Patent ID: 8658969
Filing Date: 2014-02-25
Classification: H01J

Abstract:
1. A mass spectrometer having an ion optical system for transporting ions to a next stage, which is characterized in that the ion optical system includes: a) a virtual multipole rod ion optical element having 2×N pieces of virtual rod electrodes where N is an integer equal to or greater than two, arranged so as to surround an ion beam axis, each virtual rod electrode being composed of M pieces of plate electrodes spaced along the ion beam axis where M is an integer equal to or greater than three; and b) a voltage-applying means for applying radio-frequency voltages in a following manner: in each set of the 2×N plate electrodes arranged around the ion beam axis, a same radio-frequency voltage is applied to any two plate electrodes opposing each other across the ion beam axis, and two radio-frequency voltages having a same amplitude and a phase difference of 180 degrees are respectively applied to any two plate electrodes neighboring each other around the ion beam axis; and in each set of the M plate electrodes forming one virtual rod electrode, a phase of the radio-frequency voltage applied to at least one of the plate electrodes is different from a phase of the radio-frequency voltage applied to another plate electrode.