| 摘要 |
An electron source showing little surplus current even at a time of high angular intensity operation is provided. An electron source comprising an electron emitting portion, a suppressor electrode and an extractor electrode, wherein the electron emitting portion is present at a leading edge of an end of a single crystal rod having a shape comprising a first truncated cone portion or a cone portion, and a second truncated cone portion continuing therefrom. It is preferably the electron source, wherein the single crystal rod has an oxide of a metal element selected from the group consisting of Ca, Sr, Ba, Sc, Y, La, Ti, Zr, Hf and lanthanoide elements as a diffusion source, and the single crystal rod is made of tungsten or molybden of <100> orientation.
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