Simulation of ion trajectories in a quadrupole ion trap: a comparison of three simulation programs

An attempt has been made to compare the performance, design and operation o f three simulators, ISIS, ITSIM and SIMION-3D, when applied to the calculat ion of ion trajectories in a quadrupole ion trap. For the simulation of the trajectory of a single ion in a collision-free system, the calculated spat ial trajectory components, kinetic energies and secular frequencies from th e three simulators were virtually identical. It is concluded that, despite the various approaches to electrode design, calculation of fields, integrat ion methods and ion generation tactics, there is a remarkable degree of con sistency among the products of the simulators when dealing with collision-f ree conditions. The results of the ion injection simulations under collisio nal conditions were indicative of the complexity that can be introduced int o the simulations with little effort. Random effects such as collisions of ions with He buffer gas and accumulated calculation errors together with th e different collision model settings and the different approaches to field calculation are thought to have contributed to the somewhat minor differenc es in trapping efficiency. SIMION is the simulator of choice for the simula tion of ion trajectories in hybrid instruments and in custom-designed assem blies of electrodes; and ITSIM would appear to be the best choice on the ba sis of computational speed for running multiparticle simulations and user f riendliness. Both ISIS and ITSIM are adept at providing detailed informatio n of collision events, Copyright (C) 1999 John Wiley & Sons, Ltd.