Ion motion in a polarized current sheet

TL;DR

This paper analytically investigates how a polarization electric field influences ion trajectories and transient particle behavior in thin current sheets, with implications for planetary magnetospheres.

Contribution

It introduces an analytical framework using adiabatic invariants to describe ion motion in polarized current sheets, highlighting effects on trapping and ejection of ions.

Findings

Ion trajectories are affected by the polarization electric field.

The phase space volume of transient particles depends on electric field strength.

Transient particle and current densities vary with electric field amplitude.

Abstract

We consider the effects of a polarization electric field on transient ion motion in a thin current sheet. Using adiabatic invariants, we analytically describe a variety of ion trajectories in current sheet configurations which include a local minimum or maximum of the scalar potential in the central region. Ions in the current sheet can either be trapped or ejected more efficiently than in an unpolarized current sheet, depending on the sign and magnitude of the polarization electric field. We derive an expression for the relative phase space volume filled by transient particles as a function of the electric field amplitude. This expression allows us to estimate the dependence of transient particle and current densities on the electric field. We discuss applicability of these results for current sheets observed in planetary magnetospheres.