The beamline of Isotope Separation On-Line (ISOL) system at RAON was constructed. Currently, the beamline is commissioning using 133Cs and 120Sn ion beam. The produced ion from Target Ion Source(TIS) is delivered to Electron Beam Ion Source (EBIS) charge breeder through the Radio Frequency Quadrupole Cooler Buncher (RFQ CB). The RFQ CB handles and delivers the beams required by EBIS. A sufficiently cooled and bunched beam improves the charge breeding efficiency of EBIS. The RFQ CB cools and bunches DC beam from the TIS, delivering 1E+8 ions per bunch to the EBIS. In order to increase the efficiency, the beam optics were optimized in consideration of the space charge effect. As a result, 1e+8 ions could be sent in a bunch with a length of several ten microseconds. In this presentation, the beam commissioning results for RFQ CB and EBIS will be discussed.

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.

The heavy-ion accelerator RAON is being developed by the Rare Isotope Science Project (RISP) in the Institute for Basic Science (IBS) of Korea for basic science research through experiments with rare-isotope (RI) beams. Various RI beams are transported from the Isotope Separation On-Line (ISOL) beamline, and they are accelerated in the superconducting post-accelerator. The energy requirement of the RI beams for the post-accelerator is 10 keV/u, and their charge state must be adjusted to facilitate the acceleration. The Electron Beam Ion Source (EBIS) charge breeder is installed before the post-accelerator to match the mass-to-charge ratio (A/q) of the RI beams to the accelerator condition. A singly charged ion beam is trapped in the EBIS and interacts with the compressed electron beam in a strong magnetic field. The electron beam removes electrons of the ion beam by collision and produces highly charged ions. A Cs test ion source is used for the offline test of the EBIS charge breeder, and the results will be described in this presentation.