FIELD EVAPORATION IN 2-ELECTRODE SYSTEMS

Evaporation fields as positive ions and negative ions for common elements of interest in a two-electrode system are calculated based on a charge-exchange model and an image hump model. The fields required are lower at a smaller electrode separation. For alkali metals and very soft metals, formation of 1- ions requires the lowest field. For most soft metals, 1+ ions are favored. For transition metals and Si and Ge, either 2+ or 3+ charge state is favored.