Similarity laws for glow discharges with cathodes of metal and an electrolyte

The pressure dependence of the cathodic current density in the case of an electrolyte and a metal cathode glow discharge operating in air and helium atmospheres was investigated. In all cases, at pressures above 100-200 mbar, violation of the similarity law j approximate to constant x p(2) was observed, which was attributed to the occurrence of the dissociative recombination of molecular ions of the applied gases (H2O+, N-2(+) and He-2(+)). Taking into consideration this process, the relation j approximate to constant x root p was deducted, which was found to be in accordance with experimental data. In the case of an electrolyte cathode this relation was found to be valid also at low pressures.