Radiative recombination of highly charged ions: Enhanced rates at low energies

In a single‐pass merged‐beams experiment employing a dense cold electron target recombination of highly charged ions is studied. Unexpected high recombination rates are observed at low energies Ecm in the electron‐ion center‐of‐mass frame. In particlar, theoretical estimates for radiative recombination are dramatically exceeded by the experimental recombination rates at Ecm=0 eV for U28+ and for Au25+ ions. Considerable rate enhancement is also observed for Ar15+. This points to a general phenomenon which has to be interpreted as a consequence of high electron densities, low electron beam temperatures, high ion charge states and presence of strong magnetic fields.