  The Rosetta spacecraft detected transient and sporadic diamagnetic regions
around comet 67P/Churyumov-Gerasimenko. In this paper we present a statistical
analysis of bulk and suprathermal electron dynamics, as well as a case study of
suprathermal electron pitch angle distributions (PADs) near a diamagnetic
region. Bulk electron densities are correlated with the local neutral density
and we find a distinct enhancement in electron densities measured over the
southern latitudes of the comet. Flux of suprathermal electrons with energies
between tens of eV to a couple of hundred eV decreases each time the spacecraft
enters a diamagnetic region. We propose a mechanism in which this reduction can
be explained by solar wind electrons that are tied to the magnetic field and
after having been transported adiabatically in a decaying magnetic field
environment, have limited access to the diamagnetic regions. Our analysis shows
that suprathermal electron PADs evolve from an almost isotropic outside the
diamagnetic cavity to a field-aligned distribution near the boundary. Electron
transport becomes chaotic and non-adiabatic when electron gyroradius becomes
comparable to the size of the magnetic field line curvature, which determines
the upper energy limit of the flux variation. This study is based on Rosetta
observations at around 200 km cometocentric distance when the comet was at 1.24
AU from the Sun and during the southern summer cometary season.
