| 摘要 |
PROBLEM TO BE SOLVED: To provide an electron gun equipped with an electron source in which there is no deviation of optical axes between an electrostatic lens and an electromagnetic lens, variation of lens effect of the electrostatic lens is small even if acceleration voltage and extraction voltage fluctuate widely, and the electromagnetic lens can always focus a high-brightness electron beam and output it. SOLUTION: In order to put the electromagnetic lens 3 near the electron source 1 and decrease the focal distance of the electromagnetic lens 3, pole distance between a bottom magnetic pole and a top magnetic pole is reduced, and the magnetic poles and electrodes are formed separately each other so that distance between the electrodes can be larger than that between the magnetic poles. COPYRIGHT: (C)2007,JPO&INPIT
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