Effusion. II. Angular Number Distributions of Gaseous Cadmium from a Right-Circular Cylindrical Orifice into Vacuum

Abstract

The angular number distributions of Cd(g) atoms effusing from a Pyrex right‐circular cylindrical orifice have been studied by use of a condensation target. The profile of the deposit on the condensation target was analyzed by an interferometric means. Only qualitative agreement with the Clausing prediction for the angular number distribution could be obtained. A high‐pressure limit for molecular flow was found to be $\text{3.9\hspace{0.17em}<\hspace{0.17em}K}$ (Knudsen number; ratio of mean free path to orifice diameter) <4.6. At higher pressures in the transition region, the probability of effusion in the forward direction decreases with increasing pressure.