Diagnostics of the active medium of a waveguide CO2 laser by the ‘laser spectrograph’ method

The gains were measured for the lines in the traditional bands 00⁰1–10⁰0, 00⁰1–02⁰0, in the second band of the 00⁰2–10⁰1 sequence, and in the hot band 01¹1–11¹0 emitted by the active medium of a waveguide electric-discharge CO₂ laser. The experimental results were used in a generalised theoretical model to find the translation and vibrational temperatures, and the concentration of the active molecules. The Fermi resonance between the 10⁰0 and 02⁰0 levels did not ensure a Boltzmann distribution of their populations under the conditions in the waveguide CO₂ laser. The degree of dissociation of the CO₂ molecules in the discharge did not exceed 30% when the maximum input power density was ~70 W cm^–3.