Ion Source Design for Industrial Applications

Abstract

ROAD-BEAM electron-bombardment ion sources are used for a wide range of industrial applications. There have been a number of reviews of the technology involved,15 in addition to the hundreds of papers upon which these reviews were based. Despite the availability of these publications, applications of this ion-source technology have resulted in frequent design problems and much cut-and-try development. The intent of this paper is to cover some of the more frequently used design techniques, together with examples of successful component design. There is no intent of completely covering ion-source technology. The intent is, instead, to give at least one specific design example for each component, to aid those that do not have an extensive background of ion-source design upon which to draw. The working gas Ar will be emphasized in performance calculations, although scaling relationships will be given for other gases. The presentation will.be divided into sections on the v gas feed, discharge chamber, ion optics, cathodes, magnetic design, and mechanical design. It should be mentioned that single-aperture ion sources have developed almost independently of multiaperture broadbeam sources. Although this paper has been directed primarily at broad-beam sources, much of what is presented is also applicable to single-aperture sources. Where appropriate, single-aperture technology is referenced.