Characterization of TRIUMF dc H- ion sources for enhanced brightness

Abstract

At TRIUMF, H- ion sources have been characterized on a teststand to improve the understanding of their performance. Measured beam characteristics such as current, emittance, and e H- ratio were correlated with source conditions as a function of relevant plasma parameters. Plasma densities, temperatures, and plasma potentials were measured with a Langmuir probe and correlated with beam properties for different confining magnetic fields and different values of arc power and gas pressure. The mechanism of beam extraction was studied by correlating plasma potential profiles with the corresponding plasma electrode bias voltages obtained from optimizing ion source outputs. Experiments with collar biasing and noble gas mixing were unsuccessful because of undesirable plasma potential profiles. © 2006 American Institute of Physics.