Vacuum system for EBIS charge breeder of the RAON heavy ion accelerator

An Electron Beam Ion Source (EBIS) will be utilized for charge breeder in the RAON heavy ion accelerator facility. The vacuum system for the RAON EBIS charge breeder is crucial part for the achievable charge state, breeding efficiency, and purity of the charge-bred beam. A strict vacuum level of about 10-11 mbar is required in the ion trap. The pumping system of the RAON EBIS charge breeder consists of turbo pumps (TMPs), cryo-pumps, and non-evaporable getter (NEG) ZAO modules. The material for the ion trap structures and vacuum chamber was chosen and handled carefully to satisfy the vacuum requirements in the manufacturing step with vacuum firing at 1050 degrees C for 2 h. A vacuum test of the ion trap section has been performed with baking, and final vacuum level reached 2.3 x 10-11 mbar. In this paper, the vacuum system of the RAON EBIS and test procedures and results are presented and discussed.