Patent ID: 9257257
Filing Date: 2016-02-09
CPC Classification: H01J

Claim Text:
1. An electron beam control method comprising an electron beam generating step of emitting electrons from the conical end of an emitter sharpened in the shape of a cone on the emission side of an electron beam by using a Schottky effect under an electric field applied to the conical end to thereby generate an electron beam, the method further comprising: a curvature radius adjusting step of adjusting a radius of curvature of the conical end; an electron gun focal length control step of controlling an electron gun focal length of an electron beam by a radius of curvature adjusted in the curvature radius adjusting step; and an angular current density control step of controlling an angular current density of an electron beam with a focal length controlled by the electron gun focal length control step, wherein the electron beam generating step is conducted each time emission of an electron beam in a state where an angular current density is controlled after the angular current density control step.