In this work we present field emission characteristics of four geometrically distinct carbon nanotube pillar arrays Each cathode has a unique geometric configuration with different structural parameters such as number of edges and vertices We present experimental data demonstrating a carbon nanotube cold field emitter with an emitted current density of 31 8 mA/cm(2) at an applied field of 11 V/mu m The performance of these cathodes can be directly attributed to the electric field being enhanced along the edges and vertices of the structures We investigated this phenomenon experimentally by changing the geometry of the carbon nanotube pillar structure We show that by increasing the number of edges and vertices of a structure to keep the electric field screening to a minimum the emission current can be increased (C) 2010 Elsevier Ltd All rights reserved