Mass analyser

Patent metadata

Field	Value
Publication number	US-9786485-B2
Application number	US-201515310990-A
Country	US
Kind code	B2
Filing date	Apr 29, 2015
Priority date	May 12, 2014
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

A mass analyser comprises a pair of electrode arrays. Each array has a set of focusing electrodes which are supplied, in use, with voltage to create an electrostatic field in a space between the electrode arrays causing ions to undergo periodic, oscillatory motion in the space, ions passing between electrodes of the sets of focusing electrodes and being repeatedly focused at a center plane, mid-way between the electrode arrays. At least one electrode of each set of focusing electrodes has an electrode surface closer to the center plane than the electrode surfaces of other electrodes of the same set. The analyzer may be an ion trap mass analyser or a multi-turn ToF mass analyzer.

First claim

The invention claimed is:

1. A mass analyser comprising a pair of electrode arrays, one electrode array of the pair being a mirror image of the other electrode array of the pair with respect to a centre plane mid-way between the electrode arrays, each array including a set of focusing electrodes and the electrode arrays being supplied, in use, with the same voltage pattern to create an electrostatic field in a space between the electrode arrays for causing ions to undergo periodic, oscillatory motion in said space whereby ions pass between electrodes of said sets of focusing electrodes and are repeatedly focused at the centre plane, wherein at least one electrode of each said set of focusing electrodes has an electrode surface that is closer to the centre plane than the electrode surfaces of other electrodes of the same set.

2. A mass analyser as claimed in claim 1 wherein said one electrode is positioned to face a region at the centre plane where electric field gradient has a maximum value.

3. A mass analyser as claimed in claim 1 wherein said one electrode and an immediately neighbouring electrode of the same set are supplied, in use, with voltage having opposite polarities.

4. A mass analyser as claimed in claim 3 wherein said one and immediately neighbouring electrodes have electrode surfaces that are closer to said centre plane than the electrode surfaces of other electrodes of the same set.

5. A mass analyser as claimed in claim 1 wherein said one electrode has a profiled electrode surface facing the centre plane.

6. A mass analyser as claimed in claim 4 wherein said one and immediately neighbouring electrodes both have profiled electrode surfaces.

7. A mass analyser as claimed in claim 5 wherein said profiled electrode surfaces have trapezoidal or hyperbolic cross-sections in a plane orthogonal to the centre plane and along a flight direction of ions.

8. A mass analyser as claimed in claim 1 wherein said one electrode of each said set of focusing electrodes is selected from the three outermost electrodes of the set.

9. A mass analyser as claimed in claim 1 wherein each said electrode array is mounted on a base member made from an electrically insulating material, said one electrode and or said base member being configured to increase surface tracking distance between said one and a said immediately neighbouring electrode.

10. A mass analyser as claimed in claim 9 wherein said base member is provided with a groove or recess between said one and said immediately neighbouring electrodes to increase surface tracking distance between said one and said immediately neighbouring electrodes.

11. A mass analyser as claimed in claim 9 wherein said one electrode is narrower at a lower part of the electrode, proximate the base member on which the electrode is mounted than at an upper part of the electrode further away from the base member to increase surface tracking distance between said one and a said immediately neighbouring electrode.

12. A mass analyser as claimed in claim 9 wherein said one electrode is mounted on the base member using an electrically insulating spacer to increase surface tracking distance between said one electrode and a said immediately neighbouring electrode.

13. A mass analyser as claimed in claim 12 wherein a said immediately neighbouring electrode is also mounted on said base member using an electrically insulating spacer.

14. A mass analyser as claimed in claim 9 wherein the electrodes of each electrode array are mounted on the base member by fixing members.

15. A mass analyser as claimed in claim 1 wherein the electrodes of each said set are concentric ring electrodes.

16. A mass analyser as claimed in claim 9 wherein the electrodes of each said electrode array are concentric ring electrodes, a ring electrode of an array including, and being mounted on the base member by, a plurality of electrically conductive fixing members that are angularly offset with respect to electrically conductive fixing members that mount a neighbouring ring electrode on the base member.

17. A mass analyser as claimed in claim 16 wherein the base member has grooves or slots configured to increase surface tracking distance between fixing members of neighbouring ring electrodes.

18. A mass analyser as claimed in claim 9 wherein the electrodes of each said array are mounted on the base member by brazing, soldering or adhesive bonding.

19. A mass analyser as claimed in claim 9 wherein electrodes of each electrode array are mounted on a said base member formed with a plurality of openings, at least two electrodes of the array are formed with a plurality of fixing members, a fixing member of one electrode and a fixing member of an immediately neighbouring electrode both being mounted in a respective opening in the base member with a gap between the fixing members to increase surface tracking distance between the one and immediately neighbouring electrodes.

20. A mass analyser as claimed in claim 19 wherein said fixing members are mounted on metalised edge surfaces of the openings.

21. A mass analyser comprising a pair of electrode arrays, one electrode array of the pair being a mirror image of the other electrode array of the pair with respect to a centre plane mid-way between the electrode arrays, each array including a set of focusing electrodes and the electrode arrays being supplied, in use, with the same voltage pattern to create an electrostatic field in a space between the electrode arrays for causing ions to undergo periodic, oscillatory motion in said space whereby ions pass between electrodes of said sets of focusing electrodes and are repeatedly focused at the centre plane, wherein each said electrode array is mounted on a base member made from an electrically insulating material at least one electrode of the array and or said base member being configured to increase surface tracking distance between said at least one and an immediately neighbouring electrode.

22. A mass analyser as claimed in claim 21 wherein said base member is provided with a groove or recess between said one and said immediately neighbouring electrodes to increase surface tracking distance between said one and said immediately neighbouring electrodes.

23. A mass analyser as claimed in claim 21 wherein said one electrode is narrower at a lower part of the electrode, proximate the base member on which the electrode is mounted, than at an upper part of the electrode further away from the base member to increase surface tracking distance between said one and a said immediately neighbouring electrode.

24. A mass analyser as claimed in claim 21 wherein said one electrode is mounted on the base member using an electrically insulating spacer to increase surface tracking distance between said one electrode and a said immediately neighbouring electrode.

25. A mass analyser as claimed in claim 24 wherein a said immediately neighbouring electrode is also mounted on said base member using an electrically insulating spacer.

26. A mass analyser as claimed in claim 21 wherein the electrodes of each electrode array are mounted on the base member by fixing members.

27. A mass analyser as claimed in claim 21 wherein the electrodes of each said set are concentric ring electrodes.

28. A mass analyser as claimed in claim 21 wherein the electrodes of each said electrode array are concentric ring elec

Assignees

• Shimadzu Corp

Inventors

• Ding Li
• Rusinov Aleksandr

Classifications

• H01J49/067 Primary

  Ion lenses, apertures, skimmers · CPC title

• H01J49/401 Primary

  characterised by orthogonal acceleration, e.g. focusing or selecting the ions, pusher electrode · CPC title

• H01J49/406 Primary

  with multiple reflections · CPC title

• H01J49/282

  using electrostatic analysers · CPC title

• H01J49/068

  Mounting, supporting, spacing, or insulating electrodes · CPC title