A micro-sized electron source plays an important role for new vacuum triode applications. For these applications, an electron source with CNT field emitter and micro grid for 1 mA was developed and investigated. 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 a few micrometers. Because of the threshold field strength for field emission of CNTs being in the range 1-5 V/mu m, the and voltage can be lower than 100 V. In our contribution, we discuss the influence of the micro grid on electron source properties, especially anode-current hysteresis, anode-field penetration through the micro and and micro-lensing effect. (c) 2005 Elsevier B.V. All rights reserved.