Abstract

ACEVES, H.; REYES-RUIZ, M.  and  CHAVEZ, C. E.. Effects of Magnetic Turbulence on the Dynamics of Pickup Ions the Ionosheath of Mars. Rev. mex. astron. astrofis [online]. 2012, vol.48, n.1, pp.137-148. ISSN 0185-1101.

We study some of the effects that magnetic turbulent fluctuations have on the dynamics of pickup O⁺ ions in the magnetic polar regions of the Mars ionosheath. In particular we study their effect on the bulk velocity profiles of ions as a function of altitude over the magnetic poles, in order to compare them with recent Mars Express data; that indicate that their average velocity is very low and essentially in the anti-sunward direction. We find that, while magnetic field fluctuations do give rise to deviations from simple E × B-drift gyromotion, even fluctuation amplitudes much greater than those of in situ measurements are not able to reproduce the vertical velocity profile of O⁺ ions. We conclude that other physical mechanisms, different from a pure charged particle dynamics, are acting on pickup ions at the Martian terminator. One possibility is a viscous-like interaction between the Solar Wind and the Martian ionosphere at low altitudes.

Keywords : acceleration of particles; magnetic fields; methods [numerical]; planets and satellites [individual (Mars)]; turbulence.