FIELD EMISSION TYPE CHARGED PARTICLE GUN

PROBLEM TO BE SOLVED: To provide a field emission type charged particle gun capable of emitting charged particle beam with the current value, and the point and size of emission stabilized for a long time. SOLUTION: A current control electrode 11 which gives the least effect of a lens to voltage change required for current stabilization is provided between a charged particle drawing electrode 3 and a charged particle source 1 to keep the potential of the charged particle drawing electrode 3 constant during operating a charged particle gun. A current control electrode 11 is connected to the drawing electrode 16 via a resistor 18. Charged particle beam (ion beam) 2 flows through the resistor 18 into the current control electrode 11 so that the potential of the current control electrode 11 can be automatically controlled to keep the charged particle beam at a constant current value.