Enhancement of charge breeding efficiency for rare isotope beam with the control of magnetic field profile and electron
- PDF / 1,193,941 Bytes
- 7 Pages / 595.276 x 790.866 pts Page_size
- 0 Downloads / 176 Views
RESEARCH
Enhancement of charge breeding efficiency for rare isotope beam with the control of magnetic field profile and electron beam energy in EBIS J. W. Kim1 Received: 19 December 2019 / Accepted: 8 August 2020 © Islamic Azad University 2020
Abstract The magnetic field in the ion trap of electron beam ion source (EBIS) determines the current density of electron beam and thus the depth of trap potential, which affects the charge breeding efficiency to desired charge state. An EBIS charge breeder has been constructed to be used for the Rare Isotope Science Project in Korea. A 6 T superconducting solenoid is used for the trap, and uniform magnetic field is extended with correction coils at the ends. The effect of field uniformity on the electron current density is evaluated using TRAK, and it is shown sizable improvement in the charge breeding efficiency for rare isotope beams can be obtained by elaborate magnetic design. Furthermore, the electron beam energy affects the ionization efficiency. The electron energy is often reduced in the trap for optimal matching with charge striping cross section. However, virtual cathode formation can appear in the process of energy reduction. Maximum beam currents limited by electron energy are studied analytically and by TRAK simulation in the view of improving the charge breeding efficiency. Keywords Electron beam ion source (EBIS) · Superconducting magnet · Charge breeding · Rare isotope beam · Virtual cathode
Introduction Production of high-current and high-quality beams of highly charged ions from ion source is an important consideration for the efficient operation of high-intensity heavy-ion accelerator facility. An electron beam ion source (EBIS) can provide highly charged pulsed beams for synchrotron and linear accelerator, and is well suited for charge breeding of rare isotope beams for reacceleration [1]. An EBIS has been constructed for Rare Isotope Science Project (RISP) in Korea as a charge breeder of isotopes produced by isotope separation on-line (ISOL) method [2, 3]. The isotopes will be charge-bred to have the A/q below 7 for the injection into a superconducting (SC) linac. The EBIS will be operated in a pulsed injection mode with the use of a radio frequency quadrupole cooler buncher (RFQCB) located upstream of the EBIS [4]. The EBIS is under * J. W. Kim [email protected] 1
Rare Isotope Science Project, Institute for Basic Science, Daejeon 34000, Korea
preparation for off-line test as shown in Fig. 1 prior to the final installation in the new ISOL facility in the end of 2020. A Cs surface ion source will be used in the test, and chargebred beams will be analyzed using a time-of-flight measurement system similar to the one used at Brookhaven National Laboratory [5]. Charge breeding efficiency to desired charge state is a key parameter in planning physics program using rare isotope beams. A major requirement is to breed C s1+ into Cs27+ with an efficiency of over 20%. While the structural design of this EBIS is based on that for CARIBU at Argonne Nationa
Data Loading...
