Distributions of the electromagnetic field and of the gain in a plane-parallel resonator of a CO2 gasdynamic laser at high values of the Fresnei number

An investigation is reported of changes in the characteristic lengths of the processes of exchange and their relaxation in an inverted CO₂–N₂–H₂O medium on the structure of modes in a planeparallel resonator of a CO₂ gasdynamic laser. A four-temperature kinetic model is used in the calculations. The problem of the ultimate geometric-optics distribution of the field is considered. It is shown that for sufficiently large values of the equivalent Fresnei number the modes with an intensity distribution close to that predicted by geometric optics have a minimum in the gain distribution in the downstream direction.