EP0827179B1 - Einfach-Potential Ionenquelle - Google Patents

Einfach-Potential Ionenquelle Download PDF

Info

Publication number
EP0827179B1
EP0827179B1 EP96306329A EP96306329A EP0827179B1 EP 0827179 B1 EP0827179 B1 EP 0827179B1 EP 96306329 A EP96306329 A EP 96306329A EP 96306329 A EP96306329 A EP 96306329A EP 0827179 B1 EP0827179 B1 EP 0827179B1
Authority
EP
European Patent Office
Prior art keywords
ion source
electrode
ions
ion
heating element
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 - Lifetime
Application number
EP96306329A
Other languages
English (en)
French (fr)
Other versions
EP0827179A1 (de
Inventor
Marsbed Hablanian
Asoka Ratnam
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.)
Varian Inc
Original Assignee
Varian Inc
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 Varian Inc filed Critical Varian Inc
Priority to DE1996617417 priority Critical patent/DE69617417T2/de
Priority to EP96306329A priority patent/EP0827179B1/de
Publication of EP0827179A1 publication Critical patent/EP0827179A1/de
Application granted granted Critical
Publication of EP0827179B1 publication Critical patent/EP0827179B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • H01J27/08—Ion sources; Ion guns using arc discharge
    • H01J27/14—Other arc discharge ion sources using an applied magnetic field
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J41/00—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
    • H01J41/02—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas
    • H01J41/04—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas with ionisation by means of thermionic cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/10—Ion sources; Ion guns
    • H01J49/12—Ion sources; Ion guns using an arc discharge, e.g. of the duoplasmatron type
    • H01J49/126—Other arc discharge ion sources using an applied magnetic field

Definitions

  • the present invention relates to ion sources such as those used in, e.g., mass spectrometers.
  • the present invention relates to an ion source which operates using only a single potential.
  • Mass spectrometers are known in the art, and may be used to measure the presence of a selected gas in a system.
  • a central component of a typical mass spectrometer is the ion source. Gas entering the mass spectrometer flows into the ion source. Electrons, produced typically by a hot filament, enter an ion chamber and collide with the gas molecules. This creates an environment within the chamber where ions are quantitatively proportional to the pressure in the ion chamber. Ions are withdrawn from the ionization chamber through an exit hole or slit under the influence of an electrostatic field created by a voltage potential applied at a withdrawal electrode. The ions are further guided by one or more focus plates which also produce a field created by further voltage potentials. The various voltage potentials creating the ion beam and the focus fields are chosen to ensure that a straight ribbon of ions exits from the chamber.
  • the ions from the chamber typically enter a magnetic field which deflects ions in proportion to their mass-to-charge ratio.
  • the magnetic field is typically adjusted so hydrogen ions are deflected 135°, helium ions 90°, and all heavier species less than 90°.
  • An ion collector is placed at 90° to collect the target particles, i.e., helium ions. All other ions are deflected away from the collector. The collector current is then measured by an amplifier for evaluation.
  • the ion source required the application of a number of voltages to create necessary electron trajectories and to withdraw and collimate a stream of ions for delivery through the magnetic field.
  • Most previous systems required at least four or five different voltage sources to accomplish this. This is undesirable for several reasons.
  • These voltages are varied to obtain the desired helium ion beam current and shape they tend to interact and thus require a series of iterative adjustments which makes an automatic tuning more difficult. The iterations required makes the adjustment procedure rather lengthy. Further, construction, design, and coupling of ion sources requiring several potentials is difficult. With increased complexity comes reduced reliability and increased cost.
  • Another disadvantage of existing ion sources is that they have a limited useful life.
  • the life of the source is only as good as the life of the electron emitting filament used in the system.
  • certain existing systems use redundant filaments (i.e., a spare is typically placed opposite or beside the primary filament for use when the primary expires)
  • the life of the ion source is still limited. Once both filaments have expired, the ion source is rendered useless until the source can be retrofitted with new filament(s).
  • an ion source for a mass spectrometer leak detection system is needed which is easily tuned, simple in design, low in cost, and long in life. Further, it would be desirable to provide an ion source which supports automatic tuning.
  • US-A-4862032 discloses an end-Hall ion source.
  • the device produces a plasma which provides a thrusting force suitable for use in space travel.
  • DE-A-689532 discloses a general purpose ion source. There is no disclosure of focussing of ions and production of an ion trajectory along a specific axis of an electrode (anode).
  • the invention is set out in claim 1.
  • additional heating elements when provided are preferably coupled to at least respective others of said pins and are preferably positioned between the base member and the electrode.
  • the heating elements are preferably filaments.
  • the shield when provided may be a thermal radiation shield, an insulating shield or both.
  • the electrode may be shaped to focus a collimated ion stream approximately 5 cm from the narrow end of the electrode.
  • the base when provided is preferably a demountable vacuum closure base.
  • heating elements may be arranged side by side, in a triangular arrangement or in a star arrangement, as appropriate.
  • FIG. 1 a block diagram depicting a mass spectrometer 10 for use, e.g., in a leak detection system is shown.
  • the system is shown in block form since such systems are generally known in the art. These systems are designed to detect the presence of a probe gas, typically helium, in a leak source 12. Gases present in the leak source 12 are received in an inlet 14 of the mass spectrometer 10 and are carried into an ion source 16. The ion source 16 creates ions quantitatively proportional to the gas pressure within the ion source.
  • a probe gas typically helium
  • the ions are directed to a magnetic field 18 which is designed and adjusted so that only helium ions are deflected to an ion collector 20 for subsequent measurement using, e.g., amplifier and display circuitry 22.
  • a central component of the system is the ion source 16.
  • ion source 16 is supported on a demountable vacuum closure 24 for insertion and removal into an opening in a mass spectrometer tube.
  • the closure 24 contains a conventional multi-pin vacuum tube feedthrough.
  • a number of the pins 26a-h may be used to electrically couple and/or support elements of the ion source 16.
  • the ion source 16 includes an ion chamber electrode 28 which is open to the flow of gas from an inlet opening of the mass spectrometer.
  • the ion chamber electrode 28 has an ion exit slit 31 and left and right openings 33 for the admission of electrons.
  • a thermionic filament 30 is used to produce electrons which enter the ion chamber through opening 33 and collide with gas molecules. This creates a number of ions in the chamber quantitatively proportional to the pressure in the ion source. These ions are typically repelled out of the ion source through the exit slit 31 by a repeller field created by one or more repeller electrodes 32.
  • Focus plates 34 may be used to aim or steer the stream of ions into the magnetic field 18 in the next stage of the mass spectrometer system.
  • the combined electrostatic effect of the repeller electrode or electrodes, ion chamber electrode, and focus plates colliminate the ion beam so that it enters the magnetic field as a straight ribbon of ions.
  • Sensitivity and reliability of the mass spectrometer requires that the ion source function efficiently and correctly. Ensuring that the ion source is properly adjusted, however, can become a problem when a number of different potentials are required to operate the source. In the ion source of Fig. 2, four different potentials are needed. The repeller electrode, the ion chamber electrode, and the focus plates each require a separate potential. Other ion sources require application of an even greater number of potentials. When these voltages are varied to obtain the desired helium beam current and shape, they tend to interact and thus require a few iterative adjustments which makes an automatic tuning more difficult and the procedure becomes rather lengthy.
  • Previous ion sources also require proper positioning and placement of electrodes. This becomes more complex as a greater number of precisely positioned electrodes becomes necessary. If any of the electrodes are improperly focussed or positioned, the ion stream created by the ion source may lose focus. The problem of placement is exacerbated by the use of thin sheets of bendable metal for electrodes. Improper handling and installation of these electrodes can result in loss of precision.
  • Certain prior ion sources utilized dual-redundant filaments to extend the useful life of the source.
  • the second filament was placed on the opposite side of the chamber from the primary filament.
  • Other configurations were generally impractical, as other placements of the redundant filament required substantial retuning or adjustments to the ion source.
  • the ion source 50 may be shaped to fit into vacuum tube feedthroughs designed to accommodate existing ion sources.
  • the ion source 50 is supported on a standard vacuum tube feedthrough 52 having, e.g., eight pins 54a-h.
  • One or more filaments 56 are coupled to pins 54 using wires 57 for support and electrical connection.
  • the filaments are heated using 5 Volts.
  • Those skilled in the art realize, however, that the manner of heating the filaments 56 is not critical. Other voltages or approaches may also be employed so long as sufficient energy is present to create a cloud of electrons in the area of the filaments.
  • the ion source 50 of the present invention utilizes a single conical electrode 58 coupled to a single potential source.
  • the single conical electrode 58 may be coupled to, e.g., one or more pins 54 placed at a common potential.
  • the conical electrode 58 is placed at 275-300 Volts while the base, or feedthrough, is at ground. Experimentation has shown that the conical shape of the electrode 58 serves to create an ion focus point some distance away from the center of the cone, e.g., 5 cm (2") from the cone.
  • the focus point may be modified by varying the angular shape of the conical electrode and the voltage applied.
  • the conical electrode 58 may be formed as a single cast piece or may be formed from an appropriately bent sheet of metal. Further, the entire electrode need not be conical in shape. Embodiments having both a conical portion and a cylindrical portion may also be used so long as an appropriate stream of ions and electrons is created.
  • the conical electrode 58 is encircled by a cylindrical magnet 60 which serves to increase the length of electron paths passing near the conical electrode in a manner to ensure maximum ionization.
  • the symmetrical shape of the electrode 58 and magnet 60 serve to create an ion path at the axis 59 of the ion source. That is, an electron cloud is created by the heated filaments 56 near the base of the conical electrode 58.
  • the potential and shape of the conical electrode 58 serves to accelerate the electrons into gas molecules in the ion source 50, creating ions which travel at the axis 59 of the ion source, or through the center of the conical electrode 58.
  • the result is an effective ion source 50 which is simple to fabricate and control. Only one electrode placed at a single potential is needed. This potential may be readily adjusted to properly tune the ion source to a particular peak (e.g., helium or the like). Automatic tuning is accommodated by eliminating the need to iteratively adjust more than one electrode placed at different potentials. Further, the entire structure is more easily and cheaply manufactured. Less active feedthroughs are required. Fewer wires and connections are used. In addition, there is no need to precisely position and orient a number of electrodes in the present design. Instead, a single electrode at a single potential is used. The geometry of the electrode may be optimized to accommodate different detection systems.
  • An insulative radiation shield or layer 62 may be placed between the magnet 60 and the conical electrode 58 to ensure the magnet 60 does not overheat. Those skilled in the art recognize that overheating of a magnet can impair the field created by the magnet.
  • ion sources 50 permits greater filament 56 redundancy, thereby extending the life of the ion source 50.
  • Figs. 4A-D a number of suitable filament placement schemes are shown. Three or more filaments 56 can be positioned at the base of the conical electrode 58. The primary requirement is that each filament 56 be coupled so that it may be separately activated. Further, the filaments 56 should be placed as closely together near the center of the conical electrode's axis 59 as possible. As the first filament burns out, a second filament may be activated. When the second filament burns out, the third or fourth filaments may be used. This can effectively increase the useful life of an ion source by over 30 to 50%.
  • the relative sizings of the conical electrode 58 and the magnet 60 may be modified. It has been found that diameters which fit in existing ion source enclosures produce desirable results. However, larger or smaller diameters may also be used. Different pin numbers and placements may also be employed to further take advantage of the symmetrical shape of the ion source. Further, the conical shape and/or the voltage potential applied may be modified to achieve different ion focussing effects.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Analytical Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Electron Tubes For Measurement (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

Claims (10)

  1. Ionenquelle, bei der eine gewünschte Flugbahn von Elektronen zum Erzeugen von Ionen und eine gewünschte Flugbahn der Ionen beide durch ein einzelnes elektrisches Potential erzeugt werden, wobei die Ionenquelle (50) eine achsensymmetrische Elektrode (58) zum Anlegen des einzelnen Potentials, einen Magnet (60), der ein Äußeres der Elektrode (58) umgibt, und zumindest ein erstes Heizelement (56), das an einer Basis der Elektrode (58) angeordnet ist und die Elektronen emittiert, umfaßt, wobei die Form und das einzelne elektrische Potential der Elektrode bei der Verwendung derart sind, daß die Ionen fokussiert werden und die gewünschte Flugbahn von Ionen in einer Richtung vom ersten Heizelement (56) weg zur Elektrode (58) hin entlang der Mittelachse (59) der Elektrode (58) erzeugt wird.
  2. Ionenquelle nach Anspruch 1, wobei die achsensymmetrische Elektrode (58) eine konische Elektrode ist.
  3. Ionenquelle nach Anspruch 1 oder 2, wobei die Elektrode (58) dazu ausgelegt ist, eine Flugbahn von Elektronen in Richtung des ersten Heizelements (56) zu erzeugen.
  4. Ionenquelle nach einem der Ansprüche 1 bis 3, welche ferner eine Abschirmung (62) umfaßt, die zwischen der Elektrode (58) und dem Magnet (60) angeordnet ist.
  5. Ionenquelle nach einem der Ansprüche 1 bis 4 mit einem Sockelelement (52) und einer Vielzahl von Stiften (54), die sich durch das Sockelelement (52) erstrecken, wobei die Elektrode (58) mit mindestens einem der Stifte (54) elektrisch gekoppelt ist, wobei die Elektrode (58) von dem Sockelelement (52) beabstandet ist, wobei das erste Heizelement (56) mit mindestens zwei der Stifte (54) gekoppelt ist und zwischen dem Sockelelement (52) und der Elektrode (58) angeordnet ist.
  6. Ionenquelle nach einem der Ansprüche 1 bis 5 mit zumindest einem zusätzlichen Heizelement, das benachbart zum ersten Heizelement angeordnet ist.
  7. lonenquelle nach einem der Ansprüche 1 bis 6, wobei der Magnet (60) ein zylindrischer Magnet ist.
  8. Massenspektrometer mit einer lonenquelle nach einem der Ansprüche 1 bis 7.
  9. Leckerkennungssystem mit einer Ionenquelle nach einem der Ansprüche 1 bis 7.
  10. Heliumleck-Erkennungssystem mit einer Ionenquelle nach einem der Ansprüche 1 bis 7.
EP96306329A 1996-08-30 1996-08-30 Einfach-Potential Ionenquelle Expired - Lifetime EP0827179B1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE1996617417 DE69617417T2 (de) 1996-08-30 1996-08-30 Einfach-Potential Ionenquelle
EP96306329A EP0827179B1 (de) 1996-08-30 1996-08-30 Einfach-Potential Ionenquelle

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP96306329A EP0827179B1 (de) 1996-08-30 1996-08-30 Einfach-Potential Ionenquelle

Publications (2)

Publication Number Publication Date
EP0827179A1 EP0827179A1 (de) 1998-03-04
EP0827179B1 true EP0827179B1 (de) 2001-11-28

Family

ID=8225070

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96306329A Expired - Lifetime EP0827179B1 (de) 1996-08-30 1996-08-30 Einfach-Potential Ionenquelle

Country Status (2)

Country Link
EP (1) EP0827179B1 (de)
DE (1) DE69617417T2 (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TW503432B (en) * 2000-08-07 2002-09-21 Axcelis Tech Inc Magnet for generating a magnetic field in an ion source
US7459677B2 (en) * 2006-02-15 2008-12-02 Varian, Inc. Mass spectrometer for trace gas leak detection with suppression of undesired ions

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4862032A (en) * 1986-10-20 1989-08-29 Kaufman Harold R End-Hall ion source

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE689532C (de) * 1936-08-26 1940-03-27 Siemens & Halske Akt Ges Einrichtung zur Erzeugung positiver Ionen
CH480626A (de) * 1968-12-24 1969-12-15 Balzers Patent Beteilig Ag Ionisationsmanometerröhre mit auswechselbarer Glühkathode

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4862032A (en) * 1986-10-20 1989-08-29 Kaufman Harold R End-Hall ion source

Also Published As

Publication number Publication date
EP0827179A1 (de) 1998-03-04
DE69617417T2 (de) 2002-08-08
DE69617417D1 (de) 2002-01-10

Similar Documents

Publication Publication Date Title
US5864137A (en) Mass spectrometer
US6777882B2 (en) Ion beam generator
US9653274B2 (en) Assemblies for ion and electron sources and methods of use
US5600136A (en) Single potential ion source
WO2006086722A2 (en) Generation of combination of rf and axial dc electric fields in an rf-only multipole
US6576898B2 (en) Mass spectrometer with multipole rod type ion lens
AU692761B2 (en) Cycloidal mass spectrometer and ionizer for use therein
US5543625A (en) Filament assembly for mass spectrometer ion sources
GB2244856A (en) Vacuum gauge
EP0827179B1 (de) Einfach-Potential Ionenquelle
EP0329461A2 (de) Massenspektrometer
US5376792A (en) Scanning electron microscope
US5153432A (en) Ion source for quadrupole mass spectrometer
Liebl Ion optics of ion microprobe instruments
US4891525A (en) SKM ion source
WO2018211611A1 (ja) イオン検出装置及び質量分析装置
US5675152A (en) Source filament assembly for an ion implant machine
US3742275A (en) Ion source having improved ion beam alignment and focus structure
EP4066273A1 (de) Gasanalysesystem mit ionenquelle
US3527937A (en) Electron bombardment type ion source for a mass spectrometer
US4602161A (en) Negative ion source with low temperature transverse divergence optical system
WO2022239243A1 (ja) 質量分析装置
US20230402274A1 (en) Gas discharge lamp, more particularly deuterium lamp
US20220165559A1 (en) Ion source assembly with multiple ionization volumes for use in a mass spectrometer
WO2023114166A1 (en) Ion source assembly with multiple elliptical filaments

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

17P Request for examination filed

Effective date: 19970321

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB

17Q First examination report despatched

Effective date: 19980629

AKX Designation fees paid

Free format text: DE FR GB

RBV Designated contracting states (corrected)

Designated state(s): DE FR GB

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: VARIAN, INC.

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

REF Corresponds to:

Ref document number: 69617417

Country of ref document: DE

Date of ref document: 20020110

ET Fr: translation filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20020731

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20020821

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20020830

Year of fee payment: 7

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

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20030830

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

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040302

GBPC Gb: european patent ceased through non-payment of renewal fee
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040430

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST