Dimer Concentrations in Supersonic Free Jets

Abstract

Measurements have been made of the concentration of dimers produced during the expansion from a supersonic nozzle. The gases studied were: Ar, N 2 ,O 2 , CO, CO 2 , C 2 H 4 , and N 2 O. It is shown that an effective specific heat ratio of the expanding gas offers a means of correlating the dimer concentration in terms of the source gas pressure and temperature. The two nozzles employed had opening diameters of 0.14 mm and 0.065 mm. An attempt to obtain a universal dependence for all gases in terms of reduced source parameters was partially successful. Source temperature was varied between 90 °K and 295 °K.