Electron gun, charged particle gun, and charged particle beam apparatus using electron gun and charged particle gun

A charged particle gun comprising:

• a charged particle source;
• an acceleration electrode to accelerate a charged particle emitted from the charged particle source;
• a control electrode disposed nearer to a side of the charged particle source than to a side of the acceleration electrode and having a larger aperture diameter than an aperture diameter of the acceleration electrode;
• and
• a control section to control a potential applied to the control electrode based on a potential applied to the acceleration electrode.

A charged particle gun comprising:

• a charged particle source;
• an acceleration electrode to accelerate a charged particle emitted from the charged particle source;
• a control electrode disposed nearer to a side of the charged particle source than to a side of the acceleration electrode;
• and
• a control section to control a potential applied to the control electrode based on a potential applied to the acceleration electrode, wherein the control section applies a control voltage to enhance an electric field at a tip end of the charged particle source to the control electrode when an acceleration voltage of the acceleration electrode is low whereas applying a control voltage to suppress the electric field at the tip end of the charged particle source to the control electrode when the acceleration voltage is high.