The dynamics of the magnetosphere under constant solar wind conditions was first described
by the idealized picture of the Dungey cycle (Dungey 1961). Later Angelopoulos
et al. (1992) using AMPTE/IRM satellite measurement data have shown that the dynamics
of the magnetosphere deviates from the idealized picture of the Dungey cycle. They
showed that the flow has temporal and spatial structure of a minute time scale for velocity
peaks which occur with a 10 minute time scale, named Bursty Bulk Flows (BBFs). Wiltberger
et al. (2015) have used high resolution Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamic
(MHD) simulations to study BBFs. They concluded that the qualitative
picture of the BBFs can be reproduced by the LFM simulations.
This thesis uses the high resolution LFM￿field output, which reproduces the BBF properties,
in order to study the role of BBFs in transport and energization of electrons from
the plasma sheet in to the radiation belts. The numerical methods of the rbel t3d code
have been improved, and the code has also been optimized and parallelized with hybrid
of MPI/OpenMP. Test particles were traced with the upgraded code.
The simulations showthat BBFs can inject energetic electrons of few keV to 100 keV from
the magnetotail beyond °25 RE to inward of geosynchronous orbit, while accelerating
them in the process. We also show the dependence of energization and injection on the
initial relative position of the electrons to the magnetic field structure of the BBF, and
the initial energy. In addition we have shown that the process can be nonadiabatic with
the violation of the conservation of the first adiabatic invariant (μ). Further we discuss
the mechanism of energization an injection in order to give generalized insight into the
processes of electron transport from the plasmasheet into the inner magnetosphere by
BBFs.
We show that pitch angle scattering as a result of the nonadiabatic motion can be strong
where the first adiabatic invariant changes by several factors within one equatorial crossing
of energetic electrons of a few keV when the BBFs are beyond 10 RE geocentric in the
tail. The scattering by BBFs decreases as the BBFs move towards the Earth or when the
electron energy decreases. For radiation belt electrons near or inside geosynchronous orbit
we demonstrate that the fields associated with BBFs can cause weak scattering where
the fractional change of the μ within one equatorial crossing is small, but the change
due to several crossings can accumulate. For the weak scattering case we developed a
method of calculating the pitch angle diffusion coefficient DÆÆ. The DÆÆ for radiation
belt electrons for one particular BBF were calculated as a function of initial energy, equatorial
pitch angle and radial location. These DÆÆ values were compared to the calculated
DÆÆ for a dipole field with no electric field. We further compared the DÆÆ values with
that of a stretched magnetic field. The result shows that the scattering by the BBF can
be comparable to the most highly stretched magnetic field studied by Artemyev (2008) at
º 7 RE .