Charge Breeding Experiences with an ECR and an EBIS for CARIBU

The efficient and rapid production of a high-quality, pure beam of highly charged ions is at the heart of any radioactive ion beam facility. An ECR charge breeder, as part of the Californium Rare Ion Breeder Upgrade (CARIBU) program at Argonne National Laboratory, was developed to fulfil this role. The charge breeding efficiency and high charge state production of the source are at the forefront of ECR charge breeders, but its overall performance as part of the accelerator system is limited by a pervasive stable ion background and relatively long breeding times. Steps have been taken to reduce the level of background contamination but have met with limited success. As such, an EBIS charge breeder has been developed and is now running in an off-line configuration. It has already demonstrated good breeding efficiencies, shorter residence times, and reduced background, and it is scheduled to replace the ECR charge breeder in late 2015. The resultant change in duty cycle and time structure necessitates changes to the overall facility operation. The experiences with these breeders – their strengths and their weaknesses will be discussed.