ABSTRACT
Secondary electrons are of central importance in spacecraft charging. When an electron impacts on an atom, it may impart some of its energy E to the atom, resulting in excitation or ionization, depending on the energy available. The incoming electrons are also called primary electrons. Therefore, an object placed in space plasma, or laboratory plasma, would be likely to intercept more electrons than ions. As far as the interplay between these two chess pieces, ambient electrons and ambient ions, is concerned, it is indeed true that an object placed in plasma would likely charge to negative potentials. For each incoming electron impacting on a solid surface, the number of secondary electrons coming out from the solid surface is a probability δ(E), which depends on the energy E and the properties of the solid.
