Charge breeding of isotope on-line-created radioactive ions using an electron cyclotron resonance ion trap
Résumé
In the coming years huge ion-beam projects are foreseen. They deal with specific isotope on-line (ISOL) beams such as ISOL-created radioactive ions. The beam intensities are exceptionally high (>10^12 ions/s), the radioactive lifetimes are short (<=1 s), and the ion energy is very high (>=150 GeV/u). In general in order to minimize the size of the accelerator one needs highly charged ISOL ions and therefore charge breeders are a must. In contrast with the CERN system, utilizing a Penning trap and an electron-beam ion source charge breeder (where the maximum ion beam cannot exceed 10^6 ions/s) the Grenoble group launched in 1995 an electron cyclotron resonance (ECR) system capable of storing 10^12 ions/s and delivering highly charged ISOL ions. In this article we show that this storage is possible for low-ion-energy ISOL ions following classical slowing down theory. In this case the injected ISOL ions are slowed down by ion-ion collisions which yield ion storage inside the ECR plasma, but also charge breeding by the energetic ECR electrons bombarding the slowed down ions.