Measurement of the Angular Distribution of Electrons Ejected from Tungsten by Helium Ions

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Abstract
Rotating collector measurements, made at a pressure of 10−5 mm Hg, yielded cosine distributions for all experimental conditions. Data were obtained for gas-covered and partly gas-covered target surfaces, for several beam incidence angles, and for ion energies of 40, 400, and 825 ev. It is postulated that the identical cosine distributions observed for both kinetic and potential ejection are caused by the existence of isotropic angular distributions for both mechanisms within the metal. A general expression is given for the angular distribution of emission from an arbitrarily shaped surface. This expression is a function of the fundamental angular distribution associated with a single element of area on that surface and the orientation distribution of the elements of area.