Ion implant apparatus using a drum-type scan wheel holds wafers with a total cone angle less than 60°. A collimated scanned beam of ions, for example H+, is directed along a final beam path which is at an angle of at least 45° to the axis of rotation of the scan wheel. Ions are extracted from a source and accelerated along a linear acceleration path to a high implant energy (more than 500 keV) before scanning or mass analysis. The mass analyzer may be located near the axis of rotation and unwanted ions are directed to an annular beam dump which may be mounted on the scan wheel.