A simulation study of the planar electrostatic ion trap mass analyzer.

The Planar electrostatic ion trap expands the trapping space of the linear electrostatic ion trap, giving rise to higher tolerance to space charge. A rotational symmetrical design was made, which has a trapping field between two layers of concentric circular electrodes, and the ions are trapped to oscillate around the center plane between the electrodes. The oscillatory motions of the ions were simulated and the field distribution was optimized to achieve isochronous motion against energy spread in R, z, and φ directions. The image charge signal can be picked up by more than one circular electrode and using FFT the mass resolution for the optimized trap can reach 80,000 FWHM. While Fourier transform of the image charge signal generates many high harmonic peaks, the unwanted harmonic peaks can be eliminated by linear combination of image charge signals from multiple pick-up electrodes to give satisfactory results.