Computer simulation of charged particle beam trajectories in a quadrupole ion trap mass spectrometer

A numerical simulation method has been developed for the analysis of ion mo tion in an ion trap mass spectrometer. In this method, ion motion can be si mulated with the interaction of ion - bath gas and ion - space charge durin g mass analysis scan. By applying this method, the influence of the bath ga s pressure and the space charge density on mass spectra is clarified. Furth ermore, the relationship between the scan speed and the degree of the mass shift is obtained. Based on these relationships, an advanced scanning metho d is obtained, in which the scan speed is reduced gradually over the scan t ime. The feasibility of achieving high resolution without mass shift or sca n time expansion is also examined.