EP0077738B1 - Ion source having a gas ionization chamber with oscillations of electrons - Google Patents

Ion source having a gas ionization chamber with oscillations of electrons Download PDF

Info

Publication number
EP0077738B1
EP0077738B1 EP82401920A EP82401920A EP0077738B1 EP 0077738 B1 EP0077738 B1 EP 0077738B1 EP 82401920 A EP82401920 A EP 82401920A EP 82401920 A EP82401920 A EP 82401920A EP 0077738 B1 EP0077738 B1 EP 0077738B1
Authority
EP
European Patent Office
Prior art keywords
source
lens
electrons
electron
mirror
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.)
Expired
Application number
EP82401920A
Other languages
German (de)
French (fr)
Other versions
EP0077738A1 (en
Inventor
Robert La Coudounière Boyer
Jean-Pierre Journoux
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.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Commissariat a lEnergie Atomique CEA filed Critical Commissariat a lEnergie Atomique CEA
Publication of EP0077738A1 publication Critical patent/EP0077738A1/en
Application granted granted Critical
Publication of EP0077738B1 publication Critical patent/EP0077738B1/en
Expired legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J27/00—Ion beam tubes
    • H01J27/02—Ion sources; Ion guns

Definitions

  • the present invention relates to an ion source which can be used, for example, for the analysis of gases by mass spectrometry.
  • a source of ions of a first type which comprises an ionization chamber / a source of electrons constituted by a heating filament (cathode) and a "trap" (anode) opposite.
  • the emitted electrons are accelerated between the filament and the ionization chamber and ionize the molecules of the gas contained in the chamber.
  • a servo-control system can possibly allow, thanks to the electronic current collected on the anode, to regulate the current circulating in the filament and therefore, to stabilize the flow of the electrons emitted towards the ionization zone.
  • a magnetic field directed in the direction of the electron beam channels the electrons and allows a better extraction of the ions produced towards an analysis device, such as a mass spectrometer, for example.
  • each electron emitted only crosses the ionization chamber once, when it does not come to ionize a molecule. It réseulte a low ionization efficiency, is between 10- 4 and 10- 6. This yield is defined as the ratio of the number of ions formed to the number of emitted electrons.
  • Another characteristic coefficient of the performance of an ion source is defined by the ratio of the number of ions formed to the number of molecules introduced; this coefficient is called "brightness".
  • ion sources of a second type whose ionization efficiency as well as luminosity are higher than those of the preceding sources.
  • These sources include a filament that produces electrons, an accelerating cathode, and an anode that collects electronic current. Between the cathode and the anode is an intermediate electrode and behind the anode is an anticathode. Voltage pulses are applied to the cathode so as to cause a charge between the ionizes the gas. The electrons produced then oscillate in the zone located between the intermediate electrode and the anticathode, zone in which a hollow of potential is created. The electrons cause ionization of the gas in this area.
  • This source has a better yield and better brightness than the previous source, but its structure is complicated and its implementation very difficult.
  • the aim of the present invention is to remedy the drawbacks of known sources and in particular to produce an ion source in which the electrons oscillate, which has an easier structure and implementation, a higher yield and a higher luminosity than the second type. from the source mentioned above.
  • the invention relates to an ion source comprising a gas ionization chamber and, in this chamber, at least one electron source, means for oscillating the electrons from the source in a predetermined direction so creating an ionization zone for the gas, and and means for collecting the produced ions, characterized in that the means for oscillating the electrons comprise, along the axis (XX '), a first spherical electronic mirror of which the concavity is turned towards the direction (X '), a first electronic lens whose object focus coincides with the center of the first mirror and whose axis coincides with the direction (XX'), a second electronic lens, coaxial and identical to the first lens, and a second spherical electronic mirror rotating its concavity in the opposite direction to the first mirror and the center of which coincides with the image focal point of the second lens, the electron source being located in one of the focal points of the previously designated ntilles.
  • each lens is constituted so as to accelerate the electrons reflected by the mirror which corresponds to it and to decelerate the eectrons coming from the other lens, the lens whose focus constitutes the location of the source. being able to accelerate the electrons emitted by this source.
  • the ion source comprises another electronic source located at the focal point of the other of the two lenses.
  • the lenses are brought to identical electrical potentials.
  • This source comprises an ionization chamber 1 shown diagrammatically and, in this chamber, at least one source of electrons SE, and, means for oscillating the electrons coming from the source, in a predetermined direction XX'1 of so as to create a zone Z of oriation of the gas contained in the chamber 1.
  • These means comprise two identical electronic lenses L 1 , L 2 , located opposite one another and whose axes coincide with the predetermined direction X 'X.
  • These means also include two spherical mirrors M 1 , M 2 , concave, facing one another and located respectively on either side of the two lenses L 1 , L 2 .
  • each lens is constituted so as to accelerate the electrons reflected by the mirror which corresponds to it and so as to decelerate the electrons coming from the other lens.
  • the lens L 2 makes it possible to decelerate the electrons which come from the lens L 1 and to accelerate the electrons which are reflected by the mirror L 2 , while the lens L, decelerates the electrons coming from the lens L 2 and accelerates the electrons emitted by the source SE 1 or the electrons reflected on the mirror M 1 .
  • Another source of electrons SE 2 identical to the source SE 1 can possibly be placed at the focal point F of the lens L 2 , to supply electrons, in particular in the event of failure of the source SE 1 .
  • the lenses L 1 and L 2 are brought to identical electrical potentials.
  • magnetic pole pieces N and S which possibly allow better focusing of the electrons which circulate in the ionization chamber - but which are not essential. Indeed, the focusing of the electrons can be ensured sufficiently by the lenses L 1 and L 2 .
  • FIG 2 shows in more detail an ion source according to the invention.
  • the same elements have the same references in this figure as in Figure 1. It is assumed that all the elements shown in this figure are cylindrical and that they are seen in section, the openings in these elements being rectangular.
  • the device which is shown here in more detail includes the lenses L 1 and L 2 , the mirrors M 1 and M 2 , the electron sources SE 1 and SE 2 , and the magnetic pole pieces N and S.
  • the chamber d Ionization 1 is shown schematically in broken lines.
  • the electron source SE 1 can consist for example of a heating filament, not referenced, located at the focal point F 1 of the lens L 1 and surrounded by an electrode Ci (Wehnelt).
  • the lens L 1 can be constituted by diaphragms D 11 , D 21 , D 31 .
  • the lens L 2 can be constituted by diaphragms D 12 , D 22 , D 32 .
  • the second electronic source SE 2 which is constituted by an unreferenced filament located at the focal point F 2 of the lens L 2 , and by an electrode C 2 surrounding this filament.
  • the filament, the electrode (s) C 1 C 2 are brought to the potential of the filament, close to zero volts.
  • the diaphragms D 11 and D 32 are brought to a potential close to 280 volts, the diaphragms D 11 and D 32 , which are electrically isolated from the preceding diaphragms, as well as the ionization chamber 1, its brought to a potential close to 190 volts.
  • the D 21 and D 22 sentences are brought to a negative potential close to -10 volts.
  • the shape of the oscillating electron beam is shown in 2 eur the figure.
  • the ionization zone is the zone between the diaphragms D 31 and D 12 .
  • the ions are extracted thanks to the magnetic field, by a slit 0 located midway between the lenses L 1 , L 2 and perpendicular to the plane of the figure.
  • FIG. 3 represents the distribution of the potential V along the axis XX 'of the ionization chamber.
  • the potential is constant. This potential is zero in the vicinity of the filament located at the focal point F 1 , then it increases to reach a maximum in the vicinity of the diaphragm D 21 and finally, decreases to the vicinity of the diaphragm D 31 , to then stabilize at a significant value in the ionization zone Z, between diaphragms D 31 and D 12 .
  • the potential then increases again between the diaphragms D 12 and D 22 to reach a zero value in the vicinity of the filament situated at the focal point F 2 of the lens L 2 .
  • zone Z there is an accumulation of electrons in packets, with each oscillation and this results in intense ionization in this zone.
  • each electron can perform up to 25,000 oscillations.
  • the lifetime of an electron produced by the source of the invention is about 50,000 times longer than the lifetime of an electron produced by known sources.
  • the source of the invention therefore makes it possible, by increasing the path of the electron and its lifetime (thanks to the oscillations), to obtain a yield and a luminosity much higher than those of existing devices since the number of ions formed can being much larger, it also follows that the number of gaseous molecules that can be introduced into the ionization chamber can also be much higher than for known sources.
  • any electron coming from the filament situated at the focal point F 1 of the lens L 1 is focused at the focal point F 2 of the lens L 2 , then leaves in the opposite direction after having been reflected by the mirror M 2 .
  • This electron which then comes from the lens L 2 finds identical conditions with the lens L 1 and the mirror M 1
  • the source which has just been described has many advantages compared to existing sources: the brightness is multiplied by 20, the ionization efficiency is multiplied by 200, the temperature of the chamber is greatly lowered since it goes from 80 ° C at 40 ° C (since it is not necessary to produce as many electrons as with existing devices to ionize the same number of gas molecules).
  • the temperature of the filament itself can be lowered by 500 ° since, for an equal efficiency, the number of electrons emitted by the filament must be lower, while the electric power which is supplied to this filament is twice lower.
  • the electronic emission current is divided by 10, while the average lifetime of the filament goes from 5,000 hours to 2.10 9 hours.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Electron Tubes For Measurement (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Electron Sources, Ion Sources (AREA)

Description

La présente invention concerne une source d'ons qui peut être utilisée par exemple, à l'analyse des gaz par spectrométrie de masse.The present invention relates to an ion source which can be used, for example, for the analysis of gases by mass spectrometry.

On connait une source d'ions d'un premier type, qui comprend une chambre d'ionisation/ une source d'électrons constituée par un filament chauffant (cathode) eτ une "trappe" (anode) en regard.There is known a source of ions of a first type, which comprises an ionization chamber / a source of electrons constituted by a heating filament (cathode) and a "trap" (anode) opposite.

Les électrons émis sont accélérés entre le filament et la chambre d'ionisation et ionisent les molécules du gaz contenu dans la chambre. Un système d'asservissement peut éventuellement permettre, grâce au courant électronigue recueilli sur l'anode, de réguler le courant circulant dane le filament et donc, de stabiliser le flux des électrons émis vers la zone d'ionisation.The emitted electrons are accelerated between the filament and the ionization chamber and ionize the molecules of the gas contained in the chamber. A servo-control system can possibly allow, thanks to the electronic current collected on the anode, to regulate the current circulating in the filament and therefore, to stabilize the flow of the electrons emitted towards the ionization zone.

Un champ magnétigue dirigé dans le sens du faisceau électronique, canalise les électrons et permet une meilleure extraction des ions produits vers un appareil d'analyse, tel qu'un spectrométre de masse, par exemple.A magnetic field directed in the direction of the electron beam, channels the electrons and allows a better extraction of the ions produced towards an analysis device, such as a mass spectrometer, for example.

Dans ce type de source, chague électron émis ne traverse la chambre d'ionisation qu'une seule fois, lorsgu'il ne vient pas ioniser une molécule. Il en réseulte un rendement d'ionisation faible, se situant entre 10-4 et 10-6. Ce rendement est défini par le rapport du nombre d'ions formés au nombre d'électrons émis.In this type of source, each electron emitted only crosses the ionization chamber once, when it does not come to ionize a molecule. It réseulte a low ionization efficiency, is between 10- 4 and 10- 6. This yield is defined as the ratio of the number of ions formed to the number of emitted electrons.

On définit un autre coefficient caractéristique des performances d'une source d'ions, par le rapport du nombre d'ions formes au nombre de molécules introduites ; ce coefficient est qualifié "luminosité". La luminosité des sources décrites plus haut est très faible (=10-5).Another characteristic coefficient of the performance of an ion source is defined by the ratio of the number of ions formed to the number of molecules introduced; this coefficient is called "brightness". The brightness of the sources described above is very low (= 10-5).

On connaît auesi des sources d'ione d'un deuxème type dont le rendement d'ionisation ainsi que la luminosité sont plus élevés que ceux des sources précédentes. Ces sources comprennent un filament qui produit des électrons, une cathode accélératrice et une anode recueillant le courant électronique. Entre la cathode et l'anode/ se trouve une électrode intermédiarre et derrèere l'anode, est disposée une anticathode. Des impulsions de tension sont appliquées à la cathode de manière à provoguer une dédharge entre la ionise le gaz. Les électrons produits oscillent alors dans la zone située entre l'électrode intermédiaire et l'anticathode, zone dans laquelle est créé un creux de potentiel. Les électrons provoguent une ionisation du gaz dans cette zone. Cette source présente un meilleur rendement et une meilleure luminosité que la source précédente, mais sa structure est compliquée et sa mise en oeuvre tres difficile.Also known are ion sources of a second type whose ionization efficiency as well as luminosity are higher than those of the preceding sources. These sources include a filament that produces electrons, an accelerating cathode, and an anode that collects electronic current. Between the cathode and the anode is an intermediate electrode and behind the anode is an anticathode. Voltage pulses are applied to the cathode so as to cause a charge between the ionizes the gas. The electrons produced then oscillate in the zone located between the intermediate electrode and the anticathode, zone in which a hollow of potential is created. The electrons cause ionization of the gas in this area. This source has a better yield and better brightness than the previous source, but its structure is complicated and its implementation very difficult.

La présente invention a pour but de remédier aux inconvénients des sources connues et notamment de réaliser une source d'ions dans laquelle les électrons oscillent, gui présente une structure et une mise en oeuvre plus faciles, un rendement et une luminosité plus élevés que deuxième type de source mentionné plus haut.The aim of the present invention is to remedy the drawbacks of known sources and in particular to produce an ion source in which the electrons oscillate, which has an easier structure and implementation, a higher yield and a higher luminosity than the second type. from the source mentioned above.

L'invention a pour objet une source d'ions comprenant une chambre d'ionisation à gaz et, dans cette chambre, au moins une source d'électrons, des moyens pour faire osciller les électrons issus de la source dans une direction prédéterminée de manière à créer une zone d'ionisation du gaz, et et des moyens pour recuellir les ions produits, caractérisée en ce gue les moyens pour faire osciller les électrons comprennent, le long de l'axe (XX'), un premier miroir électronique sphérigue dont la concavité est tournée vers la direction (X'), une première lentille électronique dont le foyer objet coîncide avec le centre du premier miroir et dont l'axe coïncide avec la direction (XX'), une seconde lentille électronique, coaxiale et identique à la première lentille, et un second miroir électronique sphérique tournant sa concavité dans le sens opposé au premier miroir et dont le centre coîncide avec le foyer image de la deuxième lentille, la source d'électrons étant située en l'un des foyers des lentilles précédemment désignés.The invention relates to an ion source comprising a gas ionization chamber and, in this chamber, at least one electron source, means for oscillating the electrons from the source in a predetermined direction so creating an ionization zone for the gas, and and means for collecting the produced ions, characterized in that the means for oscillating the electrons comprise, along the axis (XX '), a first spherical electronic mirror of which the concavity is turned towards the direction (X '), a first electronic lens whose object focus coincides with the center of the first mirror and whose axis coincides with the direction (XX'), a second electronic lens, coaxial and identical to the first lens, and a second spherical electronic mirror rotating its concavity in the opposite direction to the first mirror and the center of which coincides with the image focal point of the second lens, the electron source being located in one of the focal points of the previously designated ntilles.

Selon une autre caractéristique de l'invention chaque lentille est constituée de manière à accé lérer les électrons réflechis par le miroir qui lui correspond et à décélérer les éectrons provenant de l'autre lentille, la lentille dont le foyer constitue l'emplacement de la source étant apte à accélérer les électrons émis par cette source.According to another characteristic of the invention, each lens is constituted so as to accelerate the electrons reflected by the mirror which corresponds to it and to decelerate the eectrons coming from the other lens, the lens whose focus constitutes the location of the source. being able to accelerate the electrons emitted by this source.

Selon une autre caractéristique, la source d'ions comprend une autre source électronique située au foyer de l'autre des deux lentilles.According to another characteristic, the ion source comprises another electronic source located at the focal point of the other of the two lenses.

Selon une autre caractéristique, les lentilles sont portées à des potentiels électriques identiques.According to another characteristic, the lenses are brought to identical electrical potentials.

D'autres caractéristiques et avantages de l'invention ressotiront mieux de la description qui va suivre donnée en référence aux dessins annexés dans lesquels:

  • - la figure 1 est une vue schématique qui permet de mieux comprendre par analogie et · avec un système optique, la structure et le fonctionnement de la source de l'invention ;
  • - la figure 2 représente de manière plus détaillée la source d'ions de l'invention;
  • - la figure 3 représente la répartition des potentiels le long de l'axe X'X, de la chambre d'ionisation.
Other characteristics and advantages of the invention will emerge more clearly from the description which follows given with reference to the appended drawings in which:
  • - Figure 1 is a schematic view which allows a better understanding by analogy and · with an optical system, the structure and operation of the source of the invention;
  • - Figure 2 shows in more detail the source of ions of the invention;
  • - Figure 3 shows the distribution of potentials along the X'X axis of the ionization chamber.

En référence à la figure 1, on a représenté très schématiquement la source d'ions de l'invention. Cette source comprend une chambre d'ionisation 1 représentée de manière schématique et, dans cette chambre, au moins une source d'électrons SE, et, des moyens pour faire osciller les électrons issus de la source,dans une direction prédéterminée XX'1 de manière à créer une zone Z d'iorisation du gaz contenu dans la chambre 1. Ces moyens comprennent deux lentilles électroniques L1, L2 identiques, situées en regard l'une de l'autre et dont les axes coîncident avec la direction prédéterminée X'X. Ces moyens comprennent aussi deux miroirs sphériques M1, M2, concaves, tournés l'un vers l'autre et situés respectivement de-part et d'autre des deux lentilles L1,L2. Les centres de ces miroirs coîncicent respectivement avec les foyers F1, F2 des lentilles. La source d'électrons SE, est située par exemple au foyer F1 de la lentille L1. Comme on le verra plus loin en détails chaque lentille est constituée de maniîre à accélérer les électrons réfléchis par le miroir qui lui correspond et de manière à décélérer les électrons provenant de l'autre lentille. C'est ainsi par exemple que la lentille L2 permet de décélérer les électrons qui proviennent de la lentille L1 et d'accélérer les électrons qui sont réfléchis par le miroir L2,tandis que la lentille L, décélere les électrons provenant de la lentille L2 et accélère les électrons émis par la source SE1 ou les électrons réfléchis sur le miroir M1. Une autre source d'électrons SE2 identique à la source SE1 peut éventuellement être placée au foyer F de la lentille L2 , pour fournir des électrons, notamment en cas de panne de la source SE1. Comme on le verra plus loin en détail, les lentilles L, et L2 sont portées à des potentiels électriques identiques. On a également représenté sur cette figure des pièces polaires magnétiques N et S qui permettent éventuellement une meilleure focalisation des électrons qui circulent dans la chambre d,ionisation- mais ui ne sont pas indispensables. En effet la focalisation des électrons peut être assurée suffisamment par les lentilles L1 et L2.Referring to Figure 1, there is shown very schematically the ion source of the invention. This source comprises an ionization chamber 1 shown diagrammatically and, in this chamber, at least one source of electrons SE, and, means for oscillating the electrons coming from the source, in a predetermined direction XX'1 of so as to create a zone Z of oriation of the gas contained in the chamber 1. These means comprise two identical electronic lenses L 1 , L 2 , located opposite one another and whose axes coincide with the predetermined direction X 'X. These means also include two spherical mirrors M 1 , M 2 , concave, facing one another and located respectively on either side of the two lenses L 1 , L 2 . The centers of these mirrors coincide respectively with the focal points F 1 , F 2 of the lenses. The electron source SE, is located for example at the focal point F 1 of the lens L 1 . As will be seen in detail below, each lens is constituted so as to accelerate the electrons reflected by the mirror which corresponds to it and so as to decelerate the electrons coming from the other lens. Thus, for example, the lens L 2 makes it possible to decelerate the electrons which come from the lens L 1 and to accelerate the electrons which are reflected by the mirror L 2 , while the lens L, decelerates the electrons coming from the lens L 2 and accelerates the electrons emitted by the source SE 1 or the electrons reflected on the mirror M 1 . Another source of electrons SE 2 identical to the source SE 1 can possibly be placed at the focal point F of the lens L 2 , to supply electrons, in particular in the event of failure of the source SE 1 . As will be seen below in detail, the lenses L 1 and L 2 are brought to identical electrical potentials. Also shown in this figure are magnetic pole pieces N and S which possibly allow better focusing of the electrons which circulate in the ionization chamber - but which are not essential. Indeed, the focusing of the electrons can be ensured sufficiently by the lenses L 1 and L 2 .

La figure 2 représente de manière plus détaillée, une source d'ions conforme à l,invention. Les mêmes éléments portent les mêmes référencs sur cette figure que sur la figure 1. On suppose que tous les éléments représentés sur cette figure eont cylindriques et qu'ils sont vus en coupe, les ouvertures dans ces éléments étant rectangulaires. Le dispositif qui est représenté ici de manière plus détaillée comprend les lentilles L1 et L2, les miroirs M1 et M2,les sources d'électrons SE1 et SE2, et les pièces polaires magnétiques N et S. La chambre d'ionisation 1 est représentée de manière schématique en traits interrompus. La source d'électrons SE1 peut être constituée par exemple par un filament chauffant, non référencé, situé au foyer F1 de la lentille L1 et entouré d'une électrode Ci (Wehnelt). La lentille L1 peut être constituée par des diaphragmes D11, D21, D31. De la même manière, la lentille L2 peut être constituée par des diaphragmes D12, D22, D32. On a également représenté sur cette figure, la deuxieme source électronique SE2 qui est constituée par un filament non référencé situe au foyer F2 de la lentille L2, et par une électrode C2 entourant ce filament. A titre d'exemple, le filament, la ou les électrodes C1 C2, sont portés au potentiel du filament, voisin de zero volt. Les diaphragmes D11 et D32 sont porté à un potential voisin de 280 volt,les diaphragmed D11 et D32, qui sont électriquement isolés des diaphragmes précédents, ainsi que la chambre d'ionisation 1, son portés à un potentiel voisin de 190 volts. Les dia phragmes D21 et D22 sont portés à un potentiel négatif voisin de -10 volts. L'allure du faisceau d'électrone oscillante est représentée en 2 eur la figure. La zone d'ionisation est la zone comprise entre les diaphragmes D31 et D12. Les ions sont extraits grâce au champ magnétique, par une fente 0 eituée à mi-distance des lentilles L1, L2 et perpendiculaire au plan de la figure.Figure 2 shows in more detail an ion source according to the invention. The same elements have the same references in this figure as in Figure 1. It is assumed that all the elements shown in this figure are cylindrical and that they are seen in section, the openings in these elements being rectangular. The device which is shown here in more detail includes the lenses L 1 and L 2 , the mirrors M 1 and M 2 , the electron sources SE 1 and SE 2 , and the magnetic pole pieces N and S. The chamber d Ionization 1 is shown schematically in broken lines. The electron source SE 1 can consist for example of a heating filament, not referenced, located at the focal point F 1 of the lens L 1 and surrounded by an electrode Ci (Wehnelt). The lens L 1 can be constituted by diaphragms D 11 , D 21 , D 31 . Likewise, the lens L 2 can be constituted by diaphragms D 12 , D 22 , D 32 . Also shown in this figure, the second electronic source SE 2 which is constituted by an unreferenced filament located at the focal point F 2 of the lens L 2 , and by an electrode C 2 surrounding this filament. By way of example, the filament, the electrode (s) C 1 C 2 , are brought to the potential of the filament, close to zero volts. The diaphragms D 11 and D 32 are brought to a potential close to 280 volts, the diaphragms D 11 and D 32 , which are electrically isolated from the preceding diaphragms, as well as the ionization chamber 1, its brought to a potential close to 190 volts. The D 21 and D 22 sentences are brought to a negative potential close to -10 volts. The shape of the oscillating electron beam is shown in 2 eur the figure. The ionization zone is the zone between the diaphragms D 31 and D 12 . The ions are extracted thanks to the magnetic field, by a slit 0 located midway between the lenses L 1 , L 2 and perpendicular to the plane of the figure.

La figure 3 représente la répartition du potentiel V le long de l'axe XX' de la chambre d'ionisation. Dans la zone d'ionisation Z comprise entre les diaphragmes D31 et D12, le potentiel est constant. Ce potentiel est nul au voisinage du filament situé au foyer F1, puis il croît pour atteindre un maximum au voisinage du diaphragme D21 et enfin, décroit jusqu'au voisinage du diaphragme D31, pour se stabiliser ensuite à une valeur conetante dans la zone d'ionisation Z, entre les diaphragmes D31 et D12. Le potentiel croit alors de nouveau entre les diaphragmes D12 et D22 pour atteindre une valeur nulle au voisinage du filament situé au foyer F2 de la lentille L2. Dans la zone Z, il y a accumulation d'électrons par paquets, à chaque oscillation et il en résulte une ionisation intense dans cette zone.FIG. 3 represents the distribution of the potential V along the axis XX 'of the ionization chamber. In the ionization zone Z between the diaphragms D 31 and D 12 , the potential is constant. This potential is zero in the vicinity of the filament located at the focal point F 1 , then it increases to reach a maximum in the vicinity of the diaphragm D 21 and finally, decreases to the vicinity of the diaphragm D 31 , to then stabilize at a significant value in the ionization zone Z, between diaphragms D 31 and D 12 . The potential then increases again between the diaphragms D 12 and D 22 to reach a zero value in the vicinity of the filament situated at the focal point F 2 of the lens L 2 . In zone Z, there is an accumulation of electrons in packets, with each oscillation and this results in intense ionization in this zone.

Grâce au dispositif qui vient d'être décrit, chaque électron peut effectuer jusqu'à 25.000 oscillations. La durée de vie d'un électron produit par la source de l'invention est d'environ 50.000 fois plus longue que la durée de vie d'un électron produit par les sources connues. La source de l'invention permet donc, en augmentant le parcours de l'électron et sa durée de vie (grâce aux oscillations) d'obtenir un rendement et une luminosité bien supérieurs à ceux des dipositifs existants puisque le nombre d'ions formés peut être bien plus grand, il en résulte aussi que le nombre de molécules gazeuses que l'on peut introduire dans la chambre d'ionisation peut être lui aussi bien plus élevé que pour les sources connues. En fait, dans la source qui vient d'être décrite, tout électron issu du filament situé au foyer F1 de la lentille L1 est focalisé au foyer F2 de la lentille L2, puis repart en sens inverse après avoir été réfléchi par le miroir M2. Cet électron qui est alors issu de la lentille L2 retrouve des conditions identiques avec la lentille L1 et le miroir M1 Thanks to the device which has just been described, each electron can perform up to 25,000 oscillations. The lifetime of an electron produced by the source of the invention is about 50,000 times longer than the lifetime of an electron produced by known sources. The source of the invention therefore makes it possible, by increasing the path of the electron and its lifetime (thanks to the oscillations), to obtain a yield and a luminosity much higher than those of existing devices since the number of ions formed can being much larger, it also follows that the number of gaseous molecules that can be introduced into the ionization chamber can also be much higher than for known sources. In fact, in the source which has just been described, any electron coming from the filament situated at the focal point F 1 of the lens L 1 is focused at the focal point F 2 of the lens L 2 , then leaves in the opposite direction after having been reflected by the mirror M 2 . This electron which then comes from the lens L 2 finds identical conditions with the lens L 1 and the mirror M 1

La source qui vient d'être décrite présente de nombreux avantages par rapport aux sources existantes : la luminosité est multipliée par 20, le rendement d'ionisation est multiplié par 200, la température de la chambre est fortement abaissée puisqu'elle passe de 80°C à 40°C (puisqu'il n'est pas nécessaire de produire autant d'électrons qu'avec les dispositifs existants pour ioniser le même nombre de molécules de gaz). La température du filament lui-même peut être abaissée de 500° puisqu'à rendement égal, le nombre d'électrons émis par le filament doit être moins élevé, tandis que la puissance électrique qui est fournie à ce filament est deux fois plus faible. Le courant d'émission électronique est divisé par 10, tandis que la durée de vie moyenne du filament passe de 5.000 heures à 2.109 heures. Les performances bien meilleures que celles des sources connues et notamment l'augmentation de la luminosité, permettent de fournir des courants d'ions beaucoup plus intenses aux spectromètres de masse et donc d'accroître le rapport signal/bruit. Cet accroîssement de la luminosité permet, pour des courants ioniques éguivalents à ceux des sources connues, d'utiliser des gaz présentant des pressions bien plus faibles et ainsi, de ménager la durée de vie des sources. La symétrie du dispositif permet d'inverser la source émettrice d'électrons.The source which has just been described has many advantages compared to existing sources: the brightness is multiplied by 20, the ionization efficiency is multiplied by 200, the temperature of the chamber is greatly lowered since it goes from 80 ° C at 40 ° C (since it is not necessary to produce as many electrons as with existing devices to ionize the same number of gas molecules). The temperature of the filament itself can be lowered by 500 ° since, for an equal efficiency, the number of electrons emitted by the filament must be lower, while the electric power which is supplied to this filament is twice lower. The electronic emission current is divided by 10, while the average lifetime of the filament goes from 5,000 hours to 2.10 9 hours. The much better performances than those of known sources and in particular the increase in brightness, make it possible to supply much more intense ion currents to mass spectrometers and therefore to increase the signal / noise ratio. This increase in brightness allows, for ionic currents equivalent to those of known sources, to use gases having much lower pressures and thus, to save the life of the sources. The symmetry of the device makes it possible to reverse the electron-emitting source.

Claims (4)

1. lon source comprising a gas-ionisation chamber (1) and, at least one electron source (SE1) within said chamber, means for oscillating electrons emitted by the source (SE1) in a predetermined direction (X'X) whereby to create a gas-ionisation zone (Z) and means for recovering the ions produced, characterised in that the means for oscillating the electrons comprise, lengthwise of axis (XX') a first spherical electron . mirror (M1) whose concavity faces direction (X'), a first electronic lens (L1) whose object focus (F1) coincides with the centre of the first mirror (M1) and whose axis coincides with direction (XX'), a second electronic lens (L2) coaxial and identical with the first lens (L1) and a second spherical electron mirror (M2) whose concavity faces in the opposite direction to that of the first mirror (M1) and whose centre coincides with the object focus (F2) of the second lens (L2), the electron source (SE1) being located at one of the foci of the above mentioned lenses (L1, L2).
2. lon source according to Claim 1, characterised in that each lens (L1) is formed to accelerate the electrons reflected by the corresponding mirror (M1) and to decelerate the electrons from the other lens (L2), the lens (L1) whose focus (F1) constitutes the location of the source (SE1) being adapted to accelerate the electron emitted by said source.
3. Ion source according to Claim 1, characterised in that it comprises another electron source (SE2) located in the focus (F2) of the other (L2) of the two lenses.
4. lon source according to Claim 2, characterised in that the lenses (L1, L2) have identical electric potentials.
EP82401920A 1981-10-21 1982-10-19 Ion source having a gas ionization chamber with oscillations of electrons Expired EP0077738B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8119761A FR2514946A1 (en) 1981-10-21 1981-10-21 ION SOURCE COMPRISING A GAS IONIZATION CHAMBER WITH ELECTRON OSCILLATIONS
FR8119761 1981-10-21

Publications (2)

Publication Number Publication Date
EP0077738A1 EP0077738A1 (en) 1983-04-27
EP0077738B1 true EP0077738B1 (en) 1986-02-26

Family

ID=9263244

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82401920A Expired EP0077738B1 (en) 1981-10-21 1982-10-19 Ion source having a gas ionization chamber with oscillations of electrons

Country Status (5)

Country Link
US (1) US4468564A (en)
EP (1) EP0077738B1 (en)
JP (1) JPS5880255A (en)
DE (1) DE3269440D1 (en)
FR (1) FR2514946A1 (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4649278A (en) * 1985-05-02 1987-03-10 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Generation of intense negative ion beams
US4739170A (en) * 1985-05-09 1988-04-19 The Commonwealth Of Australia Plasma generator
GB2208753B (en) * 1987-08-13 1991-06-26 Commw Of Australia Improvements in plasma generators
US5028791A (en) * 1989-02-16 1991-07-02 Tokyo Electron Ltd. Electron beam excitation ion source
US4933551A (en) * 1989-06-05 1990-06-12 The United State Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Reversal electron attachment ionizer for detection of trace species
US5017780A (en) * 1989-09-20 1991-05-21 Roland Kutscher Ion reflector
DE69609358T2 (en) * 1996-09-27 2000-12-14 Arpad Barna ION SOURCE FOR GENERATING IONS FROM GAS OR VAPOR
US7323682B2 (en) * 2004-07-02 2008-01-29 Thermo Finnigan Llc Pulsed ion source for quadrupole mass spectrometer and method
WO2006120428A2 (en) * 2005-05-11 2006-11-16 Imago Scientific Instruments Corporation Reflectron

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2967943A (en) * 1958-06-19 1961-01-10 James D Gow Gaseous discharge device
US3293491A (en) * 1962-02-13 1966-12-20 Robert A Cornog Apparatus for producing charged particles
US3655508A (en) * 1968-06-12 1972-04-11 Itt Electrostatic field apparatus for reducing leakage of plasma from magnetic type fusion reactors
US3611029A (en) * 1969-09-09 1971-10-05 Atomic Energy Commission Source for highly stripped ions
US4045677A (en) * 1976-06-11 1977-08-30 Cornell Research Foundation, Inc. Intense ion beam generator
US4126806A (en) * 1977-09-26 1978-11-21 The United States Of America As Represented By The Secretary Of The Navy Intense ion beam producing reflex triode
US4282436A (en) * 1980-06-04 1981-08-04 The United States Of America As Represented By The Secretary Of The Navy Intense ion beam generation with an inverse reflex tetrode (IRT)

Also Published As

Publication number Publication date
FR2514946B1 (en) 1983-12-02
US4468564A (en) 1984-08-28
EP0077738A1 (en) 1983-04-27
FR2514946A1 (en) 1983-04-22
DE3269440D1 (en) 1986-04-03
JPS5880255A (en) 1983-05-14

Similar Documents

Publication Publication Date Title
EP0077738B1 (en) Ion source having a gas ionization chamber with oscillations of electrons
FR2666477A1 (en) HIGH FLOW NEUTRONIC TUBE.
US5747800A (en) Three-dimensional quadrupole mass spectrometer
EP0480518B1 (en) Electron source providing a particle retention device
FR2461351A1 (en) ION SOURCE AT PLASMA UHF
US3944873A (en) Hollow cathode type ion source system including anode screen electrodes
US3955091A (en) Method and apparatus for extracting well-formed, high current ion beams from a plasma source
EP0362947B1 (en) Sealed neutron tube equipped with a multicellular ion source with magnetic confinement
EP0362946A1 (en) Ion extraction and acceleration device limiting reverse acceleration of secondary electrons in a sealed high flux neutron tube
US3517240A (en) Method and apparatus for forming a focused monoenergetic ion beam
EP0295743B1 (en) Ion source with four electrodes
US6169288B1 (en) Laser ablation type ion source
US4288716A (en) Ion source having improved cathode
JPH07307140A (en) Mass spectrometer and ion source
EP0362953A1 (en) Sealed neutron tube provided with an ion source with electrostatic confinement
FR2657724A1 (en) Ion source for quadrupole mass spectrometer
JP2637948B2 (en) Beam plasma type ion gun
EP0300932B1 (en) Electron source
FR2645676A1 (en) CATHODE HAVING IMPROVED SECONDARY TRANSMISSION SURFACE AND CROSS-FIELD AMPLIFIER CONTAINING SUCH A CATHODE
JPH0935648A (en) Ion source
EP0362944A1 (en) Ion extraction and acceleration device in a sealed high flux neutron tube with addition of an auxiliary preacceleration electrode
JP2000146914A (en) Frit laser ion source
JP2637947B2 (en) Beam plasma type ion gun
JP2778227B2 (en) Ion source
TW202221760A (en) Ion source assembly with multiple ionization volumes for use in a mass spectrometer

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): DE GB NL

17P Request for examination filed

Effective date: 19830930

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): DE GB NL

REF Corresponds to:

Ref document number: 3269440

Country of ref document: DE

Date of ref document: 19860403

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19871031

Year of fee payment: 6

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19881019

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19890501

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19890701

GBPC Gb: european patent ceased through non-payment of renewal fee