We report the conversion of a conventional high energy ion gun into a low energy ion gun. The conversion procedure described here maintains the ion current capability of the high energy gun along with its good spatial and ion energy distribution characteristics. Several low energy ion guns have been described previously in the literature [J. T. Yates, Jr., Experimental Innovations in Surface Science (Springer-Verlag-AIP, New York, 1998), pp. 307-329] but all require the construction of new ion optics, whereas this approach utilizes existing ion optics and electronic control capabilities of a commercial ion gun. This ion gun,may be employed for studies where it-is desired to use ions as reactive species without significant sputter damage of the target. 2003 American Vacuum Society.