Quasi-adiabtic particle dynamics in thin current sheets with a magnetic shear

The dynamics of quasi-adiabatic ions in thin current sheets (TCSs) of the planetary magnetotails and solar wind is investigated, when the characteristic scale of the magnetic inhomogeneity is compared with proton gyroradii. A numerical model of TCS is constructed, taking into account the constant normal magnetic component and three kind of the shear magnetic field distributions: 1) constant, 2) bell-shaped relatively equatorial plane and 3) anti-symmetric ones. The Poincaré cross- sections characterizing quasi-adiabatic ion dynamics are considered. The jumps of the quasi-adiabatic invariant of motion are calculated and compared with the case of the absent magnetic shear. It is shown that the presence of constant and bell-shaped magnetic components in the current sheet leads to the asymmetry of particle scattering in the Northern-Southern direction and the peculiarities of the structure of phase space. It is shown that the jumps of the quasi-adiabatic Iz invariant differ are different for plasma flows located in the Northern and Southern hemispheres.  At the same time, for configurations with anti-symmetric shear component, the particle scattering near TCS neutral plane is insignificant and the scattering asymmetry is absent. The results of this study are discussed in terms of their application to explain experimental data.

This work is supported by RFBR grant 19-02-00957.