Patent ID: 8901486
Filing Date: 2014-12-02
Classification: H01J

Abstract:
1. A quadrupole rod set mass filter, mass analyser or ion trap comprising: a first pair of rod electrodes; a second pair of rod electrodes; and an energy filter; wherein said first pair of rod electrodes has a physical property which differs from a physical property of said second pair of rod electrodes, wherein said first and second pairs of rod electrodes have a first upstream portion and a second downstream portion, wherein said first and second pairs of rod electrodes have a substantially constant cross-sectional diameter or profile in said first upstream portion; characterised in that said physical property comprises axial length, and said first pair of rod electrodes has a first axial length and said second pair of rod electrodes has a second different axial length; or said first pair of rod electrodes comprise one or more partial or complete first voids located adjacent an exit region of said quadrupole rod set mass filter, mass analyser or ion trap.