Electron cyclotron resonance ion trap, a multicharged ion breeder/buncher

The basic mode of operation of an electron cyclotron resonance ion source is recalled, particularly when using such a device as an ion charge breeder for the production of radioactive ion beams suitable for acceleration (1 + --> n + conversion). A new mode of operation, Electron Cyclotron Resonance Ion Trap (ECRIT), permitting to trap and bunch the nf ion beams is demonstrated. The principle of the ECRIT mode is explained. The charge breeder/buncher system is experimentally verified by the injection of a 400 nA Rb1+ ion beam leading to a 11.5 mu A peak current of the Rb15+ ion beam extracted during the first ms. The temporal evolution of the cumulated particle transformation efficiency is measured in the case of Rb15+ and shows a 2.2% efficiency during the first 20 ms of the ECRIT extraction. The interest of the ECRIT mode is finally shown when used for the production of high-energy radioactive ion beams. (C) 1998 Elsevier Science B.V. All rights reserved.