SIMULATION OF EXTERNAL ION INJECTION, COOLING AND EXTRACTION PROCESSES WITH SIMION-6.0 FOR THE ION TRAP REFLECTRON TIME-OF-FLIGHT MASS-SPECTROMETER/

In this work we have developed a PC-based simulation to study ion inje ction, cooling and extraction processes for multiple ions in an ion tr ap/reflectron time-of-flight (IT/reTOF) system, This simulation is bas ed upon SIMION 6.0 with user written programs in which a 3D collision model is used to describe ion-buffer gas molecule interactions, The re sults of various simulations describing the relation between the trapp ing efficiency for external injection of ions into the trap and the RF phase, and the effects of initial kinetic energy and ramp-up rate on dynamic trapping of externally produced ions are discussed, Further, s ingle-pulsing and bipolar-pulsing schemes for ejecting ions from the t rap are examined, The simulations show that bipolar pulsing can marked ly improve the resolution, In the bipolar ejection mode the relation b etween resolution and the extraction voltages and RF ramp-off rate are studied. (C) 1997 by John Wiley & Sons, Ltd.