The effect of laser irradiation conditions on the parameters (yield and charge composition) of plasma formed upon the irradiation of solid substances was studied. It was shown that ionization processes in determining gas-forming impurities in solids on a tandem mass reflectron considerably affect the precision and accuracy of the results of analysis. A system is proposed to stabilize the ion current of a laser ion source for time-of-flight mass spectrometers. It is based on the conservation of the amounts of singly and doubly charged ions of the analyte matrix. Stabilization is attained due to the constancy of the position of the sample plane relative to the focus plane of the laser radiation. The precision of the results of analysis can be improved more than fivefold.