Time-dependent potential functions to stretch the time distributions of ion pulses ejected from EBIST

Abstract

Electron beam ion sources and traps (EBIST) produce and trap highly charged atomic ions with an electron beam of high current density. The ions are confined in the radial space-charge potential of the electron beam and a long square-shaped axial electrostatic potential well. An important field of application of EBIST is charge breeding of highly charged ions at radioactive ion beam facilities. There, highly charged radioactive isotopes are accelerated by particle accelerators for experiments in nuclear astrophysics and to study the structure of unstable nuclei. The width in time of the ion pulses ejected from EBIST can often contain too many ions for nuclear physics detection systems to efficiently detect all single radioactive isotopes or related events. Neglecting the influence of ion–ion collisions on the extraction rate, this publication derives, for different initial thermal energy distributions of the trapped ions, the time-dependent trap-opening functions to stretch the time distribution of ion pulses ejected from an EBIST trapping potential for the release of ions at a constant rate over an extended extraction period.