摘要 |
An ion gun 11 supplies an Ar gas into a main body 111 from a gas inlet 114, causes DC hot cathode discharge between a filament 113 and an anode 112 to generate Ar plasma. Next, a voltage gradient is applied to separated accelerator grids 116a, 116b having a bi-separated configuration in an ion ejecting direction. The each potential of the separated accelerator grids 116a, 116b is independently controlled by independently setting accelerator control switches 121a, 121b on or off to change the potential of that of the separated accelerator grids 116a, 116b which corresponds to an ion beam to be disabled.
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