Emission stability of a FEA observed by an emission microscope

Emission stability is the most stringent requirement for FEA in a practical application. When the fluctuating events occur stochastically, the fluctuation in electron emission reduces with 1//spl radic/N, where N is number of individual cathodes. So the total current of FEA (Field Emitter Array) is expected apparently stable. However, the fluctuation does not necessarily occur stochastically, and the mode of fluctuation of each individual micro-tip is different from tip to tip. Some emit very stable, but others fluctuate frequently. The fluctuation of each micro-tip is observed by use of a field emission microscope, and the behaviors are classified due to the emission mode. The causes of each emission modes are argued.