COLLISION BROADENING IN ELECTRON BEAMS.

A simple calculation of the energy spread induced in an electron beam as it passes through a focus is presented, showing that this energy spread can be quite large in practical situations. The relationship between this effect and the well-known Boersch effect is not at all clear. Most experimental situations involve an additional beam cross-over in the electron gun and this effect is not included in the present calculations. The results shown here differ from existing theories both in magnitude and in the dependence upon the parameters. However, the results seem consistent with simple physical arguments.