Ion implantation is a major application of plasma processing in a variety of applications in which the surfaces of materials are to be treated. The implantation process requires a source of ions and a means to accelerate them toward the surface. Two general methods are in use today: ion beam implantation, in which a beam of ions is directed toward a substrate, and plasma implantation, in which the ions produced in a plasma discharge surrounding or near the object to be implanted are extracted from the plasma and accelerated into the object.