EP0077738B1 - Ionenquelle mit Gasionisierungsraum mit Elektronenschwingungen - Google Patents

Ionenquelle mit Gasionisierungsraum mit Elektronenschwingungen Download PDF

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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
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English (en)
French (fr)
Other versions
EP0077738A1 (de
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
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Publication date
Application filed by Commissariat a lEnergie Atomique CEA filed Critical Commissariat a lEnergie Atomique CEA
Publication of EP0077738A1 publication Critical patent/EP0077738A1/de
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Publication of EP0077738B1 publication Critical patent/EP0077738B1/de
Expired legal-status Critical Current

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    • 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.

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  • 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)

Claims (4)

1. lonenquelle mit einem Gasionisierungsraum (1), wobei sich in diesem Raum wenigstens eine Elektronenquelle (SE1), Mittel zum Schwingen der von der Quelle (SE1) ausgehenden Elektronen in einer vorbestimmten Richtung (X'X) so, daß ein lonisationsbereich (Z) des ßases erzeugt wird, und Mittel befinden, um die erzeugten lonen zu sammeln, dadurch gekennzeichnet, daß die Mittel zum Schwingen der Elektronen längs der Achse (XX') einen ersten elektronischen sphärischen Spiegel (M1), dessen Konkavität zu der Richtung (X') gedreht ist, eine erste elektronische Linse (L1), deren objektseitiger Brennpunkt (F1) mit der Mitte des ersten Spiegels (M1) und deren Achse mit der Richtung (XX') zusammenfällt, eine zweite elektronische Linse (L2), die mit der ersten Linse (L1) koaxial und identisch ist, und einen zweiten elektronischen, sphärischen Spiegel (M2) aufweisen, dessen Konkavität zu derjenigen des ersten Spiegels (M1) im entgegengesetzten Sinn gedreht ist und dessen Mitte mit dem bildseitigen Brennpunkt (F2) der zweiten Linse zusammenfällt, und daß sich die Elektronenquelle (SE1) in einem der vorhergehend bezeichneten Brennpunkte der Linsen (L1, L2) befindet.
2. lonenquelle nach Anspruch 1, dadurch gekennzeichnet, daß jede Linse (L1) derart gebildet ist, daü sie die von dem ihr entsprechenden (M1) Spiegel reflektierten Elektronen beschleunigt und die von der anderen Linse (L2) herkommenden Elektronen abbremst, und daß die Linse (L1), deren Brennpunkt (F1) den Ort der Quelle (SE1) bildet, die von dieser Quelle ausgesandten Elektronen beschleunigen kann.
3. lonenquelle nach Anspruch 1, dadurch gekennzeichnet, daß sie ferner eine andere Elektronenquelle (SE2) aufweist, die sich im Brennpunkt (F2) der an-deren(L2) der zwei Linsen befindet.
4. Ionenquelle nach Anspruch 2, dadurch gekennzeichnet, daß die Linsen (L1, L2) auf identischen, elektrischen Potentialen liegen.
EP82401920A 1981-10-21 1982-10-19 Ionenquelle mit Gasionisierungsraum mit Elektronenschwingungen Expired EP0077738B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8119761A FR2514946A1 (fr) 1981-10-21 1981-10-21 Source d'ions comprenant une chambre d'ionisation a gaz avec oscillations d'electrons
FR8119761 1981-10-21

Publications (2)

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

Family

ID=9263244

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82401920A Expired EP0077738B1 (de) 1981-10-21 1982-10-19 Ionenquelle mit Gasionisierungsraum mit Elektronenschwingungen

Country Status (5)

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

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
ATE194724T1 (de) * 1996-09-27 2000-07-15 Arpad Barna Ionenquelle zur erzeugung von ionen aus gas oder dampf
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
US4468564A (en) 1984-08-28
FR2514946A1 (fr) 1983-04-22
JPS5880255A (ja) 1983-05-14
EP0077738A1 (de) 1983-04-27
DE3269440D1 (en) 1986-04-03
FR2514946B1 (de) 1983-12-02

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