Abstract: A Mark II gridless ion source and HCES5000 hollow cathode electron source are used for ion assisted deposition (IAD) of dense coatings. It is possible to check the ion beam profile with a beam probe translated at a right angle to the beam axis. By rotating the probe it is possible to eliminate the contribution form charge exchange ions and to estimate the mean free path of the energetic ions. The beam intensity is expressed as a polynomial in cosine to the angle between the ion track and the beam axis and we derive mathematical equations to describe the result in distribution of ion current density on a flat and on an umbrella shaped substrate holder. A grid of target points is introduced immediately in front of the holder an in turn we aim the ion gun towards each of these. In each case, we calculate the mean ion current density and the variance across the rotating substrate holder. Finally, we use the obtained maps to optimize the orientation of the ion gun. !17
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