outer diameter of the annular structure may be equal to the outermost diameter of the support ring seat 2.

Fig. 4 is a schematic perspective view of the working-medium-free cathode of fig. 2, showing a fixing base 1, a supporting ring seat 2, an upper ceramic ring 4, an upper fixing ring 5, an annular emitter 6, etc. As can be seen from the figure, the working medium-free cathode is of a hollow annular structure as a whole.

The working medium-free cathode is particularly externally arranged and suitable for a micro-power Hall thruster, and can have one or more of the characteristics of no working medium, low/no power, double modes, quick assembly, modularization and the like.

For example, in the embodiment with the heater, the cathode can have two working modes, namely active working mode and passive working mode, and the two working modes can complete electron emission without working medium.

The passive working mode is a powerless mode and is suitable for the conditions of small flow and low requirement on electron quantity; in this mode, the ring emitter 6 is caused to emit electrons by bombardment heating of the energetic ions emitted by the thruster, for enhanced ionization or for neutralization of Shu Liuli; the active working mode needs to start the heater 7 to generate heating power to heat the annular emitter 6, so that the active working mode is suitable for the conditions of larger flow and higher requirement on electron quantity; in this mode, the ring-shaped emitter 6 may emit a large number of electrons for enhanced ionization or for neutralizing beam ions under co-heating of the heater 7 with the outgoing energetic ions.

In both modes of operation, the ring-shaped emitter 6 is heated by the high energy ions generated by the hall thruster to generate electrons for enhanced ionization or for neutralizing beam ions. In a hall thruster, the anode of the thruster body mounted inside acts as a contact stage or grid in a conventional cathode, and the high potential of the anode can attract electrons towards the anode and accelerate the electrons; electrons are bound by the radial magnetic field binding region in the process of flowing to the anode, and circumferential Hall drift is carried out in the radial magnetic field binding region, and the electrons and working medium gas from the axial direction are ionized to generate plasma.

The cathode can be reasonably designed and the installation position is determined according to the size, the magnetic field position type and the beam divergence angle of a specific Hall thruster, so that the obstruction to emergent beam current is reduced as much as possible, and the emergent electrons can smoothly reach a radial magnetic field binding area and the end face of an anode under the attraction of high potential of the anode along magnetic lines of force to form stable discharge electron current.

In a passive working mode, the working medium-free cathode does not need any power, so that any starting process is not needed; after the thruster is started by the primary electrons and generates plasma, the annular emitter 6 is further bombarded and heated by high-energy ions, the annular emitter 6 can generate electrons to participate in ionization and neutralization processes, so that the working state of the thruster tends to be stable.

Fig. 5 and 6 are schematic cross-sectional views of a hall thruster comprising the working substance-free cathode of fig. 2 and its active and passive working mode circuit connection diagrams, respectively.

The hall thruster as shown in the figure comprises a cathode and a thruster body, wherein the cathode is the working substance-free cathode according to any one of the previous embodiments, and the thruster body is mounted on a fixed base of the working substance-free cathode and is positioned in the accommodating space 9. The fixed base 1 can be connected with a micro-power thruster to be installed through bolts so as to connect the thruster with the cathode of the invention. The anode 11 of the hall thruster, the magnetic coil 12, the thruster housing 13 etc. can also be seen from the figure.

The embodiments of the invention are particularly suitable for the micro-power Hall thruster. After the thruster is selected, the outer diameter of a discharge channel of the thruster can be considered first, the inner diameter of the annular emitter 6 is ensured to be approximately larger than the inner diameter of the discharge channel of the thruster, then the inner diameter of the annular emitter 6 is reasonably designed according to the beam divergence angle and the magnetic field position of the thruster during the discharge of the thruster, the annular emitter 6 is ensured to be arranged at the edge of the scattered beam, the obstruction to the beam is avoided, and the annular emitter 6 is arranged on a plurality of magnetic lines, so that the emergent electrons can smoothly migrate to the anode along the magnetic field lines, and the resistance in the electron migration process is reduced. In this way, the dimensions and positioning of the cathode can be substantially completed.

In addition, the circuit can be laid out before the formal work, in the active working mode, as shown in fig. 5, the anode 11 of the thruster is connected with positive high pressure, two ends of the heater 7 are connected with heating loops, the positive of the heating loops is simultaneously connected with the high pressure negative of the thruster, and the annular emitter 6 is connected with the high pressure negative of the thruster. Thus, the circuit connection of the Hall thruster in the active working mode can be completed.

In addition, the circuit may be laid out before the normal operation, and in the passive operation mode, as shown in fig. 6, the thruster anode 11 is connected to a positive high voltage, and the annular emitter 6 and the thruster casing 13 are connected to a negative high voltage. Thus, the circuit connection of the Hall thruster in the passive working mode can be completed.

Three procedures D, E, F are set forth below: (A) The high-energy ions at the extreme edge of the plume area bombard the annular emitter 6, and under the continuous bombardment of ions and the continuous heating of the heater (or no heating and only ion bombardment), the annular emitter 6 emits electrons; (B) Some of the electrons emitted by the annular emitter 6 move to the anode under the attraction of the high potential of the anode 11 and acquire energy, and do circumferential Hall drift under the constraint of the radial magnetic field of the ionization region, and ionize neutral atoms from the axial direction; (C) Another part of electrons generated by the annular emitter 6 moves downstream in the beam region under the attraction of the beam potential of the emergent ions, and the neutralization of ions is completed at the tail part of the beam region.

The working flow of the hall thruster is briefly described below.

The following is a cathode unpowered passive working mode, which is suitable for working conditions of small flow, small thrust and small power: (1) The thruster completes ignition and ignition by means of the space primary electrons, discharges to generate plasma, ions in the plasma are accelerated by a plasma electric field and an anode electric field to be ejected out of the channel at high speed, and high-energy ions at the edge of the plume bombard the surface of the annular emitter 6 to continuously bombard and heat the annular emitter 6 so as to generate electrons; (2) Part of electrons generated by the annular emitter 6 migrate to the anode along a magnetic line under the attraction of high potential of the anode to obtain energy acceleration, are bound by a radial magnetic field binding area in the process to perform circumferential Hall drift, ionize working medium gas from the axial direction in the process, transfer energy to the working medium gas, perform field-crossing drift to the anode to reach the anode, form anode electron current, and the other part of electrons drift to the emergent plasma under the attraction of the emergent plasma potential and neutralize with the emergent ions to complete the neutralization of beam current; (3) to this point the thruster enters a stable discharge mode.

When the flow of the thruster is increased and the demand for electrons is increased, the active working mode is needed to be entered, firstly, the heater 7 is started, and after the temperature of the annular emitter 6 reaches the electron emission temperature, the anode of the thruster is started, and the working flow is started; under the dual action of the heater 7 and the high-energy ions, the annular emitter 6 emits a large number of electrons, and the requirement of the thruster on the electrons is met. The rest working processes are consistent with the non-power working modes.

According to the embodiment of the invention, the working medium-free cathode has simple structure and simple structure, can be quickly assembled and replaced, can save the replacement process and improves the reliability. In addition, the volume of the working medium-free cathode is similar to that of the thruster body, so that the power, working medium and occupied volume can be effectively saved, and the task cost is saved. In addition, the cathode is only required to be connected with the thruster body through simple mechanical connection and circuit connection, is basically independent from the thruster body, is an independent module, is convenient to assemble and disassemble, has strong universality for thrusters with different power, size and other parameters, and can be flexibly and reasonably designed according to the working parameters and magnetic field position types of the thrusters.

Further, an aspect of the present invention also provides a space apparatus, wherein the thruster of the space apparatus is a hall thruster of the foregoing embodiments, and has one of the working substance-free cathodes in the foregoing embodiments. For example, these spatial devices may include, but are not limited to, satellites, space stations, and the like.

In summary, the invention provides a working-medium-free cathode, a hall thruster comprising the working-medium-free cathode and space equipment, wherein the working-medium-free cathode has the following advantages that the working-medium-free cathode can be especially more suitable for a micro-power electric thruster: (1) Dual mode of operation: the passive working mode is suitable for a small-flow working condition, the active working mode is suitable for a large-flow working condition, and the heating module needs to be started; (2) In the passive working mode, the electrons are heated and emitted through bombardment of high-energy ions emitted by the thruster without starting heating or supplying working medium, and the power is completely not needed, thus the device belongs to a passive emission cathode; (3) An active working mode, which is to start the heating module without working medium supply, and to emit sufficient electrons through dual heating of the heating module and the emergent ions, and belongs to a cathode in an active and passive combined working state; (4) Working medium-free operation, namely bombarding electrons in the emitter material by means of high-energy ions emitted by the thruster to serve as ionization or neutralization electrons; (5) The power-free operation can be converted into a passive operation mode under the condition of low electronic quantity demand of the thruster under the working condition of low flow, so that the power-free operation is realized; (6) The short starting time, under the passive working mode, depending on the original electrons, the thruster can finish ignition, and after the ignition, the ions are emitted to the surface of the cathode, the emission of electrons can be finished in a short time, and the starting time is almost not needed; (7) The structure is simple, the cathode emitter can be quickly assembled and replaced, and the replacement of cathode emitter materials can be quickly completed in a laboratory stage; (8) The module design is independent of the design and the assembly of the thrusters, can be flexibly adapted and changed according to different thrusters, has extremely high flexibility, and can be mechanically connected with the thrusters and simply connected with a circuit to form a finished thruster-cathode system; (9) The volume is smaller, basically consistent with the volume of the thruster, and the total volume of the propulsion system is effectively saved.

Based on the advantages, the invention can be especially suitable for micro-power electric thrusters, can realize working medium-free work, and can realize working medium-free work under specific working conditions, thereby greatly saving system power and working medium gas; due to the concise and modularized design, the cathode structure and assembly difficulty are effectively reduced; the thruster is independent of the cathode, low in coupling, and capable of completing the system structure only by simple mechanical connection and simple circuit connection, and high in reliability and adaptability.

The technical scope of the present invention is not limited to the above description, and those skilled in the art may make various changes and modifications to the above-described embodiments without departing from the technical spirit of the present invention, and these changes and modifications should be included in the scope of the present invention.

Claims

1. A working substance-free cathode for a hall thruster, characterized in that it has:

2. The working-medium-free cathode of claim 1, wherein an inner ring of the annular emitter has a taper angle facing the accommodating space.

3. The working-medium-free cathode of claim 2, wherein the inner ring of the annular emitter has a taper angle of 5 degrees to 15 degrees facing the accommodating space.

4. The working-medium-free cathode of claim 1, wherein the working-medium-free cathode has a heater disposed in the support ring seat and a heater housing, the heater housing being of an annular fluted structure, the heater being wound in the flute, and the annular emitter being mounted into the heater housing such that the heater is capable of heating the annular emitter through the heater housing.

5. The working-medium-free cathode of claim 4 wherein the working-medium-free cathode has an upper ceramic ring and a lower ceramic ring, each of the upper ceramic ring and the lower ceramic ring having a vertical annular sidewall and a planar bottom wall with through-holes such that each of the upper ceramic ring and the lower ceramic ring forms a hollow ceramic ring that is concave, the heater housing, the heater, and the annular emitter being interposed therebetween;

6. The working-medium-free cathode of claim 5, wherein the through-hole inner diameter of the planar bottom wall of the lower ceramic ring is smaller than the bottom outer diameter of the annular emitter and larger than the bottom inner diameter of the annular emitter, and the through-hole inner diameter of the planar bottom wall of the upper ceramic ring is smaller than the top outer diameter of the annular emitter and larger than the top inner diameter of the annular emitter;

7. The working-medium-free cathode of claim 5, wherein an inner protrusion is formed on an inner sidewall of the support ring seat, the inner protrusion is defined at a top of the accommodating space, an inner diameter of the inner protrusion is smaller than an outer diameter of the lower ceramic ring, and the outer diameter of the support ring seat is equal to the outer diameter of the upper ceramic ring so as to be able to accomplish radial positioning of the lower ceramic ring, the upper ceramic ring, the annular emitter and the heater housing.

8. The working-medium-free cathode of claim 7, wherein the working-medium-free cathode comprises an upper fixing ring and a fixing base, the upper fixing ring is fixed on the top of the supporting ring seat, the fixing base is fixed on the bottom of the supporting ring seat,

9. A hall thruster comprising the working substance-free cathode and a thruster body as defined in claim 8, said thruster body being mounted to said stationary base and being located in the receiving space.

10. A space device, characterized in that the thruster of the space device comprises a hall thruster according to the preceding claim 9.