Patent ID: 9613788
Date: 2017-04-04
CPC Classifications: H01J

Claim:
1. An apparatus, comprising: an ion source; a mass analyzer; and an RF ion guide positioned in an ion path between the ion source and the mass analyzer, the RF ion guide having an ion guide axis extending between an input end of the RF ion guide and an exit end of the RF ion guide, the RF ion guide comprising: a first electrode extending along the ion guide axis, the first electrode configured to be connected to a voltage source; and a second electrode extending along the ion guide axis, the second electrode configured to be connected to a RF source, a portion of the second electrode being positioned between the first electrode and the ion guide axis, the second electrode comprising a plurality of openings, wherein during use of the apparatus, the second electrode produces RF electric fields within a central portion of the RF ion guide throughout a region between the second electrode and the ion guide axis to radially confine ions, wherein the first and second electrodes are configured so that during operation of the RF ion guide, a DC electric field is generated between the first and second electrodes, resulting in a DC electric field at the ion guide axis that has a non-zero axial component.