Restricted ion source of high current density

Claim 1

Means for producing an ion source having a relatively small area comprising: (a) a source of gas subject to becoming ionized, (b) a plasma chamber comprising: a cathode, an anode, an insulating cylinder disposed between one end of said cylinder and said cathode, first seal means disposed between one end of said cylinder and said cathode, second seal means disposed between the other end of said cylinder and said anode, a grounded cylinder disposed about said plasma chamber retaining said insulating cylinder and said first and second seal means in place against said cathode, (c) conduit means for directing said gas into said plasma chamber, (d) bellows means disposed in said conduit means for biasing said cathode toward said anode to compress said first and second seal means, (e) a source of electrical power for ionizing said gas to produce plasma in said plasma chamber, (f) a first vacuum chamber enclosing said plasma chamber, (g) said anode forming a diaphragm having an aperture formed therein to permit said ions to pass therethrough from said plasma chamber into said first vacuum chamber, (h) first means disposed in said first vacuum chamber for focussing the ions effusing from said aperture to produce a focussed beam of ions of relatively high current density in a relatively small area, (i) a second vacuum chamber connected to said first vacuum chamber for receiving said ions from said first vacuum chamber, (j) a plate separating said first and second vacuum chambers and having an aperture to permit passage of said focussed ions from said first vacuum chamber into said second vacuum chamber, and (k) second means in said second vacuum chamber for refocussing the ions passing through the aperture in said plate to produce a refocussed beam of ions.