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 ~ 50 eV. Above ~ 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 ~ 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 2.2 times the predicted RR rate), reproducing the low-energy recombination enhancement found in other recent experiments.