The purpose of this simulation is to understand the contribution of the parameters of the new protocol of ion mass analysis which we have developed in previous papers and to improve the data treatment in order to predict the experimental results. In this first simulation paper, we limit the study to an ion cloud of the same species. The first part describes the formalism chosen to simulate the ion creation, the ion trajectory during confinement, the ion detection by time of flight measurements and the associated treatments. The second part shows the results and explains the influence of the principal parameters. Experimentally, the initial conditions of ion confinement (position and velocity in the axial and radial directions) are not fully controlled and are estimated for the simulation. For the chosen conditions, the results agree with the experimental ones. We show the influence of the different parameters on the intensity of the signal and the uniqueness of the spectral peak, and we confirm the theoretical expressions given in previous papers for the amplitude of the peaks, the signal-to-noise ratio and the resolution. The limit of sensitivity (defined for a signal-to-noise ratio equal to 6), is obtained with statistically 0.35 ion in the trap for 1024 confinement times. © 1997 Elsevier Science B.V.