High current duoplasmatron having an apertured anode positioned in the low pressure region

Claim 1

IN DUOPLASMATRON ION BEAM APPARATUS IN WHICH AN ARC IS STRUCK TO FORM IONIZABLE GS INTO A PLASMA FROM WHICH AN ION BEAM MAY BE EXTRACTED, THE COMBINATION OF A FIRST CHAMBER TO WHICH SAID GAS IS SUPPLIED, MEANS FOR PUMPING SAID FIRST CHAMBER DOWN TO A RELATIVELY HIGH PRESSURE OF SAID GAS, A SECOND CHAMBER, MEANS FOR PUMPING SAID SECOND CHAMBER DOWN TO A RELATIVELY LOW PRESSURE, MEANS INCLUDING AN INTERMEDIATE ELECTRODE SEPARATING SAID FIRST CHAMBER FROM SAID SECOND CHAMBER, SAID INTERMEDIATE ELECTRODE INCLUDING A PORTION FORMED OF SOFT IRON THROUGH WHICH A FIRST APERTURE IS FORMED FOR THE PASSAGE OF SAID ION BEAM, A CATHODE DISPOSED ADJACENT ONE SIDE OF SAID INTERMEDIATE ELECTODE AND WITHIN SAID FIRST CHAMBER, AN ANODE DISPOSED ADJACENT THE OTHER SIDE OF SAID INTERMEDIATE ELECTRODE AND WITHIN SAID SECOND CHAMBER, AT LEAST A PORTION OF SAID ANODE BEING FORMED OF SOFT IRON THROUGH WHICH A SECOND APERTURE IS FORMED FOR THE PASSAGE OF SAID ION BEAM, MEANS FOR APPLYING A MODERATELY HIGH POTENTIAL OF A FIRST POLARITY BETWEEN SAID CATHODE AND SAID ANODE AND A MODERATELY LOW POTENTIAL OF SAID FIRST POLARITY BETWEEN SAID CATHODE AND SAID INTERMEDIATE ELECTRODE WHEREBY SAID ARC IS STUCK BETWEEN SAID ANODE AND SAID CATHODE TO FORM SAID PLASMA, AND MEANS FOR PRODUC-