APPARATUS AND METHOD FOR PRODUCING A STREAM OF IONS

摘要

A method and apparatus for generating high current, negative ion beams is described. A plasma source of ions of one charge polarity includes an accelerator for accelerating the ions toward a target having a plurality of apertures. An electric field directs the ions exiting the apertures against a target surface which is arranged to emit ions of an opposite polarity. The electric field directs the opposite polarity ions away from the target forming a stream of oppositely charged ions.
In the drawing the ions produced in the plasma chamber 10 are accelerated toward the apertured grid 12 by field 8 and pass through the aligned apertures in the grid 12 and target 16. A field established between apertured grid 18 and target 16 reverses the general direction of the ion beams so that they bombard the back surface of the target. Ions of the opposite polarity are emitted from the back of the target and are accelerated away from the target by the field between the grid 18 and the target. The opposite polarity ions exit as streams through the apertures in the grid 18.