Apparatus and method for improved ion beam current

An apparatus may include an electrode system, the electrode system comprising a plurality of electrodes to guide an ion beam from an entrance aperture to an exit aperture, and a voltage supply to apply a plurality of voltages to the electrode system. The electrode system may comprise an exit electrode assembly, where the exit electrode assembly includes a first exit electrode and a second exit electrode, separated from the first exit electrode by an electrode gap. The first exit electrode and the second exit electrode may be movable with respect to one another so as to change a size of the electrode gap over a gap range.