Variation of field enhancement factor near the emitter tip

• DOI: 10.1016/j.ultramic.2017.10.016
• Publication Date: 2017-10-31T20:30:19Z
• Authors: Debabrata Biswas; Gaurav Singh; Shreya G. Sarkar; Raghwendra Kumar
• Keywords: Axial symmetry; Variation (astronomy); Ellipsoid

The field enhancement factor at the emitter tip and its variation in a close neighbourhood determines the emitter current in a Fowler-Nordheim like formulation. For an axially symmetric emitter with a smooth tip, it is shown that the variation can be accounted by a $\cos{\tilde��}$ factor in appropriately defined normalized co-ordinates. This is shown analytically for a hemi-ellipsoidal emitter and confirmed numerically for other emitter shapes with locally quadratic tips.<br/>5 pages, 6 figures<br/>