Simple geometry gridless ion mirror

A gridless variation of the cylindrical ion mirror has been designed to cre ate an electric field that is nonlinear in the axial direction and nearly h omogeneous in the radial direction. The designs may include one or two cham bers that consist of truncated cones. This new design concept yields ion mi rrors with improved energy focusing over conventional single-field and mult iple-field mirrors. Conventionally, ion mirrors with nonlinear field gradie nt use multiple diaphragm electrodes to which distinct voltages are applied . In this work, optimized nonlinear field distributions are achieved throug h shaping only two or three electrodes and applying only one or two voltage s on the electrodes. The designs presented here offer high resolving power and low ion dispersion. SIMION simulations of performance from the ion sour ce to the detector demonstrate resolving powers of 11000 and 1750 for ions with kinetic energy variations of 7.5% and 23.6%, respectively. (C) 2000 Am erican Society for Mass Spectrometry.