Current driven weak double layers

Abstract

Double layers in plasmas can be created by different means. For example, a potential difference forms between two plasmas with different temperatures (Hultqvist, 1971;Ishiguro et al., 1985), in a plasma jet flowing along a converging magnetic field (Serizawa and Sato, 1984), in a quiescent plasma submitted to an external difference of potential, or in a turbulent plasma carrying an electric current. The first three cases can be current-free, but not necessarily, although the numerical simulations have been made under such conditions for the first two points (Ishiguro et al., 1985;Serizawa and Sato, 1984). Apart from the third case, which is mainly of interest for laboratory experiments, these double layers are good candidates for accelerating the auroral electrons to the few kiloelectron volts observed.