▎ 摘　　要

A stable field emission (FE) under a high residual pressure (10(-5) Torr) was obtained by the thermal field operation of a nanoneedle cathode with a two dimensional graphene sheet structure. A high brightness electron emission of the order of 10(12) A sr(-1) m(-2), as well as stable emission, was achieved. The performance of the stabilized cathode was demonstrated by the construction of a compact FE scanning electron microscope (SEM) system, and clear FE-SEM images were obtained at a residual pressure above 10(-5) Torr. The emission current fluctuation as a function of cathode temperature was discussed based on the Poisson distribution. (c) 2007 American Institute of Physics.