Penning ionization in a plasma ion source

Results are presented of an experimental study of the efficiency of the ion source with Penning ionization. Mercury was used as a separated sample. Measurements of the source efficiency for Hg were carried out for the source operating on He and Ar, i.e. gases with which additional Hg ionization could result due to the Penning effect. A simple theoretical model of the plasma in the ion source was developed and the pressure dependence of the ratio of the source efficiencies for the separated sample and carrier gas was calculated. By parametrically fitting the predicted source efficiency ratio equation to the experimental data, estimates of certain coefficients for the processes taking place in the source plasma could be derived. (orig.)