Classifications

• • 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
• • 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
  • F03H1/0037—Electrostatic ion thrusters
  • F03H1/0062—Electrostatic ion thrusters grid-less with an applied magnetic field
  • F03H1/0075—Electrostatic ion thrusters grid-less with an applied magnetic field with an annular channel; Hall-effect thrusters with closed electron drift

Definitions

• This presentation relates to a chamber bottom for a plasma thruster making it possible to combine several functions in a single piece and, in
• Such a chamber bottom can be used for plasma thrusters of different types, and in particular Hall effect thrusters.
• Thrusters can be used in particular in the space field to propel or control the attitude of a space vehicle such as a satellite.
• Hall effect thrusters conventionally comprise a discharge chamber having ceramic insulating walls and an anode-injector assembly arranged at the bottom of the chamber; an electron gun, forming the cathode, is for its part mounted on the side of the discharge chamber and projects electrons into the space located in front of the latter so as to initiate a discharge with the anode, thus forming a plasma in the discharge chamber.
• the discharge chamber is formed using a piece
• the anode-injector assembly mechanically welded, is then attached to the bottom of the discharge chamber, most often by gluing or clamping.
• the present disclosure relates to a chamber bottom for a plasma thruster, comprising, as a single piece,
• a chamber bottom surface intended to close an annular chamber formed by the chamber bottom and at least one insulating part attached to the chamber bottom
• At least a first set of tabs comprising fixing tabs intended to fix said at least one insulating part on the chamber bottom.
• the chamber bottom is made of an electrically conductive material. It is thus possible to add the anode function to the chamber bottom, further reducing the number of parts necessary for the operation of the thruster.
• the chamber bottom is made of a metallic material.
• the chamber bottom is produced by additive manufacturing. Such a manufacturing technique makes it possible to produce the bottom of the chamber as a single piece with great freedom of geometry, which makes it possible to integrate more functions on the same part and to optimize, in particular, the distribution of the propellant gas in the bottom. of room.
• the chamber bottom surface is
• the chamber bottom surface is
• annular preferably symmetrical in revolution.
• the chamber bottom surface has in section a profile of general U-shape.
• general U-shape is understood to mean any shape having two ends substantially at the same level and a hollow of any shape. , with a minimum, spread or not, between the two ends. In particular, it is intended to encompass V-shapes.
• the sectional profile of the chamber bottom surface has at least one point of inflection, preferably at least two points of inflection.
• the profile of the chamber bottom surface is not regular: it can include one or more bumps or even form narrowings and / or enlargements. Such geometries can help optimize the flow of propellant gas in the discharge chamber.
• the chamber bottom comprises a first set of tabs, internal, comprising fixing tabs intended to fix a first insulating part on the chamber bottom, and a second set of tabs, external, comprising fixing tabs intended to fix a second insulating part on the chamber bottom.
• two separate insulating parts respectively form the inner and outer walls of the discharge chamber.
• the geometry of each of the insulating parts is thus simplified compared to the case of an annular part provided with an annular cavity, which facilitates the production of these parts, especially when they are made of ceramic.
• at least one set of tabs, preferably each set of tabs is arranged in a ring.
• the tongues are preferably distributed evenly within each crown.
• the internal set of tabs comprises between 4 and 8 fixing tabs.
• the set of outer tabs comprises between 4 and 16 fixing tabs, preferably between 4 and 8 fixing tabs.
• Such a number of tabs makes it possible to effectively hold the insulating part against the chamber bottom while preserving a certain flexibility making it possible to dissipate any shocks and vibrations, which reduces the risk of the insulating part breaking during operation.
• the outer set of tabs includes the same number of attachment tabs as the inner set of tabs.
• the outer set of tabs includes twice as many attachment tabs as the inner set of tabs.
• At least one fixing tongue preferably each fixing tongue of one or each set of tongues, extends axially, substantially perpendicularly to the chamber bottom, beyond the chamber bottom surface.
• At least one fixing tab preferably each fixing tab of one or each set of tabs, has a length of between 1 and 30 mm, preferably between 10 and 25 mm .
• At least one fixing tab preferably each fixing tab of one or each set of tabs, has a width of between 1 and 220 mm, preferably between 1 and 55 mm .
• At least one fixing tab preferably each fixing tab of one or each set of tabs, extends over an angular sector between 1 and 180 °, preferably between 1 and In some embodiments, at least one fixing tab, preferably each fixing tab of one or each set of tabs, has a thickness between 0.1 and 5 mm.
• At least one attachment tab preferably each attachment tab of one or each set of tabs, has a Young's modulus of between 50 and 300 GPa. These settings allow you to adjust the elasticity of the fixing tabs. The goal is to remain within the elastic range of the tabs at all times, without entering the plastic range, neither during assembly nor in operation.
• At least one fixing tongue preferably each fixing tongue of one or each set of tongues, has at its distal end a projection configured to cooperate with a notch, a groove or a shoulder of an insulating part.
• At least one set of tabs comprises dummy tabs configured not to cooperate with said at least one insulating part.
• These tabs can be useful during additive manufacturing because they make it possible to reduce the distance between two successive tabs, and therefore the angle of the arch formed between these two successive tabs, which makes it possible to reduce the need for temporary supports. during additive manufacturing.
• These dummy tabs do not participate in the fixing of the insulating parts, they can be partially or totally machined after manufacture to prevent them from rubbing on the insulating parts and wearing them out.
• the internal set of tabs comprises between 0 and 4 dummy tabs.
• the set of outer tabs comprises between 4 and 8 dummy tabs.
• the chamber bottom further comprises at least one distribution cavity communicating with the chamber by virtue of injection orifices opening out on the chamber bottom surface. This makes it possible to add the injector function to the chamber bottom, further reducing the number of parts required for the operation of the thruster.
• the chamber bottom comprises a
• first distribution cavity communicating with a second distribution cavity through a first series of injection ports
• second distribution cavity communicating with the chamber through a second series of injection ports.
• At least one distribution cavity preferably each distribution cavity, is annular, preferably symmetrical in revolution.
• each injection port has a diameter greater than or equal to 0.7 mm, preferably greater than or equal to 1 mm. Such a diameter allows good injection of the propellant gas as well as good dusting of the distribution cavities at the end of additive manufacturing.
• each injection port has a diameter less than or equal to 4 mm, preferably less than or equal to 1.5 mm.
• all of the injection ports have the same diameter.
• the chamber bottom comprises a
• the chamber bottom further comprises at least one fixing lug, and preferably several fixing lugs, extending from the underside of the chamber bottom, making it possible to fix the chamber bottom on a thruster body.
• the chamber bottom comprises at least one axisymmetric shoulder, provided on the underside of the chamber bottom.
• This shoulder can form a reference surface for installing the chamber bottom on a machining tool.
• the chamber bottom may include a first shoulder located on the internal edge of its lower face and a second shoulder located on the external edge of its lower face.
• This presentation also relates to a plasma propellant
• At least one insulating piece attached to the chamber bottom using at least the first set of tabs.
• the plasma thruster comprises a first radially inner insulating part forming a radially inner wall of the chamber, and a second radially outer insulating part forming a radially outer wall of the chamber.
• first radially inner insulating part forming a radially inner wall of the chamber
• second radially outer insulating part forming a radially outer wall of the chamber.
• each insulating part takes the form of a cylindrical ring.
• each insulating part is made of a ceramic material.
• each insulating part has an annular groove designed to cooperate with the fixing tongues of the chamber bottom.
• at least one insulating part, and preferably each insulating part is pressed against the chamber bottom. This ensures a seal between the chamber bottom and the insulating parts, thus reducing the risk of propellant gas leakage.
• a small space is left between at least one insulating part, preferably each insulating part, and the chamber bottom.
• the insulating parts are held in suspension above the chamber bottom by the tabs.
• This attachment method makes it possible to better withstand mechanical stresses, in particular vibrations and shocks.
• a sealing structure can be constructed or added to the interface between the insulating part and the chamber bottom; in particular, it may be a seal or a labyrinth.
• axial plane is understood to mean a plane passing through this main axis of the turbomachine and the term “radial plane” means a plane perpendicular to this main axis.
• elastic fitting also frequently called “snap-fit” or “clipping” is meant a method of assembling two parts by engagement and elastic deformation (in general
• the two parts When the two parts are engaged in the nesting position, the parts have generally returned to their original shape and no longer exhibit elastic deformation (or less elastic deformation).
• the two parts When the two parts are engaged with each other in the interlocking position, they cooperate with each other so as to oppose, or even block, the relative movements of said parts in the direction of release. (opposite sense to the sense of commitment).
• the two parties In the nesting position, the two parties can also cooperate so as to oppose, or even block, their relative movements in the direction of the extension of the engagement, beyond the position
• Figure 1 is a perspective view of a first example of a chamber bottom.
• Figure 2 is a perspective and sectional view of the first
• Figure 3 is a sectional view of the first example according to another sectional plane.
• Figure 4 is a sectional view of the chamber bottom equipped with
• Figure 5 is a sectional view illustrating the manufacture of the first example.
• Figure 6 is a perspective view of a second example of a chamber bottom.
• Figure 7 is a sectional view of a third example of a chamber bottom.
• FIG. 1 represents a first example of a chamber bottom 1 for a plasma thruster.
• This same chamber bottom 1 is shown in axial section, along two different planes of section, in Figures 2 and 3.
• This chamber bottom 1 is circular, of main axis A, forming a central passage 2. Most of its characteristics are axisymmetric with respect to this main axis A.
• the chamber bottom 1 comprises a chamber bottom surface 10
• the chamber bottom surface 10 opening upwards on the upper face 3 of the chamber bottom 1, thus forms a chamber bottom cavity 1 1 open on the upper face 3.
• the profile of the chamber bottom surface 10 is irregular: its outer part, descending, comprises a convex section 10a followed by a concave section 10b while its internal part, rising, is more regular with however a change of slope 10c.
• the chamber bottom cavity 1 1 thus has a first portion 11 a, upper, funnel-shaped and a second portion 11 b, lower, forming a fold.
• the chamber bottom 1 also comprises an injector 20 here comprising a first distribution cavity 21 and a second distribution cavity 22.
• An injection duct 23 extends from the lower face 4 of the chamber bottom 1: it is provided with a central injection channel 23a making it possible to introduce a propellant gas into the first distribution cavity 21.
• the first distribution cavity 21 is connected to the second distribution cavity 22 using a plurality of first injection orifices 24 distributed evenly along the circumference of the first distribution cavity 21.
• the second distribution cavity 22 is connected for its part to the chamber bottom cavity 1 1 using a plurality of second injection orifices 25 evenly distributed along the circumference of the second cavity of distribution 22.
• the second injection orifices 25 open into the folded portion 11 b of the chamber bottom cavity 11.
• the bottom of the chamber 1 comprises the first 10
• the chamber bottom 1 also comprises a first set of tabs 30 and a second set of tabs 40.
• the first set of tabs 30 comprises a plurality of first
• fixing tabs 31 arranged in a crown in a regular manner along the internal circumference of the chamber bottom 1.
• Each fixing tab 31 extends rectilinearly upwards from a circular base 32 projecting within the passage 2, at a level closer to the lower face 4 than to the upper face 3.
• Each fixing tab 31 thus extends within the passage 2, along the internal surface 5 of the chamber bottom 1, before protruding on the upper face 3.
• each fixing tab 31 is provided with a projection 33
• Each tab 31 is connected to its neighbors by arches 34 whose apex angle a is less than 60 °, in this case equal to 40 °.
• each tab 31 has a length 11 of 29 mm measured from the base 32 and a length I2 of 24 mm measured from the start of the arches 34; each tongue 31 has a width m of 16.5 mm and a thickness n of 1 mm.
• the first set of tabs 30 comprises 6
• the second set of tabs 40 comprises a plurality of second
• fixing tabs 41 arranged in a crown evenly along the outer circumference of the chamber bottom 1.
• Each fixing tab 41 extends rectilinearly upwards from a circular base 42 protruding from the outer surface 6 of the bottom chamber 1, at a level closer to the lower face 4 than to the upper face 3, in this case at the same level as the base 32 of the first set of tabs 30.
• Each fixing tab 41 thus extends along the outer surface 6 of the chamber bottom 1, before protruding from the upper face 3.
• each fixing tab 41 is provided with a projection 43
• Each tab 41 is connected to its neighbors by arches 44.
• each tab 41 has a geometry
• the second set of tabs 40 comprises 6
• the chamber bottom 1 also comprises fixing lugs 51 extending axially from the lower face 4; it also comprises an internal shoulder 52, symmetrical of revolution, provided on the internal edge between the lower face 4 and the internal surface 5, and an external shoulder 53, symmetrical of revolution, provided on the external edge between the lower face 4 and the outer surface 6.
• These insulating parts 60 made of ceramic material, comprise a first insulating ring 61, internal, and a second insulating ring 62, external. These two insulating rings 61, 62 are invariant by rotation about the axis A.
• the inner insulating ring 61 has an outer surface 61 a, smooth and
• the outer insulating ring 62 has for its part an inner surface 62a, smooth and rectilinear in the axial direction, and an outer surface 62b provided with a circular groove 62c.
• the internal insulating ring 61 is attached to the chamber bottom 1 in
• the outer insulating ring 62 is attached to the chamber bottom 1 by engaging its outer surface 62b around the tabs 41 of the first set of tabs 30, the latter then deforming elastically outwardly, and in pushing the ring 62 up to the stop against the upper face 3 of the chamber bottom 1: the projections 43 of the fixing tongues 41 then engage in the groove 62c of the outer ring 62 and block the position of the outer ring 62 by elastic release of the tabs 31.
• the insulating rings 61, 62 and the chamber bottom 1 define a discharge chamber 63, symmetrical in revolution, delimited by the outer wall 61a of the inner ring 61, the inner wall 62a of the outer ring 62 and the chamber bottom surface 10 of the chamber bottom 1.
• the chamber bottom 1 is made of metal by additive manufacturing.
• the chamber bottom 1 is manufactured layer by layer by partial melting of a metal powder using a high energy beam, such as a laser or a laser beam. electrons. Manufacturing takes place in the direction of the main axis A from a build plate P; the chamber bottom is manufactured from its upper face 3 towards its lower face 4.
• the chamber bottom is made of a nickel-based alloy, for example of lnconel718.
• portions of sacrificial part and / or additional elements such as supports can be added to the target geometry of the final part.
• the internal 12 'and external 13' walls of the chamber bottom cavity 1 1 'of the blank 1' extend to the distal end of the tongues 31 and 41 in order to '' be manufactured directly from the build plate P.
• Additional dummy tabs can also be added, in particular within the second set of tongues 40 in order to reduce the range of the arches 44, thus limiting the angle formed by the latter.
• an internal shell 71 cylindrical, is manufactured just along the internal tabs 31, without contact, in order to support the latter during manufacture.
• a cylindrical outer shell 72 is fabricated just along the outer tabs 41, non-contacting, to support the latter during manufacture.
• the internal 71 and / or external 72 shells can be sectored to facilitate their removal after manufacture.
• Dedusting holes 73 can also be provided in
• the shells 71, 72 are removed and the blank 1' is positioned on a machining tool using its shoulders 52 and 53 in order to remove the portions sacrificial, in particular the dummy tabs 45, which results in the final chamber bottom 1.
• Figure 6 illustrates a second embodiment of a chamber bottom 101 in which the dummy tongues 145 have not been machined. It will be noted on this occasion that the dummy tongues 145 do not have a projection at their end and therefore do not interact with the insulating ring.
• FIG. 7 illustrates a third exemplary embodiment of a chamber bottom 201 in which the injector 210 only comprises a single distribution cavity 21 1.
• the first distribution cavity 211 is supplied. via the injection channel 223a of the injection duct 223 and directly connected to the bottom cavity of the chamber 21 1 via injection orifices 225.

Landscapes

• 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)
• Plasma Technology (AREA)
• Electron Sources, Ion Sources (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=67810713

Family Applications (1)

Country Status (5)

Families Citing this family (2)

Family Cites Families (8)

• 2019
  • 2019-03-15 FR FR1902712A patent/FR3093771B1/fr active Active
• 2020
  • 2020-03-11 US US17/439,097 patent/US20220145865A1/en active Pending
  • 2020-03-11 WO PCT/FR2020/050501 patent/WO2020188185A1/fr active Application Filing
  • 2020-03-11 CN CN202080021269.1A patent/CN113597510B/zh active Active
  • 2020-03-11 EP EP20725875.7A patent/EP3938652B1/de active Active

Also Published As

Similar Documents

Legal Events