  It is well known that a charged particle cannot be in stable equilibrium in a
purely electrostatic field. The situation is different in a magnetostatic
field; consequently, magnetic levitation is possible while electrostatic
levitation is not. In this paper, motivated by an analogy with a mechanical
system, we show that the addition of a small oscillating electrical field to an
otherwise electrostatic configuration leads to the stabilisation of unstable
equilibrium points. Therefore, levitation becomes possible in an "almost
electrostatic" field.
