Visual study of the microdrop component in sodium vapor-inert gas mixtures in a heat pipe

The parameters (size, density, and velocity) of the microdrop component in the cooling zone of a heat pipe in Na + He and Na + Kr mixtures have been determined by visualization. It is found that particles in helium have an average size of 14 μm and concentration of 1.6 × 10⁴ cm^?3, while the corresponding values for krypton are 42 μm and 3 × 10³ cm^?3. The effect of microdrops as causes of nonequilibrium enhanced concentration of sodium trimers is analyzed. Such a concentration of trimers can explain the high IR absorption coefficients (above 0.9 μm), which were previously observed in heat pipes.