• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a Hall effect plasma thruster (10) comprising: - an annular discharge channel (121) around a main axis (A) with an open downstream end, having an ionisation zone (128) between a inner wall (116) and an outer wall (118), and further comprising an anode (154) and a distributor (151) located upstream of the ionization zone (128). Characteristically, at least one transverse wall ( 152a, 152b; 253d, 253e) of material different from that of the anode (154,254) partially separates the distributor (151,251) from the ionization zone (128,228)
    公开号:FR3018316A1
    申请号:FR1451912
    申请日:2014-03-07
    公开日:2015-09-11
    发明作者:Vanessa Marjorie Vial；Stephan Zurbach；Thierry Chartier；Fabrice Rossignol
    申请人:SNECMA SAS；
    IPC主号:
    专利说明:

    [0001] The invention relates to a Hall effect plasma thruster comprising an annular discharge channel (forming a main channel for ionization and acceleration) around a main axis with an open downstream end, having an ionisation zone. between an inner wall and an outer wall, and further comprising an anode and a distributor placed upstream of the ionization zone, at least one cathode, a magnetic circuit for creating a magnetic field in said channel, and a channel for supplying ionizable gas to the channel, said manifold being connected to the pipe and allowing the ionizable gas to flow into the ionization zone of the channel concentrically about the main axis. This type of engine is still called plasma engine drift closed electron or stationary plasma engines. The invention particularly relates to Hall effect plasma thrusters used for space electric propulsion, in particular for the propulsion of satellites, such as geostationary telecommunication satellites. Thanks to their high specific impulse (from 1500 to 3000s), they allow considerable weight gains on satellites compared to engines using chemical propulsion.
    [0002] One of the typical applications of this type of engine is the north / south control of geostationary satellites, for which we obtain mass gains of 10 to 15%. This type of engine is also used in interplanetary primary propulsion, low orbit drag compensation, sun-synchronous orbit retention, orbit transfer and end-of-life de-orbiting. It can be used occasionally, possibly by combining electric and chemical propulsion, to avoid a collision with debris or to compensate for a failure when placed in a transfer orbit. Figures 1 and 2 relate to a Hall effect thruster 10 of the prior art. In FIG. 1, the hall effect thruster 10 is shown schematically. A central magnetic coil 12 surrounds a central core 14 extending along the main longitudinal axis A. An annular inner wall 16 encircles the central coil 12. This inner wall 16 is surrounded by an annular outer wall 18, the inner wall 16 and the outer wall 18 delimiting between them an annular space extending around the main axis A.
    [0003] In the remainder of the description, the term "internal" designates a part close to the principal axis A while the term "external" designates a part remote from the main axis A. Also, the "upstream" and the "Downstream" are defined with respect to the normal flow direction of the gas (from upstream to downstream) through the annular space delimited by the walls 16,18. Usually, the inner wall 16 and the outer wall 18 form part of a single ceramic part or discharge channel 21, this ceramic being insulating and homogeneous, in particular made from boron nitride. Boron nitride ceramics allow Hall effect thrusters to achieve high performance in terms of efficiency, but nevertheless exhibit high erosion rates under ion bombardment, which limits the life of thrusters. The upstream end 21a of the discharge channel 21 (on the left in FIG. 1) is closed by a bottom wall 17 and comprises an injection system with a pipe 24 for supplying the ionizable gas (generally xenon). , the pipe 24 being connected by a feed hole 25 to an anode 26 placed in the upstream section of the discharge zone and delimiting a distributor 51 for the injection of the gas molecules into the discharge channel 21. In the present context, the term "distributor" a cavity, or series of cavities, for distributing the ionizable gas flow transversely in the discharge channel to obtain a homogeneous flow in the discharge channel. In order to connect the pipe 24 to the distributor 51, the bottom wall 17 of the annular and radial discharge channel 21 has an opening for the passage of the pipe 24. At the level of the anode 26, the gas molecules pass from a tubular run from the pipe 24 to an injection according to an annular section in the upstream end 21a of the discharge channel 21. The downstream end 21b of the discharge zone 21 is open (right in the figure 1). The discharge chamber 19, the pipe 24, and the distributor anode 26 form the discharge channel 21. Several peripheral magnetic coils 30 having an axis parallel to the main axis A are arranged all around the outer wall 18. The central magnetic winding 12 and the peripheral magnetic windings 30 make it possible to generate a radial magnetic field B whose intensity is maximum at the downstream end 21b of the discharge channel 21.
    [0004] A hollow cathode 40 is disposed outside the peripheral windings 30, its output being oriented in order to eject electrons towards the main axis A and the zone situated downstream of the downstream end 20b of the discharge 20. A potential difference is established between the cathode 40 and the anode 26.
    [0005] The electrons thus ejected are partly directed inside the discharge channel 21. Some of these electrons arrive, under the influence of the electric field generated between the cathode 40 and the anode 26, to the anode 26 while that the majority of them is trapped by the intense magnetic field B near the downstream end 21b of the discharge channel 21. Electrons escaping towards the anode 26 collide with molecules of gas flowing from the upstream downstream in the discharge channel 21, and thus realize an ionization of these gas molecules in the ionization zone 28.
    [0006] On the other hand, the electrons caught by the magnetic field B in the vicinity of the downstream end 21b of the discharge channel 21 create an axial electric field E, which accelerates the ions between the anode 26 and the output (the end downstream 21b) of the discharge channel 201, so that these ions are ejected at high speed from the discharge channel 21, which causes the propulsion of the engine. However, in particular because of the presence of the radial magnetic field B (field lines 42), the trajectory of the ions is not parallel to the main axis A of the thruster 10, corresponding to the thrust direction, but this trajectory is subject to angular deflection.
    [0007] This situation subjects the outlet section of the discharge channel 21 to a significant stress due to the erosion experienced by the walls 16, 18, which are struck at high speed by a part of the ions. Furthermore, the assembly forming the discharge channel 21 and comprising the anode 26 and the discharge chamber 19, must withstand thermomechanical stresses throughout the life of the engine (at least 15 years) while ensuring the various functions that it fills and in particular by remaining tight so that the trajectory of the gas molecules and ions remains confined to the course delimited in particular by the distributor 51 upstream of the ionization zone 28. With this directed course, it is possible to , taking into account the radial magnetic field at the downstream end of the discharge channel, generating the desired movement for the ionized gas at the outlet of the discharge channel 21. In the example of FIG. 2, the distributor 51 comprises several successive chambers 51a, 51b and 51c formed directly in the anode 26. Conventionally, the anode 26 is made of technically conductive material, such as carbon (graphite) or a metal or metal alloy such as stainless steel. Furthermore, conventionally, the discharge channel 21 (bottom wall 17, inner wall 16 and outer wall 18) is made of ceramic and is sealingly connected with the anode 26. Thus, using for the anode 26 and for the discharge chamber 19 of the materials having a coefficient of near thermal expansion, a tight connection is maintained between the anode 26 and the inner and outer walls 16 and 18 at the chambers 26a, 26b and 26c of the distributor formed by the anode 26. This connection is made for example by soldering in different attachment zones 60 (see Figure 2) between the anode 26 and the walls 16, 17 and 18 of the discharge chamber 19 , which ensures the sealing of the chambers 51a, 51b and 51c of the distributor 51. Alternatively, this connection is made by a pin or any other fixing element between the anode 26 and the discharge channel 21. In this case, the sealing of the chambers 51a, 51b and 51c es This is ensured by sealing the side walls of the anode (by brazing). Given the geometric complexity required of the anode 26 to form the successive chambers of the distributor 51, this anode 26 is typically made of several parts, manufactured by machining independently, and which are then assembled together, in particular by brazing, before being mounted at the bottom of the discharge channel 21.
    [0008] The manufacture of these different parts is made even more complex by the presence of the series of orifices 27a, 27b, 27c of small diameter (of the order of 0.4 mm) ensuring the flow of gas flow from the feed hole 25, through the different chambers 51a, 51b and 51c formed in the anode which acts as distributor, towards the outlet of the anode 26. Moreover, when it comes to annular pieces of large diameter, the result is a certain deformation like curl which prevents a good flatness of these parts.
    [0009] Also, the various parts forming the anode 26 to be assembled tightly, the brazing technique is used, which is used in many locations given the large number of parts making up the anode, which multiplies the time required to their realization as well as the risk of leakage.
    [0010] The present invention aims to provide a plasma thruster to overcome the disadvantages of the prior art and in particular offering the possibility of simplifying the manufacture of the discharge channel, to reduce costs without losing thermomechanical performance and durability of life.
    [0011] For this purpose, according to the present invention, there is provided a plasma propellant which is characterized in that at least one transverse wall of material different from that of the anode partially separates the distributor from the ionization zone. In this way, it is possible to reduce the number of parts constituting the discharge channel. In order to simplify the structure of the discharge channel, said at least one transverse wall may in particular be formed in a one-piece assembly delimiting said distributor. Said pipe may then also be formed in said one-piece assembly. Alternatively, however, said at least one transverse wall may be located downstream of said anode, which makes it possible to integrate the anode at the bottom of the distributor. In particular, the anode may be made of metal or an electrically conductive ceramic. As the metal can be used stainless steel, and especially stainless steel of the "Kovar" type, and as electrically conductive ceramic, a metallo-ceramic material can be used. Furthermore, said transverse wall may be made of a dielectric material such as BN boron nitride or A1203 alumina. In order to facilitate their integration, the inner and outer walls of said discharge chamber may be made of the same dielectric material as said transverse wall. Furthermore, in order to prevent erosion of the outlet of the discharge channel, it can be provided that the discharge channel further comprises at least one wear ring placed at its downstream end, on the internal face of the outlet section. of the discharge chamber, said wear ring being made of ceramic, in a ceramic chosen for these erosion resistance properties and in particular based on boron nitride. In order to easily allow the manufacture of such a discharge channel, the invention also relates to the method of manufacturing a discharge channel for a plasma thruster such as that previously defined, and which is characterized in that the wall transversal at least is achieved by additive manufacturing. By "additive manufacturing" is meant any manufacturing process, such as stereolithography, based on the construction of the piece layer by layer by addition of material. With such a manufacturing technique it is possible to produce complex shapes with more precise dimensional tolerances than with production techniques by ablation of material or machining, and this especially for ceramic materials. The anode can be attached to a substrate of different material by soldering. The invention thus provides a discharge channel 30 which is formed by a reduced number of parts. Other advantages and characteristics of the invention will emerge on reading the following description given by way of example and with reference to the appended drawings, in which: FIG. 1, already described, is a diagrammatic sectional view of FIG. a prior art Hall effect plasma thruster; FIG. 2, already described, is an enlarged sectional view of the radial section of the anode of FIG. 1; FIG. 3 is a view similar to that of FIG. FIG. 2 for a first alternative embodiment of the discharge channel, and FIG. 4 is a view similar to that of FIG. 2 for a second alternative embodiment of the discharge channel, and is now described with reference to FIGS. and 4 different embodiments of the plasma thruster discharge channel according to the invention.
    [0012] In a first variant embodiment, illustrated in FIG. 3, the discharge channel 121, which is of symmetry of revolution about the main axis A, comprises an upstream portion 152, closing the upstream end of the discharge channel 121. delimiting the distributor 151, and having at least one duct 124 supplying gas to the distributor 151, a downstream portion 156, delimiting the ionization zone 128 by means of an annular inner wall 116 and an annular outer wall 118 , and an anode 154 located between the upstream portion 152 and the downstream portion 156 and sealingly joined thereto by soldering, in particular by vitreous brazing (by means of a filler material for example siliceous placed on the liaison areas). This anode 154 is formed by two coaxial and concentric rings 154a, 154b aligned respectively with the inner 116 and outer 118 walls of the downstream portion 156. In addition, at the downstream end, open, of the downstream portion 156, two rings are provided. 172 and 174 are respectively placed on the face facing the ionization zone 128 of the downstream end of the annular inner wall 116 and the annular outer wall 118. For this purpose, it is provided during the manufacture of the walls 116 and 118, a recess shoulder 116a and 118a placed the downstream end of the annular inner wall 116 and the annular outer wall 118, to create an annular housing for receiving the wear rings 172 and 174 flush with the remainder of the annular inner wall 116 and the annular outer wall 118. The wear rings 172 and 174 are manufactured separately, for example by machining, preferably in BNSiO 2, and mounted by means of a solder connection or by co-sintering with the walls 116 and 118.
    [0013] According to an alternative not shown, a single wear ring, either the wear ring 172 or the wear ring 174, is used on the wall of the two walls 116 and 118, which is further subjected to the ionic flow.
    [0014] In this first variant, the upstream portion 152 and the downstream portion 156 are made of a first material (dielectric material, preferably A1203 alumina, or BN boron nitride) while the anode 154 is made in a second conductive material (stainless steel or "Kovar").
    [0015] At least the upstream portion 152 may be performed by an additive manufacturing technique. For example, one can use the technique of laser projection (Direct Metal Deposition, DMD) or selective laser melting (Selective Laser Melting, SLM) of powder beds. In both cases, the laser beam scans at least one region of a previously deposited layer of powder, and follows a predetermined part profile. To do this, the galvanometric head is controlled according to the information contained in the database of the computer tool used for computer-aided design and manufacture of the part to be manufactured.
    [0016] It is also possible to use the technique of photopolymerization (or UV polymerization or selective UV stereolithography). In this case, the piece is built layer by layer by stereolithography and a UV laser beam consolidates on each successive layer surfaces programmed by CAD (computer-aided design).
    [0017] It is therefore clear that the manufacturing method for obtaining the upstream portion 152 according to the first variant of Figure 3 implements a one-piece assembly, defining the distributor 151, and made in one piece by additive manufacturing. In this way, the distributor 151 is formed in a single piece of complex shape, closing the upstream end of the discharge channel 121. The distributor 151 comprises annular chambers 151a and 151b superimposed in axial direction, connected to the conduit 124 opening in the first annular chamber 151a, according to the arrow 160. At the outlet of the first annular chamber 151a, a series of axially directed flow orifices 151c lead, according to the arrow 162, the gas in the separate second annular chamber 151b. partially from the ionization zone 128 by transverse walls 151d, 151e. An annular exhaust orifice 151f between the walls 151d, 151e connects the distributor 151 to the ionization zone 128, near the anode 154.
    [0018] In the second variant embodiment of FIG. 4, the discharge channel 221, which is symmetrical in revolution around the main axis A, comprises: an upstream portion 252, in the form of a flat one-piece ring closing the end upstream of the discharge channel 221, an intermediate portion 253 in the form of hollow and split ring superimposed on and downstream of the upstream portion 255; the intermediate portion 253 comprising, from upstream to downstream, two axial and cylindrical walls 253a, 253b, coaxial with each other, equipped at their upstream end with several superposed rows of radial orifices 253c, and two transverse walls 253d, 253e separated by a annular exhaust port 253f connecting a distributor 251 delimited by the upstream portion 252 and the downstream portion 253 to an ionization zone 228 downstream, - an anode 254 disposed on an inner face of the upstream portion 255 in the distributor 251, A downstream portion 256 comprising an annular and axial inner wall 216 and an outer wall 218, extending downstream from said upstream and intermediate portions 252, 253 in order to delimit the ionization zone 228 and presenting upstream at least one channel 224, supply of gas in communication with the distributor 251 through the orifices 253c of the intermediate portion 253, and - two wear rings 272 and 274, placed respectively on the face facing the ionization zone 228 of the downstream end of the annular inner wall 216 and the annular outer wall 218. The anode 254 is manufactured separately and is fixed on a non-conductive substrate formed by the upstream portion 252 in a sealed manner by soldering, in particular by vitreous brazing (by means of a filler material, for example siliceous, placed on the connection zones, the discharge channel 221 being placed under stress in an oven at a temperature greater than the operating temperature of the thruster).
    [0019] Furthermore, according to this second embodiment, the intermediate portion 253 is fixed on the one hand to the downstream portion 256 and on the other hand to the upstream portion 252 of the distributor assembly 251 also by brazing.
    [0020] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that various modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In addition, individual features of the various embodiments mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.
    权利要求:
    Claims (11)
    [0001]
    REVENDICATIONS1. A Hall effect plasma thruster comprising: - an annular discharge channel (121,221) around a main axis (A) with an open downstream end, having an ionization zone (128,228) between an inner wall (116,216) and a wall external (118,218), and further comprising an anode (154,254) and a distributor (151,251) located upstream of the ionization zone (128,228), - at least one cathode, - a magnetic circuit for creating a magnetic field in said channel, and - a pipe (124,224) for supplying the channel (121,221) with ionizable gas, said distributor (151,251) being connected to the pipe (124,224) and allowing the ionizable gas to flow into the ionization zone 15 (128,228) of the channel (121,221) concentrically about the main axis (A), characterized in that at least one transverse wall (152a, 152b; 253d, 253e) of material different from that of the anode (154,254) partially separates the distributor (151,251) from the zone Ionization (128,228). 20
    [0002]
    2. Propellant according to the preceding claim, characterized in that said at least one transverse wall (152a, 152b) is formed in a one-piece assembly (152) defining said distributor (151).
    [0003]
    3. Propeller according to the preceding claim, characterized in that said duct (124) is also formed in said monobloc assembly (152).
    [0004]
    The thruster of claim 1, wherein said at least one transverse wall (253d, 253e) is located downstream of said anode (254).
    [0005]
    5. Propellant according to any one of the preceding claims, characterized in that said anode (154; 254) is made of metal or an electrically conductive ceramic.
    [0006]
    6. Propellant according to any one of the preceding claims, characterized in that said transverse wall is made of a dielectric material such as boron nitride BN or alumina A1203.
    [0007]
    7. Propellant according to any one of the preceding claims, characterized in that said inner and outer walls (116,118; 216, 218) are made of the same dielectric material as said transverse wall (152a, 152b; 253d, 253e).
    [0008]
    8. Propellant according to any one of the preceding claims, characterized in that the discharge channel (121; 221) further comprises a wear ring (172, 174; 272, 274) placed at its downstream end, on at at least one of said inner and outer walls (116,118; 216,218) facing the ionization zone (128,228), said wear ring (172,174; 272,274) being made of ceramic.
    [0009]
    9. Propellant according to the preceding claim, characterized in that the ceramic of the wear ring (172, 174; 272, 274) is based on boron nitride.
    [0010]
    10. A method of manufacturing a discharge channel (121; 221) for a plasma thruster according to any one of claims 1 to 9, characterized in that said at least one transverse wall is made by additive manufacturing.
    [0011]
    11. The manufacturing method according to the preceding claim, characterized in that the anode (154,254) is fixed on a substrate of different material by soldering.
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    同族专利:
    公开号 | 公开日
    WO2015132534A1|2015-09-11|
    FR3018316B1|2020-02-28|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US5218271A|1990-06-22|1993-06-08|Research Institute Of Applied Mechanics And Electrodynamics Of Moscow Aviation Institute|Plasma accelerator with closed electron drift|
    US5763989A|1995-03-16|1998-06-09|Front Range Fakel, Inc.|Closed drift ion source with improved magnetic field|
    US6612105B1|1998-06-05|2003-09-02|Aerojet-General Corporation|Uniform gas distribution in ion accelerators with closed electron drift|
    RU2209533C2|2001-10-10|2003-07-27|Сорокин Игорь Борисович|Plasma accelerator with closed electron drift|CN107387348A|2017-09-13|2017-11-24|哈尔滨工业大学|A kind of a wide range of adjustable plasma microthruster using solid working medium|
    FR3093771A1|2019-03-15|2020-09-18|Safran Aircraft Engines|Plasma thruster chamber bottom|FR2743191B1|1995-12-29|1998-03-27|Europ Propulsion|ELECTRON-CLOSED DRIFT SOURCE OF IONS|CN107165793B|2017-06-12|2019-10-01|北京航空航天大学|A kind of electric propulsion engine gas distributor|
    CN110469472B|2019-07-19|2020-05-12|北京航空航天大学|Gas distributor of electric thruster|
    法律状态:
    2016-02-24| PLFP| Fee payment|Year of fee payment: 3 |
    2017-03-08| PLFP| Fee payment|Year of fee payment: 4 |
    2018-02-20| PLFP| Fee payment|Year of fee payment: 5 |
    2018-06-29| CD| Change of name or company name|Owner name: SAFRAN AIRCRAFT ENGINES, FR Effective date: 20170719 |
    2019-02-20| PLFP| Fee payment|Year of fee payment: 6 |
    2020-02-20| PLFP| Fee payment|Year of fee payment: 7 |
    2021-02-19| PLFP| Fee payment|Year of fee payment: 8 |
    2022-02-21| PLFP| Fee payment|Year of fee payment: 9 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1451912A|FR3018316B1|2014-03-07|2014-03-07|HALL EFFECT PLASMIC PROPELLER|
    FR1451912|2014-03-07|FR1451912A| FR3018316B1|2014-03-07|2014-03-07|HALL EFFECT PLASMIC PROPELLER|
    PCT/FR2015/050545| WO2015132534A1|2014-03-07|2015-03-05|Hall-effect plasma thruster|
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