  We describe the influence of electron-impact multiple ionization (EIMI) on
the ionization balance of collisionally ionized plasmas. We are unaware of any
previous ionization balance calculations that have included EIMI, which is
usually assumed to be unimportant. Here, we incorporate EIMI cross-section data
into calculations of both equilibrium and non-equilibrium charge-state
distributions (CSDs). For equilibrium CSDs, we find that EIMI has only a small
effect and can usually be ignored. However, for non-equilibrium plasmas the
influence of EIMI can be important. In particular, we find that for plasmas in
which the temperature oscillates there are significant differences in the CSD
when including versus neglecting EIMI. These results have implications for
modeling and spectroscopy of impulsively heated plasmas, such as nanoflare
heating of the solar corona.
