Electron source of lanthanum hexaboride and method of constructing same.

摘要

An electron emitter comprises a single, cubic lanthanum hexaboride crystal (1) mounted in a supporting material heatable by heating wires (3), the arrangement being such that a naturally grown edge (2) between two crystal faces, preferably (1,0,0) faces, forms a line emitter which has high length to radius and width ratios, preferably of at least 50 : 1.