Calculations of Effusive-Flow Patterns. I. Knudsen-Cell Results

A simple and direct procedure has been used to calculate the flux gradients inside Knudsen cells and the related effusive-flow patterns. Knudsen cells of simple geometries with knife-edge orifices and flat sources are considered. The calculated value of the Motzfeldt factor (1. 020) is in very good agreement with the literature value (1. 020) and the Monte Carlo calculations (1. 020) for a cell of reduced height $H=4.0$ and the knife-edge orifice of reduced diameter=0.1064. It is suggested that an extension of these calculations has an importance in solving some of the problems encountered in determining the absolute total scattering cross section from scattering measurements.