Gas electrolytic ionization ion source and methods of use thereof, as well as, ion beam apparatus, and an emitter tip and a method of manufacturing the same

Providing high radiation angle current density gas field ion source. A metal of at least the substrate is single crystal emitter tip constituting the gas field ion source, a pyramid shape or a conical shape the tip of the emitter tip to the apex of the single atom, and the helium gas in the single atom extraction voltage at which ionization was made up to above 10 kV.