Simulation study and analysis of a compact einzel lens-deflector for low energy ion beam

A three-element einzel lens is a standard ion optics used to focus a low energy ion beam. In certain applications like injection of a low energy ion beam into a strong magnetic field of a Penning trap, it is necessary to combine a lens with a small angle beam steerer. The middle electrode is often slit in parallel or diagonal in order to combine the steering field with the focusing field. Here we study and analyze the performances of these two designs of same dimension and show that the diagonal-slit configuration is the better choice to achieve comparatively larger steering and focusing within acceptable aberration.