RF power supply for a mass spectrometer

Patent metadata

Field	Value
Publication number	US-9472385-B2
Application number	US-201514677857-A
Country	US
Kind code	B2
Filing date	Apr 2, 2015
Priority date	Jun 21, 2004
Publication date	Oct 18, 2016
Grant date	Oct 18, 2016

Abstract

The present invention provides a radio frequency (RF) power supply in a mass spectrometer. The power supply provides an RF signal to electrodes of a storage device to create a trapping field. The RF field is usually collapsed prior to ion ejection. In an illustrative embodiment the RF power supply includes a RF signal supply; a coil arranged to receive the signal provided by the RF signal supply and to provide an output RF signal for supply to electrodes of an ion storage device; and a shunt including a switch operative to switch between a first open position and a second closed position in which the shunt shorts the coil output.

First claim

What is claimed is:

1. A method of operating a mass spectrometer, comprising:
introducing a group of ions into an ion injector along a first axis, the ion injector including a plurality of electrodes;
shutting off an RF potential applied to a first set of electrodes of the plurality of electrodes;
applying a DC offset to a second set of electrodes of the plurality of electrodes to generate an electric field causing the group of ions to be ejected from the ion injector along a second axis substantially orthogonal to the first axis; and
directing the group of ions ejected from the ion injector to a pulsed mass analyzer;
wherein the DC offset has a rise time shorter than a period over which all ions of the group of ions are ejected from the ion injector.

2. The method of claim 1 , further comprising a step of generating a trapping field within the ion injector to confine the group of ions prior to shutting off the RF potential.

3. The method of claim 1 , wherein the step of applying a DC offset is performed after a predetermined delay following the step of shutting off the RF potential.

4. The method of claim 1 , wherein at least a portion of the plurality of electrodes are elongated along the first axis.

5. The method of claim 1 , wherein the step of shutting off the RF potential is performed at the point where the RF potential passes through its average value.

6. The method of claim 1 , wherein the pulsed mass analyzer is an electrostatic trap mass analyzer.

7. The method of claim 1 , wherein the pulsed mass analyzer is a time-of-flight mass analyzer.

8. A mass spectrometer, comprising:
an ion injector having a plurality of electrodes, the ion ejector being arranged to accept a group of ions along a first axis;
a power supply coupled to the ion injector;
a controller, configured to cause the power supply to shut off an RF potential applied to a first set of electrodes of the plurality of electrodes and to apply a DC offset to a second set of electrodes of the plurality of electrodes to generate an electric field causing the group of ions to be ejected from the ion injector along a second axis substantially orthogonal to the first axis, the DC offset having a rise time shorter than a period over which all ions of the group of ions are ejected from the ion injector; and
a pulsed mass analyzer arranged to receive the group of ions ejected from the ion injector.

9. The mass spectrometer of claim 8 , wherein the pulsed mass analyzer is an electrostatic trap mass analyzer.

10. The mass spectrometer of claim 8 , wherein the pulsed mass analyzer is a time-of-flight mass analyzer.

11. The mass spectrometer of claim 8 , wherein at least a portion of the plurality of electrodes are elongated along the first axis.

Assignees

• Thermo Finnigan Llc

Inventors

• Makarov Alexander A
• Denisov Eduard V
• Kholomeev Alexander

Classifications

• H01J49/0031 Primary

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

• H01J49/022

  Circuit arrangements, e.g. for generating deviation currents or voltages (regulating electric or magnetic variables in general, e.g. current, magnetic field G05F); Components associated with high voltage supply (high voltage supply per se H02M) · CPC title

• H01J49/36

  Radio frequency spectrometers, e.g. Bennett-type spectrometers, Redhead-type spectrometers · CPC title

• H01J49/423 Primary

  with radial ejection · CPC title

• H01J49/427 Primary

  Ejection and selection methods · CPC title