Patent ID: 8253118

Claim:
A charged particle beam system, comprising: a plasma chamber for containing a plasma gas at a plasma chamber gas pressure; an extraction electrode to which a voltage can be applied for extracting ions or electrons from the plasma chamber; a power supply for supplying power to the plasma chamber to maintain a plasma in the plasma chamber; a gas supply for supplying the plasma gas to the plasma chamber; a focusing column comprising a plurality of lenses for focusing ions or electrons extracted from the plasma chamber; and a computer readable memory storing a set of operating parameters for each of multiple operating modes, the operating parameters including one or more of: the plasma chamber gas pressure; the plasma gas species; the power supplied to the plasma; the voltage supplied to the extraction electrode, a controller programmed to selectively switching the charged particle beam system between operating modes, the controller causing at least one of the operating parameters of the charged particle beam system to be set in accordance with the stored operating parameters for the selected mode; and one or more beam-limiting apertures and an aperture positioning actuator, the controller programmed to selectively position a beam-limiting aperture corresponding to the selected operating mode in the path of the charged particle beam depending on the beam current required for the selected operating mode.