Velocity analysis of on-axis cesium atoms by the time-of-flight method

Time-of-flight distributions of cesium atoms effusing from the near-ideal orifice of an oven have been measured for Knudsen numbers ranging from 1 to 370. The apparatus consisting of a single-disk chopper and a single-ion counting detector is described. The experimental results are compared with theoretical data computed by using the free-molecule flow model. Experiment and theory are in good agreement. An error analysis is carried out. Deviations from the results of other studies are discussed. The influence of the scattering of cesium atoms by residual gas particles is demonstrated by a distorted distribution curve.