| abstract |
An electron source that even at high-angle current density operation, realizes low excess current. The electron source is one having electron emission part (8), a suppressor electrode and an extraction electrode, characterized in that the electron emission part (8) is positioned at the apex of one end of a single-crystal rod having the form consisting of first circular truncated cone portion or circular cone portion (23) and, continuing thereto, second circular truncated cone portion (22). Preferably, the electron source is characterized in that the single-crystal rod contains an oxide of metal element selected from the group consisting ofCa, Sr, Ba, Sc, Y, La, Ti, Zr, Hf and lanthanoid series as a diffusion source and is composed of orientation of tungsten or molybdenum. |