Is uniform electron emission possible at low macroscopic fields ?

Summary form only given. For existing thin-film electron emitters (except bulk diamond), low-macroscopic-field (LMF) emission occurs primarily because nanostructure in the film generates local field enhancement (by a factor g) at the vacuum interface, allowing electron tunnelling. Electrostatic considerations then mean significant emission occurs from at most a fraction (about 1/g*g) of the surface. The original hope with carbon thin-film emitters was that LMF emission would occur uniformly over a broad area. This paper looks again at the underlying physics, including space-charge considerations. It defines conditions under which uniform LMF emission might occur at room temperature and relatively low applied voltage.