Recombination of bare Cl17+ ions in an electron cooler

Using an electron beam merged with an energetic ion beam in a storage ring, non-resonant recombination between multiply charged ions and free electrons is studied by measuring directly the rate of recombination products leaving the interaction zone. The relative electron-ion energy was varied from meV energies up to similar to 50 eV. Above similar to 0.5 eV the measured rates are well represented by the calculated RR into final states up to the experimental Rydberg-ion detection limit. Between similar to 0.01 and 0.5 eV the calculated RR rates are 10% experimental data. As the relative energy is decreased below 0.01 eV the observed recombination rates rise strongly (to less than or similar to 2.2 times the predicted RR rate), reproducing the low-energy recombination enhancement found in other recent experiments.