Characterization of multi-beam cathode using thermionic emission microscope

Abstract

Thermionic emission microscope (THEM) is an analytical research tool to study the emission uniformity of a thermionic cathode. In this paper, the design of electrostatic lens for a multi-beam cathode (MBC) has been given using 2-D TRAK and Omni-TRAK codes. The design of single beam lens system, available with us, containing a small cathode has been modified to study large size MBC using scaling laws. The present MBC contains 19 protruding buttons contributing to 19 beamlets whose image is projected onto the screen for study. The influence of various parameters such as protrusion, diameter of button, and their interspacing has been studied. The studies prove that THEM could be used as an effective tool for the characterization of MBC.