Patent ID: 7075069
Filing Date: 2006-07-11
Classification: H01J

Abstract:
1. An ion trap type mass spectrometer comprising: a ring electrode; a pair of end cap electrodes arranged facing one another so as to arrange said ring electrode between said end cap electrodes; a radio-frequency power supply for applying to said ring electrode a radio-frequency voltage that generates a radio-frequency electric field in the space formed between said ring electrode and end cap electrodes; an ion generator for creating ions inside said inter-electrode space or creating ions outside said space and introducing the ions thereinto; an alternating-current (AC) electric field generator for generating in said space a wideband auxiliary AC electric fields, the frequency range of which are corresponding to the mass-to-charge ratio range of undesired ions to eject the undesired ions by resonant ejection; and a detector for separating sequentially the ions trapped in said space in terms of mass according to the particular mass-to-charge ratio of the ion and detecting the mass of these ions after the trapped ions have been emitted from said space; an electric field changer varying the strength of wideband auxiliary AC electric fields comprising the frequency components within the required frequency range according to the strength of the radio-frequency electric field generated in said space.