Naked singularities, event horizons, and charged particles

The motion of charged test particles in a Reissner-Nordstr\"om field is investigated. It is shown that naked singularities can be destroyed by shooting in suitably charged test particles to produce an event horizon around the source where none previously existed. It is also shown that existing event horizons cannot be destroyed by bombardment with charged test particles. In this manner existing naked singularities can be destroyed but not created while event horizons can be created but not destroyed. Furthermore, a simple explanation is given for radial test-particle oscillations---a phenomenon with no Newtonian analog.