Reasons for a reduction in the efficiency of a pulse-periodic CO2 laser with a non-self-sustained discharge at increased input energies

A theoretical and experimental investigation was made of the dependences of the energy characteristics of a pulsed atmospheric pressure electron-beam-controlled CO₂ laser with added water vapor on the electric field strength and the specific pump power. A nonthermal mechanism, lowering the lasing efficiency when the input energy was raised and associated with a non-Boltzmann population of the upper vibrational levels of the nitrogen, was discovered. A purpose-developed calculation method makes it possible to explain the experimental results.