[en] This letter is motivated by recent results concerning the occurrence of runaway-dominated discharges in many toroidal devices, and the effects connected with non-Maxwellian character of the electron distribution function in the Alcator device. The collisional evolution of a stable, fully ionized plasma, initially isotropical, is considered under the influence of an applied electric field. No magnetic field and no space gradient are taken into account, but the trapping effect is simulated by means of ad hoc interventions either on the force term or directly on the electron distribution function