Initial comparative performances of conventional 'surface' and 'volume' type, all-permanent-magnet, ECR ion sources (abstract)

An all-permanent-magnet, 6 GHz 'volume-type', flat central-field concept ECR ion source has been constructed and initially evaluated at the Holifield Radioactive Ion Beam Facility, Oak Ridge National Laboratory. The source is designed so that it can be easily converted from a flat-B configuration to the traditional minimum-B configuration and vice versa, so that comparisons can be made of the performances of the source in the 'volume' ECR and 'surface' ECR modes of operation under the same conditions. Descriptions of the source, the experimental equipment, and the procedures for evaluation are given, and comparisons of the performances of both volume and surface modes of operation are presented with and without gas mixing. The present studies clearly show that the volume ECR configuration is superior to the surface configuration in terms of charge-state distribution and intensity within a particular charge state, under the same operating conditions