Inverted magnetron ion source

An ion source comprising in combination:

• A hollow cathode chamber formed by having a substantially cylindrical wall and end pieces fitted at the ends of said cylindrical wall and said hollow cathode chamber further formed to hold ionizable gas;
• at least first and second apertures formed in said substantially cylindrical wall;
• anode means formed and disposed to extend substantially axially through said cathode chamber and extending from at least one of said end pieces;
• insulation means formed and disposed to electrically insulate said cathode means from said anode means;
• magnetic flux generating means formed and disposed to generate lines of magnetic flux which pass, from one of said end pieces to the other end piece, through said cathode chamber and substantially coaxially with said anode means;
• voltage source means connected to said cathode means and said anode means to produce an electrostatic field therebetween within said cathode chamber;
• ionizable gas source means coupled to said first aperture to provide ionizable gas to said cathode chamber whereby said gas will be ionized and ions will be accelerated toward said cathode chamber wall thereby causing some of said ions to pass in a stream through said second aperture;
• and ion beam focusing means disposed in close proximity to said second aperture to focus to a point an ion stream emanating therefrom to produce greater ion current at a lower chamber pressure.