Ion mirror for multi-reflecting mass spectrometers

Patent metadata

Field	Value
Publication number	US-11239067-B2
Application number	US-201816636865-A
Country	US
Kind code	B2
Filing date	Jul 26, 2018
Priority date	Aug 6, 2017
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

Improved ion mirrors (30) (FIG. 3) are proposed for multi-reflecting TOF MS and electrostatic traps. Minor and controlled variation by means of arranging a localized wedge field structure (35) at the ion retarding region was found to produce major tilt of ion packets time fronts (39). Combining wedge reflecting fields with compensated deflectors is proposed for electrically controlled compensation of local and global misalignments, for improved ion injection and for reversing ion motion in the drift direction. Fine ion optical properties of methods and embodiments are verified in ion optical simulations.

First claim

The invention claimed is:

1. An ion mirror comprising:
a plurality of electrodes and at least one voltage supply connected thereto that are configured to generate an electric field region that reflects ions in a first dimension (X-dimension), and wherein at least part of the electric field region through which ions travel in use has equipotential field lines that diverge, converge or curve as a function of position along a second, orthogonal dimension (Z-direction); and
electrodes arranged on opposing sides of the ion mirror in a third dimension (Y-dimension) that is orthogonal to the first and second dimensions, wherein the ion mirror comprises one or more voltage supply configured to apply different voltages to different ones of these electrodes for generating said equipotential field lines that diverge, converge or curve;
wherein said electrodes arranged on opposing sides of the ion mirror in a third dimension comprise one or more first electrode arranged on a first side of the ion mirror, in the third dimension, and a plurality of second electrodes arranged on a second opposite side of the ion mirror; wherein the ion mirror is configured to apply different voltages to different ones of the second electrodes for generating said equipotential field lines that diverge, converge or curve.

2. The ion mirror of claim 1 , wherein said least part of the electric field region having equipotential field lines that diverge, converge or curve is configured to tilt the time front of ions being reflected in the ion mirror.

3. The ion mirror of claim 1 , wherein said least part of the electric field region is arranged at or proximate an end of the ion mirror, in the second dimension, and wherein the equipotential field lines converge as a function of distance, in the second dimension, away from said end.

4. The ion mirror of claim 1 , wherein said one or more first electrode and/or said plurality of second electrodes are arranged on a printed circuit board (PCB).

5. The ion mirror of claim 1 , comprising a voltage supply and electrodes configured to apply a static electric field in an ion acceleration region adjacent to, in a direction in which the ions are reflected, said part of the electric field region having equipotential field lines that diverge, converge or curve said ion acceleration region having parallel equipotential field lines for accelerating the ions out of the ion mirror.

6. The ion mirror of claim 1 , wherein the ion mirror has a first length in the second dimension that comprises said at least part of the electric field region having equipotential field lines that diverge, converge or curve, and a second length in the second dimension that includes only parallel equipotential field lines for reflecting ions.

7. The ion mirror of claim 1 , wherein said electrodes arranged on opposing sides of the ion mirror in the third dimension are tuning electrodes and the one or more voltage supply configured to apply different voltages to different ones of the electrodes are configured to be adjustable so as to adjust the voltages applied to the tuning electrodes.

8. The ion mirror of claim 7 , comprising electrodes that are tilted at an angle with respect to each other in a plane defined by the first and second dimensions (X-Z plane); and/or
comprising one or more electrodes that are bent in a plane defined by the first and second dimensions (X-Z plane).

9. A method of mass spectrometry comprising:
providing an ion mirror or mass spectrometer as claimed in claim 1 ;
applying voltages to electrodes of the ion mirror so as to generate said electric field region having equipotential field lines that diverge, converge or curve as a function of position along the second dimension (Z-direction); and
reflecting ions in the ion mirror in the first dimension (X-dimension).

10. A method of tuning an ion mirror comprising:
providing an ion mirror as claimed in claim 7 ; and
adjusting the voltage supplies as a function of time so as to vary the voltages applied to the tuning electrodes and the divergence, convergence or curvature of said equipotential field lines.

11. A mass spectrometer comprising:
a time-of-flight mass analyser or electrostatic ion trap having at least one ion mirror and a pulsed ion accelerator for pulsing ion packets into the ion mirror;
wherein the at least one ion mirror comprises a plurality of electrodes and at least one voltage supply connected thereto that are configured to generate an electric field region that reflects ions in a first dimension (X-dimension), wherein at least part of the electric field region through which ions travel in use has equipotential field lines that diverge, converge or curve as a function of position along a second, orthogonal dimension (Z-direction); and
wherein the mass spectrometer is configured so that one of the ion mirrors receives ions from the ion accelerator with a time front that is tilted relative to the second, orthogonal dimension, and wherein said electric field region having equipotential field lines that diverge, converge or curve is configured to tilt the time front of the ions passing therethrough so as to at least partially counteract the tilt of the time front that the ions have when they are received at the ion mirror.

12. The spectrometer of claim 11 , wherein the time-of-flight mass analyser or electrostatic ion trap is a multi-pass time-of-flight mass analyser or electrostatic ion trap having said at least one ion mirror, and electrodes arranged and configured so as to provide an ion drift region that is elongated in a drift direction (z-dimension) and to reflect or turn ions multiple times in an oscillating dimension (x-dimension) that is orthogonal to the drift direction.

13. The spectrometer of claim 12 , wherein:
(i) the multi-pass time-of-flight mass analyser is a multi-reflecting time of flight mass analyser having two ion mirrors that are elongated in the drift direction (z-dimension) and configured to reflect ions multiple times in the oscillation dimension (x-dimension); or
(ii) the multi-pass time-of-flight mass analyser is a multi-turn time of flight mass analyser having an ion mirror and at least one electric sector configured to reflect and turn ions multiple times in the oscillation dimension (x-dimension).

14. The spectrometer of claim 12 , comprising an ion deflector configured to back-steer the average ion trajectory of the ions, in the drift direction, thereby tilting the angle of the time front of the ions, and wherein said electric field region having equipotential field lines that diverge, converge or curve is configured to tilt the time front of the ions passing therethrough so as to at least partially counteract a tilting of the time front by the ion deflector.

15. The spectrometer of claim 14 , wherein the ion deflector is configured to generate a quadrupolar field for controlling the spatial focusing of the ions in the drift direction.

16. A multi-reflecting mass spectrometer comprising:
(a) a pulsed ion source or a pulsed converter generating ion packets substantially elongated in the first Z-direction;
(b) a pair of parallel gridless ion mirrors separated by a drift space; electrodes of said ion mirrors are substantially elongated in the Z-direction to form an essentially two-dimensional electrostatic field in an orthogonal XY-plane; said field provides for an isochronous repetitive multi-pass ion motion and spatial ion confinement along a zigzag mean ion trajectory lying within the XY symmetry plane;
(c) an ion detector;
(d) at least one electrically adjustable electrostatic deflector, arranged fo

Assignees

• Micromass Ltd

Inventors

• Verenchikov Anatoly
• Yavor Mikhail

Classifications

• H01J49/405 Primary

  characterised by the reflectron, e.g. curved field, electrode shapes · CPC title

• H01J49/406 Primary

  with multiple reflections · CPC title