Field Optimization in a Segmented-Electrode Orbitrap

This paper presents an optimization method for the imperfect potential field of a segmented-electrode Orbitrap. The segmented-electrode Orbitrap consists of a complete cylindrical inner electrode and a set of concentrically arranged segmented conical outer electrodes, offering a design that is more straightforward to manufacture than the traditional spindle-shaped Orbitrap. With appropriate potentials applied to each outer electrode, frequency shifts caused by higher order harmonic potentials of the imperfect field can be effectively canceled, achieving ultrahigh mass resolution. This study performs numerical simulations of the segmented-electrode Orbitrap based on the finite element method, analyzing the ion trajectories, frequency shifts, and mass resolution. The results show that this method effectively addresses the problem of imperfect harmonic potential fields, resulting in a mass resolution exceeding 200,000. Within acceptable machining tolerances, errors induced by the mechanical structure can be compensated for by finely adjusting the bias voltages on the outer electrodes, thereby ensuring mass resolution.