Parametric experimental and theoretical study of a cold-cathode electron-beam-controlled CO2 laser

This paper presents parametric studies of the performance of a 10-liter atmospheric-pressure CO2 laser system controlled by a 4-μsec 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 of E/P the 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 CO2 gas. The model also predicts the shapes of oscillator pulses satisfactorily.