Experimental study of charge breeder based on an 18GHz room-temperature ECR ion source

Abstract: To enhance the post-acceleration efficiency of radioactive ion beam devices, charge breeders are commonly employed to convert singly charged ions into highly charged state. Based on an 18GHz high charge state room-temperature ECR ion source, an ECR source charge breeder (ECRCB) was designed and constructed, and ion beam charge breeding experiments were conducted. We designed an injection structure for the ECRCB, which is a ground electrode drift tube that directly extends into the discharge chamber of the ion source. The beam envelope of the ECRCB and the electric field distribution of the injection structure were calculated using the finite element analysis method. The calculation results indicate that the injection structure can not only effectively inject the singly charged ion beam into the plasma in the discharge chamber, but also control the electric field strength at the injection position within an acceptable range.Charge breeding experiments were conducted on Kr⁺ and Ar⁺ ion beams using the ECRCB and highly charged ion beams were generated. The charge-to-mass ratios of the two ion beams reached 1:5.60 and 1:4.44 respectively, and the total breeding efficiencies were 8.17% and 29.37% respectively.