Theoretical study of the effect of ion trap geometry on the dynamic behavior of ions in a Paul trap

The influence of the ion trap geometrical shape, ring and end-cap electrodes, on the dynamical behavior of the confined ions is studied. At first by considering the geometrical parameter z0=(1/n)r0, where n is a real number, in the quadrupole potential, we solve Mathieu's differential equation for the first stability region using the six-order Runge–Kutta method. The numerical results show that, for a given ion trap mode i.e., rf only mode, the electrode geometry plays an important role both in higher ion mass confinement range and in a higher fractional mass resolution m/Δm.

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► We worked on the stretched Paul trap with changing the size of n   in z0=(1/n)r0 parameter.
► With decreasing n, the ion trajectory is more restricted in the r and z directions.
► With decreasing n, the first stability region in a–q plane is compacted.
► With decreasing n, the first stability diagram in U–V plane for a typical ion is enlarged.
► With decreasing n, the fractional mass resolution is higher.