Analysis of a model for a current-carrying plasma

The collisional evolution of a stable, fully ionized plasma under the effect of an applied electric field is studied in the context of recent work on runaway-dominated discharges in toroidal devices and the effects connected with the non-Maxwellian nature of the electron distribution function in the Alcator device. The trapping effect, characterizing hot toroidal plasmas, is simulated by two models whose aim is to investigate the collisional interaction of the current-carrying electron population with the plasma and the resulting shape of the electron distribution function which may strongly affect the stability properties of the plasma. The formation of ion-acoustic instabilities driven by an electron drift higher than ion-acoustic velocity is considered.