Determination of the gain of a 10.6 $\mu$ signal in an active medium of a rectangular metal waveguide

The gain a was determined as a function of the pressure $p$ in an active medium of a $CO_2$ waveguide amplifier. The gain of a waveguide representing a metal-reflecting coating structure, measured at the maximum of the function $\alpha(p)$, was 30% higher than the gain of a similar amplifier enclosed in a BeO discharge tube. An analysis was made of the main factors responsible for the improvement of the gain of this structure at the wavelength of 10,6 $\mu m$.