Extraction from ECR ion sources: a new way to increase beam brightness

International audienceOne of the goals of work on ion sources is to provide the highest beam intensity in the smallest emittance. As computer power has increased so rapidly over the last few years, it is now possible to simulate the extraction from the ECR ion sources with greater accuracy, taking into account the physics of the several processes involved in the beam creation. In the last section of their paper, R. Leroy and co-workers [1] showed 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 0 V down to -60 V). The simulations have been computed for the MONO1000 [2] and SUPERSHyPIE [3] ion sources. All the simulations showed an increase of the beam brightness with more or less important 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 around 40% in terms of emittance has been obtained on an 84Kr1+ beam