A negative ion source that can provide high yields of nearly all known stable negative ions and enables the user to vary the ion species within minutes has been developed by Roy Middleton and Charles T. Adams of the University of Pennsylvania, Philadelphia. The negative ions are formed directly from a solid surface by the sputter action of 30‐keV positive cesium ions resulting in a negative ion current of the order of 10 microamps. A unique feature here is that a simple, long‐lived surface ionization source (similar to a type used in thrusters for space satellites) produces the cesium ion beam, rather than the duoplasmatron conventionally used in negative‐ion sources, eliminating the problems caused by the presence of plasmas and gases. This new source, developed at the Penn Tandem Accelerator Laboratory, is particularly applicable to Tandem Van de Graaff accelerators, which must use negative ions and have, until now, been unable to live up to their full potential as universal accelerators of all varieties of ions. High‐energy linear accelerators, as well as atomic‐beam experiments, could also incorporate these sources.
Marian S. Rothenberg; Quick‐change negative‐ion source for accelerators. Physics Today 1 December 1974; 27 (12): 19–20. https://doi.org/10.1063/1.3129031
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