Influence of Cathode Size on Field Emission Properties of a Single Vertical Carbon Nanotube Material

In this work, we study the field emission properties of a single vertical carbon nanotube with cathode radius changing. The carbon nanotube is considered as purely perfect conductor, and the anode and cathode are modeled as discs. The radius of anode is kept as 24m, then the radius of cathode is changed from 24 m to 1 m. The emitter of that CNT consists of a hemispherical cap of 4 nm radius (r) on top of a cylinder height of 2 m (h). The distance from anode to cathode is w=h+20m. The overall surface area of the CNT and cathode are all grounded, and the anode plate has a constant potential value of 100 V. The distribution of potential and electric field, field emission current are obtained by simulating with the help of COMSOL Multiphysics 4.3b electrostatics module. We find that with cathode radius decrease, the electric field strength over the surface of carbon nanotube (CNT) strengthening and field emission current increase.