US3427449A - Cycloidal mass spectrometer employing crossed uniform magnetic and electric fields - Google Patents

Cycloidal mass spectrometer employing crossed uniform magnetic and electric fields Download PDF

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Publication number
US3427449A
US3427449A US561526A US3427449DA US3427449A US 3427449 A US3427449 A US 3427449A US 561526 A US561526 A US 561526A US 3427449D A US3427449D A US 3427449DA US 3427449 A US3427449 A US 3427449A
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United States
Prior art keywords
wire
mass spectrometer
electric fields
cycloidal
uniform magnetic
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Expired - Lifetime
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US561526A
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English (en)
Inventor
Derek Andrew
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Philips North America LLC
US Philips Corp
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US Philips Corp
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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
    • H01J49/28—Static spectrometers
    • H01J49/32—Static spectrometers using double focusing
    • H01J49/328—Static spectrometers using double focusing with a cycloidal trajectory by using crossed electric and magnetic fields, e.g. trochoidal type

Definitions

  • the present invention relates to a mass spectrometer, more particularly to a so-called cycloidal mass spectrometer, in which ions leave an ion source through a gap and cover cycloidal paths in crossed uniform electric and magnetic fields and finally reach a collecting electrode through a gap.
  • the uniform electric field is obtained by providing a plurality of parallel fiat plates each applied to a fixed voltage and provided with apertures for passing the ions.
  • the object of the invention is to provide an improvement of cycloidal mass spectrometers obtained by a novel structure for producing the uniform electric field in a mass spectrometer which permits readily outgassing of the spectrometer.
  • the uniform electric field is produced according to the invention by means of a wire which is helically wound around a region in which the ions cover their paths, voltage difference being applied between the ends of this wire.
  • the overall electric field can be produced by means of more than one wire helix, for example, by means of two wire helices each located on one side of a central plate.
  • the wire of each helix is wound around posts having a metal core surrounded by a ceramic sleeve. Adjacent at least one of these posts, a leaf spring lying between the core and the sleeve pushes the sleeve towards the outer side of the wire helix.
  • the Wire is stretched and slackening of the wire due to heat developed by the resistance of the wire is neutralized.
  • Use may be made, for example, of four posts arranged as the ribs of a rectangular parallelepipedon.
  • a cycloidal mass spectrometer having one or more wire helices by means of which the electric field is produced may be readily outgassed and requires a minimum number of electrical connections for producing the electric field.
  • FIG. 1 is a perspective view of part of a mass spectrometer
  • FIG. 2 is a sectional view of one of the posts around which the wire helix is wound
  • FIG. 3 is a schematic sectional view of FIG. 1 taken on the axis of the wire helix and at right angles to the magnetic field in which a few ion paths are outlined.
  • FIG. 1 The structure shown in FIG. 1 is mounted on a flange and is located within a vacuum envelope consisting of a tube of stainless steel.
  • the flange, the vacuum envelope and various electrical connections are not shown in the figure, since these form no part of the invention.
  • the structure includes a central plate 1, which supports the ion source 2 having a gap (3, FIG. 3) in its side (not shown in FIG. 1) from which the ions emanate.
  • the ion beam can reach through an aperture 4 in the central plate 1 and through a gap 5 the collecting electrode (6, FIG. 3) behind the gap 5.
  • a plate 7 is secured by four posts 8, 9, 10 and 11 to a detachable frame 12 clamped to the plate 1. Since 12 is detachable, the ion source is readily accessible.
  • FIG. 2 one of the posts is shown on an enlarged scale.
  • This post consists of a metal core 13 and a ceramic sleeve 14 provided with notches 15. 16 serves for spacing purposes.
  • the core 13 is bolted to the plate 7 and the frame 12 but the sleeve is capable of performing a rotation and a limited translation.
  • the sleeve 14 is spaced apart from the core 13 by a leaf spring 17.
  • Two diagonally opposite posts are constructed in this manner.
  • the other pair of posts each consist of a metal core, a ceramic sleeve serving the purpose of 16 and the outer sleeve with notches which is not capable of performing a translation.
  • a wire having a diameter of 0.025 mm. and a resistance of 2200 Q/m.
  • this wire helix 18 is partly broken away for the sake of clarity.
  • the wire extends through the notches spaced apart by 0.5 mm.
  • the expansion coefiicient of the wire is equal to that of the plate 7 and of the frame 12 so that the wire is not displaced during outgassing. Slackening of the wire due to the heat developed by its resistance is counteracted by the leaf springs.
  • This structure is capable of withstanding electric fields of 10 v./m.
  • the ceramic sleeves are coated with a thin layer of tin oxide having a resistance of the order of 10 9/ per square, which value is sufficiently high to prevent the potential distribution established by the wire from being disturbed and sutficiently low to prevent surface charge from being concentrated on the insulators.
  • FIG. 1 shows a second wire helix 19.
  • This helix is mounted between the plate 20 and the plate 1 like the first wire helix between the plate 5 and the plate 1.
  • the beginning of the first wire helix is connected to the plate 5 having a negative potential.
  • the end of the first helix and the beginning of the second helix are connected to the earthed plate 1.
  • the end of the second helix is connected to the plate 20 having a positive voltage.
  • FIG. 3 is a schematic sectional view of FIG. 1 taken on the axis of the turns and at right angles to the magnetic field.
  • the figure indicates the direction of the magnetic field H of the order of 2,000 gauss and that of the electric field E and outlines a few paths of ions focussed in the gap 5' before the collecting electrode 6.
  • a cycloidal mass spectrometer employing substantially perpendicular magnetic and electric fields comprising an ion source, a collector electrode for ions leaving said source, means for producing substantially perpendicular magnetic and electric fields in which ions from said source cover cycloidal paths before reaching the collector electrode, said electric field means comprising a high resistance wire helically wound around a region in which ions cover their paths, said helically wound wire producing a uniform electric field in a direction parallel to the axis of the helically wound wire when a potential is applied between the ends of the wire, said helically wound wire being wound about posts, having ceramic sleeves, at least one of which is spring loaded away from the center of the helix to take up wire slack caused by ohmic heating during operation of the spectrometer, and means to apply a potential difference between the ends of said wire to produce an electric field.
  • a mass spectrometer as claimed in claim 1 in which the overall electric field is produced by more than one Wire helix.

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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)
US561526A 1965-06-30 1966-06-29 Cycloidal mass spectrometer employing crossed uniform magnetic and electric fields Expired - Lifetime US3427449A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB27736/65A GB1114445A (en) 1965-06-30 1965-06-30 Mass spectrometer

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US3427449A true US3427449A (en) 1969-02-11

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US561526A Expired - Lifetime US3427449A (en) 1965-06-30 1966-06-29 Cycloidal mass spectrometer employing crossed uniform magnetic and electric fields

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US (1) US3427449A (enEXAMPLES)
CH (1) CH446766A (enEXAMPLES)
DE (1) DE1598861C3 (enEXAMPLES)
GB (1) GB1114445A (enEXAMPLES)
SE (1) SE323234B (enEXAMPLES)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6624410B1 (en) * 2002-02-25 2003-09-23 Monitor Instruments Company, Llc Cycloidal mass spectrometer

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2769910A (en) * 1952-09-30 1956-11-06 Hartford Nat Bank & Trust Co Mass spectrometer

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2769910A (en) * 1952-09-30 1956-11-06 Hartford Nat Bank & Trust Co Mass spectrometer

Also Published As

Publication number Publication date
GB1114445A (en) 1968-05-22
DE1598861B2 (de) 1974-06-27
DE1598861C3 (de) 1975-02-06
SE323234B (enEXAMPLES) 1970-04-27
DE1598861A1 (de) 1970-08-13
CH446766A (de) 1967-11-15

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