Special features of electron sources with CNT field emitter and micro grid

A micro-sized electron source has been developed for new vacuum triode applications. The miniaturisation of the electron source was achieved by the use of a carbon nanotube (CNT) field emitter and a micro grid, with a distance of only some micrometers. Because of the threshold field strength for field emission of CNTs being in the range 1 to 5 V//spl mu/m, the grid voltage can be lower than 100 V. In our contribution, we discuss the influence of the micro grid on electron source properties, especially anode field penetration through the micro grid, and micro-lensing effect.