A single beam plasma or ion source apparatus is provided. Another aspect employs an ion source including multiple magnets and magnetic shunts arranged in a generally E cross-sectional shape. A further aspect of an ion source includes magnets and/or magnetic shunts which create a magnetic flux with a central dip or outward undulation located in an open space within a plasma source. In another aspect, an ion source includes a removeable cap attached to an anode body which surrounds the magnets. Yet a further aspect provides a single beam plasma source which generates ions simultaneously with target sputtering and at the same internal pressure.