Computational fluid dynamics-Monte Carlo method for calculation of the ion trajectories and applications in ion mobility spectrometry

Abstract A computational fluid dynamics-Monte Carlo approach (abbreviated as CMC) based on SIMION has been developed for simulating the ions trajectories in both the fluid and electric fields simultaneously, the gas flow effect and collision of the ions with the gas molecules are considered within this approach. Four kinds of physical parameters of the instruments can be obtained by this model: the flow field, the electric field, the ion trajectories and the mobility spectrum. A drift tube ion mobility spectrometer was built and simulated to verify this model. The distribution of gas flow field (velocity, pressure, temperature) was simulated by a 2D geometry. The ions trajectories and ion mobility spectra of the IMS were then calculated. The good agreements between simulation and experiment show that the CMC model has predictive power for modeling ion motion at ambient pressure, and this model can serve as visual aids for intuitively understanding the factors that determine ion transport.