Electron gun, electron microscope, three-dimensional laminated modeling device, and current adjustment method for electron gun

摘要

PROBLEM TO BE SOLVED: To add a complicated mechanism in order to suppress an ion bombard generated at a cathode. An electron gun (11) has a cathode (20) that is heated to emit thermoelectrons, a cathode heating power source that supplies a cathode current for heating the cathode (20), and a first along the central axis of the tip of the cathode (20). An aperture is formed, and the grid voltage applied at a potential lower than that of the cathode 20 forms a grid 21 that focuses thermoelectrons passing through the first aperture and a second aperture along the central axis, and the applied anode voltage. The anode 22 allows the thermoelectrons drawn from the cathode 20 to pass through the second opening as the electron beam B, the anode voltage power supply 25 for applying the anode voltage to the anode 22, and the anode voltage as a positive potential from the anode voltage power supply 25. A control unit 10 for applying to the anode 22 is provided. [Selection diagram] Fig. 3