This paper presents parametric studies of the performance of a 10‐liter atmospheric‐pressure CO2laser system controlled by a 4‐&mgr;sec pulse of electrons from a cold‐cathode gun. The experimental results are compared to the predictions of a theoretical model described in this paper. For various laser gas mixtures and values ofE/Pthe peak small‐signal‐gain coefficients range up to 4.7% cm−1. Measurements of gain uniformity across the laser medium and of the time dependence of the small‐signal gain are also presented. Operation of the device as an oscillator over a range of parameters has shown that the output pulse typically consists of a sharp gain‐switched spike followed by a longer tail with energies up to 30 J in the spike and 200 J in the entire pulse. The theoretical model generally predicts peak small‐signal gain well for gas mixtures containing nitrogen; the largest discrepancy is for pure CO2gas. The model also predicts the shapes of oscillator pulses satisfactorily.