7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

EBIS charge breeder producing highly charged ions for RAON facility
K. Yoo1, S. Heo1, T. Hashimoto1, H.-J. Yim1, J. Lee1, and T. Shin1
1
Institute for Rare Isotope Science, Institute for Basic Sciencee-mail (speaker): ykh8287@ibs.re.kr

The Rare Isotope Accelerator complex for ON-line
experiments (RAON), a Korean heavy-ion accelerator, isunder development at the Institute for Basic Science andis currently in the commissioning phase.[1,2] Within theRAON facility, diverse rare isotope (RI) ions aregenerated through the Isotope Separation On-Line(ISOL) system and subsequently transported to thepost-accelerator. The ISOL system is composed ofseveral components, including the Cyclotron, the Target
Ion Source (TIS) module, the pre-mass separator, and thebeam transport and manipulation line.[3] In the TIS
module, a 70 MeV proton beam collides with the target,
resulting in the creation of RI elements, which aresubsequently ionized and extracted. These various RI
ions are then separated based on their mass using thedipole magnet in the pre-mass separator, enabling theselection of specific elements. The RI ions with thedesired mass are required to undergo manipulation
before being utilized in the post-accelerator. Thismanipulation is necessary because the post-accelerator
has specific criteria, namely a mass-to-charge (A/q) ratioof less than 6 and an energy per nucleon matched to 10
keV/u.
The Electron Beam Ion Source (EBIS) is utilized tomeet these criteria by generating ions with a high charge
state. The design and installation of the EBIS charge
breeder are focused on harnessing an electron beam witha maximum intensity of 2 A, operating within a 6 T
superconducting magnet, as illustrated in Figure 1.[4,5]with adjustments made to the high voltage (HV) platform
to ensure their energy reaches 10 keV/u.
As part of the commissioning process for the ISOL
system, the EBIS charge breeding experiment
incorporates the utilization of several stable ions,specifically Cs, Sn, and Na. These ions are sourced fromeither the test ion source or the ISOL beamline.[4,5] By
applying an electron beam current of 1 A, ions such as133
Cs27+, 120Sn24+, and 23Na7+ have been effectivelygenerated and categorized. The outcomes of the A/q
distribution of charge-bred Sn ions are presented in
Figure 2. Following this, the A/q separator is employed
to classify these ions based on their A/q ratio. Those ionsthat fulfill the predefined selection criteria aresubsequently transported to the post-accelerator,
satisfying the distinct prerequisites of that stage. The
performance of the EBIS has been verified through theoutcomes of the commissioning process. Furthermore,ongoing tests of the RAON EBIS are being conductedusing RI ions.

Figure 2. A/q (mass-to-charge ratio) distribution ofcharge-bred Sn ions with residual gases.[3]Figure 1. Installation of the RAON EBIS charge
breeder.[5]The electron beam originates from the E-Gun section andis directed toward the Collector section. Here, it
undergoes radial compression through a powerfulmagnetic field. Interaction takes place between theelectron beam and a singly charged RI ion beam that is
introduced and subsequently trapped within the EBIS.
This interaction leads to the removal of electrons fromthe ion beam. Through the EBIS process, highly charged
ions are generated, thereby fulfilling the prerequisites
necessary for achieving the desired A/q value. These
highly charged ions are then extracted from the EBIS,

References[1] S. Jeong et al, Proc. of 7th Int. Particle Accelerator
Conf.(IPAC’16). 2016[2] Y. S. Chung et al, J. Korean Phys. Soc. 82, 613(2023)[3] J. Lee et al, Nucl. Instrum. Methods Phys. Res. B 542,
17-21 (2023)[4] K. Yoo, Ph.D Thesis “Production of Highly Charged
Ions using Electron Beam Ion Source Charge Breeder for
RAON Accelerator Facility” (2023)[5] K. Yoo et al, Nucl. Instrum. Methods Phys. Res. B
541, 286-288 (2023)