US3076112A - Ion source - Google Patents

Ion source Download PDF

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Publication number
US3076112A
US3076112A US2877A US287760A US3076112A US 3076112 A US3076112 A US 3076112A US 2877 A US2877 A US 2877A US 287760 A US287760 A US 287760A US 3076112 A US3076112 A US 3076112A
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United States
Prior art keywords
rod
ion source
ionizing
electrode
space
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Expired - Lifetime
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US2877A
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English (en)
Inventor
Wasserman Marien
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.)
Thales SA
Original Assignee
CSF Compagnie Generale de Telegraphie sans Fil SA
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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
    • H01J27/20—Ion sources; Ion guns using particle beam bombardment, e.g. ionisers

Definitions

  • the present invention relates to an apparatus constituting an ion source, and more particularly relates to an ion source apparatus producing a hollow ion beam for use in connection with utilization devices in which a magnetic field having a circular symmetry is used.
  • Utilization devices for ionized gases are known in the prior art in which the ions have to be placed into a magnetic field with circular symmetry which may be produced, as known, by the flow of an intense current through an axial metallic rod or conductor.
  • the ion source produces a hollow beam having as its axis the metallic rod or conductor in question.
  • the present invention has for its principal object to provide a source furnishing a hollow ion beam which is injected into the utilization vessel or enclosure both axially and symmetrically about the central rod or conductor of this vessel, whereby the rod or conductor is traversed by a current generating the magnetic field having lines of force with circular symmetry.
  • the ion source according to the present invention belongs generally to the type in which the ionizing electrons move in mutually crossed electric and ma netic fields, as described for example in the United States Patent 2,935,- 634, filed on lune 13, 1957, in the name of A. Lerbs and assigned to the assignee of the present invention which patent describes a source providing a plane ion beam.
  • Another object of the present invention resides in the provision of an ion source producing a hollow circular ion beam which may be used within a utilization enclosure or vessel in which a magnetic field with circular symmetry is established.
  • FEGURE l is an axial, longitudinal cross-sectional view of a first embodiment of an ion source in accordance with the present invention.
  • FIGURE 2 is an axial, longitudinal cross-sectional view through a modified embodiment of an ion source in accordance with the present invention.
  • the present invention is characterized by the fact that the ion source comprises an electron-optical and ionic system of electrodes with symmetry of revolution about the magnetic-field-producing axial rod or conductor, and that not only the ionizing electrons but also the was leaving the ionization space move within crossed electric and magnetic fields, established within a cylindrical space comprised between the electrode for the extraction of the ions and the axial rod or conductor in such a manner that the ions are concentrated or focused into a hollow beam within this space.
  • reference numeral 1 designates therein an ion stabilization vessel or enclosure which is defined or limited by the walls 2 and includes within the axis thereof a metallic rod or conductor
  • a source of current supply 4 which is connected between the ends of the rod 3, sends current therethrough in the direction indicated in PEGURE l by the arrow, that is, from the right to the left as viewed in FIGURE 1, which establishes a magnetic field with the circular lines of force about the axis, this field being directed toward the plane of the drawing in the upper part of the cross-sectional view of FIGURE 1 and toward the observer or viewer in the lower part thereof, as indicated also by the encircled small cross and dot, respectively, and designated by reference character B.
  • the vessel or enclosure 1 is supplied with ions from the left thereof by means of an ion source constructed in accordance with the present invention.
  • This ion source cornprises an electrode system including a cathode electrode in the form of two cylinders 5- and 6, separated by a gap 7; an ion extraction electrode in the form of two cylinders S and separated by a gap lb and disposed between the cylinders 57 and 6 and axial rod 3; an annular cathode 11, supported on the cylinder 5; an electron-optical or focusing anode in the form of a cylinder 12, facing the cathode ll; and an anode electrode in the form of a cylinder 13, surrounding the cylinders 5 and 6. All of these electrodes have a symmetry of revolution about rod 3.
  • the electrodes 12 and 13, for example, are incorporated into the walls 14 of the glass vessel or enclosure which contains the gun and which belongs to the enclosure or vessel 1.
  • This vessel is closed by an annular member 15 made of Kovar, secured to the ring member 16 which is adapted to slide along the rod- 3.
  • the ring member 36 is connected by means of bellows 1'7 made of tombac to a boss 13 provided on the rod 3. in that manner, the rod 3 may expand freely without damaging the glass structure M.
  • the electrodes 5 and a are interconnected with each other in any suitable manner and are also connected to a positive potential with respect to the rod 3.
  • the cathode ll supplied from a source not illustrated, is also connected to the potential of electrode 5.
  • the anodes l2 and 13 are carried at suitable positive potentials with respect to electrodes 5 and 6 by means of source 19.
  • the electrodes 8 and 9 are interconnected in any suitable manner and are also carried at a potential suitably chosen intermediate that of the rod 3 and that of electrodes 5 and 6 by means of the same source 19.
  • the parallel electron paths define a cylindrical pattern of the ionizing beam which is coaxial with the rod 3.
  • the electron paths pass through what are in efiect a plurality of ionizing areas located at difierent angularly spaced points around the rod 3, these ionizing areas combining with each other to form an ionizing chamber completely encircling the rod 3.
  • the electrons are captured by collector 2.5.
  • the gas emitted into the same space through tubular member 2% is ionized by these electrons.
  • the positive ions are attracted by the negative extraction electrode 8, 9 and leave the ionization space through successive gaps 7 and 16.
  • the ions which leave through gap 10 find themselves anew within the mutual crossed electric and magnetic fields, these fields being established between the cylindrical space between the extraction electrode 8, 9 and the rod 3.
  • the transverse magnetic field and the radial electric field have here the same direction as in the ionization space.
  • the electric field in effect, is directed from the interior toward the exterior, thanks to the difference of potential between electrodes 3 and 8 or 9. It is known that when neither the direction of the magnetic field nor that of the electric field changes, the ions move in the same axial direction as the electrons of the beam 26. Consequently, the ions eventually move in parallel paths and are concentrated into a hollow beam 27 directed from the left to the right as viewed in the drawing and are thereupon injected into the enclosure 1.
  • the parallel paths of the ions define a cylindrical pattern of the ion beam which is also coaxial with the rod 3.
  • FIGURE 2 in which the same parts are designated by identical reference numerals as in FIGURE 1 discloses an arrangement in which the current in rod 3 has been reversed with respect to that of FIGURE 1.
  • the magnetic field has changed its direction and is directed toward the observer in the upper portion of the crosssectional View of the drawing, and toward the plane of the paper in the lower portion thereof.
  • the electric field within the ionization space remaining directed from the interior toward the exterior, the movement of the electrons which ionize the gas changes its direction, and is directed from right to left as viewed in FIGURE 2.
  • the arrangement of the electrodes within the ionization space is therefore modified in FIGURE 2 by placing the cathode 11 and the focusing anode 12 toward the right, and the cylinder 13 with the collector 25 toward the left thereof.
  • the electrodes 8, 9 are now carried at a negative potential with respect to rod 3.
  • the electric field within the space between these electrodes 8, 9 and rod 3 is directed from the outside toward the inside, and is, therefore, inverse with respect to the electric field within the ionization space. Thanks to this simultaneous inversion of the magnetic field and of the electric field with respect to the conditions of FIGURE 1, the ion beam 27 moves in FIGURE 2 in the same direction as in FIGURE 1, and in the opposite direction with respect to the flow of electrons in FIGURE 2, that is, from left to right as viewed in FIGURE 2. Otherwise, the operation of the device shown in FIGURE 2 is the same as that of FIGURE 1.
  • an ion source having a cylindrical extraction electrode coaxial with said rod, an evacuated vessel surrounding said electrode, means for feeding gas to be ionized into said vessel, means for emitting a hollow electron beam propagating substantially parallel to said rod through said gas thereby ionizing it including first radial electric field generating means acting together with said circular magnetic field on said electrons to direct the same substantially perpendicularly to both said fields, and means for generating a second radial electric field in the space between said rod and said extraction electrode, said last-mentioned space receiving ions produced by said ionizing electrons and extracted through said extraction electrode, and said circular magnetic field acting on said ions to concentrate said ions into a hollow tubular beam propagating in said space substantailly parallel to said.
  • An ion source having an ionization space for producing a hollow ion beam, comprising means for establishing crossed magnetic and electric fields in said space with the magnetic field being generally circular about a predetermined axis and the electric field being radial with respect to said axis, gas supply means for supplying a gaseous medium adapted to be ionized by an electron beam generally encircling said axis within said ionization space, and means including said first-mentioned means for producing said ionizing electron beam and for extracting the ions created by the said ionizing electron beam in the form of a hollow cylindrical ion beam encircling said axis.
  • An ion source having a generally annular ionization space for producing a hollow ion beam, comprising means for establishing crossed magnetic and electric fields in said space including axial conductor means through which current fiows for setting up a circular magnetic field thereabout, gas supply means for supplying a gaseous medium adapted to be ionized by an electron beam Within said ionization space, means including said first-mentioned means for producing said ionizing electron beam, and means including electrode means in combination with said first-mentioned means for directing the ions produced by the said ionizing electron beam in such a manner that the ions move in the form of a hollow cylindrical ion beam encircling said conductor within said crossed electric and magnetic fields.
  • An ion source having an ionization space for producing a hollow ion beam, comprising means for establishing crossed magnetic and electric fields in said space including axial conductor means through which current passes for setting up a circular magnetic field thereabout, gas supply means for supplying a gaseous medium adapted to be ionized by an ionizing electron beam within said ionization space, electron emissive means for emitting an ionizing electron beam guided by said first-mentioned means and encircling said conductor in said space, and means including said first-mentioned means and additional electrode means for establishing a second electric field to focus and guide said ions produced in said space by the said ionizing electron beam in such a manner that the ions move in the form of a hollow cylindrical ion beam encircling said conductor within said crossed electric and magnetic fields.
  • An ion source having an ionization space for producing a hollow ion beam, comprising means for establishing crossed magnetic and electric fields including axial conductor means through which current passes for setting up a circular magnetic field thereabout and electrode means having a symmetry of revolution about said conductor means for establishing at least one electric field, gas supply means for supplying a gaseous medium adapted to be ionized by an ionizing electron beam within said ionization space, and means for producing said electron beam propagating within said fields, the ions produced by said ionizing electron beam also propagating within said fields and being focused thereby into a hollow cylindrical ion beam within said crossed electric and magnetic fields.
  • An ion source having an ionization space for producing a hollow ion beam by the interaction with a gaseous medium of the electrons in an electron beam propagating within crossed magnetic and electric fields, comprising axial conductor means through which current passes for setting up said magnetic field having a circular configuration thereabout, gas supply means for introducing a gaseous medium to be ionized into said ionization space, and electron-optical electrode means generally encircling said conductor means for establishing said electric field and for extracting the ions produced by the said ionizing electron beam from said ionizing space and pro pagating the same in the form of a hollow cylindrical ion beam within said crossed electric and magnetic fields.
  • An ion source for producing a hollow ion beam comprising means for producing a generally cylindrical ionizing electron beam including means for establishing crossed magnetic and electric fields for guiding said electron beam, said last-rnentioned means including an axial conductor through which current passes for setting up the magnetic field as circular thereabout, gas supply means for introducing a gaseous medium to be ionized into said ionization space, an electrode means for focusing and separately grouping said electrons and ions in such a manner that the ions produced by said ionizing electrons move also Within said crossed electric and magnetic fields in the form of a hollow cylinder.
  • An ion source having an ionization space for producing a hollow ion beam by the interaction with a gaseous medium of the electrons in an electron beam propagating within crossed magnetic and electric fields, comprising axial conductor means through which current passes for setting up said magnetic field having a circular configuration thereabout, electron-optical electrode means for establishing said electric field and for extracting the ions produced by the said ionizing electron beam from said ionizing space and propagating the same in the form of a hollow cylindrical ion beam within said crossed electric and magnetic fields, said electrode means including two concentric electrode systems disposed about said conductor means, and means for establishing a first electric field between said two electrode systems and a second electric field in the space between the inter electrode system and said conductor means.
  • An ion source for producing ions propagating in parallel paths generally defining a cylindrical pattern, comprising means for establishing crossed magnetic and electric fields at ionizing areas located at difierent angularly spaced points around the axis of said cylindrical pattern, said last-mentioned means including a conductor extending coaxially of said cylindrical pattern and means for passing a current through said conductor for establishing said magnetic field as a circular field thereabout, means for supplying an ionizable medium to the ionizing areas in said crossed fields, and means including said crossed field establishing means for producing ionizing electrons moving in said ionizing areas parallel to said conductor to ionize said ionizable medium, and means including electrode means in combination with said firstmentioned crossed field establishing means for separating ions from said ionizing electron for propagating said ions in said parallel paths along said cylindrical pattern.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Electron Sources, Ion Sources (AREA)
US2877A 1959-02-02 1960-01-18 Ion source Expired - Lifetime US3076112A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR785529A FR1224888A (fr) 1959-02-02 1959-02-02 Source d'un faisceau ionique creux pour enceintes d'utilisation traversées par un champ magnétique à symétrie circulaire

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US3076112A true US3076112A (en) 1963-01-29

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DE (1) DE1204754B (xx)
FR (1) FR1224888A (xx)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3212974A (en) * 1959-06-23 1965-10-19 Csf Particle injecting device
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

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2760101A (en) * 1950-11-30 1956-08-21 Csf Electron gun for a tubular beam
US2761088A (en) * 1949-02-22 1956-08-28 Csf Travelling-wave amplifying tube
US2935634A (en) * 1956-06-22 1960-05-03 Csf Ion source

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2761088A (en) * 1949-02-22 1956-08-28 Csf Travelling-wave amplifying tube
US2760101A (en) * 1950-11-30 1956-08-21 Csf Electron gun for a tubular beam
US2935634A (en) * 1956-06-22 1960-05-03 Csf Ion source

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3212974A (en) * 1959-06-23 1965-10-19 Csf Particle injecting device
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

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Publication number Publication date
DE1204754B (xx)
FR1224888A (fr) 1960-06-28

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