Perpendicular electron trapping associated with nonlinear whistlers

Kinetic effects leading to the particle trapping are studied in a magnetized, inhomogeneous plasma configuration within the framework of the gyrokinetic theory in the frequency and spatial scale range that corresponds to the whistler waves. This treatment accounts for finite electron Larmor radius and polarization effects. A coherent nonlinear structure is found, which is identified as a magnetic vortex coupled with an electron hole. This novel electron hole is characterized by a strong magnetic field, and has a typical perpendicular size somewhat shorter than the electron collisionless skin depth. Electrons are trapped in the perpendicular direction by the combination of the electrostatic field, arising from the charge separation, and of the Lorentz force resulting from the propagation of the structure relative to the perturbed magnetic field lines. The trapping effects are restricted to the region at the center of the vortex. The size of this region is related to the electron Larmor-radius and to the Debye length