Motion of energetic particles in a magnetospheric model including a convection electric field

A magnetospheric model including convection and corotation electric fields is developed. Drift shells and pitch-angle evolution are obtained through perturbation methods. The asymmetry of the shell is maximum in a plane different from the noon-midnight meridian. As a consequence the dip in fluxes is not maximum in this meridian and the amount of shift is shown to be directly proportional to the convection electric field intensity. It is inversely proportional to the energy or the pitch-angle of the particles.     

An analytical approach to the Choe-Beard magnetosphere

An analytical simplified model of the Choe-Beard magnetosphere is obtained through a perturbation method. As only the most important terms are selected, the field line topology up to the synchronous region is described in a compact form. One application of this allows the diurnal motion of conjugate points to be derived analytically.     

Motion and diffusion of energetic particles in the outer zone

The longitudinal changes in drift velocity and bounce period are obtained using two theorems on magnetic flux conservation. As a consequence radial diffusion due to pitch-angle scattering is derived. The use of the same analytical model enables the comparison of this process with radial diffusion due to compressions of the magnetosphere. The two processes are competitive for intermediate colatitudes.     

Influence of a sudden compression of the magnetosphere on outer zone electron fluxes measured at arbitrary pitch-angle

Analytical laws of motion of individual particles are used to evaluate the effects of a sudden compression on the outer radiation zone. A modulation of fluxes can be detected by synchronous satellites. Its intensity increases with the pitch-angle of the particles and the inward convection of field lines.     

Quantitative magnetospheric magnetic field modelling with toroidal and poloidal vector fields

Toroidal and poloidal vector fields allow divergence free magnetic field representations in regions where currents flow. We derive general magnetospheric magnetic fields using combinations of spherical harmonic expansions of the toroidal and poloidal fields. Adding restrictive conditions like the field line topology symmetry or the magnetic field measurements, more specific magnetospheric magnetic field models can be derived. Two examples of this technique are given : an axisymmetric model with a ring current in the equatorial region and a time-dependent model of the Earth's magnetosphere. Our results are compared with the Olson-Pfitzer model.