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US 2022/0102135 A1Published application
Auto Gain Control for Optimum Ion Trap Filling
AssigneeDH Technologies Development Pte. Ltd.
InventorJames W. Hager
Life of this patent
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Abstract
Methods and systems for loading an ion trap are provided herein in which the total ion beam intensity and/or content of the ion beam are quickly interrogated so as to determine an optimum fill time for an ion trap. In various aspects, the methods and systems described herein are effective to prevent overfilling of the ion trap while decreasing the time associated with known techniques utilized to obtain a survey scan of the ion beam.
Claims20
A method of performing mass analysis in a mass spectrometer including an ion trap, the method comprising:
- passing an ion beam comprising a plurality of ions through a quadrupole assembly having a quadrupole rod set extending from an input end for receiving the ions to an output end through which ions exit the quadrupole rod set,
- applying at least one RF voltage to each of the rods of the quadrupole rod set so as to generate a field for radial confinement of the ions as they pass therethrough,
- while applying said at least one RF voltage to each of the rods, applying a voltage pulse across the quadrupole assembly so as to excite radial oscillations of at least a portion of the ions at secular frequencies thereof, wherein fringing fields in proximity to said output end convert said radial oscillations of at least a portion of said excited ions into axial oscillations as said excited ions exit the quadrupole rod set,
- detecting at least a portion of said axially oscillating ions exiting the quadrupole rod set to generate a time-varying signal,
- obtaining a Fourier transform of said time-varying signal so as to generate a frequency-domain signal containing information of the ion beam composition, and
- determining a fill time of the ion trap based on said ion beam composition information.
3 more elements
A mass spectrometer system, comprising:
- an ion source for generating an ion beam comprising a plurality of ions;
- an ion trap;
- a quadrupole assembly having a quadrupole rod set extending from an input end for receiving the ions to an output end through which ions exit the quadrupole rod set;
- one or more power sources configured to provide i) at least one RF voltage to each of the rods of the quadrupole rod set so as to generate a field for radial confinement of the ions as they pass therethrough, and ii) a voltage pulse across the quadrupole assembly so as to excite radial oscillations of at least a portion of the ions at secular frequencies thereof, wherein fringing fields in proximity to said output end convert said radial oscillations of at least a portion of said excited ions into axial oscillations as said excited ions exit the quadrupole rod set;
- a detector for detecting at least a portion of said axially oscillating ions exiting the quadrupole rod set so as to generate a time-varying signal;
- and
- a controller comprising one or more analysis modules configured to:
- obtain a Fourier transform of said time-varying signal so as to generate a frequency-domain signal containing information of the ion beam composition, and
- determine a fill time of the ion trap based on said ion beam composition information.
6 more elements
Dependencies are inferred from the claim text.