  The electron distribution of open-ended single-walled carbon nanotubes with
chirality indexes (7,0) and (5,5) in the field emission conditions was
calculated via a multi-scaled algorithm. The field emission images were
produced numerically. It was found that the emission patterns change with the
applied macroscopic field. Especially, the symmetry of the emission pattern of
the (7,0) carbon nanotube is breaking in the lower field but the breaking is
less obvious in the higher field. The enlargement factor increases with the
applied macroscopic field.
