Operation of an Ecris Charge State Breeder at Triumf

After initial commissioning of the charge state breeder for radioactive ions at the TRIUMF/ISAC facility further tests on the performance of the system have been done., One of the major problems found was the high background of stable ions from the ECR source. The main source of those is the residual gas and sputtered material from the plasma chamber wall and from the surrounding electrodes. Although, their intensity is small it can be orders of magnitude more than the intensity from the radioactive ions. Therefore, the original stainless steel plasma chamber of the Pantechnik PHOENIX ECR source has been exchanged to aluminium with a pure aluminium coating, all electrodes for injection and extraction of the ions have been replaced with aluminium and the iron joke at the extraction side, which is part of the vacuum system in the PHOENIX source has been coated as well. This combined effect has reduced the amount of background ions substantially. Together with some beam purification in the accelerator chain the background could be reduced to a level acceptable for experiments with radioactive ions. A low transport efficiency of ions with very high charge states can be explained by to charge changing collisions with residual gas