RF power supply for a mass spectrometer

• US 9,472,385 B2
• Filed: 04/02/2015
• Issued: 10/18/2016
• Est. Priority Date: 06/21/2004
• Status: Active Grant

• Current Assignee: Thermo Finnigan LLC (Thermo Fisher Scientific Incorporated)
• Original Assignee: Thermo Finnigan LLC (Thermo Fisher Scientific Incorporated)
• Inventors: Makarov, Alexander A., Denisov, Eduard V., Kholomeev, Alexander
• Primary Examiner(s): Wells, Nikita
• Application Number:
  US14/677,857
• Publication Number:
  US 20150214019A1
• Time in Patent Office: 565 Days
• Field of Search: 250/292, 250/282, 250/281, 250/283, 250/286, 250/287, 250/290, 250/293
• US Class Current: 1/1
• CPC Class Codes: H01J 49/0031 Step by step routines describing the use of the apparatus H01J49/0081 takes precedence
• CPC Class Codes: H01J 49/022 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 Class Codes: H01J 49/36 Radio frequency spectrometers, e.g. Bennett-type spectrometers, Redhead-type spectrometers
• CPC Class Codes: H01J 49/423 with radial ejection
• CPC Class Codes: H01J 49/427 Ejection and selection methods

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.

Claims

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.