Experimental verification of revised roles played by helium and nitrogen in CO₂ lasers

In one of our previous papers we presented a fast axial flow CO₂ laser excited by 150 kHz resonant silent discharge. The optimized gas mixing ratio of this setup was CO₂:N₂:He = 1:22:5. This ratio was very peculiar but the laser efficiency thus achieved was optimized and comparable to that of other fast axial flow CO₂ lasers. We have already put forth some preliminary postulations explaining the reason for this particular result; nevertheless in order to obtain a clearer insight into this laser we designed and carried out a series of experiments. The data collected were helpful for understanding why N₂ is more important than He, and what roles they play in such a laser system.