A model is developed for electron-ion recombination in a gas capacitor in which the cathode is irradiated simultaneously by an electron beam and a defocused flux of soft-landing ions, under conditions such as encountered in variable pressure scanning electron microscopes (SEMs). The model describes the dependence of the secondary electron (SE) emission current (injected into the gas from the cathode) on the distance above the cathode, and the effects of SE-ion recombination on electron imaging signals utilized in SEMs. The model is tested experimentally, and is used to construct a simple procedure for quantification of the effects of SE-ion recombination on emissive signals in a gas capacitor. The presented method allows for quantification of electron emission current measurements obtained in a variable pressure SEM.