Investigation of a cooled electron-beam-controlled CO laser. II. Laser action in CO-buffer gas mixtures

Investigations were made of the threshold, energy, temporal, and spectral characteristics of a cryogenic pulsed electron-beam-controlled CO laser utilizing mixtures of CO with helium and nitrogen. The active volume of the experimental system was ~5 liters, the excitation duration was 30–300 μsec, and the active gas density was ≤ 1.5 amagat. It was shown that cooling the active medium to 80–100°K made it possible to increase the gain to 1.5×10^–2 cm^–1, the energy output to ~100 J· liter·amagat^–1, and the efficiency to 35%. Radiation energies of ~250 J and 400 J were obtained at densities of 0.5 and 1.5 amagat, respectively. Laser action was observed in the spectral range 4.95–5.5 μ. On increasing the pump energy and the buffer gas concentration, the stimulated emission spectrum was shifted toward shorter wavelengths. Decreasing the CO concentration in a nitrogen mixture to 2.5% for a constant exciting pulse duration of ~100 μsec increased the radiation pulse duration (at half-height) from ~100 μsec (pure CO) to ~3 msec. A comparison was made between the results of theoretical calculations and the experimental data given by other authors.