Space-charge effects in the catcher gas cell of a rf ion guide

摘要

Slow radioactive ion beams have been produced with an overall efficiency of 4 by thermalizing energetic ions produced by a projectile fragment separator in a He-gas cell and guiding them to a vacuum vessel by dc and rf fields. Space charge was observed to have a limiting effect. Since the ionization of He atoms by energetic ions creates a region of high space charge, many thermalized ions of interest are pushed toward the walls of the gas cell. Such losses have been investigated for different incoming ion intensities. (c) 2005 American Institute of Physics.