Patent ID: 8716660

Claim:
A mass spectrometer comprising: an RF ion guide comprising a plurality of electrodes; a control system, wherein said control system is arranged and adapted in a first mode of operation to apply a DC voltage to said electrodes in order to confine ions radially within said ion guide within a DC potential well, and wherein said control system is arranged and adapted to switch said ion guide to operate in a second mode of operation wherein said DC voltage applied to said electrodes is varied so that a portion of said ions experience an electric field in a direction which is substantially orthogonal to an initial direction of said ions so that ions are orthogonally sampled from said ion guide; and a device arranged and adapted to apply an AC or RF voltage additionally to said electrodes in order to confine ions within said ion guide in a vertical direction (y), wherein ions are not confined axially within said ion guide during said first mode of operation.