CIMAP, Caen
GANIL, Caen
One of the goals pursued by the people working on ion sources is to provide the highest beam intensity in the smallest emittance. As the computer power has increased so fast for the last years, it is possible nowadays to simulate with more accuracy the extraction of the ECR ion sources taking into account the several Physics processes involved in the beam creation. From the last chapter of the paper written by R. Leroy and coworkers [1], it has been shown experimentally that the intensity of a beam can be improved significantly by biasing the plasma electrode. The idea was to use the isolated plasma electrode as a 'biased disk'. We have calculated the influence on the extracted ion trajectories of this additional potential (from +3 V down to -100 V). The simulations have been computed for the MONO1000 and SUPERSHyPIE ion sources. All the simulations showed an increase of the brightness of the beam with more or less gain depending on the extraction voltage and the extraction conditions. A recent experiment performed on the MONO1000 ECRIS has confirmed the feasibility of this method: a gain of 40% in terms of emittance has been obtained on an 84Kr1+ beam.
[1] R. Leroy et al., Proceedings of the 12th International Workshop on ECR Ion Sources, April 25-27, 1995, RIKEN, Japan
ANL, Argonne, Illinois
Northern Illinois University, DeKalb, Illinois
A prototype injector capable of producing multiple-charge-state heavy-ion beams has been constructed at ANL. The injector consists of an ECR ion source, a 100-kV platform and an achromatic Low Energy Beam Transport (LEBT) system. Several charge states of bismuth ions from the ECR have been extracted, accelerated to an energy of 1.8 MeV, separated and then recombined into a high quality beam ready for further acceleration. This technique allows us to double heavy-ion beam intensity in a high-power driver linac for a future radioactive beam facility. Another application is in post-accelerators of radioactive ions based on charge breeders. The intensity of rare isotope beams can be doubled or even tripled by the extraction and acceleration of multiple charge state beams. Experimental results of multiple-charge state beam studies will be reported.
INFN/LNS, Catania