Dynamics of population of the A3∑u+ nitrogen metastable state in a self-sustained volume discharge of a pulsed CO2 laser

Intracavity laser spectroscopy was used to study the dynamics of population of the ν = 2–8 vibrational levels of the A³∑_u⁺ state in order to establish the possible influence of multistage ionization on the evolution of instability in a self-sustained volume discharge in CO₂ laser active mixtures. The populations of the nitrogen vibrational levels N_ν were calculated taking into account the real output pulse profile of a dye laser. It was found that multistage ionization can only influence the duration of stable operation of a self-sustained volume discharge by increasing the rate of growth of the spark channel in the discharge gap. This is why the addition of readily ionized substances to the gas that reduce the electron energy and therefore lower N_ν can substantially improve the stability of the volume discharge and increase the active volume and output energy of a CO₂ laser.