Very-low-energy-spread ion sources

Axial ion energy spread of multicusp sources has been measured by three different techniques: an electrostatic energy analyzer for plasma ion measurement at the source exit; a magnetic deflection spectrometer; and a retarding-field energy analyzer for measurement of the accelerated beam. By introducing a magnetic filter inside the multicusp source chamber, it is shown that the energy spread of positive hydrogen ions can be reduced to approximately 1 eV. The energy-spread values for H^- ions are lower. New ion source configurations are now being investigated to further reduce the ion energy spread to below 1 eV and maximize source performance reliability and lifetime