Production of highly charged ions inside a cryogenic Penning trap by electron-impact ionisation

Abstract

We have built and operated a cryogenic Penning trap arrangement
that allows for the efficient production, selection, and long-term storage of highly
charged atomic ions. In close similarity to an electron-beam ion trap (EBIT)
it works by electron-impact ionisation of atoms inside a dedicated confinement
region. The electrons are produced by field emission at liquid-helium temperature
and are subsequently accelerated to the keV energy range. The electron beam is
reflected through the trap multiple times to increase the ionisation efficiency. We
show a characterisation of the system and measurements with argon and tungsten
ions up to Ar16+ and W27+, respectively.