Field emission electron gun and electron beam device with such a field emission electron gun

摘要

Field emission electron gun in which an electron beam is extracted from a cathode and the extracted electron beam is collimated with a magnetic field lens (207, 209) arranged such that the cathode is within the magnetic field of the lens; and with an extraction electrode (203, 403, 503, 603, 703) for extracting electrons from the cathode, characterized in that the extraction electrode has a cylindrical shape of constant internal diameter (d) without a diaphragm structure.