FIELD-EMISSION ELECTRON GUN, AND CONTROL METHOD THEREFOR

PROBLEM TO BE SOLVED: To provide a method of using stably a field-emission electron gun, using a feature of an attenuation way of an emission current from the (310) surface of W. SOLUTION: This invention discloses a charged corpuscular beam device provided with: a field-emission electron source composed of a single crystal of tungsten; a vacuum chamber arranged with the electron source; an evacuation system for evacuating the vacuum chamber; a filament connected to the electron source, and for heating the electron source by a flow of a current, an electric power source for making the current flow in the filament; and an ammeter for measuring total current amount emitted from the electron source. Here, the total current amount is measured periodically, and a control section is provided to control the electric power source to make the current flow in the filament, when the total current amount comes to a prescribed ratio or less relative to the total current amount from the electron source just after initial electron beam emission, or total current amount from the electron beam just after making the current flow in the filament. COPYRIGHT: (C)2011,JPO&INPIT