EP2359001A1 - Electronegative plasma thruster with optimized injection - Google Patents

Electronegative plasma thruster with optimized injection

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Publication number
EP2359001A1
EP2359001A1 EP09756319A EP09756319A EP2359001A1 EP 2359001 A1 EP2359001 A1 EP 2359001A1 EP 09756319 A EP09756319 A EP 09756319A EP 09756319 A EP09756319 A EP 09756319A EP 2359001 A1 EP2359001 A1 EP 2359001A1
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EP
European Patent Office
Prior art keywords
gas
plasma thruster
thruster according
ionization
stage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP09756319A
Other languages
German (de)
French (fr)
Other versions
EP2359001B1 (en
Inventor
Pascal Chabert
Ane Aanesland
Albert Meige
Gary Leray
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Centre National de la Recherche Scientifique CNRS
Ecole Polytechnique
Original Assignee
Centre National de la Recherche Scientifique CNRS
Ecole Polytechnique
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Publication of EP2359001A1 publication Critical patent/EP2359001A1/en
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Publication of EP2359001B1 publication Critical patent/EP2359001B1/en
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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
    • F03H1/0025—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
    • F03H1/0012—Means for supplying the propellant
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/54—Plasma accelerators

Definitions

  • the invention lies in the field of plasma thrusters. These thrusters may for example be used in satellites or in spacecraft whose propulsion requires low thrusts over long periods, such as probes.
  • Plasma thrusters achieve these high ejection speeds.
  • the principle of the plasma thrusters (conventional) described in the diagram illustrated in FIG. 1 is as follows: the "fuel" (gas) X is first ionized to form positive ions X + and electrons e " . Positive are accelerated by an electric field E, created by accelerating gates, and are thus ejected from the system, before being neutralized by an electron beam Fe " annex, positioned downstream of the accelerator zone, generated by a cathode . Neutralization is essential to prevent space vehicles from charging electrically.
  • the various prototypes of plasma propellants existing to date generally use an ionization stage to generate a source of positively charged material (positive ions), an acceleration stage and a neutralization structure. Sources of ionization, accelerating and neutralizing structures can be varied. But, all the propellers existing today use only the positively charged material (positive ions) for propulsion, the negative charge (the electrons) serving only for ionization and neutralization.
  • an electronegative gas gas with high electron affinity
  • an electropositive gas gas with high electron affinity
  • the two gases are different and it is two separate ion sources, or be used alone and, in the latter case, the flow of negative ions and the flow of positive ions are generated from this same electronegative gas.
  • FIG. 2 illustrates this type of thruster configuration. More precisely, this thruster comprises a structure fed with electronegative gas and:
  • An electronegative gas flow A 2 is introduced into the ionization stage 1. Under the action of an electrical power schematized by the arrow Pe, the electronegative gas generates positive ions A + , negative ions
  • the ionization stage 1 is coupled to a filter stage
  • the filtering means which can be for example a static magnetic field.
  • Plasma extraction is ensured, in the case schematized here, by two grids polarized negatively 4 and positively 5, according to a first possible extraction method.
  • the extraction of the plasma can also be ensured by a polarized grid alternately positively and negatively according to a second extraction method.
  • the first and second extraction methods can also be combined or arranged in a matrix (for example to increase the size of the system).
  • the thrust is therefore ensured by the two types of ions (the negative charge and the positive charge). Downstream neutralization is no longer necessary because the ion beams neutralize downstream (recombination) to form a beam of fast neutral molecules.
  • the plasma thruster has a single ionization stage in which a positive ion and negative ion plasma is created.
  • the Applicant proposes to exploit the temperature difference of the electrons within the ionization stage: the so-called "hot” electrons favor the positive ionization of the electronegative gas, thus creating positive ions, while the so-called less "hot” electrons favor the creation of negative ions, by attachment of these electrons.
  • the subject of the present invention is a plasma thruster comprising the extraction of a positive ion flux and a negative ion flux characterized in that it comprises:
  • ionizable gas injection means of said ionization stage said means comprising at least first injection means of a first gas and second injection means of a second electronegative gas;
  • means for creating an electric power so as to produce the ionization of the gases in the ionization stage said means creating a first so-called hot zone at the level of the ionization stage; - the first gas being distributed in the first so-called hot zone, the second gas being distributed in a second zone less hot than said first zone;
  • first means for extracting a flow of negative ions second means for extracting a flow of positive ions, connected to the ionization stage; the extraction of a flow of positive ions and the extraction of a flow of negative ions ensuring the electrical neutrality of the propellant.
  • first gas and the second gas are identical.
  • the thruster comprises two constituent compartments of the first and second zones.
  • the first injection means of the first gas are located at a first face of the ionization stage, the second injection means being distributed along a second transverse face. to said first face, so as to dispense a series of second gas streams into the ionization stage.
  • the second second gas injection means distribute different flow rates in the ionization stage.
  • the propellant further comprises means for filtering the electrons released in the ionization stage, during the ionization of the gas.
  • the means for creating an electric field comprise two conductive elements placed at the ends of the ionization stage to place said stage under tension.
  • the means for creating an electric field comprise a coil supplied with a radiofrequency current.
  • the means for creating an electric field comprise a helicon antenna powered by a radio frequency (RF) current.
  • the electronegative gas is a dihalogen.
  • the electronegative gas is of the diode type.
  • the electronegative gas is oxygen
  • the electronegative gas is sulfur hexafluoride (SF 6 ).
  • the thruster comprises means for creating a pulsed plasma.
  • the thruster comprises means for generating a static magnetic field within the ionization stage, so as to filter the electrons.
  • the thruster comprises permanent magnets placed at the periphery of the ionization stage to create the magnetic field within said ionization stage.
  • the thruster comprises means for extracting negative and / or positive ion fluxes in a direction perpendicular to the direction of the magnetic field applied at the level of the ionization stage.
  • the thruster comprises a temporal modulation system of the ion extraction means.
  • the positive and negative ions are extracted alternately by the same extraction means.
  • the ion flux extraction means comprise at least one polarized gate.
  • FIG. 1 schematizes a conventional plasma thruster according to the prior art comprising an electropositive gas for generating a positive ion flux which is neutralized with an electron beam downstream of the accelerating zone;
  • FIG. 2 schematizes a plasma thruster according to the prior art comprising an electronegative gas for simultaneously generating a flow of positive ions and a flow of negative ions;
  • FIG. 3 illustrates an example of a thruster according to the invention comprising the injection of two different gases at dissociated and optimized locations;
  • FIG. 4 illustrates the evolution of the electron temperature as a function of a distance away from electric field generating means perpendicular to an applied magnetic field creating an electron heating zone
  • FIG. 5 illustrates the evolution of the ratio of negative ions per electron, generated by attachment collision, as a function of a distance away from electrical field creation means perpendicular to an applied magnetic field, creating a zone electron heating
  • FIG. 6 illustrates the rate of generation of negative ions by collision with electrons (attachment) as a function of temperature and the ionization rate creating positive ions by collision with electrons as a function of temperature;
  • FIG. 7 schematizes a second variant of the invention comprising a series of means for injecting the second gas into the ionization stage;
  • FIGS. 8a, 8b and 8c illustrate an example of a thruster according to the invention.
  • the propellant of the invention comprises a single ionization stage coupled to means for ionizing one or more gases intended for propulsion, said stage comprising at least first injection means of a first gas and second means for injecting a second gas.
  • the second injected gas is an electronegative gas and is diffused in the ionization stage in a so-called colder region, with respect to a so-called hot zone located near the means for creating an electric field necessary for the ionization of the ions. gas.
  • These means for coupling the electrical energy to the plasma may be of the type of two plates polarized continuously, at low frequency or radiofrequency, radiofrequency supplied coil for inductive coupling, or even microwave source.
  • FIG. 3 schematizes a first example of an ionization stage comprising a gas supply Gi and an electronegative gas supply G 2 , the coupling means of the electrical energy being represented by a power Pe of supply and generating electrons represented e " .
  • the so-called hot region of the ionization stage is referenced Zi close to the RF source, the so-called colder region and remote from the RF source being referenced Z 2 .
  • the electronegative gas is injected into the least hot region.
  • the first gas may be an electropositive or electronegative gas, introduced into the so-called hot region Zi at the plasma core in which the RF power is coupled with the electrons.
  • the second gas is introduced into a region Z 2 close to the extraction means in which the electrons have a lower temperature.
  • the second gas is electronegative and ensures efficient generation of negative ions.
  • Extraction means Me are provided for extracting the positive ions and the negative ions.
  • FIG. 4 illustrates in this respect the evolution of the electron temperature as a function of a distance X within the ionization stage, the distance being located from the zone located near the electric field creation (reference 0) along the horizontal axis shown in FIG. 4.
  • FIG. 5 illustrates the evolution of the ratio of negative ions by an electron as a function of the same distance X. It appears that the generation of negative ions is very marked beyond a distance in the case considered of about 40 mm. Curve 5a is relative to a gas O 2 , the curve
  • the rate of creation of negative ions is a decreasing function of the electron temperature
  • the ionization rate, creating positive ions, by collision with electrons is an exponential function of the electron temperature
  • FIG. 6 illustrates these behaviors for an electronegative gas, curve 6a being respectively relative to the first phenomenon (attachment reaction), curve 6b being relative to the second phenomenon (ionization reaction).
  • Negative ions are created in the low temperature region and become dominant when the temperature is typically below 1 -2 eV, whereas positive ions are created in a region of high temperature for the electrons and become dominant for energies higher than about 4-5 eV (the threshold values vary greatly according to the type of gas).
  • the electronegative gas used may advantageously be a dihalogen of the type I 2 .
  • Such a gas has several interests, it is cheap compared to other electronegative gases and has the great advantage of being solid at room temperature which can strongly favor all packaging and storage operations.
  • the propellant can use as a first gas, a Xenon type gas for generating positive ions and as a second gas, a dihalogen capable of generating negative ions.
  • the thruster comprises two zones respectively called hot and cold in which, respectively, are injected a first gas and a second electronegative gas via two injection means.
  • the thrust is ensured by the two types of ions (positive and negative). Downstream neutralization is no longer necessary because the ion beams neutralize downstream (recombination) to form a beam of fast neutral molecules.
  • the previously described ionization stage can be coupled to a filtering stage like that illustrated in FIG.
  • the filtering stage can be realized in at least two ways: - (i) by modulating the creation of the plasma (pulsed plasmas: ON-OFF alternation of the electric power) and by using the OFF period for the extraction, period during which the electrons disappeared by attachment on the molecules. According to this configuration, the ionization and filtering stages are common. - (ii) by using a static magnetic field to trap the electrons, the ions, much heavier, are not.
  • the thruster of the invention also comprises an extraction stage that can consist of accelerating grids whose dimensions are not necessarily similar to those of conventional grid thrusters, because the properties of the space charge sheaths are different in the absence of electrons.
  • the plasma is created by an RF radio frequency antenna whose active surface is optimized and sized according to the intended applications.
  • FIGS. 8a and 8b illustrate different views of the RF antenna and of the two hot and cold zones Z 1 and Z 2 in which the plate 80 is respectively inserted and closes the enclosure into which the gas is introduced.
  • the temperature is sufficiently high in the Zi volume to create positive ions by ionization, and thus obtain a high density of positive ions in this region.
  • a second electronegative gas G 2 is injected into the volume Z 2 to produce the negative ions.
  • the extraction volume is separated into two regions by permanent magnets, the installation of two acceleration grids is also provided at the output of volume Z 2 .
  • Permanent magnets 70 are placed on one side and in the middle of the volume Z 2 to filter the electrons so as to keep in the medium only positive ions and negative ions at the output of volume Z 2 . In this region the temperature of the electrons decreases and the negative ions are produced by collision of attachment with electrons.
  • the applied magnetic field has two functions:
  • Extraction means 40 and 50 shown in FIG 8c are used to accelerate the ions and cause the output of the propellant, the ionic entities A " and A + are thus extracted from the propellant.
  • These means can typically be grid type, a grid that can be used to accelerate the negative ions, another grid that can be used to accelerate the positive ions.
  • the two extracted ion beams neutralize each other downstream (in space). Neutralization is therefore automatic and does not require additional electron beam.
  • the two beams can also recombine to form a beam of fast neutral molecules.

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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)
  • Spectroscopy & Molecular Physics (AREA)
  • Plasma Technology (AREA)

Abstract

The invention relates to a plasma thruster involving the extraction of a stream of positive ions, characterized in that it comprises: - a single ionisation stage; - means of injecting ionisable gas for said ionisation stage, said means comprising at least first means of injecting a first gas (G1) and second means of injecting an electronegative second gas (G2); - means of creating an electrical field (Pe, RF) so as to cause the gases to ionise in the ionisation stage, said means creating a first zone known as a hot zone in the ionisation stage, whereby the first gas is distributed in the first zone (Z1) known as the hot zone and the second gas is distributed in a second zone (Z2) that is not as hot as the first zone; - first means (40) of extracting a stream of negative ions and second means (50) of extracting a stream of positive ions, which are both connected to the ionisation stage, the extraction of a stream of positive ions and the extraction of a stream of negative ions ensuring that the thruster is electrically neutral.

Description

Propulseur à plasma électronégatif à injection optimisée Optimized injection electronegative plasma thruster
L'invention se situe dans le domaine des propulseurs à plasma. Ces propulseurs peuvent par exemple être utilisés dans les satellites ou bien dans les engins spatiaux dont la propulsion nécessite des poussées faibles sur des temps longs, comme par exemple les sondes.The invention lies in the field of plasma thrusters. These thrusters may for example be used in satellites or in spacecraft whose propulsion requires low thrusts over long periods, such as probes.
La propulsion d'engins dans l'espace (où la gravitation terrestre devient négligeable) requiert de faibles poussées (faible flux de matière éjectée), mais de fortes vitesses d'éjection du « carburant » pour minimiser la masse embarquée. En effet, l'augmentation de vitesse d'un engin spatial est reliée à la vitesse d'éjection des gaz uΘ et aux masses initiales m0 et finale mf de carburant par l'équation suivante dite « rocket équation »: The propulsion of machines in space (where terrestrial gravitation becomes negligible) requires low thrusts (low ejected material flow), but high ejection speeds of the "fuel" to minimize the onboard weight. Indeed, the speed increase of a spacecraft is related to the ejection velocity of the gases u Θ and to the initial masses m 0 and final m f of fuel by the following equation called "rocket equation":
Une vitesse d'éjection des gaz importante est donc impérative si l'on veut économiser du carburant. Les propulseurs plasma permettent d'atteindre ces fortes vitesses d'éjection. Deux quantités sont utilisées pour caractériser un propulseur, l'impulsion spécifique : exprimée en secondes, où g0 est la constante de gravité à la surface de la terre, et la poussée : T = mue où m est le débit massique.A high gas ejection speed is therefore imperative if we want to save fuel. Plasma thrusters achieve these high ejection speeds. Two quantities are used to characterize a thruster, the specific impulse: expressed in seconds, where g 0 is the gravitational constant at the earth's surface, and the thrust: T = mu e where m is the mass flow.
Le principe des propulseurs à plasma (classique) décrit sur le schéma illustré en figure 1 , est le suivant : le « carburant » (gaz) X est d'abord ionisé pour former des ions positifs X+ et des électrons e". Les ions positifs sont accélérés grâce à un champ électrique E, créé par des grilles accélératrices, et sont ainsi éjectés du système, avant d'être neutralisés par un faisceau d'électrons Fe" annexe, positionné en aval de la zone accélératrice, généré par une cathode. La neutralisation est indispensable pour éviter que les engins spatiaux ne se chargent électriquement. Les différents prototypes de propulseurs plasmas existant à ce jour, utilisent de manière générale un étage d'ionisation pour générer une source de matière chargée positivement (ions positifs), un étage d'accélération et une structure de neutralisation. Les sources d'ionisation, les structures accélératrices et neutralisatrices peuvent être variées. Mais, tous les propulseurs existant à ce jour n'utilisent que la matière chargée positivement (les ions positifs) pour la propulsion, la charge négative (les électrons) servant uniquement à l'ionisation et à la neutralisation.The principle of the plasma thrusters (conventional) described in the diagram illustrated in FIG. 1 is as follows: the "fuel" (gas) X is first ionized to form positive ions X + and electrons e " . positive are accelerated by an electric field E, created by accelerating gates, and are thus ejected from the system, before being neutralized by an electron beam Fe " annex, positioned downstream of the accelerator zone, generated by a cathode . Neutralization is essential to prevent space vehicles from charging electrically. The various prototypes of plasma propellants existing to date, generally use an ionization stage to generate a source of positively charged material (positive ions), an acceleration stage and a neutralization structure. Sources of ionization, accelerating and neutralizing structures can be varied. But, all the propellers existing today use only the positively charged material (positive ions) for propulsion, the negative charge (the electrons) serving only for ionization and neutralization.
Dans ce contexte, la demanderesse a déjà proposé, dans une demande de brevet antérieure publiée sous le numéro 2 894 301 , d'utiliser un flux d'ions positifs et un flux d'ions négatifs pour la poussée. Pour cela, un gaz électronégatif (gaz à forte affinité électronique) est utilisé comme carburant. Il peut être utilisé en combinaison avec un gaz électropositif, dans ce cas les deux gaz sont différents et il s'agit de deux sources d'ions séparées, ou bien être utilisé seul et, dans ce dernier cas, le flux d'ions négatifs et le flux d'ions positifs sont générés depuis ce même gaz électronégatif.In this context, the applicant has already proposed, in an earlier patent application published under number 2 894 301, to use a positive ion flow and a negative ion flow for the thrust. For this, an electronegative gas (gas with high electron affinity) is used as fuel. It can be used in combination with an electropositive gas, in this case the two gases are different and it is two separate ion sources, or be used alone and, in the latter case, the flow of negative ions and the flow of positive ions are generated from this same electronegative gas.
La figure 2 illustre ce type de configuration de propulseur. Plus précisément ce propulseur comprend une structure alimentée en gaz électronégatif et :Figure 2 illustrates this type of thruster configuration. More precisely, this thruster comprises a structure fed with electronegative gas and:
- un étage d'ionisation 1 ,an ionization stage 1,
- un étage de filtrage 2,a filtering stage 2,
- un étage d'extraction 3.- an extraction stage 3.
Un flux de gaz électronégatif A2 est introduit dans l'étage d'ionisation 1 . Sous l'action d'une puissance électrique schématisé par la flèche Pe, le gaz électronégatif génère des ions positifs A+, des ions négatifsAn electronegative gas flow A 2 is introduced into the ionization stage 1. Under the action of an electrical power schematized by the arrow Pe, the electronegative gas generates positive ions A + , negative ions
A" et des électrons e". L'étage d'ionisation 1 est couplé à un étage de filtrageA " and electrons e " . The ionization stage 1 is coupled to a filter stage
2 des électrons de manière à disposer dans l'étage d'extraction 3 d'un plasma d'ions positifs et d'ions négatifs dépourvus d'électrons. Les moyens de filtrage, pouvant être par exemple un champ magnétique statique. L'extraction du plasma est assurée, dans le cas ici schématisé, par deux grilles polarisées négativement 4 et positivement 5, selon une première méthode d'extraction possible.2 electrons so as to have in the extraction stage 3 a positive ion plasma and negative ions without electrons. The filtering means, which can be for example a static magnetic field. Plasma extraction is ensured, in the case schematized here, by two grids polarized negatively 4 and positively 5, according to a first possible extraction method.
L'extraction du plasma peut aussi être assurée par une grille polarisée alternativement positivement et négativement selon une seconde méthode d'extraction. Les première et seconde méthodes d'extraction peuvent aussi être combinées ou être disposées en matrice (par exemple pour augmenter la taille du système).The extraction of the plasma can also be ensured by a polarized grid alternately positively and negatively according to a second extraction method. The first and second extraction methods can also be combined or arranged in a matrix (for example to increase the size of the system).
La poussée est donc assurée par les deux types d'ions (la charge négative et la charge positive). La neutralisation en aval n'est plus nécessaire car les faisceaux d'ions se neutralisent en aval (recombinaison) pour former un faisceau de molécules neutres rapides.The thrust is therefore ensured by the two types of ions (the negative charge and the positive charge). Downstream neutralization is no longer necessary because the ion beams neutralize downstream (recombination) to form a beam of fast neutral molecules.
Le propulseur à plasma possède un étage unique d'ionisation au sein duquel est créé un plasma d'ions positifs et d'ions négatifs. Afin de perfectionner un tel propulseur, la demanderesse propose d'exploiter la différence de température des électrons au sein de l'étage d'ionisation : les électrons dits « chauds » favorisent l'ionisation positive du gaz électronégatif, donc créent des ions positifs, alors que les électrons dits moins « chauds » favorisent la création d'ions négatifs, par attachement de ces électrons.The plasma thruster has a single ionization stage in which a positive ion and negative ion plasma is created. In order to perfect such a propellant, the Applicant proposes to exploit the temperature difference of the electrons within the ionization stage: the so-called "hot" electrons favor the positive ionization of the electronegative gas, thus creating positive ions, while the so-called less "hot" electrons favor the creation of negative ions, by attachment of these electrons.
L'optimisation de ce type de propulseur repose ainsi notamment sur l'injection optimisée du gaz électronégatif au sein de l'étage d'ionisation.The optimization of this type of thruster thus relies in particular on the optimized injection of the electronegative gas within the ionization stage.
Plus précisément la présente invention a pour objet un propulseur à plasma comprenant l'extraction d'un flux d'ions positifs et d'un flux d'ions négatifs caractérisé en ce qu'il comprend :More precisely, the subject of the present invention is a plasma thruster comprising the extraction of a positive ion flux and a negative ion flux characterized in that it comprises:
- un unique étage d'ionisation ;a single ionization stage;
- des moyens d'injection en gaz ionisable dudit étage d'ionisation, lesdits moyens comportant au moins des premiers moyens d'injection d'un premier gaz et des seconds moyens d'injection d'un second gaz électronégatif ;ionizable gas injection means of said ionization stage, said means comprising at least first injection means of a first gas and second injection means of a second electronegative gas;
- des moyens de création d'une puissance électrique de manière à produire l'ionisation des gaz dans l'étage d'ionisation, lesdits moyens créant une première zone dite chaude au niveau de l'étage d'ionisation ; - le premier gaz étant distribué dans la première zone dite chaude, le second gaz étant distribué dans une seconde zone moins chaude que ladite première zone ;means for creating an electric power so as to produce the ionization of the gases in the ionization stage, said means creating a first so-called hot zone at the level of the ionization stage; - the first gas being distributed in the first so-called hot zone, the second gas being distributed in a second zone less hot than said first zone;
- des premiers moyens d'extraction d'un flux d'ions négatifs, des seconds moyens d'extraction d'un flux d'ions positifs, reliés à l'étage d'ionisation ; - l'extraction d'un flux d'ions positifs et l'extraction d'un flux d'ions négatifs assurant la neutralité électrique du propulseur. Selon une variante de l'invention, le premier gaz et le second gaz sont identiques. Selon une variante de l'invention, le propulseur comporte deux compartiments constitutifs des première et seconde zones.first means for extracting a flow of negative ions, second means for extracting a flow of positive ions, connected to the ionization stage; the extraction of a flow of positive ions and the extraction of a flow of negative ions ensuring the electrical neutrality of the propellant. According to a variant of the invention, the first gas and the second gas are identical. According to a variant of the invention, the thruster comprises two constituent compartments of the first and second zones.
Selon une variante de l'invention, les premiers moyens d'injection du premier gaz sont situés au niveau d'une première face de l'étage d'ionisation, les seconds moyens d'injection étant distribués le long d'une seconde face transverse à ladite première face, de manière à distribuer une série de flux de second gaz dans l'étage d'ionisation.According to a variant of the invention, the first injection means of the first gas are located at a first face of the ionization stage, the second injection means being distributed along a second transverse face. to said first face, so as to dispense a series of second gas streams into the ionization stage.
Selon une variante de l'invention, les seconds moyens d'injection de second gaz distribuent des flux de débit différents dans l'étage d'ionisation.According to a variant of the invention, the second second gas injection means distribute different flow rates in the ionization stage.
Selon une variante de l'invention, le propulseur comporte en outre des moyens de filtrage des électrons libérés dans l'étage d'ionisation, lors de l'ionisation du gaz.According to a variant of the invention, the propellant further comprises means for filtering the electrons released in the ionization stage, during the ionization of the gas.
Selon une variante de l'invention les moyens pour créer un champ électrique comprennent deux éléments conducteurs placés aux extrémités de l'étage d'ionisation pour placer ledit étage sous tension. Selon une variante de l'invention, les moyens pour créer un champ électrique comprennent une bobine alimentée par un courant radiofréquence. Selon une variante de l'invention, les moyens pour créer un champ électrique comprennent une antenne hélicon alimentée par un courant radio- fréquence (RF). Selon une variante de l'invention, le gaz électronégatif est un dihalogène.According to a variant of the invention the means for creating an electric field comprise two conductive elements placed at the ends of the ionization stage to place said stage under tension. According to a variant of the invention, the means for creating an electric field comprise a coil supplied with a radiofrequency current. According to a variant of the invention, the means for creating an electric field comprise a helicon antenna powered by a radio frequency (RF) current. According to a variant of the invention, the electronegative gas is a dihalogen.
Selon une variante de l'invention, le gaz électronégatif est de type diiode.According to a variant of the invention, the electronegative gas is of the diode type.
Selon une variante de l'invention, le gaz électronégatif est de l'oxygène.According to a variant of the invention, the electronegative gas is oxygen.
Selon une variante de l'invention, le gaz électronégatif est de l'hexafluorure de soufre (SF6).According to a variant of the invention, the electronegative gas is sulfur hexafluoride (SF 6 ).
Selon une variante de l'invention, le propulseur comprend des moyens pour créer un plasma puisé. Selon une variante de l'invention, le propulseur comprend des moyens pour générer un champ magnétique statique au sein de l'étage d'ionisation, de manière à filtrer les électrons.According to a variant of the invention, the thruster comprises means for creating a pulsed plasma. According to a variant of the invention, the thruster comprises means for generating a static magnetic field within the ionization stage, so as to filter the electrons.
Selon une variante de l'invention, le propulseur comprend des aimants permanents placés en périphérie de l'étage d'ionisation pour créer le champ magnétique au sein dudit étage d'ionisation.According to a variant of the invention, the thruster comprises permanent magnets placed at the periphery of the ionization stage to create the magnetic field within said ionization stage.
Selon une variante de l'invention, le propulseur comprend des moyens d'extraction de flux d'ions négatifs et/ou positifs dans une direction perpendiculaire à la direction du champ magnétique appliqué au niveau de l'étage d'ionisation.According to a variant of the invention, the thruster comprises means for extracting negative and / or positive ion fluxes in a direction perpendicular to the direction of the magnetic field applied at the level of the ionization stage.
Selon une variante de l'invention, le propulseur comprend un système de modulation temporelle des moyens d'extraction des ions.According to a variant of the invention, the thruster comprises a temporal modulation system of the ion extraction means.
Selon une variante de l'invention, les ions positifs et négatifs sont extraits alternativement par le même moyen d'extraction. Selon une variante de l'invention, les moyens d'extraction de flux d'ions comprennent au moins une grille polarisée.According to a variant of the invention, the positive and negative ions are extracted alternately by the same extraction means. According to a variant of the invention, the ion flux extraction means comprise at least one polarized gate.
L'invention sera mieux comprise et d'autres détails apparaîtront à la lecture de la description qui va suivre donnée à titre non limitatif et grâce aux figures annexées parmi lesquelles :The invention will be better understood and other details will become apparent on reading the following description given by way of non-limiting example and with reference to the appended figures among which:
- la figure 1 schématise un propulseur plasma classique selon l'art antérieur comportant un gaz électropositif pour générer un flux d'ions positifs qui est neutralisé avec un faisceau d'électrons en aval de la zone accélératrice ;FIG. 1 schematizes a conventional plasma thruster according to the prior art comprising an electropositive gas for generating a positive ion flux which is neutralized with an electron beam downstream of the accelerating zone;
- la figure 2 schématise un propulseur plasma selon l'art antérieur comportant un gaz électronégatif pour générer simultanément un flux d'ions positifs et un flux d'ions négatifs ;FIG. 2 schematizes a plasma thruster according to the prior art comprising an electronegative gas for simultaneously generating a flow of positive ions and a flow of negative ions;
- la figure 3 illustre un exemple de propulseur selon l'invention comportant l'injection de deux gaz différents à des endroits dissociés et optimisés ;FIG. 3 illustrates an example of a thruster according to the invention comprising the injection of two different gases at dissociated and optimized locations;
- la figure 4 illustre l'évolution de la température des électrons en fonction d'une distance d'éloignement par rapport à des moyens de création de champ électrique perpendiculaire à un champ magnétique appliqué créant une zone de chauffage d'électrons ; la figure 5 illustre l'évolution du rapport ions négatifs par électron, générés par collision d'attachement, en fonction d'une distance d'éloignement par rapport à des moyens de création de champ électrique perpendiculaire à un champ magnétique appliqué, créant une zone de chauffage d'électrons ;FIG. 4 illustrates the evolution of the electron temperature as a function of a distance away from electric field generating means perpendicular to an applied magnetic field creating an electron heating zone; FIG. 5 illustrates the evolution of the ratio of negative ions per electron, generated by attachment collision, as a function of a distance away from electrical field creation means perpendicular to an applied magnetic field, creating a zone electron heating;
- la figure 6 illustre le taux de génération d'ions négatifs par collision avec des électrons (attachement) en fonction de la température et du taux d'ionisation créant des ions positifs par collision avec des électrons en fonction de la température ; - la figure 7 schématise une seconde variante de l'invention comprenant une série de moyens d'injection du second gaz dans l'étage d'ionisation ;FIG. 6 illustrates the rate of generation of negative ions by collision with electrons (attachment) as a function of temperature and the ionization rate creating positive ions by collision with electrons as a function of temperature; FIG. 7 schematizes a second variant of the invention comprising a series of means for injecting the second gas into the ionization stage;
- les figures 8a, 8b et 8c illustrent un exemple de propulseur selon l'invention.FIGS. 8a, 8b and 8c illustrate an example of a thruster according to the invention.
De manière générale, le propulseur de l'invention comporte un étage unique d'ionisation couplé à des moyens pour ioniser un ou plusieurs gaz destinés à la propulsion, ledit étage comportant aux moins des premiers moyens d'injection d'un premier gaz et des seconds moyens d'injection d'un second gaz. Le second gaz injecté est un gaz électronégatif et est diffusé dans l'étage d'ionisation dans une région dite plus froide, par rapport à une zone dite chaude située à proximité des moyens de création d'un champ électrique nécessaire à l'ionisation des gaz.In general, the propellant of the invention comprises a single ionization stage coupled to means for ionizing one or more gases intended for propulsion, said stage comprising at least first injection means of a first gas and second means for injecting a second gas. The second injected gas is an electronegative gas and is diffused in the ionization stage in a so-called colder region, with respect to a so-called hot zone located near the means for creating an electric field necessary for the ionization of the ions. gas.
Ces moyens de couplage de l'énergie électrique au plasma peuvent être de type deux plaques polarisées en continu, à basse fréquence ou en radiofréquence, bobine alimentée en radiofréquence pour un couplage inductif, ou bien encore source microonde.These means for coupling the electrical energy to the plasma may be of the type of two plates polarized continuously, at low frequency or radiofrequency, radiofrequency supplied coil for inductive coupling, or even microwave source.
La figure 3 schématise un premier exemple d'étage d'ionisation comportant une alimentation en gaz Gi et une alimentation en gaz électronégatif G2, les moyens de couplage de l'énergie électrique étant représentés par une puissance Pe d'alimentation et générant des électrons représentés e" .FIG. 3 schematizes a first example of an ionization stage comprising a gas supply Gi and an electronegative gas supply G 2 , the coupling means of the electrical energy being represented by a power Pe of supply and generating electrons represented e " .
La région dite chaude de l'étage d'ionisation est référencée Zi proche de la source RF, la région dite plus froide et éloignée de la source RF étant référencée Z2. Selon l'invention, le gaz électronégatif est injecté dans la région la moins chaude.The so-called hot region of the ionization stage is referenced Zi close to the RF source, the so-called colder region and remote from the RF source being referenced Z 2 . According to the invention, the electronegative gas is injected into the least hot region.
Plus précisément, le premier gaz peut être un gaz électropositif ou électronégatif, introduit dans la région dite chaude Zi au niveau du cœur du plasma dans laquelle la puissance RF est couplée avec les électrons.More precisely, the first gas may be an electropositive or electronegative gas, introduced into the so-called hot region Zi at the plasma core in which the RF power is coupled with the electrons.
La génération efficace d'ions positifs et d'ions négatifs (en utilisant un gaz électronégatif) à partir du gaz Gi est réalisée dans cette région Z-i.The efficient generation of positive ions and negative ions (using an electronegative gas) from the Gi gas is carried out in this region Z-i.
Le second gaz est introduit dans une région Z2 proche des moyens d'extraction dans laquelle les électrons ont une température moins élevée. Le second gaz est choisi électronégatif et permet d'assurer une génération efficace d'ions négatifs.The second gas is introduced into a region Z 2 close to the extraction means in which the electrons have a lower temperature. The second gas is electronegative and ensures efficient generation of negative ions.
Des moyens d'extraction Me sont prévus pour extraire les ions positifs et les ions négatifs.Extraction means Me are provided for extracting the positive ions and the negative ions.
La figure 4 illustre à ce titre l'évolution de la température des électrons en fonction d'une distance X au sein de l'étage d'ionisation, la distance étant repérée depuis la zone située à proximité de la création de champ électrique (référence 0), selon l'axe horizontal représenté sur ladite figure 4.FIG. 4 illustrates in this respect the evolution of the electron temperature as a function of a distance X within the ionization stage, the distance being located from the zone located near the electric field creation (reference 0) along the horizontal axis shown in FIG. 4.
La figure 5 illustre l'évolution du rapport d'ions négatifs par un électron en fonction de la même distance X. Il apparait que la génération d'ions négatifs est très marquée au-delà d'une distance dans le cas considéré d'environ 40 mm. La courbe 5a est relative à un gaz O2, la courbeFIG. 5 illustrates the evolution of the ratio of negative ions by an electron as a function of the same distance X. It appears that the generation of negative ions is very marked beyond a distance in the case considered of about 40 mm. Curve 5a is relative to a gas O 2 , the curve
5b est relative à un gaz SF6.5b relates to a SF 6 gas.
Par ailleurs, la vitesse de création d'ions négatifs est une fonction décroissante de la température des électrons, alors que la vitesse d'ionisation, créant des ions positifs, par collision avec des électrons est une fonction exponentielle de la température des électrons.On the other hand, the rate of creation of negative ions is a decreasing function of the electron temperature, while the ionization rate, creating positive ions, by collision with electrons is an exponential function of the electron temperature.
La figure 6 illustre ces comportements pour un gaz électronégatif, la courbe 6a étant relative respectivement au premier phénomène (réaction d'attachement), la courbe 6b étant relative au second phénomène (réaction d'ionisation).FIG. 6 illustrates these behaviors for an electronegative gas, curve 6a being respectively relative to the first phenomenon (attachment reaction), curve 6b being relative to the second phenomenon (ionization reaction).
Ces deux procédés interfèrent pour des températures électroniques comprises entre 2 et 4 eV, selon les gaz. Les ions négatifs sont créés dans la région de basse température et deviennent dominants quand la température est inférieure typiquement à 1 -2 eV, alors que les ions positifs sont créés dans une région de forte température pour les électrons et deviennent dominants pour des énergies supérieures à environ 4-5 eV (les valeurs seuils varient grandement selon le type de gaz).These two processes interfere with electronic temperatures between 2 and 4 eV, depending on the gas. Negative ions are created in the low temperature region and become dominant when the temperature is typically below 1 -2 eV, whereas positive ions are created in a region of high temperature for the electrons and become dominant for energies higher than about 4-5 eV (the threshold values vary greatly according to the type of gas).
Le gaz électronégatif utilisé peut avantageusement être un dihalogène du type I2. Un tel gaz présente plusieurs intérêts, il est peu cher comparativement à d'autres gaz électronégatifs et présente le grand avantage d'être solide à température ambiante ce qui peut en favoriser fortement toutes les opérations de conditionnement et de stockage.The electronegative gas used may advantageously be a dihalogen of the type I 2 . Such a gas has several interests, it is cheap compared to other electronegative gases and has the great advantage of being solid at room temperature which can strongly favor all packaging and storage operations.
Il est aussi très électronégatif et son seuil d'ionisation est relativement faible, il peut ainsi générer non seulement des ions négatifs mais également des ions positifs de manier très efficace. Il peut aussi être utilisé dans un propulseur selon l'invention aussi bien en tant que premier gaz Gi que second gaz G2.It is also very electronegative and its ionization threshold is relatively low, so it can generate not only negative ions but also positive ions to handle very efficiently. It can also be used in a propellant according to the invention both as first gas Gi and second gas G 2 .
Selon une variante de l'invention, le propulseur peut utiliser comme premier gaz, un gaz type Xénon permettant de générer des ions positifs et comme second gaz, un dihalogène capable de générer des ions négatifs.According to a variant of the invention, the propellant can use as a first gas, a Xenon type gas for generating positive ions and as a second gas, a dihalogen capable of generating negative ions.
Dans les précédentes variantes de l'invention, le propulseur comprend deux zones dénommées respectivement chaude et froide dans lesquelles, sont respectivement injectées un premier gaz et un second gaz électronégatif via deux moyens d'injection.In the previous variants of the invention, the thruster comprises two zones respectively called hot and cold in which, respectively, are injected a first gas and a second electronegative gas via two injection means.
Selon une autre variante de l'invention plus élaborée, il est proposé d'utiliser une série de moyens d'injection de second gaz, avec des débits d'injections pouvant être optimisés en fonction de l'évolution de la température dans l'étage d'ionisation et donc en fonction de la température des électrons. Ces injections sont ainsi effectuées dans une série de régions Z-i,..., Z1,..., ZN avec des débits variables. Cette variante schématisée en figure 7 est relative à un exemple dans lequel, l'unique gaz électronégatif I2 est injecté pour générer aussi bien les ions positifs que les ions négatifs.According to another variant of the more elaborate invention, it is proposed to use a series of second gas injection means, with injection rates that can be optimized according to the evolution of the temperature in the stage. ionization and therefore depending on the temperature of the electrons. These injections are thus carried out in a series of regions Z 1 ,..., Z 1 ,..., Z N with variable flow rates. This variant shown schematically in FIG. 7 relates to an example in which the single electronegative gas I 2 is injected to generate both positive and negative ions.
Dans ces différentes variantes, la poussée est donc assurée par les deux types d'ions (positifs et négatifs). La neutralisation en aval n'est plus nécessaire car les faisceaux d'ions se neutralisent en aval (recombinaison) pour former un faisceau de molécules neutres rapides. De manière connue, l'étage d'ionisation précédemment décrit peut être couplé à un étage de filtrage comme celui illustré en figure 2.In these different variants, the thrust is ensured by the two types of ions (positive and negative). Downstream neutralization is no longer necessary because the ion beams neutralize downstream (recombination) to form a beam of fast neutral molecules. In known manner, the previously described ionization stage can be coupled to a filtering stage like that illustrated in FIG.
L'étage de filtrage, peut être réalisé de deux manières au moins : - (i) en modulant la création du plasma (plasmas puisés : alternance ON-OFF de la puissance électrique) et en utilisant la période OFF pour l'extraction, période durant laquelle les électrons ont disparus par attachement sur les molécules. Selon cette configuration, les étages d'ionisation et de filtrage sont communs. - (ii) en utilisant un champ magnétique statique pour piéger les électrons, les ions, beaucoup plus lourds, ne le sont pas. Le propulseur de l'invention comporte également un étage d'extraction pouvant être constitué de grilles accélératrices dont les dimensions ne sont pas nécessairement similaires à celles des propulseurs à grille classique, car les propriétés des gaines de charge d'espace sont différentes en absence d'électrons.The filtering stage can be realized in at least two ways: - (i) by modulating the creation of the plasma (pulsed plasmas: ON-OFF alternation of the electric power) and by using the OFF period for the extraction, period during which the electrons disappeared by attachment on the molecules. According to this configuration, the ionization and filtering stages are common. - (ii) by using a static magnetic field to trap the electrons, the ions, much heavier, are not. The thruster of the invention also comprises an extraction stage that can consist of accelerating grids whose dimensions are not necessarily similar to those of conventional grid thrusters, because the properties of the space charge sheaths are different in the absence of electrons.
Exemple de propulseur selon l'invention :Example of propellant according to the invention:
Dans cet exemple de propulseur selon l'invention, le plasma est créé par une antenne radio fréquence RF dont la surface active est optimisée et dimensionnée en fonctions des applications visées. Les figures 8a et 8b illustrent des vues différentes de l'antenne RF et des deux zones dites chaude et froide Zi et Z2 dans lesquelles sont respectivement introduits les e plaque 80 ferme l'enceinte dans laquelle est introduit le gaz In this example of a thruster according to the invention, the plasma is created by an RF radio frequency antenna whose active surface is optimized and sized according to the intended applications. FIGS. 8a and 8b illustrate different views of the RF antenna and of the two hot and cold zones Z 1 and Z 2 in which the plate 80 is respectively inserted and closes the enclosure into which the gas is introduced.
La température est suffisamment élevée dans le volume Zi pour créer des ions positifs par ionisation, et ainsi obtenir une forte densité d'ions positifs dans cette région.The temperature is sufficiently high in the Zi volume to create positive ions by ionization, and thus obtain a high density of positive ions in this region.
Un second gaz électronégatif G2 est injecté dans le volume Z2 pour produire les ions négatifs.A second electronegative gas G 2 is injected into the volume Z 2 to produce the negative ions.
Le volume d'extraction est séparé en deux régions par des aimants permanents, l'installation de deux grilles d'accélération est par ailleurs prévue en sortie du volume Z2. Des aimants permanents 70 sont placés sur une face et au milieu du volume Z2 pour filtrer les électrons de manière à ne conserver dans le milieu que des ions positifs et des ions négatifs en sortie de volume Z2. Dans cette région la température des électrons décroit et les ions négatifs sont produits par collision d'attachement avec des électrons. Le champ magnétique appliqué a deux fonctions :The extraction volume is separated into two regions by permanent magnets, the installation of two acceleration grids is also provided at the output of volume Z 2 . Permanent magnets 70 are placed on one side and in the middle of the volume Z 2 to filter the electrons so as to keep in the medium only positive ions and negative ions at the output of volume Z 2 . In this region the temperature of the electrons decreases and the negative ions are produced by collision of attachment with electrons. The applied magnetic field has two functions:
- (i) augmenter l'efficacité d'ionisation grâce à un meilleur confinement des électrons ;- (i) increase ionization efficiency through better electron confinement;
- (ii) créer le filtre magnétique pour les électrons, i.e. « magnétiser » les électrons, pour les empêcher de diffuser vers les moyens d'extraction.- (ii) create the magnetic filter for the electrons, i.e. "magnetize" the electrons, to prevent them from diffusing towards the extraction means.
Des moyens d'extraction 40 et 50 représentés en figure 8c sont utilisés pour accélérer les ions et en provoquer la sortie du propulseur, les entités ioniques A" et A+ sont ainsi extraites du propulseur. Ces moyens peuvent typiquement être de type grille, une grille pouvant être utilisée pour accélérer les ions négatifs, une autre grille pouvant être utilisée pour accélérer les ions positifs.Extraction means 40 and 50 shown in FIG 8c are used to accelerate the ions and cause the output of the propellant, the ionic entities A " and A + are thus extracted from the propellant.These means can typically be grid type, a grid that can be used to accelerate the negative ions, another grid that can be used to accelerate the positive ions.
Il est également possible de n'introduire qu'une seule grille, polarisée alternativement pour extraire des ions négatifs en alternance avec des ions positifs. Il peut également être envisagé d'utiliser un ensemble de grilles.It is also possible to introduce only one grid, alternately polarized to extract negative ions alternately with positive ions. It can also be envisaged to use a set of grids.
Finalement, les deux faisceaux d'ions extraits, de signes opposés, se neutralisent en aval (dans l'espace). La neutralisation est donc automatique et ne nécessite pas de faisceau additionnel d'électrons. Les deux faisceaux peuvent également se recombiner pour former un faisceau de molécules neutres rapides. Finally, the two extracted ion beams, of opposite signs, neutralize each other downstream (in space). Neutralization is therefore automatic and does not require additional electron beam. The two beams can also recombine to form a beam of fast neutral molecules.

Claims

REVENDICATIONS
1. Propulseur à plasma comprenant l'extraction d'un flux d'ions positifs caractérisé en ce qu'il comprend :Plasma thruster comprising the extraction of a flow of positive ions characterized in that it comprises:
- un unique étage d'ionisation ;a single ionization stage;
- des moyens d'injection en gaz ionisable dudit étage d'ionisation, lesdits moyens comportant au moins des premiers moyens d'injection d'un premier gaz (G-i) et des seconds moyens d'injection d'un second gaz électronégatif (G2) ;means for injecting ionizable gas into said ionization stage, said means comprising at least first injection means for a first gas (Gi) and second injection means for a second electronegative gas (G 2 );
- des moyens de création d'un champ électrique (Pe, RF) de manière à produire l'ionisation des gaz dans l'étage d'ionisation, lesdits moyens créant une première zone dite chaude au niveau de l'étage d'ionisation ;means for creating an electric field (Pe, RF) so as to produce the ionization of the gases in the ionization stage, said means creating a first so-called hot zone at the level of the ionization stage;
- le premier gaz étant distribué dans la première zone (Z-i) dite chaude, le second gaz étant distribué dans une seconde zone (Z2) moins chaude que ladite première zone ; - des premiers moyens d'extraction (Me, 40) d'un flux d'ions négatifs, des seconds moyens d'extraction (Me, 50) d'un flux d'ions positifs, reliés à l'étage d'ionisation ;- The first gas being distributed in the first zone (Zi) said hot, the second gas being distributed in a second zone (Z 2 ) less hot than said first zone; first extraction means (Me, 40) of a flow of negative ions, second extraction means (Me, 50) of a flow of positive ions, connected to the ionization stage;
- l'extraction d'un flux d'ions positifs et l'extraction d'un flux d'ions négatifs assurant la neutralité électrique du propulseur.the extraction of a flow of positive ions and the extraction of a flow of negative ions ensuring the electrical neutrality of the propellant.
2. Propulseur à plasma selon la revendication 1 , caractérisé en ce que le premier gaz et le second gaz sont identiques.2. Plasma thruster according to claim 1, characterized in that the first gas and the second gas are identical.
3. Propulseur à plasma selon l'une des revendications 1 ou 2, caractérisé en ce qu'il comporte deux compartiments constitutifs des première et seconde zones.3. Plasma thruster according to one of claims 1 or 2, characterized in that it comprises two constituent compartments of the first and second zones.
4. Propulseur à plasma selon l'une des revendications 1 à 3, caractérisé en ce que les premiers moyens d'injection du premier gaz sont situés au niveau d'une première face de l'étage d'ionisation, les seconds moyens d'injection étant distribués le long d'une seconde face transverse (Zi,..., Zi,..., ZN) à ladite première face de manière à distribuer une série de flux de second gaz dans l'étage d'ionisation. 4. Plasma thruster according to one of claims 1 to 3, characterized in that the first injection means of the first gas are located at a first face of the ionization stage, the second means of injection being distributed along a second transverse face (Zi, ..., Zi, ..., ZN) to said first face so as to distribute a series of second gas streams in the ionization stage.
5. Propulseur selon la revendication 4, caractérisé en ce que les seconds moyens d'injection de second gaz distribuent des flux de débit différents dans l'étage d'ionisation.5. Propellant according to claim 4, characterized in that the second second gas injection means distribute different flow rates in the ionization stage.
6. Propulseur à plasma selon l'une des revendications 1 à 5, caractérisé en ce qu'il comporte en outre des moyens de filtrage des électrons libérés dans l'étage d'ionisation, lors de l'ionisation du gaz.6. Plasma thruster according to one of claims 1 to 5, characterized in that it further comprises means for filtering the electrons released in the ionization stage, during the ionization of the gas.
7. Propulseur à plasma selon l'une des revendications 1 à 6, caractérisé en ce qu'il comprend un système de modulation temporelle des moyens d'extraction des ions.7. Plasma thruster according to one of claims 1 to 6, characterized in that it comprises a temporal modulation system of the ion extraction means.
8. Propulseur à plasma selon la revendication 7, caractérisé en ce que le même moyen est utilisé pour extraire alternativement les ions positifs et les ions négatifs.8. Plasma thruster according to claim 7, characterized in that the same means is used to extract alternately positive ions and negative ions.
9. Propulseur à plasma selon l'une des revendications 1 à 8, caractérisé en ce que les moyens d'extraction de flux d'ions comprennent au moins une grille polarisée (Me).9. Plasma thruster according to one of claims 1 to 8, characterized in that the ion flux extraction means comprise at least one polarized gate (Me).
10. Propulseur à plasma selon l'une des revendications 1 à 9, caractérisé en ce que les moyens pour créer un champ électrique comprennent deux éléments conducteurs placés aux extrémités de l'étage d'ionisation pour placer ledit étage sous tension.10. Plasma thruster according to one of claims 1 to 9, characterized in that the means for creating an electric field comprise two conductive elements placed at the ends of the ionization stage for placing said stage under tension.
1 1 . Propulseur à plasma selon l'une des revendications 1 à 10, caractérisé en ce que les moyens pour créer un champ électrique comprennent une bobine alimentée par un courant radiofréquence.1 1. Plasma thruster according to one of Claims 1 to 10, characterized in that the means for creating an electric field comprise a coil supplied with a radiofrequency current.
12. Propulseur plasma selon l'une des revendications 1 à 1 1 , caractérisé en ce que les moyens pour créer un champ électrique comprennent une antenne hélicon alimentée par un courant radio-fréquence (RF). 12. Plasma thruster according to one of claims 1 to 1 1, characterized in that the means for creating an electric field comprise a helicon antenna powered by a radio frequency (RF).
13. Propulseur plasma selon l'une des revendications 1 à 12, caractérisé en ce que le gaz électronégatif est un dihalogène.13. Plasma thruster according to one of claims 1 to 12, characterized in that the electronegative gas is a dihalogen.
14. Propulseur à plasma selon la revendication 13, caractérisé en ce que le gaz électronégatif est de type diiode.14. Plasma thruster according to claim 13, characterized in that the electronegative gas is of the diode type.
15. Propulseur à plasma selon l'une des revendications 1 à 12, caractérisé en ce que le gaz électronégatif est du SF6.15. Plasma thruster according to one of claims 1 to 12, characterized in that the electronegative gas is SF 6 .
16. Propulseur à plasma selon l'une des revendications 1 à 12, caractérisé en ce que le gaz électronégatif est de l'oxygène.16. Plasma thruster according to one of claims 1 to 12, characterized in that the electronegative gas is oxygen.
17. Propulseur plasma selon l'une des revendications 5 à 16, caractérisé en ce qu'il comprend des moyens pour créer un champ alternatif générant un plasma puisé permettant simultanément l'extraction des flux d'ions en absence de champ électrique et la filtration des électrons.17. Plasma thruster according to one of claims 5 to 16, characterized in that it comprises means for creating an alternating field generating a pulsed plasma simultaneously allowing the extraction of ion fluxes in the absence of electric field and the filtration electrons.
18. Propulseur plasma selon l'une des revendications 5 à 17, caractérisé en ce qu'il comprend des moyens pour générer un champ magnétique statique au sein de l'étage d'ionisation, de manière à filtrer les électrons.18. Plasma thruster according to one of claims 5 to 17, characterized in that it comprises means for generating a static magnetic field within the ionization stage, so as to filter the electrons.
19. Propulseur plasma selon la revendication 18, caractérisé en ce qu'il comprend des aimants permanents placés en périphérie de l'étage d'ionisation pour créer le champ magnétique au sein dudit étage d'ionisation.19. Plasma thruster according to claim 18, characterized in that it comprises permanent magnets placed at the periphery of the ionization stage to create the magnetic field within said ionization stage.
20. Propulseur à plasma selon l'une des revendications 18 ou 19, caractérisé en ce qu'il comprend des moyens d'extraction de flux d'ions négatifs et/ou positifs (40, 50) dans une direction perpendiculaire à la direction du champ magnétique appliqué au niveau de l'étage d'ionisation. 20. Plasma thruster according to one of claims 18 or 19, characterized in that it comprises means for extracting negative and / or positive ion fluxes (40, 50) in a direction perpendicular to the direction of the magnetic field applied at the ionization stage.
EP09756319.1A 2008-11-28 2009-11-24 Electronegative plasma thruster with optimized injection Not-in-force EP2359001B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0858077A FR2939173B1 (en) 2008-11-28 2008-11-28 ELECTRONEGATIVE PLASMA PROPELLER WITH OPTIMIZED INJECTION.
PCT/EP2009/065688 WO2010060887A1 (en) 2008-11-28 2009-11-24 Electronegative plasma thruster with optimized injection

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US9856862B2 (en) * 2013-03-13 2018-01-02 Wesley Gordon Faler Hybrid electric propulsion for spacecraft
DE102013217059B3 (en) * 2013-08-27 2014-11-20 Pascal Koch Electric engine and method of operation
FR3020235B1 (en) 2014-04-17 2016-05-27 Ecole Polytech DEVICE FOR FORMING A NEAR-NEUTRAL BEAM OF PARTICLES OF OPPOSED LOADS.
CN104863811B (en) * 2015-04-15 2017-06-27 大连理工大学 negative particle thruster
FR3046520B1 (en) 2015-12-30 2018-06-22 Centre National De La Recherche Scientifique - Cnrs PLASMA BEAM GENERATION SYSTEM WITH CLOSED ELECTRON DERIVATIVE AND PROPELLER COMPRISING SUCH A SYSTEM
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US10233912B2 (en) 2019-03-19
FR2939173A1 (en) 2010-06-04
FR2939173B1 (en) 2010-12-17
US20110232261A1 (en) 2011-09-29
WO2010060887A1 (en) 2010-06-03
EP2359001B1 (en) 2017-10-04

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