Linear optics theory of ion beamlet steering

Based on the paraxial approximation, a linear optics theory which accounts for steering effects in multibeamlet ion sources is presented. For a triode accelerating structure, the steering is independent of the accel potential and is in the opposite direction to the electrode displacement. For a tetrode, the steering is dependent on the potential distribution and may be in either direction relative to the displacement. With arrangements used for best optics, in tetrodes, the beam steering may be in the opposite direction to that of triodes.