Brightness measurements of nanometer-sized field-emission-electron sources

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Abstract
The brightness of nanometer‐sized field‐emission‐electron sources have been measured experimentally. Ultrasharp tungsten (111) single‐crystal tips were fabricated in situ using Ne sputtering and field evaporation, and monitored using field ion microscopy. The average brightness of single‐atom‐terminated nanotips was found to be 3.3×108 A cm−2 sr−1 at 470 V, or 7.7×1010 A cm−2 sr−1 when extrapolated to 100 kV. These results show an improvement of about two orders of magnitude in source brightness over existing cold field‐emission‐electron sources, and produce a beam with greater particle flux per unit energy than those obtainable using current synchrotron/wiggler/undulator devices.