Charge breeding of radioactive ions with EBIS and EBIT

A charge state breeder, which transforms externally injected singly charged ions to a higher charge state q+, is an important tool which has applications within atomic, nuclear and even particle physics. The charge breeding concept of radioactive ions has already been demonstrated at REX-ISOLDE/CERN with the use of an Electron beam Ion Source (EBIS) and at several facilities employing Electron Resonance Cyclotron Ion Sources (ECRIS). As will be demonstrated in this paper, EBIS and Electron Beam Ion Traps (EBIT), are well suited for the task as they are capable of delivering clean, highly charged beams within a short transformation time. The increasing demand for highly charged ions of all kind of elements and isotopes, stable and radioactive, to be used for low-energy experiments such as TITAN at TRIUMF and MATS at FAIR, but also for post-acceleration to higher energies, is now pushing the development of the breeders. The next challenge will be to satisfy the needs, for example space-charge capacity, of the second generation radioactive beam facilities presently under construction or in the design stage, such as the MSU re-accelerator (ReA3), SPIRAL2, SPES and later on EURISOL. Radioactive trap facilities will also require high performance breeders geared towards rapid breeding times. The requirements and the critical issues of the breeding concept will be discussed and a review of the different facilities, operational and planned, will be given. The paper does furthermore feature a summary of the extensive breeding experience gained under operational conditions at REX-ISOLDE, including results from dedicated beam cleaning tests, isotope production using in-trap decay, high-current and continuous ion injection into the breeder, and closed-shell breeding.