Axial ejection with improved geometry for generating a two-dimensional substantially quadrupole field

2488 44 2A mass spectrometer having an elongated rod set, and a method of operating same. The rod set has an entrance end, an exit end and a longitudinal axis. Ions are admitted into the entrance end of the rod set. At least some of the ions are trapped in the rod set by producing a barrier field at...

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Bibliographic Details
Main Authors Sudakov, Mikhail, Douglas, Donald J, Ding, Chuan-Fan
Format Patent
LanguageEnglish
Published 16.05.2006
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Summary:2488 44 2A mass spectrometer having an elongated rod set, and a method of operating same. The rod set has an entrance end, an exit end and a longitudinal axis. Ions are admitted into the entrance end of the rod set. At least some of the ions are trapped in the rod set by producing a barrier field at an exit member adjacent to the exit end of the rod set and by producing an RF field between the rods of the rod set adjacent at least the exit end of the rod set. The RF and barrier fields interact in an extraction region adjacent to the exit end of the rod set to produce a fringing field. Ions in the extraction region are energized to mass selectively eject at least some ions of a selected mass to charge ratio axially from the rod set past the barrier field. The RF field is a two-dimensional substantially quadrupole field having a quadrupole harmonic with amplitude A, an octopole harmonic with amplitude A, and a hexadecapole harmonic with amplitude A. Ais less than A, and Ais greater than 0.1% of A.