Carbon-nanotube(CNT) is well fitted to field emission for its geometry.A very high electric field can be gotten near its apex.Some of advantages

such as low turn of voltage and stable field emission

made CNTs as an ideal field emission material.The field enhancement factor is an important parameter which effects on the emission current obviously.Soluting the Laplace function is needed

however the special geometry made this solution difficult.Finite element method is a good choice with the increase ment of speed and memory of computer.A commercial code ANSYS was used to analyze the field enhancement factor of CNTs.A single CNT model is extracted from the whole array and some suitable boundary conditions are applied to the model.In order to increase the speed of solution

1/4 part of single CNT model is used in fact.The more accurate results can be got by refining the meshes near apex.The distribution of electric field near the apex of single CNT was analyzed finally.To make the whole process easy and learn better the electric field’s dependence on aspect ratio

an ANSYS parametric design language(APDL)

by which great efficient can also be gained

was used.The results are well fitted by the other papers

which testified the whole process:model

mesh and computation.Those methods are good choice to things like this.