Triply charged argon and neon ion beams from rf sources

Slight modification of a classical rf ion source allows routine production of triply charged neon and argon ion beams in an upgraded (7 MV) CN Van de Graaff accelerator. Absolute current measurements yield analysed beam intensities in the 100-500 nA range. Identification of beam particles is verified by observing their far UV emission spectrum after passage through a thin carbon exciter foil. Essential requirements for producing such beams are a small but critical reduction of the exit canal diameter and close monitoring of rf oscillator power. (Auth.)