A broad beam microwave O+ ion source

An electrostatic reflex ion source (ERIS) equipped with an ECR cathode at 2.45 GHz has been devised for the production of broad oxygen ion beams 84 mm in diameter. The proportion of atomic ions in the total extracted beam is studied in relation to the main plasma parameters: pressure of neutrals, discharge voltage, microwave injected power. The optimum conditions leading to a proportion of over 90% of the O+ atomic species have been determined: gas pressure in the anodic chamber, 2.5*10-3 mbar; microwave power, 125 W; discharge voltage, 250 V.