Patent ID: 8847153

Claim:
An ion guide or ion trap comprising: a plurality of electrodes; an RF voltage source applying an RF voltage to at least some of said plurality of electrodes in order to confine radially at least some ions within said ion guide or ion trap; a voltage supply maintaining one or more substantially quadratic potential wells along at least a portion of the axial length of said ion guide or ion trap in a first mode of operation, said one or more substantially quadratic potential wells having a minimum; a modulator oscillating the position of said one or more substantially quadratic potential wells in a substantially periodic manner about a reference point and along at least a portion of the axial length of said ion guide or ion trap wherein said modulator is arranged and adapted to oscillate the position of said one or more substantially quadratic potential wells with or at a first frequency f 1 , wherein said first frequency f 1 is greater than the resonance or fundamental harmonic frequency of at least 5% of the ions located within an ion trapping region within said ion guide or ion trap; and an ejector in said first mode of operation ejecting at least some ions from a trapping region of said ion guide or ion trap in a substantially non-resonant manner whilst other ions are arranged to remain substantially trapped within said trapping region of said ion guide or ion trap.