Patent ID: 8704172

Claim:
An ion cyclotron resonance (ICR) measurement cell having an axis and trapping electrodes with trapping spoke grids, of which alternating spokes are connected to positive and negative DC potentials in order to generate a motion-induced pseudopotential, the measurement cell comprising: at least three sets of longitudinal electrodes spaced along the cell axis between the trapping spoke grids, each set of longitudinal electrodes having a plurality of electrodes positioned radially about the cell axis and the electrodes in each set being aligned longitudinally with electrodes in other sets to form rows of electrodes extending across all sections between the trapping spoke grids; a radiofrequency generator connected to a plurality of rows of longitudinal electrodes in order to supply excitation pulses to the electrodes so that within the center set of longitudinal electrodes, ions are homogeneously excited to cyclotron orbits; and a switchable DC voltage generator that is connected to longitudinal electrodes located in outer sets and that is configured to generate an additional trapping voltage in the center set during ion excitation and to remove said additional trapping voltage after excitation.