P2–12: The field emission behavior of nano-patchwork cathodes

A numerical calculation of the patch-field distribution across nano-patchwork surfaces has been developed. Results show that the low work function nanosize zones are intrinsically protected by an electrostatic screen, which is induced by the surrounding area having higher work function. In presence of an applied field, during field emission, a preferential opening of the surface barrier just over the nano-patches induces a field emission array of parallel e-beams whose geometrical distribution is defined by the positions of the nano-patches.