Mechanism of population inversion in He(Ne,Ar)–NF3 mixtures pumped by a self-sustained discharge

Studies of spontaneous radiation and lasing, measurements of the electron density and temperature, and also an analysis of the rates of various processes in mixtures of helium, neon, and argon with NF₃ (pumped by a self-sustained discharge)were used to show that, under conditions of lasing due to atomic transitions in rare gases, the upper active level is filled by electronic excitation processes and the lasing pulse duration in the afterglow is limited by ion-ion recombination.