The formation of H+from H-ions by electron impact

Cross sections of the reaction H - +e to H + +3e have been measured for interaction energies between 17.8 and 1000 eV. Comparison with the only other measurement shows present results to be much smaller. The discrepancy ranges from a factor four at low energies to a factor 12 at high energies. The influence of positive ion trapping in the electron beam has been carefully investigated in the course of this study as it could explain the large discrepancy.