US3614420A - Monopole mass spectrometer - Google Patents

Monopole mass spectrometer Download PDF

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Publication number
US3614420A
US3614420A US674579A US3614420DA US3614420A US 3614420 A US3614420 A US 3614420A US 674579 A US674579 A US 674579A US 3614420D A US3614420D A US 3614420DA US 3614420 A US3614420 A US 3614420A
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Prior art keywords
electrode
mass spectrometer
electrodes
monopole
end plate
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Expired - Lifetime
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US674579A
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English (en)
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Robert H Dillenbeck
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General Electric Co
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General Electric Co
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/26—Mass spectrometers or separator tubes
    • H01J49/34—Dynamic spectrometers
    • H01J49/42—Stability-of-path spectrometers, e.g. monopole, quadrupole, multipole, farvitrons
    • H01J49/4205—Device types
    • H01J49/421—Mass filters, i.e. deviating unwanted ions without trapping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/26—Mass spectrometers or separator tubes
    • H01J49/34—Dynamic spectrometers
    • H01J49/42—Stability-of-path spectrometers, e.g. monopole, quadrupole, multipole, farvitrons
    • H01J49/4205—Device types
    • H01J49/4255—Device types with particular constructional features

Definitions

  • Woods, Oscar B. Waddell and Joseph B. Forman ABSTRACT Improved electrode mounting means for a monopole mass spectrometer comprising a rigid end plate and a flexible end plate and means for rigidly supporting one of the electrodes therebetween and flexibly supporting the other.
  • TM ATTORNEY ⁇ PATENTEDUBT 1 9 I911 sum 2 BF 2 INVENTOR ROBERT H. DILLENBECK, BY @7 w IS TTORNEY.
  • MONOPOLE MASS SPECTROMETER This invention relates to monopole mass spectrometers generally and more particularly to a monopole mass spectrometer having an improved analyzing tube structure which permits high resolution of the mass to be analyzed.
  • Mass spectrometers are well-known devices which are particularly applicable for use as partial pressure analyzers or for different gas determination.
  • a mass spectrometer operates to analyze gas ions in a precisely determined uniform electrical and/or magnetic field wherein, depending on the mass of the ions, the ions describe different trajectories. These ions may then be collected at different positions based upon their ion trajectories and the current generated thereby is a measurement of certain gas characteristics which may include the kind of gas or the density of the gas.
  • a monopole mass spectrometer or analyzer is to be distinguished from the prior analyzing devices wherein the interaction between electric and magnetic fields causes separation of the particles and from the quadrupole mass spectrometer or analyzer in which a beam of ions is longitudinally accelerated along and within an array of four parallel rods to which rods balanced electrical potentials are applied.
  • a monopole mass spectrometer is one in which a single conducting electrode, usually cylindrical, is partially surrounded by a metallic shield electrode in the form of a V, which V simulates the zero equipotential lines of the quadrupole.
  • ions of the gases being analyzed are injected into the mass analyzer region of the analyzer tube by conventional Nier-type ion source.
  • the entering ions After passing through an aperture into the area between the electrodes, the entering ions are subjected to a combined unidirectional and alternating electric field which is applied to the electrodes, a predetermined set of combined voltages normally being applied to the conducting rod with the metallic shield, V-electrode, normally being grounded or at ground potential.
  • a predetermined set of combined voltages normally being applied to the conducting rod with the metallic shield, V-electrode, normally being grounded or at ground potential.
  • the equations of motions of charged particles in such a field (Mathieu functions) demonstrates that for any given set of operating parameters, only particles of a very small range of charge-to-mass ratio will have stable trajectories and pass through the analyzing region.
  • a particular mass may be chosen out of those directed along the length of the monopole for collection by a collector so that a signal is generated by the collector which is indicative of the concentration of the selected mass.
  • different masses may be chosen to be impinged upon the detector.
  • a range of masses may be swept so that an analysis over a wide range of masses may be conducted in a predetermined period of time.
  • Another object of the invention is to provide a mechanical and electrical interference-free electrical field for a monopole mass spectrometer.
  • Yet another object of the invention is to provide an electric field for a monopole mass spectrometer by a pair of elongated parallel spaced-apart electrodes wherein the spacing of the electrodes is accurately and uniformly maintained.
  • a further object of the invention is to provide improved electrodes, for a monopole mass spectrometer which may be readily manufactured and easily assembled in accurate relation.
  • a monopole mass spectrometer comprising a pair of Iongitudinally extending electrodes defining an analyzing region therebetween, means connecting said electrodes to a source of electric potential for establishing an electric field between said electrodes throughout said analyzing region, and means for insulatively supporting said electrodes in parallel, spaced relation to one another, said last-mentioned means comprising a rigid end plate and a relatively flexible end plate, means for fixedly securing one of said electrodes to said end plates in electrically conducting relation thereto and means for flexibly supporting the outer electrode to said end plates in electrically insulating relation theretol 7
  • FIG. 1 is a diagrammatic representation of a monopole mass spectrometer or analyzer
  • FIG. 2 is a side elevational and partial sectional view of an analyzer tube of the preferred embodiment of this invention
  • FIG. 3 is a view of the left end of the analyzer tube of FIG. 2;
  • FIG. 4 is a view of the other end of the analyzer tube shown in FIG. 2.
  • a monopole mass spectrometer or analyzer is illustrated in diagrammatic form in FIG. 1 of the drawing and includes an ion source I, an analyzer tube 2, and an ion detector 3 mounted within an evacuable enclosure structure 4. Suitable electric power supplies 5, 6 and 7 are provided and connected to the respective elements of the analyzer through vacuumtight feed-throughs.
  • the ion source may be conventional and may be conveniently the same ion source as is disclosed in copending application Ser. No. 327,617 filed Dec. 3, I963, now U.S. Pat No. 3,230,360 issued Jan. I5, 1966, and assigned to the assignee of the present invention.
  • the ion detector means 3 may be the electrode structure of a Dumont-type 24 l -1 l9 photomultiplier tube having input leads for supplying power thereto and a pair of output leads for reading information therefrom, which leads are connected to power supply 7, which is of conventional design and may include an oscilloscope and/or recorder output.
  • the power supply 6 for the analyzer tube 2 may be of the type disclosed in copending application Ser. No. 646,947 filed June 19, 1967, and assigned to the assignee of the present invention.
  • the enclosure 4 may be of any type which may be evacuated by a suitable pumping system and provided with an inlet for the gas to be analyzed (not shown). If the analyzer were used to detect gases in outer space, such auxiliary equipment and enclosure would be unnecessary.
  • the monopole mass analyzer tube 2 is also illustrated in diagrammatic form in FIG. 1 of the drawing and basically comprises a pair of electrodes 8 and 9, electrode 8 consisting of a single centrally located metallic rod electrode to which an electrical voltage is applied and electrode 9 being a V-shaped metallic shield electrode partially enclosing rod electrode 8.
  • ions are emitted into the space between rod 8 and shield 9 and carefully controlled interrelated alternating and unidirectional voltages are applied to rod electrode 8 to establish a uniform predetermined electric field therebetween.
  • the incident ions provide a signal which is then amplified and recorded by the power supply and signal output 7.
  • FIG. 2 The preferred embodiment of analyzing tube 2 of the monopole mass spectrometer in accordance with the invention is illustrated in FIG. 2 wherein radiofrequency rod electrode 8 and V-shaped shield 9 are mounted within an envelope member 10, which envelope comprises a tube or cylinder II which may be of stainless steel or like material terminated at its ends by flanges l2 and 13.
  • the flange 13 should be of suitable design to coact with a flange 14 (FIG. 1) on the type of enclosure 4 with which the analyzer is to be used.
  • the electrodes 8, 9 are secured to an end plate 15, end plate being secured to the flange 12 by any suitable securing means which as illustrated includes the shoulders 16 made a part of flange 12 which cooperate with the overlying screws 17.
  • An aperture 18 is provided in the central portion of end plate 15 to permit entry of ions from ion source into the analyzing space between RF electrode 8 and shield electrode 9.
  • the shield 9 is secured to the end plate 15 by suitable means such as, for example, by tap screws 19.
  • the RF polepiece rod electrode 8 is insulatively supported from end plate 15 by suitable means illustrated in FIG. 2 as comprising a recess 20 provided in end plate 15 of suitable configuration so as to provide a shoulder or rest point 21 properly spaced from the electrode 9.
  • a tapered bore or recess 22 is provided in the end of electrode 8 and a ceramic sphere or ball 23 insulatively supports and aligns electrode 8 with electrode 9.
  • a spring end plate 24 is secured to the other end of electrode 9 by suitable means such as the screws 25 illustrated, circular openings 26 (FIG. 4) and 27 being provided therein.
  • the opening 26 provides means whereby the ions which maintain their trajectory throughout the longitudinal length of the analyzer region may exit to be impinged upon the electron multiplier detector 3 to provide a signal indicating the mass range measured.
  • the opening 27 provides a seat for ball 28 which is received in a tapered bore 29 in the end of the pole electrode 8. It will thus be seen that the RF electrode 8 may be closely and reproducibly aligned with the shield electrode 9 by maintenance of close tolerance on the location of the shoulder 21 and opening 27 with respect to the location of the V-block electrode 9 on end member 15 and 24 respectively.
  • pole electrode 8 and shield electrode 9 The electric field established between pole electrode 8 and shield electrode 9 by application of energy from power supply 6 must be completely uniform. Such uniformity, of course, will be affected by irregular or variable spacing between the pole pieces, which is eliminated by the above construction. Another factor to be considered in the mounting of the pole pieces is that they must be electrically insulated from each other which is accomplished by the ceramic balls 23 and 28.
  • the ceramic pieces have been eliminated from the area of the electric field by recessing the ceramic pieces into the end plates 15 and 24 and the electrode 8 as shown.
  • any accumulated charge on the ceramic pieces does not affect the electric field through which the ions from the ion source traverse in proceeding through the analyzer region of the spectrometer.
  • the variable that might have been introduced by placement of the ceramic pieces in a region whereby such charge could affect the field is eliminated.
  • the rod electrode may have a toroidal end portion 30 of reduced diameter so as to more completely surround ceramic ball 23.
  • the rod electrode 8 to which the combined unidirectional and alternating electric energy is applied must be a nonmagnetic material, capable of withstanding the high temperatures utilized during bakeout of the system and corrosion resistant to withstand attack from the various gases that may be analyzed by the spectrometer. It must also be dimensionally stable and of high strength. While metal-coated high-temperature ceramic such as the aluminas or forsterite, or quartz may be used, the stainless steels having these characteristics are preferred. A specific example of such a stainless steel is I-Iastalloy alloy-X. It will be appreciated that if the rod 8 is of a conductively coated insulating material the balls 23 and 28 need not be of insulating material.
  • the ion analyzer tube portion of the mass spectrometer may be assembled as a unit upon end plate 15 for insertion within enclo-, sure 10.
  • a plurality of setscrews 44 are provided which generally align the analyzer tube electrodes 8, 9 within the center of enclosure 10 and support the spring plate end thereof.
  • end plate 15 may be provided with welding recesses 31 so that the shield electrode 9 may be tackwelded to the end plate 15 at its intersections 32 with the recesses as illustrated in FIG. 3.
  • the shield electrode 9 may be tackwelded to end plate 24 at points 33,-the intersections of the circular end plate 24 and the circular portion of shield electrode 9 (FIG. 4).
  • the V-Shaped shield electrode 9 preferably is manufactured from a single piece of electrically conductive rod of suitable high-temperature, high-strength, and nonmagnetic material.
  • the material must also be dimensionally stable and corrosion resistant. Examples of such materials are the stainless steels, a specific example thereof being Hastalloy alloy-X.
  • a round stock rod of such material is first planned to give it a chordal surface.
  • a V is then milled or broached therein by use of either a tool or a 45 tool used and two passes made to cut the the inclined sides of the V. After milling, if necessary, the inclined sides of the V may be further polished but such is not generally required if suitable care is taken in operation of the milling machine.
  • Such an electrode may be readily manufactured and is dimensionally extremely stable.
  • the cylinder 11 of the analyzer tube is provided with a plurality of apertures or slots 34 (FIG. 2) around its periphery at its end adjacent the flange 13.
  • a toroidal support 35 is secured to the flange l3 and the cylinder 11 is secured within the support 35 by a plurality of lock screws 36.
  • Suitable means 37 may also be provided on the flange 13 for mounting of the ion detector 3 and also appropriate vacuumtight electric lead throughs may be provided thereon.
  • the flange 13 is adapted to coact with whatever type of apparatus in which the monopole mass spectrometer is to be used.
  • the flange 13 is provided with a seal seat 38 and a plurality of apertures 39 adjacent its outer periphery, and flange 14 of enclosure 4 has mating seal seat 40 and apertures 41.
  • Suitable securing means 42 extend through the apertures 39, 41 to secure the flanges together and clamp upon a sealing ring 43, which sealing ring is normally of copper to make a vacuumtight seal.
  • a monopole mass spectrometer including first and second electrodes defining an analyzing region therebetween, means for providing ions in said analyzing region, means for detecting ions exiting said analyzing region and means connecting said electrodes to a source of electric potential for establishing an axially uniform electric field between said electrodes throughout said analyzing region, the improvement of means for insulatively supporting said electrodes in parallel, spaced relation to one another, said means comprising a rigid end plate and a flexible end plate, means for fixedly and rigidly securing said first electrode to said end plates in electrically conducting relation thereto and rigid means coacting with each of said end plates for supporting said second electrode between said end plates in accurately spaced, parallel relation to said first electrode and in electrically insulating relation thereto, said rigid means for supporting said second electrode including a pair of spherical members, said second electrode having tapered recesses in the ends thereof receiving said spherical members and said end plates being provided with means cooperating with said spherical members to secure said second electrode
  • said second electrode is formed of an insulating material having a conductive coating formed thereon.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Electron Tubes For Measurement (AREA)
US674579A 1967-10-11 1967-10-11 Monopole mass spectrometer Expired - Lifetime US3614420A (en)

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DE (1) DE1800183A1 (enrdf_load_stackoverflow)
FR (1) FR1587479A (enrdf_load_stackoverflow)
GB (1) GB1233952A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050211895A1 (en) * 2001-09-17 2005-09-29 Shimadzu Corporation Method of preparing and reconditioning an electrode of mass spectrometer
US20130015340A1 (en) * 2011-07-15 2013-01-17 Bruker Daltonics, Inc. Multipole assembly having a main mass filter and an auxiliary mass filter

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3517667A1 (de) * 1985-05-15 1986-11-20 Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V., 3400 Göttingen Laser-massenspektrometer

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3105899A (en) * 1960-03-25 1963-10-01 Siemens Ag Electric mass filter
US3182190A (en) * 1962-07-31 1965-05-04 Gulf Research Development Co Magnetic field free ion source with adjustable electron gun
US3197633A (en) * 1962-12-04 1965-07-27 Siemens Ag Method and apparatus for separating ions of respectively different specific electric charges
US3350559A (en) * 1965-01-26 1967-10-31 Gen Electric Monopole mass spectrometer having one ceramic electrode coated with metal to within a short distance of each end

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3105899A (en) * 1960-03-25 1963-10-01 Siemens Ag Electric mass filter
US3182190A (en) * 1962-07-31 1965-05-04 Gulf Research Development Co Magnetic field free ion source with adjustable electron gun
US3197633A (en) * 1962-12-04 1965-07-27 Siemens Ag Method and apparatus for separating ions of respectively different specific electric charges
US3350559A (en) * 1965-01-26 1967-10-31 Gen Electric Monopole mass spectrometer having one ceramic electrode coated with metal to within a short distance of each end

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050211895A1 (en) * 2001-09-17 2005-09-29 Shimadzu Corporation Method of preparing and reconditioning an electrode of mass spectrometer
US7119329B2 (en) * 2001-09-17 2006-10-10 Shimadzu Corporation Method of preparing and reconditioning an electrode of mass spectrometer
US20130015340A1 (en) * 2011-07-15 2013-01-17 Bruker Daltonics, Inc. Multipole assembly having a main mass filter and an auxiliary mass filter

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DE1800183A1 (de) 1969-06-26
GB1233952A (enrdf_load_stackoverflow) 1971-06-03
FR1587479A (enrdf_load_stackoverflow) 1970-03-20

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