Simulation and design of an electron beam ion source charge breeder for the californium rare isotope breeder upgrade

Clayton Dickerson,Sergey Kondrashev,Brahim Mustapha,Alexander Pikin,Peter Ostroumov,Rick Fischer,Anthony Levand

doi:10.1103/physrevstab.16.024201

Abstract

An electron beam ion source (EBIS) will be constructed and used to charge breed ions from the californium rare isotope breeder upgrade (CARIBU) for postacceleration into the Argonne tandem linear accelerator system (ATLAS). Simulations of the EBIS charge breeder performance and the related ion transport systems are reported. Propagation of the electron beam through the EBIS was verified, and the anticipated incident power density within the electron collector was identified. The full normalized acceptance of the charge breeder with a 2 A electron beam, $0.024\ensuremath{\pi}\text{ }\text{ }\mathrm{mm}\text{ }\mathrm{mrad}$ for nominal operating parameters, was determined by simulating ion injection into the EBIS. The optics of the ion transport lines were carefully optimized to achieve well-matched ion injection, to minimize emittance growth of the injected and extracted ion beams, and to enable adequate testing of the charge bred ions prior to installation in ATLAS.

Highlights

The californium rare isotope breeder upgrade (CARIBU) has been commissioned, and at full capacity will produce $80 to 160 amu fission fragments at intensities up to $107 ions=s from a 1 Curie 252Cf source [1]
The electron cyclotron resonance (ECR) has produced charge breeding efficiencies into a single charge state of up to 15% for radioactive 143Csþ27 [2], but extracted beams can contain significant contamination due to plasma-surface interactions within the ECR chamber which can subsequently obscure the signal of low intensity radioactive ion beams (RIB)
A charge breeder based on the electron beam ion source (EBIS) concept [3] will be constructed for the CARIBU system, and will improve the purity and the intensity of ion beams for acceleration in Argonne tandem linear accelerator system (ATLAS) [4]

Summary

Introduction

The californium rare isotope breeder upgrade (CARIBU) has been commissioned, and at full capacity will produce $80 to 160 amu fission fragments at intensities up to $107 ions=s from a 1 Curie 252Cf source [1]. Fragments are thermalized in a He gas catcher, mass separated into low-energy ion beams, charge bred, and injected into the Argonne tandem linear accelerator system (ATLAS). An electron cyclotron resonance (ECR) ion source currently charge breeds ions from CARIBU. A charge breeder based on the electron beam ion source (EBIS) concept [3] will be constructed for the CARIBU system, and will improve the purity and the intensity of ion beams for acceleration in ATLAS [4]. EBIS charge breeders, while more complicated, have produced better breeding efficiencies and ion beams with fewer contaminants than ECR sources [5,6]. A single charge state breeding efficiency of 17% was reported for 133Csþ from 133Csþ at the T-EBIS using a 1.5 A electron beam, an electron beam current density in the trap of 76 A=cm, an electron beam energy of 19 keV, and a breeding time of 5.3 ms [10]

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Conclusion