Heating in a CO2 waveguide laser

The heating of a CO2 waveguide laser is calculated for the case when the thermal conductivity of the wall material of the gas discharge tube is finite. The output power is shown to be insensitive to heating when wall materials (such as sapphire) with conductivities over 10 W/(m-K) are used. A prototype cw CO2 laser on a leucosapphire waveguide was built; it had a radiation power of 22 W/m per unit length, and the active medium was cooled by diffusion.