On-line ECR ion sources: Present and future

On-line ECR ion sources are presently used for radioactive ion beam production at ISOL facilities. This type of ion sources has proven to be very efficient for the ionization of radioactive gases and elements with high ionization energies. This paper gives a review of the different ECR ion sources used on line on the current facilities with their limits due to the hostile environment (radioactivity, target out-gassing, etc.). The future projects need more and more radioactive ion beam intensities that increase the radiation level around the ion source. Furthermore, the ion sources have to accept higher and higher gas flow delivered by the production target. Therefore, research and developments are very active to overcome all constraints related to the on-line operation while maintaining the high ionization efficiencies of this kind of sources. An overview of the ongoing developments of on-line ECRIS is presented.