Accelerator for multi-pass mass spectrometers

Patent metadata

Field	Value
Publication number	US-11817303-B2
Application number	US-201816636877-A
Country	US
Kind code	B2
Filing date	Jul 26, 2018
Priority date	Aug 6, 2017
Publication date	Nov 14, 2023
Grant date	Nov 14, 2023

Abstract

Improved pulsed ion sources and pulsed converters are proposed for multi-pass time-of-flight mass spectrometer, either multi-reflecting (MR) or multi-turn (MT) TOF. A wedge electrostatic field ( 45 ) is arranged within a region of small ion energy for electronically controlled tilting of ion packets ( 54 ) time front. Tilt angle γ of time front ( 54 ) is strongly amplified by a post-acceleration in a flat field ( 48 ). Electrostatic deflector ( 30 ) downstream of the post-acceleration ( 48 ) allows denser folding of ion trajectories, whereas the injection mechanism allows for electronically adjustable mutual compensation of the time front tilt angle, i.e. γ=0 for ion packet in location ( 55 ), for curvature of ion packets, and for the angular energy dispersion. The arrangement helps bypassing accelerator ( 40 ) rims, adjusting ion packets inclination angles α 2 and what is most important, compensating for mechanical misalignments of the optical components.

First claim

The invention claimed is:

1. A mass spectrometer having:
a pulsed ion accelerator; wherein the pulsed ion accelerator is configured to receive ions travelling in a first direction between electrodes that converge in the first direction, and wherein the pulsed ion accelerator comprises:
at least one voltage supply arranged and configured to apply a pulsed voltage to said electrodes for generating a wedge shaped electric field that pulses ions out of the ion accelerator, wherein the ions have a time front arranged in a first plane at the time the pulsed voltage is initiated, and wherein the wedge-shaped electric field causes the time front of the ions to be tilted at an angle to the first plane; and
an ion acceleration region downstream of the wedge-shaped electric field region for amplifying the time front tilt introduced by the wedge-shaped electric field, wherein the pulsed ion accelerator comprises a plurality of ion acceleration region electrodes configured to apply an electric field in the ion acceleration region having parallel equipotential field lines for accelerating the ions; and

an ion deflector located downstream of the pulsed ion accelerator and configured to deflect the average ion trajectory of the ions, thereby tilting the angle of the time front of the ions received by the ion deflector, wherein the wedge-shaped electric field region of the pulsed ion accelerator is configured to tilt the time front of the ions passing therethrough so as to at least partially counteract the tilting of the time front by the ion deflector; and
an ion mirror, wherein the ion deflector is arranged to receive ions after they have been reflected in the ion mirror.

2. The mass spectrometer of claim 1 , wherein the pulsed ion accelerator is an orthogonal accelerator.

3. The mass spectrometer of claim 1 , wherein said electrodes are arranged and configured for generating said wedge-shaped electric field region therebetween such that equipotential field lines in the wedge-shaped electric field region are angled to each other so as to form the wedge-shape.

4. The mass spectrometer of claim 1 , wherein said electrodes comprise one or more first electrode arranged in a first plane and one or more second electrode arranged in a second plane that is angled to the first plane so as to define the wedge-shaped electric field region between the one or more first electrode and one or more second electrode.

5. The mass spectrometer of claim 1 , wherein said electrodes comprise one or more first electrode arranged in a first plane and a plurality of second electrodes arranged in a second plane, wherein the ion accelerator is configured to apply different voltages to different ones of the second electrodes so as to define the wedge-shaped electric field region between the one or more first electrode and the second electrodes.

6. The mass spectrometer of claim 1 , wherein the electrodes for generating said wedge-shaped electric field region are arranged so that equipotential field lines of the wedge-shaped electric field extend substantially in the first direction and the ion accelerator is configured to pulse the ions through the wedge-shaped electric field substantially transverse to the equipotential field lines.

7. The mass spectrometer of claim 1 , wherein the ion accelerator is arranged and configured to receive ions travelling in the first direction along a first axis that is substantially parallel to equipotential field lines of the wedge-shaped electric field.

8. The mass spectrometer of claim 1 , comprising two ion mirrors, wherein the ion deflector is arranged to receive ions after they have been reflected in a first of the two ion mirrors for the first time but before being reflected in a second of the two ion mirrors for a first time.

9. The mass spectrometer of claim 8 , wherein said plurality of ion acceleration region electrodes are a plurality of parallel electrodes.

10. The mass spectrometer of claim 8 , wherein the deflector is configured to tilt the angle of the time front of the ions received by the ion deflector such that the time front of the ions is parallel to the first plane immediately after leaving the deflector.

11. The mass spectrometer of claim 1 , wherein the ion deflector is configured to generate a quadrupolar field for controlling the spatial focusing of the ions.

12. A mass spectrometer comprising:
a multi-pass time-of-flight mass analyser or electrostatic ion trap having the pulsed ion accelerator of claim 1 , 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), wherein the pulsed ion accelerator is arranged to receive ions and accelerate them into one of the ion mirrors; or
(ii) the multi-pass time-of-flight mass analyser is a multi-turn time of flight mass analyser having at least two electric sectors configured to turn ions multiple times in the oscillation dimension (x-dimension), wherein the pulsed ion accelerator is arranged to receive ions and accelerate them into one of the sectors.

14. The spectrometer of claim 12 , comprising an ion deflector located downstream of said pulsed ion accelerator, and that is 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 received 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 method of mass spectrometry comprising:
providing the mass spectrometer as claimed in claim 1 ;
applying the pulsed voltage to said at least one of said electrodes for pulsing said wedge-shaped electric field region so as to pulse ions out of the ion accelerator, wherein the ions have a time front arranged in the first plane at the time the pulsed voltage is initiated, and wherein the ions pass through the wedge-shaped electric field region so as to cause the time front of the ions to be tilted at the angle to the first plane.

17. The mass spectrometer of claim 1 , wherein the deflector comprises two plates arranged in planes substantially orthogonal to the ion path between them.

18. The mass spectrometer of claim 1 , wherein the mass spectrometer is gridless.

19. A mass spectrometer having:
a pulsed ion accelerator, said ion accelerator comprising:
a plurality of electrodes and at least one voltage supply arranged and configured to generate a wedge-shaped electric field region within the ion accelerator; wherein the plurality of electrodes comprises one or more first electrode arranged in a first plane and a plurality of second electrodes arranged in a second plane, wherein the ion accelerator is configured to apply different voltages to different ones of the second electrodes so as to define the wedge-shaped electric field region between the one or more first electrode and the second electrodes; and
an ion acceleration region downstream of the wedge-shaped electric field region for amplifying the time front tilt introduced by the wedge-shaped electric

Assignees

• Micromass Ltd

Inventors

• Verenchikov Anatoly
• Yavor Mikhail

Classifications

• H01J49/403 Primary

  characterised by the acceleration optics and/or the extraction fields · CPC title

• H01J49/0031

  Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence) · CPC title

• H01J49/025

  Detectors specially adapted to particle spectrometers (data acquisition H01J49/0036; detectors per se G01T, e.g. G01T1/28, G01T1/29) · CPC title

• H01J49/061

  Ion deflecting means, e.g. ion gates · CPC title

• H01J49/164

  Laser desorption/ionisation, e.g. matrix-assisted laser desorption/ionisation [MALDI] (sample holders H01J49/0418) · CPC title