Abstract

Analysis of plasma sheet electron temperature distribution and electron flux fluctuations show on the unmagnetized stochastic character of motion of plasma sheet electrons (and not only ions as it was usually considered). Stochastization of plasma sheet ions is mainly connected with ion motion in the inhomogeneous magnetic field where the Larmor radius of ion is comparable with characteristic scale of magnetic field inhomogeneity. Stochastization of electron motion may be the consequence of its interaction with inhomogeneous electric fields when the characteristic scale of such inhomogeneity is comparable with electron Larmor radius. Chaotization of particle trajectories may be the part of stochastization process. Particle motion in the homogeneous magnetic field and regular inhomogeneous electric field having sinusoidal distribution in one direction and homogeneous distribution in perpendicular direction is analyzed as an example of a chaotic motion. The examined electric field configuration may be the characteristic feature of auroral ribbon band. By the method of calculating Lyapunov exponent it is shown the such motion can became chaotic. The characteristic time of chaotization is determined. © 1999 COSPAR. Published by Elsevier Science Ltd.