Formation of Helium Ion Beams by the Injection of a Neutral Helium Beam into a Tandem Accelerator

Abstract
A neutral helium beam, obtained by charge‐exchange of fast He+ in helium gas, was injected into a tandem accelerator. The energetic neutral beam drifted to the central terminal where electron stripping occurred in oxygen gas, and the resulting He+ and He++ ions were accelerated from the terminal to ground. These ions were then separated by a 90° analyzing magnet. Approximately 1.6 μa He+ and 1.0 μa He++ were obtained at an injection energy of 450 kev independent of the tandem terminal voltage. Beam intensities have been measured before and after the charge‐exchange reactions.
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