Magnification and mass resolution in local-electrode atom probes

The mass resolution of a local-electrode atom probe can be improved by accelerating the evaporated ions to a higher energy in order to reduce the energy-deficit-related dispersion. A simple model of the instrument is developed and used to estimate the effects of this secondary acceleration on image magnification and mass resolution. Effects of non-instantaneous secondary acceleration, variations in the secondary acceleration field distribution and electrode length are evaluated using the model. The addition of an acceleration electrode after the extraction electrode is shown to improve the performance of local-electrode atom probes.