| 摘要 |
An ion source apparatus of surface ionization type comprises an emitter tip in the form of a round rod having a sharp-pointed end, an ion source material holder for holding the emitter tip coaxially within a crucible made of a material of a high melting point, the crucible having an opening formed in a bottom wall thereof through which the sharp-pointed end of the emitter tip extends outwardly, the ion source material is being filled in the crucible so as to enclose the outer periphery of the sharp-pointed end of the emitter tip, a filament for emitting electrons with which the emitter tip is bombarded from below, a heating power supply for the filament, an ion beam extracting electrode disposed between the emitter tip and the filament and maintained at a potential of a substantially the level as that of the filament, and an accelerating voltage power supply for applying a high voltage between the ion beam extracting electrode and the emitter tip to accelerate the electrons and ion beam.
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