Beschreibung:
<jats:p>The Boersch effect is calculated for two electron-beam configurations: an ideal lens leading to a single crossover and an electron gun which has no crossover. The results agree with previous work both as to the spatial spreading caused by space charge and the energy broadening due to electron-electron interactions. The energy spread produced in a gun with no crossover is clearly demonstrated and shown as a function of emitting area and beam current.</jats:p>