Progress and status of RAON EBIS charge breeder

An electron beam ion source (EBIS) was considered as a charge breeder for rare isotopes produced from isotope separation on-line (ISOL) system of the heavy ion accelerator RAON in Korea. The off-line installation of the RAON EBIS was conducted at the Korea University, Sejong from 2017 to 2020. A lot of effort went into getting very low vacuum pressure of around 1E-10 torr at the breeding region adopting cryopumps and getter pumps as well as vacuum-firing the chambers. In order to find and align the central magnetic field lines of the solenoids, we used a gimbal mount for a hall probe with rotation, tilt, and translation functions. With the help of four sets of steering coils around the drift tube chamber, we successfully transport electron beam of 2 A at a magnetic field of 6 T producing charge bred ions from the residual gas. After confirming the performance of our EBIS system at the off-line site, we moved it to RAON accelerator site at Shindong and started the on-line installation from 2021. Cesium test ion beam was used for the first charge breeding experiment showing a relative abundance of Cs27+ ions more than 20 % with electron beam current of 1 A in breeding time of 40 ms.