Ion trajectories and projection geometry in the fieldion microscope
Abstract
Exact numerical computations are presented for the ion trajectories in the fieldion microscope for certain symmetric emitter shapes. Two mathematical models of emitter shape were used which yield exact solutions to Laplace equation for the electric potential, the first assuming the specimen a hyperboloid of revolution and the second a paraboloid of revolution, both with respect to cylindrical coordinates (y, 3). The computations illustrated the variation in the shapes of the ion trajectories as a function of several parameters. In all cases the curvature of the trajectory is small and varies slightly with the emitter geometry, and this explains why the point projection models have been successfully used to analyze micrographs. Results show that the projection is almost independent of emitter radius and tip to screen distance.
 Publication:

Unknown
 Pub Date:
 March 1977
 Bibcode:
 1977itpg.rept.....S
 Keywords:

 Field Emission;
 Ion Microscopes;
 Particle Trajectories;
 Projective Geometry;
 Electric Potential;
 Emitters;
 Hyperbolas;
 Laplace Equation;
 Mathematical Models;
 Parabolic Bodies;
 Atomic and Molecular Physics