Performances of Volume Versus Surface ECR Ion Sources.

An all-permanent, 6 GHz ECR ion source has been constructed at the Holifield Radioactive Ion Beam Facility (HRIBF), Oak Ridge National Laboratory (ORNL), that permits configuration of the central magnetic field in either conventional parabolic or flat minimum-B profiles. The magnitude of the central flat field configuration extends over an axial region of ∼ 2 cm to form a large and uniformly distributed ECR volume. The capability of operating the source in either volume or surface modes permits direct comparison of the performances of each source type. The studies show that the volume ECR source produces higher charge-states and higher intensities within a particular charge-state than does the surface form of the source. The X-ray spectra derived during operation of the source also suggest that the enhanced performance of volume ECR source is attributable to its ability to accelerate a larger population of electrons to higher energies than its conventional counterpart. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]