Preliminary calculations of the electric field and the stress on a field-ion specimen

Abstract

A general solution to the problem of the electric field acting over a field-ion tip has been attempted. The tip is assumed to be smooth and axially symmetric. The forces acting on such a tip can be deduced from a knowledge of the field; it is, however, very difficult to determine an elastic stress function. Average values of the principal stresses can be calculated by integration. These can be used to investigate the extent to which glissile lattice defect configurations are modified by the field stress acting when specimens are studied. Under typical conditions for imaging, the tensile and shear stresses near the apex are of the same order as the theoretical cleavage and shear strengths, and even 1 μ from the apex the shear stress is of the same order as the bulk yield stress.