Computer simulation of electron and ion trajectories in electron-impact ion sources of a quadrupole mass spectrometer

Electron and ion trajectories have been simulated in electron-impact ion sources of a quadrupole mass spectrometer. The ion trajectories in the conventional Nier-type ion source show poor extraction efficiency of the generated ions into the quadrupole. Based on the electron and ion trajectory simulation results, the Nier-type ion source has been modified to improve the ion extraction efficiency. The modified ion source exhibits much better ion extraction efficiency and smaller kinetic energy spread than the Nier-type ion source.